Blunt pancreatic trauma. Role of CT

PURPOSE

To define the evolution patterns of blunt pancreatic trauma, and to point out the CT features most significant for the diagnosis.

MATERIAL AND METHODS

Ten cases of pancreatic trauma, observed over a period of about 10 years, were analyzed in retrospect. The cases were divided into 3 groups according to the time that had elapsed between trauma and first CT: early phase (within 72 h: n=3/10); late phase (after 10 days: n=3/10); and following pancreatic drainage (n=4/10).

RESULTS

In the early phase, one case showed a blood collection surrounding the pancreatic head and duodenum, and displacing the mesenteric vessels to the left. In the 2 other cases it was possible to demonstrate a tear in the pancreas at the neck, perpendicular to the main pancreatic axis. In the late phase in all 3 cases, one cystic lesion was present at the site of the tear, either surrounding the gland or embedded - more or less deeply - within the parenchyma. One of the lesions subsided spontaneously; the 2 others required surgery. In the postoperative phase, an external fistula was demonstrated in 2 cases following percutaneous drainage of pancreatic cysts; the fistula was fed by a cystic lesion in the pancreatic neck. In the 2 other cases a pseudocyst developed.

CONCLUSION

Early demonstration of a parenchymal tear was difficult. At a later stage the diagnosis was easier owing to the demonstration of cystic lesions within the parenchyma at the site of the tear. The surgical drainage of this lesion does not usually lead to healing since an external fistula or a pseudocyst may develop.

Ciliary neurotrophic factor corrects obesity and diabetes associated with leptin deficiency and resistance

Receptor subunits for the neurocytokine ciliary neurotrophic factor (CNTF) share sequence similarity with the receptor for leptin, an adipocyte-derived cytokine involved in body weight homeostasis. We report here that CNTF and leptin activate a similar pattern of STAT factors in neuronal cells, and that mRNAs for CNTF receptor subunits, similarly to the mRNA of leptin receptor, are localized in mouse hypothalamic nuclei involved in the regulation of energy balance. Systemic administration of CNTF or leptin led to rapid induction of the tis-11 primary response gene in the arcuate nucleus, suggesting that both cytokines can signal to hypothalamic satiety centers. Consistent with this idea, CNTF treatment of ob/ob mice, which lack functional leptin, was found to reduce the adiposity, hyperphagia, and hyperinsulinemia associated with leptin deficiency. Unlike leptin, CNTF also reduced obesity-related phenotypes in db/db mice, which lack functional leptin receptor, and in mice with diet-induced obesity, which are partially resistant to the actions of leptin. The identification of a cytokine-mediated anti-obesity mechanism that acts independently of the leptin system may help to develop strategies for the treatment of obesity associated with leptin resistance.

Serous cystadenoma of the pancreas: report of 30 cases with emphasis on the imaging findings

PURPOSE

Our goal was to evaluate retrospectively 30 cases of serous cystadenoma (SCA) to determine its main imaging features as well as to discuss the differential diagnosis problems versus the other cystic lesions of the pancreas.

METHOD

Thirty SCAs were analyzed; they were all benign lesions, proven at surgery. Twenty-three tumors were evaluated with US, 26 with CT, and 5 with MRI.

RESULTS

Three different morphostructural patterns were identified: microlacunar (n = 19), mixed (n = 6), and macrolacunar (n = 5). The diagnosis of SCA, possible in either the microlacunar or the mixed patterns, was achieved in 74% of cases with US (17/23) and in 61.5% with CT (16/26). Among the 19 patients evaluated with both modalities, the joint information allowed a correct diagnosis in 16 cases (84%). The five macrolacunar tumors were undistinguishable from other cystic masses of the pancreas.

CONCLUSION

The diagnosis of SCA can be considered certain in the microlacunar, likely in the mixed, and not possible in the macrolacunar type.

