Quantitative 2D 1H, 13C HSQC NMR Spectroscopy for the Determination of Chondroitin Sulfate and Dermatan Sulfate Content in Danaparoid Sodium

OBJECTIVE

 Danaparoid sodium is a biopolymeric complex drug composed of the most abundant heparan sulfate (HS) followed in descending order by dermatan sulfate (DS) and chondroitin sulfate (CS). This composite nature explains its peculiar antithrombotic and anticoagulant properties and make it particularly advantageous when the risk of heparin-induced thrombocytopenia occurs. A specific control of the danaparoid composition is required by the Ph. Eur. The monograph includes the CS and DS limit contents and describes the method for their quantification through selective enzymatic degradations.

MATERIALS AND METHODS

 In this study, a quantitative two-dimensional nuclear magnetic resonance (NMR) method is proposed as a new method suitable for CS and DS quantification. Statistical comparison of the results provided by the analysis of a series of danaparoid samples with both NMR and enzymatic methods highlights a small systematic difference, likely derived from lyase-resistant sequences bearing oxidized terminals. Some modified structures, whose survival to the enzymatic action was confirmed by mass spectrometry, can be detected and quantified by NMR.

CONCLUSION AND RESULTS

 The proposed NMR method can serve for the determination of DS and CS contents, is an easy-to-apply method with no dependence from enzymes and standards, and provides extensive structural information on the overall glycosaminoglycans mixture.

Heparin-Superparamagnetic Iron Oxide Nanoparticles for Theranostic Applications

In this study, superparamagnetic iron oxide nanoparticles (SPIONs) were engineered with an organic coating composed of low molecular weight heparin (LMWH) and bovine serum albumin (BSA), providing heparin-based nanoparticle systems (LMWH@SPIONs). The purpose was to merge the properties of the heparin skeleton and an inorganic core to build up a targeted theranostic nanosystem, which was eventually enhanced by loading a chemotherapeutic agent. Iron oxide cores were prepared via the co-precipitation of iron salts in an alkaline environment and oleic acid (OA) capping. Dopamine (DA) was covalently linked to BSA and LMWH by amide linkages via carbodiimide coupling. The following ligand exchange reaction between the DA-BSA/DA-LMWH and OA was conducted in a biphasic system composed of water and hexane, affording LMWH@SPIONs stabilized in water by polystyrene sulfonate (PSS). Their size and morphology were investigated via dynamic light scattering (DLS) and transmission electron microscopy (TEM), respectively. The LMWH@SPIONs’ cytotoxicity was tested, showing marginal or no toxicity for samples prepared with PSS at concentrations of 50 µg/mL. Their inhibitory activity on the heparanase enzyme was measured, showing an effective inhibition at concentrations comparable to G4000 (N-desulfo-N-acetyl heparin, a non-anticoagulant and antiheparanase heparin derivative; Roneparstat). The LMWH@SPION encapsulation of paclitaxel (PTX) enhanced the antitumor effect of this chemotherapeutic on breast cancer cells, likely due to an improved internalization of the nanoformulated drug with respect to the free molecule. Lastly, time-domain NMR (TD-NMR) experiments were conducted on LMWH@SPIONs obtaining relaxivity values within the same order of magnitude as currently used commercial contrast agents.

SAX-HPLC and HSQC NMR Spectroscopy: Orthogonal Methods for Characterizing Heparin Batches Composition

Heparin is a complex mixture of heterogeneous sulfated polysaccharidic chains. Its physico-chemical characterization is based on the contribution of several methods, but advantages of the use of complementary techniques have not been fully investigated yet. Strong-Anion-Exchange HPLC after enzymatic digestion and quantitative bidimensional ¹H-¹³C NMR (HSQC) are the most used methods for the determination of heparin structure, providing the composition of its building blocks. The SAX-HPLC method is based on a complete enzymatic digestion of the sample with a mixture of heparinases I, II and III, followed by the separation of the resulting di- and oligo-saccharides by liquid chromatography. The NMR-HSQC analysis is performed on the intact sample and provides the percentage of mono- and di-saccharides by integration of diagnostic peaks. Since, for both methods, accuracy cannot be proved with the standard procedures, it is interesting to compare these techniques, highlighting their capabilities and drawbacks. In the present work, more than 30 batches of porcine mucosa heparin, from 8 manufacturers, have been analyzed with the two methods, and the corresponding results are discussed, based on similarities and differences of the outcomes. The critical comparison of both common and complementary information from the two methods can be used to identify which structural features are best evaluated by each method, and to verify from the concordance of the results the accuracy of the two methods, providing a powerful tool for the regular characterization of single, commercial preparations of Heparin.

