Abstract 1467: Development of a HER2-based GEDI microfluidic device for the molecular characterization of CTCs from metastatic breast cancer patients

Microtubule targeting drugs (MTDs) constitute the mainstay of the most active chemotherapy regimens against breast cancer (BC) and have been standard therapy for locally advanced and metastatic disease for the last 20 years. However, metastatic BC (MBC) is still incurable mainly because of acquired drug resistance. The molecular basis of clinical drug resistance is not well understood which together with the lack of predictive biomarkers in the clinical setting prevents us from personalizing MTD-based therapy.

Isolation of Circulating Tumor Cells (CTCs) from the blood of metastatic patients has emerged as a valid source of tumor tissue in the form of liquid biopsy that is being used as prognostic biomarker based on CTC enumeration. To be able to perform molecular CTC analyses we have developed a BC specific microfluidic device that operates on the principle of geometrically enhanced differential immunocapture (GEDI), using antibody-coated microposts. We selected HER2 as BC selective surface antigen to isolate CTCs from MBC patients as it is expressed in 90% of breast tumors and overexpressed in 30%, while it is minimally affected by epithelial-to-mesenchymal transition (EMT) often occurring in metastasis. We previously demonstrated that the ability of the HER2 GEDI microfluidic device to capture BC cells expressing high and intermediate to low levels of HER2 expression confirming its suitability for BC patients with highly heterogeneous HER2 levels.

We have tested the HER2-based GEDI in MBC patients and have confirmed CTC capture. To test the performance of our device we are currently comparing it to the FDA approved CellSearch using blood from the same patient where CTCs are enumerated by both Cell Search and our device.

Importantly, the retained viability of GEDI-captured CTCs provides us the opportunity to functionally test CTC response to chemotherapy directly on the device, in an effort to develop an assay predictive of clinical response so that we can tailor chemotherapy to the individual. In this assay, we are treating the GEDI-captured CTCs with physiologically relevant concentrations of MTDs and are subsequently assaying drug-induced target modifications. As a proof of principle, we have demonstrated that taxane sensitive BC cell lines captured on the GEDI device showed evidence of effective drug-target engagement by the presence of microtubule bundling following Docetaxel treatment. We are currently evaluating the response of GEDI-captured BC taxane-resistant cells to ex-vivo drug treatment to evaluate the dynamic range of our assay.

We are currently conducting a clinical trial that characterizes GEDI-captured CTCs isolated from MTD treated MBC patients where we will monitor the molecular characteristics of the CTCs during chemotherapy treatment and at disease relapse. This approach will give us significant insight of the mechanisms of resistance of MTDs.

Citation Format: Giuseppe Galletti, Brian Kirby, Linda T. Vahdat, Paraskevi Giannakakou. Development of a HER2-based GEDI microfluidic device for the molecular characterization of CTCs from metastatic breast cancer patients. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1467. doi:10.1158/1538-7445.AM2013-1467

Abstract 3492: Using CTCs to interrogate mechanisms of taxane resistance in the prospective TAXYNERGY clinical trial in prostate cancer

