Alternative splicing of the ErbB-4 cytoplasmic domain and its regulation by hedgehog signaling identify distinct medulloblastoma subsets

Medulloblastoma (MB) results from aberrant development of cerebellar neurons in which altered hedgehog (Hh) signalling plays a major role. We investigated the possible influence of Hh signalling on ErbB-receptor expression in MB, in particular that of the ErbB-4 CYT-1 and CYT-2 isoforms generated by alternative splicing of the cytoplasmic domain. ErbB-4 expression was downregulated in Hh-induced MBs from Patched-1(+/-) mice. Hh signalling (reflected by enhanced expression of the Gli1 transcription factor) inhibited ErbB-4 expression in mouse cerebellar granule progenitors and human MB cells. Analysis of 26 human primary MBs revealed a subset of 11 tumors characterized by low Gli1 levels, upregulated ErbB-4 expression and increased CYT-1:CYT-2 ratios. Interestingly, CYT-1 and Gli1 levels were inversely correlated. ErbB-4 CYT-1 and CYT-2 had different phenotypic effects in cultured MB cells: in response to neuregulin treatment, CYT-2 overexpression inhibited proliferation whereas CYT-1, which includes a phosphatidylinositol 3-kinase (PI3K)-binding site that is missing in CYT-2, enhanced resistance to starvation- and etoposide-induced apoptosis by activating PI3K/Akt signalling. CYT-1:CYT-2 ratios displayed correlation with tumor histotype and ErbB-2 levels, which are established prognostic indices for MB. These findings demonstrate that low-level Hh signalling in human MB is associated with the selective maintenance of high ErbB-4 CYT-1 expression, an alteration that exerts tumor-promoting effects.

Functional analyses and molecular modeling of two c-Kit mutations responsible for imatinib secondary resistance in GIST patients

Imatinib-acquired resistance related to the presence of secondary point mutations has become a frequent event in gastrointestinal stromal tumors. Here, transient transfection experiments with plasmids carrying two different KIT-acquired point mutations were performed along with immunoprecipitation of total protein extracts, derived from imatinib-treated and untreated cells. The molecular mechanics/Poisson Boltzmann surface area computational techniques were applied to study the interactions of the wild-type and mutated receptors with imatinib at the molecular level. Biochemical analyses showed KIT phosphorylation in cells transfected with vectors carrying the specific mutant genes. Imatinib treatment demonstrated that T670I was insensitive to the drug at all the applied concentrations, whereas V654A was inhibited by 6 microM of imatinib. The modeling of the mutated receptors revealed that both substitutions affect imatinib-binding site, but to a different extent: T670I substantially modifies the binding pocket, whereas V654A induces only relatively confined structural changes. We demonstrated that T670I and V654A cause indeed imatinib-acquired resistance and that the former is more resistant to imatinib than the latter. The application of molecular simulations allowed us to quantify the interactions between the mutated receptors and imatinib, and to propose a molecular rationale for this type of drug resistance.

Non-fermi liquid behavior in nearly charge ordered layered metals

Non-Fermi liquid behavior is shown to occur in two-dimensional metals which are close to a charge ordering transition driven by the Coulomb repulsion. A linear temperature dependence of the scattering rate together with an increase of the electron effective mass occur above T*, a temperature scale much smaller than the Fermi temperature. It is shown that the anomalous temperature dependence of the optical conductivity of the quasi-two-dimensional organic metal alpha-(BEDT-TTF)2MHg(SCN)4, with M = NH4 and Rb, above T* = 50-100K, agrees qualitatively with predictions for the electronic properties of nearly charge ordered two-dimensional metals.

Simvastatin protection against acute immune-mediated glomerulonephritis in mice

In addition to cholesterol lowering, 3-hydroxy-3-nethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors limit inflammatory changes associated with atherosclerosis. There is also support for their use as inhibitors of progression in chronic renal disease, irrespective of cause. In this study, their capacity to limit acute renal inflammation was evaluated. For this purpose, mice were treated with Simvastatin either prior to, at the time of, or shortly after induction of nephrotoxic nephritis. The severity of disease was determined by evaluation of blood urea nitrogen (BUN), proteinuria, and renal histologic changes. The reversibility of benefit was evaluated by the administration of mevalonic acid along with nephrotoxic serum (NTS) and Simvastatin The severity of the acute nephritis, including proteinuria, elevated BUN, and histologic changes, was ameliorated in a dose-dependent manner, when Simvastatin was administered either prior to NTS injection or at the time of NTS injection. By contrast, Simvastatin did not alter the course of established nephritis. Coadministration of mevalonic acid, the immediate substrate following HMG-CoA reductase, abolished Simvastatin's renoprotective effect, indicating that the benefit is, at least in part, due to interference with HMG-CoA reductase and biosynthetic substrates downstream from the enzyme. These findings provide the rationale for the evaluation of the efficacy of HMG-CoA reductase inhibitors in patients with recurrent forms of renal inflammation, to limit the severity of acute exacerbations of disease, prevent renal scarring and slow the rate of progression.