Structural Features of Heparan Sulfate from Multiple Osteochondromas and Chondrosarcomas

Multiple osteochondromas (MO) is a hereditary disorder associated with benign cartilaginous tumors, known to be characterized by absence or highly reduced amount of heparan sulfate (HS) in the extracellular matrix of growth plate cartilage, which alters proper signaling networks leading to improper bone growth. Although recent studies demonstrated accumulation of HS in the cytoplasm of MO chondrocytes, nothing is known on the structural alterations which prevent HS from undergoing its physiologic pathway. In this work, osteochondroma (OC), peripheral chondrosarcoma, and healthy cartilaginous human samples were processed following a procedure previously set up to structurally characterize and compare HS from pathologic and physiologic conditions, and to examine the phenotypic differences that arise in the presence of either exostosin 1 or 2 (EXT1 or EXT2) mutations. Our data suggest that HS chains from OCs are prevalently below 10 kDa and slightly more sulfated than healthy ones, whereas HS chains from peripheral chondrosarcomas (PCSs) are mostly higher than 10 kDa and remarkably more sulfated than all the other samples. Although deeper investigation is still necessary, the approach here applied pointed out, for the first time, structural differences among OC, PCS, and healthy HS chains extracted from human cartilaginous excisions, and could help in understanding how the structural features of HS are modulated in the presence of pathological situations also involving different tissues.

Fine structural characterization of sulodexide

Sulodexide is a heparinoid which combines the properties of its components heparin and dermatan sulfate and is used not only for the prophylaxis and treatment of thromboembolic diseases but also for the treatment of diabetic nephropathy. Despite many clinical studies have been conducted to investigate its activity and safety, no data are available on the fine chemical characterization of its components. In this work, the in-depth investigation on the structural features of both the whole mixture and the isolated components was accomplished, involving the analysis of molecular weight distribution and of their mono, di and oligosaccharide composition by HP-SEC/TDA, 2D-NMR and HPLC-MS techniques. Moreover, also the separation of fractions endowed of graded affinity to antithrombin was achieved followed again by detailed structural analysis. The combination of different techniques permits to profile in depth the structural features of such a drug and offers a useful tool for possible analysis of batch production.

Characterization of Danaparoid Complex Extractive Drug by an Orthogonal Analytical Approach

Danaparoid sodium salt, is the active component of ORGARAN, an anticoagulant and antithrombotic drug constituted of three glycosaminoglycans (GAGs) obtained from porcine intestinal mucosa extracts. Heparan sulfate is the major component, dermatan sulfate and chondroitin sulfate being the minor ones. Currently dermatan sulfate and chondroitin sulfate are quantified by UV detection of their unsaturated disaccharides obtained by enzymatic depolymerization. Due to the complexity of danaparoid biopolymers and the presence of shared components, an orthogonal approach has been applied using more advanced tools and methods. To integrate the analytical profile, 2D heteronuclear single quantum coherence (HSQC) NMR spectroscopy was applied and found effective to identify and quantify GAG component signals as well as those of some process signatures of danaparoid active pharmaceutical ingredient (API) batches. Analyses of components of both API samples and size separated fractions proceeded through the determination and distribution of the molecular weight (Mw) by high performance size exclusion chromatographic triple detector array (HP-SEC-TDA), chain mapping by LC/MS, and mono- (¹H and ¹³C) and bi-dimensional (HSQC) NMR spectroscopy. Finally, large scale chromatographic isolation and depolymerization of each GAG followed by LC/MS and 2D-NMR analysis, allowed the sequences to be defined and components to be evaluated of each GAG including oxidized residues of hexosamines and uronic acids at the reducing ends.