Prostate cancer progression into castration-resistant prostate cancer (CRPC) is driven by continued androgen receptor (AR) signaling despite surgical and chemical androgen ablation. The taxanes represent the only class of chemotherapy that improves overall survival in CRPC patients. Despite their success, CRPC patients do progress on taxane treatment rendering taxane-resistant tumors. The molecular mechanisms underlying clinical taxane resistance in CRPC have not been well elucidated due to the lack of available tumor tissue to study. Circulating tumor cells (CTCs) represent a liquid biopsy of the original tumor and isolation of them can lead to their molecular characterization potentially revealing predictive biomarkers for taxane sensitivity or resistance. Here, we use a geometrically enhanced differential immunocapture (GEDI) microfluidic device that couples an anti-prostate specific membrane antigen (PSMA) antibody with optimized 3D geometry to capture and isolate live CTCs from whole blood of CRPC patients. The GEDI-microfluidic device was shown to have a 2-400 fold higher sensitivity for CTC capture than the FDA-approved CellSearch® system. We have previously shown that CRPC patient CTCs can be used to derive functional information that correlates to clinical response to taxane chemotherapy, namely AR subcellular localization status. We have developed a suite of other functional assays that can be performed on live GEDI-captured CTCs that enable their molecular characterization and allow us to test specific mechanistic hypotheses based on our extensive preclinical data. Included, and herein described, are the determination of AR subcellular localization, extent of effective drug-target engagement assessed by microtubule bundling, identification of RNA species relevant to the mechanism of taxane resistance and computer vision algorithms that will allow for enriched and automated analysis of high-volume image sets of GEDI-captured CTCs. In addition, we will be testing the hypothesis that distinct AR splice variants may affect patient sensitivity to taxane-based chemotherapy. This suite of assays are being rigorously applied in a phase II clinical trial in which chemotherapy-naïve CRPC patients will be initially treated with either docetaxel or cabazitaxel and clinically evaluated for an early switch to the other taxane following disease progression. This prospective, randomized, multi-site clinical trial will enroll 100 CRPC patients within one year. Patients will be followed until relapse and each patient will have 15 independent GEDI assays performed across five time points from baseline to chemotherapy crossover to relapse. The depth of coverage this suite of assays provides will offer unique insights for potential mechanisms of clinical taxane resistance and predictive biomarkers for taxane sensitivity in CRPC patient CTCs.

Citation Format: Matthew S. Sung, Ada Gjyrezi, Guang Yu Lee, Alexandre Matov, Giuseppe Galletti, Matthew Loftus, Yusef Syed, Timothy Lannin, Atanas Hristov, Christopher Mason, Scott Tagawa, Brian Kirby, David Nanus, Paraskevi Giannakakou. Using CTCs to interrogate mechanisms of taxane resistance in the prospective TAXYNERGY clinical trial in prostate cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3492. doi:10.1158/1538-7445.AM2013-3492

Abstract LB-59: ERG induces taxane resistance in castration-resistant prostate cancer

Taxanes are the only chemotherapies to prolong survival for patients with metastatic castration-resistant prostate cancer (CRPC), and both docetaxel (doc) and cabazitaxel (cab) are FDA approved for this indication. Despite the initial efficacy of taxanes in treating CRPC, all patients ultimately fail due to the development of drug resistance. In this study we show that ERG over-expression, which occurs in roughly 50% of prostate cancers, is associated with both doc and cab resistance using in vitro and in vivo models of CRPC. Using either tetracycline-inducible or constitutively active expression systems in multiple prostate cancer cell lines, we found that ERG over-expression leads to at least a 10 fold increase in IC50 doses of doc or cab based on cell viability assays and inhibition of taxane-induced apoptosis. Similarly, ERG over-expressing prostate cancer xenografts were reproducibly more resistant to cab compared to the cab-sensitive control xenografts. Based on a biochemical and cell biological characterization, we observed that ERG binds directly to tubulin in the cytoplasm of prostate cancer cells, as well as in circulating tumor cells from patients treated with doc, and prevents taxane-induced microtubule stabilization. ERG over-expression affects several parameters of microtubule dynamics and inhibits effective drug-target engagement of doc or cab with tubulin, either directly via its tubulin interaction or indirectly by affecting transcription of genes that modulate microtubule homeostasis. In addition, ERG induces and binds to clusterin, a molecular chaperone also associated with taxane resistance. Clusterin knock-down with siRNA abrogates ERG-induced taxane resistance. Altogether, this data suggests that ERG, an oncogenic transcription factor, plays a novel role beyond regulating gene expression and functions outside the nucleus to cooperate with clusterin and tubulin in promoting taxane resistance. Determining ERG status in patient tumors may aid in patient selection for doc or cab therapy and/or influence co-targeting approaches using the clusterin antisense inhibitor OGX-011.