Functional expression of soluble human interleukin-11 (IL-11) receptor alpha and stoichiometry of in vitro IL-11 receptor complexes with gp130

The interleukin-6 (IL-6) family of cytokines activates signaling through the formation of either gp130 homodimers, as for IL-6, or gp130-leukemia inhibitory factor receptor (LIFR) heterodimers as for ciliary neurotrophic factor (CNTF), leukemia inhibitory factor, oncostatinM, and cardiotrophin-1. Recent in vitro studies with IL-6 and CNTF have demonstrated that higher order hexameric receptor complexes are assembled in which signaling chain dimerization is accompanied by the dimerization of both the cytokine molecule and its specific receptor alpha subunits (IL-6Ralpha or CNTFRalpha, respectively). IL-11 is a member of the IL-6 family and known to require gp130 but not LIFR for signaling. In this study we investigate the functional and biochemical composition of the IL-11 receptor complex. The human IL-11 receptor alpha-chain was cloned from a human bone marrow cDNA library. IL-11Ralpha was shown to confer IL-11 responsiveness to human hepatoma cells either by cDNA transfection or by adding a soluble form of the receptor (sIL11Ralpha) expressed in the baculovirus system to the culture medium. In vitro immunoprecipitation experiments showed that sIL11Ralpha specifically binds IL-11 and that binding is enhanced by gp130. Similarly to IL-6 and CNTF, gp130 is able to induce dimerization of the IL-11.IL-11Ralpha subcomplex, the result of which is the formation of a pentameric receptor complex. However, in contrast to the other two cytokines, IL-11 was unable to induce either gp130 homodimerization or gp130/LIFR heterodimerization. These results strongly suggest that an as yet unidentified receptor beta-chain is involved in IL-11 signaling.

Identification of ciliary neurotrophic factor (CNTF) residues essential for leukemia inhibitory factor receptor binding and generation of CNTF receptor antagonists

Ciliary neurotrophic factor (CNTF) drives the sequential assembly of a receptor complex containing the ligand-specific alpha-receptor subunit (CNTFR alpha) and the signal transducers gp130 and leukemia inhibitory factor receptor-beta (LIFR). The D1 structural motif, located at the beginning of the D-helix of human CNTF, contains two amino acid residues, F152 and K155, which are conserved among all cytokines that signal through LIFR. The functional importance of these residues was assessed by alanine mutagenesis. Substitution of either F152 or K155 with alanine was found to specifically inhibit cytokine interaction with LIFR without affecting binding to CNTFR alpha or gp130. The resulting variants behaved as partial agonists with varying degrees of residual bioactivity in different cell-based assays. Simultaneous alanine substitution of both F152 and K155 totally abolished biological activity. Combining these mutations with amino acid substitutions in the D-helix, which enhance binding affinity for the CNTFR alpha, gave rise to a potent competitive CNTF receptor antagonist. This protein constitutes a new tool for studies of CNTF function in normal physiology and disease.

[Imaging of bronchogenic cysts]

Bronchogenic cysts, unlike the other mediastinal cysts, exhibit a high incidence of complications, which makes their resection advisable even if no symptoms are present. The correct diagnosis should thus be made with the available imaging modalities. We reviewed our series of 11 bronchogenic cysts, all of them studied with conventional radiology (CR), as well as with such newer imaging modalities as CT and/or MRI. All mediastinal lesions had fluid density at CT and were homogeneously hyperintense on T2-weighted MR images. On the contrary, on T1-weighted images, some lesions were hypointense and some hyperintense, probably because of their rich protein content. In contrast, hilar or pulmonary lesions had air inside, except for one case--characterized by multiple localizations--in which the hilar lesion exhibited the same fluid density as the mediastinal lesions. The CT or MR finding of a lesion with fluid content below the carina permits a nearly unquestionable diagnosis of bronchogenic cyst since the other cystic lesions involve this region very rarely. In all the other cases, other types of mediastinal or hilar-pulmonary lesions cannot be ruled out. In particular, in case of cysts in paraesophageal site, no imaging modality permits to differentiate bronchogenic from enteric cysts; in some cases, the differential diagnosis may be impossible even with histology of the resected specimen.

Papillary cystic neoplasm of the pancreas: radiological findings

We report a series of 10 papillary cystic neoplasms of the pancreas evaluated in our institution. The lesions are analyzed in retrospect to define the existence of eventual specific imaging patterns as well as to point out the existing problems of differential diagnosis versus other pancreatic tumors.