PDGFRα, PDGFRβ and KIT expression/activation in conventional chondrosarcoma

Chondrosarcomas represent 20% of all primary bone sarcomas, and many studies have attempted to unravel molecular targets for future development of new therapies. The aim of this study was to investigate the expression/activation of PDGFRalpha, PDGFRbeta and KIT receptor tyrosine kinases (RTKs) as potential therapeutic targets in conventional central primary chondrosarcomas (CCS). The expression of PDGFRalpha, PDGFRbeta and KIT RTKs was detected in 16 CCSs using immunohistochemistry (IHC), and their level of expression and activation status were analysed by immunoprecipitation and western blot experiments. PDGFRalpha, PDGFRbeta and KIT cDNAs were screened to verify the presence of activating mutations and the presence of the cognate ligands was analysed by means of RT-PCR. RTK gene amplification was further studied by means of fluorescence in situ hybridization (FISH) analysis. The immunophenotyping and biochemical analyses showed that the CCSs co-expressed PDGFRalpha and PDGFRbeta, with the latter showing definitively greater protein expression and phosphorylation levels. PDGFRbeta was expressed but not activated in control healthy joint cartilage, in line with no PDGFB detection. Conversely, the KIT gene product did not seem to play a relevant role. These findings, in the absence of activating mutations or an abnormal genomic profile and the presence of PDGFA and PDGFB expression, are consistent with an autocrine/paracrine loop activation of the corresponding receptors. The CCS gene profile described here offers a rationale for the use of RTK inhibitors alone or in combination with chemotherapy, and supports further investigation of RTKs and their downstream signals.

Quality control of automatically defined cancer cases by the automated registration system of the Venetian Tumour Registry. Quality control of cancer cases automatically registered

BACKGROUND

In the Venetian Tumour Registry a substantial quota of cases (55%) is accepted using an algorithm that automatically evaluates diagnostic evidence: this study aims at assessing the reliability of the information produced in this way.

METHODS

A reabstraction study was conducted, which put a stratified sample of 1539 automatically accepted cases through a double-blind manual revision.

RESULTS

A significantly higher proportion of prevalent cases were found among breast, prostate and larynx cancer cases without microscopic confirmation, while there is a clear strong inverse relationship between the number of concordant diagnostic sources and the proportions of discordant diagnoses: cases based only on a single cytology record are particularly unreliable. A small number of multiple cancers are not detected because of one of the rules applied.

CONCLUSION

The overall proportion of incorrect decisions is not high and similar to those reported by other registries, but errors are correlated to the diagnostic evidence pattern. As a further check, we decided to revise clinical cases for the three sites mentioned manually, in order to reduce the numbers proportion of both prevalent cases, and all cytology-based diagnoses, so as to reduce the number of 'false positives'. Coverage of hospital discharge source has been extended in order to decrease the proportion of cases based only on pathology records.

Prevalence of hypercalcemia in hospitalised patients: effects of "correction" for serum albumin values

Hypercalcemia is ideally detected by the measurement of serum ionised calcium. Because this is not widely available, in common clinical practice "albumin-corrected" calcium values are often utilized. Our study investigated whether the method used to measure serum albumin concentration may significantly interfere in the derived serum calcium values and, consequently, in the identification of hypercalcemic patients. In 170 consecutive patients admitted to our Department of Internal Medicine we measured serum total calcium, total protein, and albumin by colorimetric method; albumin concentration was also derived by electrophoresis assessment. After correcting serum calcium for colorimetrically (CA) and electrophoretically (EA) measured albumin values, the detected frequencies of hypercalcemia were compared, utilizing different cut-off limits (i.e. 11.0, 10.4 and 10.2 mg/dl). In our patients, the CA values were significantly lower than EA levels. As a consequence, EA-corrected calcium, as well as total calcium concentration were significantly lower than CA-corrected values. This may also account for the very different prevalence of hypercalcemic patients identified by serum total, EA-corrected and CA-corrected calcium values. Our data therefore indicate the importance of the method of albumin measurement in the determination of "corrected" calcium concentration.

Influence of cognitive impairment and comorbidity on disability in hospitalized elderly patients

BACKGROUND

The effects of cognitive impairment and comorbidity on the prevalence of disability in elderly patients who are hospitalized in acute wards are not well defined.

OBJECTIVES

To evaluate the role of comorbidity and cognitive impairment on the prevalence of disability in a cohort of hospitalized older patients.