Structural Characterization of the Low-Molecular-Weight Heparin Dalteparin by Combining Different Analytical Strategies

A number of low molecular weight heparin (LMWH) products are available for clinical use and although all share a similar mechanism of action, they are classified as distinct drugs because of the different depolymerisation processes of the native heparin resulting in substantial pharmacokinetic and pharmacodynamics differences. While enoxaparin has been extensively investigated, little information is available regarding the LMWH dalteparin. The present study is focused on the detailed structural characterization of Fragmin^® by LC-MS and NMR applied both to the whole drug and to its enzymatic products. For a more in-depth approach, size homogeneous octasaccharide and decasaccharide components together with their fractions endowed with high or no affinity toward antithrombin were also isolated and their structural profiles characterized. The combination of different analytical strategies here described represents a useful tool for the assessment of batch-to-batch structural variability and for comparative evaluation of structural features of biosimilar products.

Heparin dodecasaccharide containing two antithrombin-binding pentasaccharides: structural features and biological properties

The antithrombin (AT) binding properties of heparin and low molecular weight heparins are strongly associated to the presence of the pentasaccharide sequence AGA*IA (A(NAc,6S)-GlcUA-A(NS,3,6S)-I(2S)-A(NS,6S)). By using the highly chemoselective depolymerization to prepare new ultra low molecular weight heparin and coupling it with the original separation techniques, it was possible to isolate a polysaccharide with a biosynthetically unexpected structure and excellent antithrombotic properties. It consisted of a dodecasaccharide containing an unsaturated uronate unit at the nonreducing end and two contiguous AT-binding sequences separated by a nonsulfated iduronate residue. This novel oligosaccharide was characterized by NMR spectroscopy, and its binding with AT was determined by fluorescence titration, NMR, and LC-MS. The dodecasaccharide displayed a significantly increased anti-FXa activity compared with those of the pentasaccharide, fondaparinux, and low molecular weight heparin enoxaparin.

Anti-metastatic semi-synthetic sulfated maltotriose C-C linked dimers. Synthesis and characterisation

This manuscript describes the preparation and the spectroscopic characterisation of semi-synthetic sulfated maltotriose C-C linked dimers (SMTCs) where the natural C-O-C anomeric bond was substituted by one direct central C-C bond. This C-C bond induces conformation and flexibility changes with respect to the usual anomeric bond. SMTCs neutral precursors came from maltotriosyl bromide electroreduction through maltotriosyl radical intermediate dimerisation. The new C-C bond configuration, named for convenience α,α, α,β and β,β as the natural anomeric bond, dictated the statistic ratio formation of three diastereoisomers. They were separated by silica gel flash chromatography followed by semi preparative HPLC chromatography. Each diastereoisomer was exhaustively sulfated to afford the corresponding SMTCs. SMTCs were huge characterised by NMR spectroscopy which provided the sulfation degree, too. α,α and α,β were found quite homogeneous samples with a high degree of sulfation (85-95%). β,β appeared a non-homogeneous sample whose average sulfation degree was evaluated at around 78%. Mass spectroscopy experiments confirmed the sulfation degree range. Some considerations were proposed about SMTCs structure-biological properties.

Monitoring prion protein expression in complex biological samples by SERS for diagnostic applications

Surface-enhanced Raman spectroscopy (SERS) allows a new insight into the analysis of cell physiology. In this work, the difficulty of producing suitable substrates that, besides permitting the amplification of the Raman signal, do not interact with the biological material causing alteration, has been overcome by a combined method of hydrothermal green synthesis and thermal annealing. The SERS analysis of the cell membrane has been performed with special attention to the cellular prion protein PrP(C). In addition, SERS has also been used to reveal the prion protein-Cu(II) interaction in four different cell models (B104, SH-SY5Y, GN11, HeLa), expressing PrP(C) at different levels. A significant implication of the current work consists of the intriguing possibility of revealing and quantifying prion protein expression in complex biological samples by a cheap SERS-based method, replacing the expensive and time-consuming immuno-assay systems commonly employed.