Intraductal mucin-producing tumors of the pancreas: imaging findings

PURPOSE

To evaluate the radiologic characteristics of intraductal mucin-producing tumors of the pancreas.

MATERIALS AND METHODS

Sixteen patients with intraductal tumors underwent ultrasound (US); (n = 15), computed tomography (CT); (n = 16), endoscopic retrograde cholangiopancreatography (ERCP); (n = 12), and intraoperative pancreatography (n = 2). Findings were compared with those from surgery (n = 14) or biopsy (n = 2).

RESULTS

Lesions were classified as either main duct type or branch duct type tumors. Main duct tumors were characterized at US and CT by either diffuse or segmental dilatation of the Wirsung duct. Pancreatography showed ductal dilatation and filling defects caused by mucin deposits. At US and CT, branch duct tumors, which were mainly located at the uncinate process, were seen as fluid-filled masses with central septa and the pancreatic duct was dilated. ERCP showed partial or complete opacification of the lesion. In four patients, endoscopy showed protrusion of the papilla into the duodenal lumen and mucin leaking from its dilated orifice.

CONCLUSION

Imaging modalities, especially US and ERCP, enable early diagnosis of mucin-producing pancreatic tumors.

Definition of a composite binding site for gp130 in human interleukin-6

The helical cytokine interleukin-6 (IL-6) assembles a multiprotein receptor complex. The starting event in the activation of intracellular signaling is the binding of the IL-6/IL-6R alpha subcomplex to two gp130 chains. The homodimerization of gp130 is triggered by two distinct and independent regions of IL-6 called sites 2 and 3. Several IL-6 antagonists have been obtained that affect signaling, but not IL-6 IL-6R alpha subcomplex formation. In this paper, we analyze in detail the impact of these antagonists on gp130 binding and dimerization and show that each signaling variant affects gp130 dimerization in vitro and that biological activity on cells decreases in precise parallel to the decrease in gp130 dimerization in vitro. All IL-6 antagonists can be classified into two groups, mapping at either site 2 or 3 in correspondence to their mode of interaction with gp130. We found that site 3 is a large region, which includes residues at the beginning of helix D spatially flanked by residues in the putative AB loop and located at one extremity of the cytokine 4-helix bundle. Interestingly, in leukemia inhibitory factor, another cytokine that signals through gp130, site 3, is topologically conserved but has evolved to bind leukemia inhibitory factor receptor.

In vitro binding of ciliary neurotrophic factor to its receptors: evidence for the formation of an IL-6-type hexameric complex

Ciliary neurotrophic factor (CNTF) is a cytokine sharing structural and functional similarities with interleukin-6 (IL-6) and other helical cytokines that utilize the common signalling chain gp130. While IL-6 induces gp130 dimerization, CNTF, after the initial interaction with the specific, non-signalling receptor subunit, CNTFR, induces the formation of gp130/LIF-receptor heterodimers. Through immunoprecipitation experiments with tagged soluble receptor molecules, we recently demonstrated that IL-6 drives the formation of a hexameric receptor complex with a defined topology and composed of two IL-6, two IL-6R alpha and two gp130 molecules. Here, we apply the same strategy to study the assembly in vitro of the CNTF receptor complex. We present evidence that both the cytokine and the specific binding chain undergo dimerization in the presence of gp130. Furthermore, although gp130 and LIFR are able to bind independently to the CNTF/CNTFR sub-complex, they never form homodimers but only heterodimers. We propose that CNTF assembles a hexameric receptor complex composed of two CNTF, two CNTFR, one gp130 and one LIFR molecule, and present a model of the reciprocal interaction of these molecules based on similarities with the IL-6 hexameric complex.

Papillary cystic neoplasm of the pancreas: radiological findings

We report a series of 10 papillary cystic neoplasms of the pancreas evaluated in our institution. The lesions are analyzed in retrospect to define the existence of eventual specific imaging patterns as well as to point out the existing problems of differential diagnosis versus other pancreatic tumors.

Spontaneous rupture of a pancreatic pseudocyst into the portal vein

Spontaneous rupture of a pancreatic pseudocyst into the portal vein is described. This has been previously reported in only five cases. Diagnosis was made by computed tomography (CT) and was confirmed by CT-guided transhepatic portography.