PATIENTS AND METHODS

This study included 179 patients aged 65 years and over admitted to the Geriatric Unit of the Casa Sollievo della Sofferenza Hospital, in Italy. Cognitive status was evaluated by means of the Mini Mental State Examination (MMSE) and Clinical Dementia Rating Scale (CDR); the functional status was evaluated according to the Activity of Daily Living (ADL) and Instrumental Activities of Daily Living (IADL) indices. Comorbidity was identified using the Cumulative Illness Rating Scale (CIRS index).

RESULTS

Of the 179 patients enrolled 73 patients were diagnosed with dementia [Alzheimers' Disease (AD) = 49 patients, Vascular Dementia (VD) = 24 patients], 35 patients with Mild Cognitive Impairment (MCI) and 71 patients had no cognitive impairment. The severity of disability was significantly higher in patients with dementia (ADL = 3.1 +/- 2.1, IADL = 1.5 +/- 2.0) than patients with MCI (ADL = 5.1 +/- 1.4, IADL = 5.2 +/- 2.2) (p < 0.0001) and patients without cognitive impairment (ADL = 5.5 +/- 0.9, IADL = 6.4 +/- 1.9) (p < 0.0001). No significant differences in CIRS index were observed between patients with dementia and MCI and no cognitive impairment patients (Dementia = 2.4 +/- 1.4 vs MCI = 2.9 +/- 1.4 vs No cognitive impairment = 2.7 +/- 1.2; p = 0.1). Moreover, a significant correlation between cognitive impairment and functional status (MMSE/ADL: r = 0.45, p = 0.0001, MMSE/IADL: r = 0.54, p = 0.0001) but not between comorbidity and functional status (CIRS/ADL: r = 0.0007, CIRS/IADL: r = 0.040) was observed. Separating patients with dementia by diagnosis of AD or VD, no significant differences in MMSE (AD = 12.2 +/- 6.7 vs VD = 13.2 +/- 6.5, p = 0.6), CDR (AD = 2.2 +/- 0.8 vs VD = 2.1 +/- 0.7, p = 0.6), ADL (AD = 3.1 +/- 2.1 vs VD = 3.0 +/- 2.1, p = 0.8), IADL (AD = 1.3 +/- 1.9 vs VD = 2.0 +/- 2.2, p = 0.1) or CIRS (AD = 2.2 +/- 1.5 vs VD = 2.8 +/- 1.3, p = 0.06) scores were observed.

CONCLUSIONS

Cognitive impairment and not comorbidity, was significantly associated with disability in hospitalized older patients.

Tuberous sclerosis: immunohistochemistry expression of tuberin and hamartin in a 31-week gestational fetus

Tuberous sclerosis complex (TSC) is a common autosomal dominant disorder in which affected patients develop a wide variety of benign and malignant tumors. We report here on a 31-week gestational age fetus with pathological features of TSC. Developmental expression of hamartin and tuberin in various tissues was studied using immunohistochemistry. There was loss of expression of hamartin in the tuber and weak expression of the tuberin. Both hamartin and tuberin were expressed in bronchial epithelial cells, cardiac muscles, renal collecting tubules, and neural tissues. The rhabdomyomas stained negatively for tuberin and hamartin. Two genetic loci are responsible for TSC-TSCI and TSC2. The TSC1 gene on chromosome 9 encodes a protein termed hamartin that lacks sequence similarity to any known proteins, whereas the TSC2 gene on chromosome 16 codes for a protein termed tuberin. These results indicate that tuberin and hamartin may play a critical role in development and thus provide a framework for understanding the developmental and hamartomatous manifestations of tuberous sclerosis.

Actinomycosis of submandibular gland: an unusual presentation

An unusual presentation of oro-facial actinomycosis, mimicking the clinical appearance of a malignant lesion is reported. The patient, a 74-year-old female, presented with a right submandibular mass, which slowly grew in size over a period of about 2 months, and a modest dysphagia. A painless cervical mass was palpable over the submandibular region. The rhino-pharyngo-laryngeal region, explored by flexible fiberoptic examination, was normal. At ultrasonography, a 2x2 cm infiltrating dyshomogeneous mass, involving the right submandibular gland, was visible. No connection with adjacent organs was found. There was no associated cervical lymphoadenopathy. Ultrasound-guided fine-needle aspiration cytology, performed on lesion, revealed no evidence of malignancy. The presence of characteristic colonies of actinomyces infection was found. The patient was treated initially with tetracycline chloridrate 100 mg: 1 tablet every 12 hours for 7 weeks, but a repeat ultrasonography showed no resolution. A further fine-needle aspiration cytology showed no actinomyces infection in the specimen. The patient was treated with methylprednisolone, 20 mg every 24 hours, for 5 days. After steroid treatment, the patient has been well and, upon repeat ultrasonography, total resolution of the submandibular lesion was confirmed. In conclusion, the clinical presentation of cervicofacial actinomycosis is variable and may mimic a malignant lesion or chronic granulomatous infections. Diagnostic and therapeutic findings are discussed.