Cell-free circulating DNA as a promising marker of colorectal cancer detection and progression

11059

Background: Since the pathologic stage is the most powerful prognostic factor for colorectal cancer (CRC), there is a strong need of non-invasive methods for early detection. Cell-free circulating DNA (cfDNA) released from cancer cells varies in size. It has been suggested that cfDNA (ALU repeats of 115 bp, representative of total DNA; ALU repeats of 247 DNA, representative of tumor DNA) may be associated with presence of tumor. Aim of this study was then to investigate whether the cfDNA may have a role as marker of CRC detection and progression. Methods: cfDNA was extracted from plasma samples from 136 patients with primary CRC at different stages [median age 64 yrs; male/female 78/58; stages I-II, 61; stages III-IV, 75], and from 24 patients with adenomas [median age 67 yrs; male/female 17/7)] and from 55 clean-colon healthy subjects [median age 56 yrs; male/female 13/43). cfDNA was assessed by quantitative real-time PCR (qPCR) of ALU repeats with 2 sets of primers (115 and 247 bp) amplifying different lengths of DNA. The levels of cfDNA (ALU-115, ALU-247) of CRC patients (stages I-II and stages III-IV) were compared with those of healthy subjects and patients with adenoma. Results: The median concentrations of total cfDNA (ALU115) in the plasma samples from patients with stages III-IV and stages I-II CRC, adenoma and normal controls were 52,4, 11.9; 1.9, and 1.7 ng/ml, respectively (p<.0001). The corresponding figures for tumor-related cfDNA (ALU247) were 48.8, 4.7, 2.2, and 0.7 ng/ml, respectively. (p<.0001). With a cut-off of 4.86 ng/ml, total DNA (ALU115) showed a sensitivity of 78.52 (95% CI 70.6–85.1) and a specificity of 86.08 (95% CI 76.4–92.8) in distinguishing patients with CRC from non-CRC [AUC: 0.860 (95% CI 0.81–0,90), p-value=.0001]. With a cut-off of 3.04, cfDNA tumor-related (ALU247) showed a sensitivity of 77.94 (95% CI 70.0–84.6) and a specificity of 82.28 (95% CI 72.1–90.0) in distinguishing patients with CRC from non-CRC [AUC: 0.864 (95% CI 0.81–0,91), p-value=.0001]. Conclusions: Both ALU115 and ALU 247 fragments of circulating cfDNA seem promising non-invasive molecular markers of detection and progression of CRC. The findings of the current study require to be confirmed on larger cohorts of patients with CRC and colonic adenoma.

No significant financial relationships to disclose.

Proximal colon cancer in patients aged 51-60 years of age should be tested for microsatellites instability. A comment on the Revised Bethesda Guidelines

PURPOSE

The Bethesda guidelines suggest to perform microsatellite instability (MSI) test in early onset rectal cancer and not in patients>50 years with proximal colon cancer. The aim of the study was to evaluate whether the risk of high MSI (MSI-H) is greater in proximal colon cancer of patients 51-60 years old than in early-onset rectal cancer.

METHODS

Consecutive colorectal cancer (CRC) patients were evaluated. Tumor location, cancer family history, MSI status and histology were recorded. Mutations in MLH1/MSH2 were investigated in MSI-H tumors. Patients were subdivided into groups: group A, proximal colon cancer patients 51-60 years old and groups B, C and D, patients<or=50 years old, with rectal cancer, proximal and distal colon cancer, respectively.

RESULTS

Out of 409 CRC patients evaluated, 48 (12%) showed tumors with MSI-H. No MSI-H tumors were found in distal and rectal tumors of patients at sixth decade of life. Group A included 27 patients, eight (29.7%) MSI-H cancers, four missense mutations in MLH1/MSH2; groups B, C and D included 26, 11 and 11 patients with two (7.7%), two (18%) and two (18%) MSI-H cancers, respectively. One missense mutation on MSH2 in group B, one pathogenetic mutation on MSH1 in group C and one pathogenetic mutation on MSH2 in group D were found. Tumors of group A showed an increased probability to have MSI-H if compared to those of group B (OD=4.907, p=0.043).

CONCLUSIONS

The Bethesda criteria should be broadened to include patients 51-60 years old with proximal colon cancer.