Two distinct and independent sites on IL-6 trigger gp 130 dimer formation and signalling

The helical cytokine interleukin (IL) 6 and its specific binding subunit IL-6R alpha form a 1:1 complex which, by promoting homodimerization of the signalling subunit gp130 on the surface of target cells, triggers intracellular responses. We expressed differently tagged forms of gp130 and used them in solution-phase binding assays to show that the soluble extracellular domains of gp130 undergo dimerization in the absence of membranes. In vitro receptor assembly reactions were also performed in the presence of two sets of IL-6 variants carrying amino acid substitutions in two distinct areas of the cytokine surface (site 2, comprising exposed residues in the A and C helices, and site 3, in the terminal part of the CD loop). The binding affinity to IL-6R alpha of these variants is normal but their biological activity is poor or absent. We demonstrate here that both the site 2 and site 3 IL-6 variants complexed with IL-6R alpha bind a single gp130 molecule but are unable to dimerize it, whereas the combined site 2/3 variants lose the ability to interact with gp130. The binding properties of these variants in vitro, and the result of using a neutralizing monoclonal antibody directed against site 3, lead to the conclusion that gp130 dimer is formed through direct binding at two independent and differently oriented sites on IL-6. Immunoprecipitation experiments further reveal that the fully assembled receptor complex is composed of two IL-6, two IL-6R alpha and two gp130 molecules. We propose here a model representing the IL-6 receptor complex as hexameric, which might be common to other helical cytokines.

Sudden death in diabetic subjects: evidence for a peculiar circadian variation in occurrence

Anatomo-physiopathological and chronobiological features of 59 diabetic subjects out of 610 non hospitalized individuals observed for sudden death (SD) in an Emergency Room, over an 8-year period, were studied. Mean age and anatomopathological causes of SD were not different between diabetic (DMs) and non-diabetic subjects (NDs). However the frequency of DMs was higher among subjects who died from circulatory failure death (CFD), rather than from arrhythmic death (AD). Diabetics presented a prevalent peak incidence of SD in the afternoon-late evening; whereas in NDs two peaks were present, respectively in the morning and in the afternoon. According to anatomo-physiopathological causes, DMs presented a higher incidence of acute myocardial infarction (AMI) and CFD between 21:01 and 24:00, whereas in NDs the prevalent peak of AMI was observed in the early afternoon (13:01 to 16:00). Moreover, in DMs SD from acute myocardial failure prevalently occurred in the early afternoon (13:01 to 16:00), whereas in NDs it was uniformly distributed throughout the day. The present study seems to indicate that different anatomo-physiopathological causes of SD may present specific temporal patterns in diabetics.

Nonradioactive receptor binding assay for ciliary neurotrophic factor

A nonradioactive receptor binding assay for ciliary neurotrophic factor (CNTF) is described. The assay is based on the interaction between biotinylated human CNTF, soluble gp130, and soluble myc-tagged CNTF receptor captured on a microtiter plate via an antibody against the myc epitope tag. Bound cytokine is revealed by alkaline phosphatase-conjugated avidin. Purified human and rat CNTF competed with biotinylated CNTF for receptor binding, with IC50 values of 29 and 2 nM, respectively. Since the higher affinity of rat vs human CNTF has been previously shown to be conferred by the arginine residue at position 63 of the rat protein, we also tested a human CNTF mutant carrying a Q63R substitution. Secreted forms of wild-type and mutant CNTF were expressed in Escherichia coli, and the amount of cytokines in periplasmic extracts was determined by quantitative Western blotting analysis. The human CNTF mutant (Q63R, N137S) was found to compete with biotinylated CNTF for binding to soluble CNTF receptor with an eightfold higher apparent affinity than wild-type human CNTF. The present method thus faithfully reproduces the relative activities of CNTF analogs determined in other assay systems. The possibility of assaying cytokines in crude bacterial extracts makes the new technique particularly suitable for rapidly determining the receptor binding potencies of genetically engineered CNTF variants.