[Case report: Acro-necrosis of the upper limbs caused by gemcitabine therapy]

INTRODUCTION

Even if infrequent, a digital necrosis after chemotherapy can occur in cancer patients. The gemcitabine is generally well tolerate; the cutaneous toxic ulcerations only in 0.3% of the cases induces the suspension of the treatment.

CLINICAL CASE

A 70 year old patient, female, with a bladder cancer, after a trans-urethral resection, is submitted to adjuvant chemotherapy with Gemcitabine 1700 mg (total dose/die), with administration in the days 1st and 8th, while in the 15th day was not effected because, to distance of 3-4 days from the second administration, appear paresthesies of the fingers of the hands, together with Raynaud type phenomenon, 38-39 degrees C intermittent fever, digital necrosis and fingertips gangrene. Laboratory: (Normal): RF; AutoAb: AMA, ASMA, APCA, anti-DNA; ENA; lupus anti-coagulant; Ab-anti-cardiolipin; C3-C4, CIC; homocysteine, anti-thrombin, protein C, protein S, mutation of the factor V of Leiden, plasminogen, alfa 2-antiplasmin. (Altered): Auto-antibody: ANA (on Hep-2): positive (title 1/160, speckled pattern), cryoglobulin positive, ESR 29; Instrumental examinations: Superior Limbs Angiograpy: Occlusion of the digital arteries proper of 2nd, 3rd and 4th finger of the hands. Electromyography Inferior Arts: normal. Superior Arts: bilateral suffering of the median nerve at the carpal tunnel. Biopsy of the hand cutis: Hyperkeratosis, acanthosis and papillomatosis of the skin. Arterial vases with signs of endothelioangiitis and aspecific inflammation.

CONCLUSIONS

Even if acronecrosis of the superior limbs is a rare effect of the gemcitabine, we would recommend particular caution in the administration of this drug in patient with known autoimmune disorders.

[Isoprostanes and oxidative stress in brain damage in newborns]

Isoprostanes are a family of biologically active molecules recently characterized, which is emerging as a new class of specific and reliable markers of in vivo and ex vivo lipid peroxidation and oxidative damage. These molecules are stable, relatively abundant and easily detectable by sensitive and specific analytical methods. In the last years, the measurement of their levels in tissue homogenates or biological fluids has significantly improved our knowledge on the involvement of oxidative stress in several neurological diseases. Here we present evidence indicating that isoprostanes can be successfully used also to study the mechanisms involved in free radical brain damage following hypoxic-ischaemic or inflammatory conditions in newborns and preterm infants.

Influence of collective effects and the d charge-density wave on electronic raman scattering in high-T(c) superconductors

Electronic Raman scattering in high-T(c) superconductors is studied within the t-J model. It is shown that the A(1g) and B(1g) spectra are dominated by amplitude fluctuations of the superconducting and the d charge-density-wave order parameters, respectively. The B(2g) spectrum contains no collective effects and its broad peak reflects vaguely the doping dependence of T(c), similarly to the pronounced peak in the A(1g) spectrum. The agreement of our theory with the experiment supports the picture of two different, competing order parameters in the underdoped regime of high-T(c) superconductors.

Biological activity of the thyroid TRK-T3 oncogene requires signalling through Shc

The thyroid TRK-T3 oncogene, produced by a chromosomal translocation, is a chimeric, constitutively activated version of the NTRK1/NGF receptor and it is able to transform NIH3T3 cells and differentiate PC12 cells. TRK-T3 oncoprotein triggers multiple signal transduction pathways. Among others, TRK-T3 binds and phosphorylates the Shc and SNT1/FRS2 adaptor proteins both involved in coupling the receptor tyrosine kinase to the mitogen-activated protein kinase pathway by recruiting Grb2/SOS. We were interested in defining the role of Shc in the oncogenesis by TRK-T3. The mutation of TRK-T3 tyrosine 291, docking site for both Shc and FRS2, abrogates the oncogene biological activity. To directly explore the role of Shc we used the ShcY317F mutant, which carries the mutation of a tyrosine residue involved in Grb2 recruitment. We demonstrated that the ShcY317F mutant exerts an inhibitory effect on TRK-T3 transforming activity. Such effect can be modulated by the amount of ShcY317F protein and affects the viability of cells expressing TRK-T3 by means of a mechanism involving apoptosis. Our results indicate a definitive role of the adaptor protein Shc in TRK-T3 transforming activity.