Prediction of rectal lymph node metastasis by pelvic computed tomography measurement

AIM

Rectal cancer staging represents a crucial step to select the best treatment for this tumour. Particularly after neo-adjuvant chemoradiotherapy (CRT), it may influence the surgical procedure (e.g. radical resection vs. local excision). The aim of this study was to determine the best lymph node size cut-off at computed tomography (CT) to predict nodal metastasis in rectal cancer patients with and without preoperative CRT.

METHODS

A consecutive series of patients operated on for primary mid-low rectal adenocarcinoma, all staged with pelvic CT scan, were subdivided as follows: those who underwent surgery alone treatment without CRT (Group A) and those who underwent preoperative CRT (Group B). All CT scans were re-viewed by a single radiologist and, based on the lymph node size, findings were compared with pathologic lymph node status (pN). At each lymph node size cut-off value, the following were calculated: accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). The best cut-off value was defined as having an accuracy >or=70% with the highest NPV.

RESULTS

The study population consisted of 162 patients: Group A (n=52) and Group B (n=110). Patients classified as pN-positive (n=45) had a higher number of and larger sized lymph nodes by CT scan than patients classified as pN-negative (n=117). The cut-off values with an accuracy >or=70% ranged between 7 and 11 mm in Group A and between 9 and 14 mm in Group B. The cut-off with the best NPV was 7 mm for Group A and 10mm for Group B.

CONCLUSIONS

Acknowledging the limitations of the dimensional criterion, lymph node size cut-off values found in our study may be useful for planning rectal cancer treatment using CT scan.

High-performance liquid chromatographic/mass spectrometric studies on the susceptibility of heparin species to cleavage by heparanase

Heparanase is an endo-beta-D-glucuronidase that cleaves the heparan sulfate chains of heparan sulfate proteoglycans and is implicated in angiogenesis and metastasis. With the aim of establishing a simple and reliable method for studying the susceptibility of heparin/heparan sulfate oligosaccharides to be cleaved by heparanase, an on-line ion pair reversed-phase high-performance liquid chromatographic/electrospray ionization mass spectrometric method was set up. The method works in the micromolar range of concentration and does not require derivatization of the substrate or of the products. It is based on mass identification of oligosaccharide fragments generated by heparanase and their quantification with reference to an internal heparin disaccharide standard. Substrates were (1) the synthetic pentasaccharides GlcN (NS,6S) - GlcA - GlcN (NS,3S,6S) - IdoA (2S) - GlcN (NS,6S) - OMe (AGA*IA (M)) and GlcN (NS,6S) - GlcA - GlcN (NS,6S) - IdoA (2S) - GlcN (NS,6S) - OMe (AGAIA (M)), corresponding to the heparin/heparan sulfate active site for antithrombin, and to the same sequence devoid of the 3- O-sulfate group in the central glucosamine, respectively; and (2) two natural heparin octasaccharides containing the AGA*IA sequence in different locations along the chain. The two pentasaccharides exhibited a higher susceptibility to heparanase cleavage with respect to the octasaccharides. The commercial availability of AGA*IA (M) makes it an ideal substrate to determine the specific activity of heparanase preparations. The present method could also be used for rapid screening of potential heparanase inhibitors.

Two-dimensional gel electrophoresis of peripheral nerve proteins: Optimized sample preparation

For proteomic analysis, sample preparation plays a crucial role in two-dimensional gel electrophoresis (2DE), since, very often, each tissue or cell culture requires specific treatments. In the present paper, we report a sample preparation procedure suitable for 2DE that was done on peripheral nerve using bovine sciatic nerves and human sural nerve biopsies. We obtained an appreciable reduction of tissue heterogeneity using protein extracts obtained from nerve-fiber bundles instead of the entire nerve. In addition, we optimized 2DE protein separation using a combination of CHAPS, Triton X-100, and SB3-10 detergents in an isoelectric-focusing (IEF) buffer. The reported experimental procedures appear to be essential for 2DE separation of peripheral nerve proteins for the establishment of a reference map.