Production and structural characterization of amino terminally histidine tagged human oncostatin M in E. coli

Oncostatin M is a cytokine that acts as a growth regulator on a wide variety of cells and has diverse biological activities including acute phase protein induction, LDL receptor up-regulation and cell-specific gene expression. In order to gather information about the Onc M structure, we established a protocol for large scale production and single step purification of this functional cytokine from bacterial cells. The cDNA of human Onc M was cloned by RT-PCR from total RNA of PMA induced U937 cells. After the addition of a six histidine tag at the N-terminus, the coding region of mature Onc M was cloned in the pT7.7 expression vector. Histidine tagged Onc M was overexpressed in bacterial cells and purified to homogeneity in one step on a metal chelating column. We found that recombinant 6xHis-OncM remains fully active in a growth inhibition assay. Structural characterization of the purified protein was performed by electrospray mass spectrometry, automated Edman degradation and peptide mapping by high-pressure liquid chromatography/fast-atom-bombardment mass spectrometry. Thermal and pH stability dependence of Onc M was assessed by circular dichroism spectroscopy; the helical content is about 50%, in agreement with the four helix bundle fold postulated for cytokines that bind haematopoietic receptors of type I.

Oncostatin M binds directly to gp130 and behaves as interleukin-6 antagonist on a cell line expressing gp130 but lacking functional oncostatin M receptors

Oncostatin M (OM) and interleukin 6 (IL-6) are functionally related cytokines, which trigger similar biological responses because they share gp130 as a common signal transducing transmembrane receptor. While IL-6 recruits gp130 only upon binding to its specific receptor subunit (IL-6R alpha), reconstitution and cross-linking experiments on cell membranes suggest that OM can directly interact with gp130 and that this interaction is necessary but not sufficient to stimulate cells. However, the issue of the direct binding between gp130 and OM, in the absence of any additional membrane component, remained essentially unclarified. In this paper we show that, uniquely among the family of cytokines that transduce through gp130, OM directly binds in vitro with a 10(-8) M affinity sgp130, a soluble form of gp130. Moreover, titration of sgp130 with OM inhibits the formation of a ternary complex comprising IL-6, sIL-6R alpha, and sgp130. These in vitro properties of OM are consistent with the additional finding that on human hepatoma Hep3B cells, which express gp130 but not functional OM receptors, OM does not mimic IL-6 activity, but rather behaves, at high doses, as an IL-6 antagonist.

[Invasive pulmonary aspergillosis: possibility of radiologic diagnosis]

The incidence of invasive pulmonary aspergillosis is increasing in the patients with malignant hematologic diseases; this occurs in the phase of granulocytopenia induced by chemotherapy. In these cases an early diagnosis is mandatory to start a prompt antimycotic treatment. The authors reviewed the personal series of 56 patients with malignant hematologic diseases who, in the phase of granulocytopenia, developed a pulmonary lesion: 32/56 with invasive pulmonary aspergillosis; 8/56 with Candida and 16/56 with bacterial infection. All patients underwent several conventional radiologic controls: 9 cases with invasive pulmonary aspergillosis were also studied with Computed Tomography (CT). After a short pathologic introduction, the conventional radiologic and CT patterns of invasive pulmonary aspergillosis are analyzed, both at onset and over its evolutive phase. The most significant feature for an early conventional radiologic diagnosis is the nodular pattern--single or multiple--; this allowed a correct diagnosis, at onset, of 20/32 (62%) invasive pulmonary aspergillosis cases. CT provided a further diagnostic contribution by showing a peri-nodular halo. Of interest was also the CT demonstration of high-density pleural thickening adjacent to the mycotic lesion, probably due to fungal involvement of the sub-pleural space. The routine chest roentgenogram is the modality of choice; CT may be useful in questionable cases.

Duodenal duplication in the adult: its relationship with pancreatitis

Seven cases of duodenal duplication in the adult are reported. The ultrasound and computed tomographic findings are analyzed. The relationship between duodenal duplication and pancreatitis is discussed.

Multiplanar study of the mediastinum with electronically reconstructed computed tomography images

Refinements of computer software permit electronic reconstructions of CT sagittal, parasagittal, and coronal planes, which have markedly improved our understanding of the relations among mediastinal structures, most of which present a vertical course, as well as between focal lesions and adjoining structures.