Complications, functional outcome and quality of life after intensive preoperative chemoradiotherapy for rectal cancer

AIMS

To investigate early and late complications in 44 patients with locally advanced mid-low rectal cancer enrolled in a phase I-II study, who had received an aggressive chemoradiation treatment (50.4Gy/28F; 5-FU continuous infusion and weekly Oxaliplatin) followed by total mesorectal excision and 5-FU based postoperative chemotherapy. The aim of the present study is also to evaluate functional outcome and quality of life (QoL) in a sub-group of 22 patients.

METHODS

Standardized forms for early and late surgical complications were completed for all patients. Anorectal function and QoL were also investigated in 22 patients who underwent surgery in the same surgical unit, using the fecal incontinence scoring system (FIS) and EORTC-QLQ-CR38 questionnaires, compiled before and after radiotherapy and at least 8 months after surgery. The differences over time in scores were analyzed using repeated measure ANOVA.

RESULTS

The median age of patients (25 males and 19 females) was 58 (range: 34-73) years. A low anterior resection was performed in 39 cases, radical resection in 41, and 12 patients had a pathological complete response. There were no operative deaths; 4 and 9 patients required re-operation for early and late complications, respectively. FIS score did not present a significant worsening over time. According to data in the EORTC-QLQ-CR38 questionnaire, a significant improvement over time was found only for "future perspective".

CONCLUSION

Our findings seem to indicate that this aggressive 5-FU-Oxalipaltin-based treatment implies no impairment of QoL and anorectal function, even if a high rate of late major complications was observed. Studies on larger series are required to confirm these results.

Proteomics of bovine myelin sheath: characterization of a truncated form of P0 by MALDI-TOF/TOF mass spectrometry

The glycoprotein P0, the major structural protein of the peripheral nerve myelin, plays a critical role in holding myelin lamellae together via interaction of both extracellular and cytoplasmic domains. Mutations in the human P0 gene give rise to severe and progressive forms of dominantly inherited peripheral neuropathies like CMT1B. Here we report on the characterization of a bovine P0-derived protein of nearly 26 kD that corresponds to the P0 protein truncated in its cytoplasmic domain. Matrix assisted laser desorption ionization (MALDI)-time-of-flight/time-of-flight (TOF/TOF) mass spectrometry (MS) analysis on its tryptic digest has provided a peptide mapping, the main difference of which from the normal P0 analog was represented by the absence of the cluster of peaks at m/z 1513.7501, 1530.7701, and 1546.7651. The latter corresponds to the P0 fragment QTPVLYAMLDHSR and to its pyroglutamic and methionine-oxidized derivatives. The species at 1530.7701 covering the sequence 186-198 of P0 is not an artifact and might have a functional role in the myelin architecture.

Gas-phase chemistry of the negative ions of fully-protected peptides by high-resolution electrospray ionization tandem mass spectrometry

Fully-protected C-terminal free peptides can be conveniently analyzed by high-resolution electrospray tandem mass spectrometry (ESI-MS/MS) in a quadrupole quadrupole time-of-flight tandem hybrid mass spectrometer, operated in the negative (-) ionizaionization mode. The unusual choice of negative ions in mass spectrometry applications to peptide analysis was needed to obtain exhaustive sequence and structural data. The low-energy collision-induced dissociation (CID) experiments provided, in fact, tandem mass spectra displaying highly diagnostic fragments with a good signal-to-noise ratio. The method is applied to segments of porcine calcitonin (Cal), Cal (1016, 1), Cal (1724, 2) and Cal (2528, 3) whose [M H]- deprotonated molecular ions provided low-energy CID mass spectra which allow the evaluation either of the primary structure of the peptide and of the location of the side-chain protective groups. ESI (+) MS can be conveniently used, in the high resolution mode, to achieve precise information on the elemental composition of the examined peptides.

Identification and assay of wild-type and modified nucleoside mixtures by turbo ionspray ionization tandem mass spectrometry

A method is presented which allows the identification and assay of a nucleoside in the presence of other analogues and homologues. The method is based on the conventional multiple reaction monitoring approach performed on the [M + H]+ ions of wild-type and modified nucleosides produced by the turbo ionspray ionization method on a triple-quadrupole mass spectrometer. The accuracy of the quantitative determination relies on the evaluation of a response factor rho, which takes into account the kinetics of dissociation of the parent ions into the protonated [B + 2H]+ nucleobase ions. The evaluation of the absolute concentration of each analyte in the examined mixture does not require any previous chromatographic separation.

Yttrium-aluminum-garnet laser therapy of esophageal granular cell tumor

BACKGROUND

Granular cell tumor (GCT) is a rare lesion. Approximately 4% to 6% of these tumors occur in the gastrointestinal tract, one-third of them affecting the esophagus. Almost all GCTs are benign lesions. Approximately 1% to 3% are malignant. Endoscopic ultrasonography (EUS) is a diagnostic support. The best treatment for esophageal GCT is not yet clear, whether surgical excision, periodic observation, endoscopic excision, or yttrium-aluminum-garnet (YAG) laser therapy.

METHODS

From November 1992 to December 2000, four patients with GCTs of the esophagus were observed. All the patients underwent EUS evaluation and endoscopic YAG laser therapy of the esophageal neoplasm. At each session, a biopsy at the tumor site was obtained. The treatment was continued until endoscopic and histologic evidence of the tumor disappeared.

RESULTS

After the YAG laser therapy, no evidence of the tumor was found in any of the four patients with esophageal GCT. At this writing, the patients remain disease free after a mean follow-up period of 66 months. No complication has been observed. Only four sessions for each patient were necessary to eliminate the tumor.

CONCLUSIONS

Therapy with YAG laser was effective in all four patients with esophageal GCT, and complete necrosis of the submucosal neoplastic cells was achieved. Endoscopic YAG laser therapy appears to be a good compromise between esophageal dissection and long-term observation without tumor excision. Esophageal laser therapy is safe if correctly used, and previous EUS evaluation increases treatment safety.

[Primitive adenocarcinoma of the duodenum. Description of two clinical cases]

Two cases of a primitive adenocarcinoma of the duodenum are presented. Both cancers were localized near the papilla. Duodenocephalopancreatectomy was the surgical treatment for each patient. One patient died of myocardial infarction eight months after surgery, without any sign of recurrence of the cancer; the other is in good health three months after surgery. The rarity of such a tumor is underlined: in 44 papers published in various journals from 1971 to 1993, 88 cases of primitive adenocarcinoma of the duodenum were examined; the average number of cases per author was two. Between 1980 and 1993, an Italian multicenter study carried out in 36 hospital and university centers, showed only 89 cases of primitive duodenal adenocarcinoma.

[Reintervention in mitral valve prostheses. Analysis of risk factors]

From 1980 to 1996, 111 patients (83 females, 28 males, mean age 51.47 +/- 15.73 years, range 1-76) underwent mitral valve replacement. Seventy-five patients underwent replacement of a biological valve and 36 of a mechanical valve. Three patients underwent a third operation. Seventy prostheses were replaced because of a structural dysfunction. Other causes of valve failure were: 24 thrombosis (23 mechanical and 1 biological), 10 endocarditis (7 mechanical, 3 biological) and 4 leakages (3 mechanical and 1 biological). One patient who had recurrent anticoagulant-related haemorrhage underwent reoperation to replace his mechanical valve with a biological prosthesis. Two patients had their valve replaced because of mismatch between size of the valve and body surface area. Thirteen operations were performed on emergency and 29 on urgency. There were 22 in-hospital deaths with a hospital mortality of 19.82%. Fourteen deaths (63.63%) occurred in patients operated on emergency or urgency. All deceased patients were in NYHA functional class III or IV. Our data suggest that risk of reoperation on mitral prosthesis is highly influenced by the preoperative functional class. In spite of the fact that replacement of biological valves should be more elective than that of mechanical valves, we did not find any difference between the two groups of patients.

[Laser therapy of esophageal tumors. Technical notes and personal experience]

In Italy the incidence of oesophageal cancer is very low: 4 cases every 100,000. More than 60% of patients are observed with dysphagia and oesophageal stenosis. For these patients their is no surgical indication and prognosis is less than 1 year. We have applied the recanalization of oesophagus with laser in 137 patients (range 47-88 years). One year survival was 53.1%, three years 5.8%. The aim of this paper is to describe our techniques and analyze 5 years of activity.