Citation Format: Giuseppe Galletti, Himisha Beltran, Alexandre Matov, Jacqueline Fontugne, Juan Miguel Mosquera, Ladan Fazli, Scott Tagawa, David Nanus, Martin Gleave, Mark Rubin, Paraskevi Giannakakou, David S. Rickman. ERG induces taxane resistance in castration-resistant prostate cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-59. doi:10.1158/1538-7445.AM2013-LB-59

Clinical and preclinical evaluation of taxane sensitivity in gastric cancer (GC): Relevance of GC histology

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Background: Docetaxel (D) is a standard treatment for advanced gastric cancer based on the TAX-325 study (van Cutsem, JCO 2006). We asked the question, do all subtypes of GC benefit equally from D therapy? Methods: We performed a post-hoc analysis of the TAX-325 study. We classified randomized patients as diffuse or non-diffuse histology and correlated histology with clinical outcomes using a Cox proportional hazards model. Preclinical studies involved 13 GC cell lines (4 intestinal subtype, 7 diffuse subtype, 2 unknown), assessed for D sensitivity using the Sulforhodamine B (SRB) cytotoxicity assay, microtubule bundling, mitotic arrest by immunofluorescence as evidence of drug-target engagement, and apoptosis assessment by Caspase 8, Caspase 3, and PARP cleavage by Western Blot. Results: In post hoc analysis of TAX-325, patients were classified as diffuse (n=206) or non-diffuse (n=239). Non-diffuse GC showed a significant improvement in overall survival with the addition of D (12.1 v 8.8 mo, p=0.002), whereas diffuse histology was not associated with an improvement in survival (8.3 v 8.5 mo, p=0.66). Preclinical studies similarly reveal that 5/7 diffuse GC cell lines were resistant to D by SRB assay compared with 1/4 intestinal GC cell lines (IC50 > 600 nM). To examine drug target engagement, a dynamic measure of D activity, 4/6 diffuse GC cell lines showed lack of D engagement on the microtubule network at physiologic D concentrations (0-100 nM). 5/6 diffuse cell lines demonstrated no apoptosis. Additionally, we found that 0/9 GC cell lines expressed P-glycoprotein, ruling out multidrug resistance as an etiology for diffuse GC resistance to D. Conclusions: In exploratory analysis, we observed diffuse GC to be resistant to the addition of D to standard chemotherapy in a random assignment phase III clinical trial. In vitro analyses support these clinical findings and demonstrate intrinsic D resistance in diffuse GC, unrelated to multidrug resistance. Ongoing mechanistic studies focus on the molecular basis of taxane sensitivity in GC to predict treatment efficacy. These findings will inform future clinical studies aimed at individualized therapy.

Abstract 2376: Development of a novel microfluidic device for the capture and molecular characterization of circulating tumor cells from metastatic breast cancer patients

Breast cancer (BC) is the most commonly diagnosed malignancy and the second leading cause of cancer death among women in the United States. Microtubule targeting drugs (MTDs) represent the most active chemotherapy against BC and are standard therapy for locally advanced and metastatic disease. However, metastatic BC (MBC) remains an incurable disease due to acquired drug resistance. The molecular basis of clinical resistance to MTD therapy is not well understood, primarily due to the lack of readily accessible BC tissue during therapy and at the time of relapse precluding the development of rational approaches to overcome it. Circulating Tumor Cells (CTCs) have emerged as a reliable and accessible source of tumor tissue enabling molecular analysis of CTCs during disease progression. However, the extremely low purity associated with the use of the commercially available EpCAM-based CTC capture technology, precludes accurate CTC molecular analyses. To overcome this limitation, we are developing a novel BC-specific microfluidic device that operates on the principle of geometrically enhanced differential immunocapture (GEDI), using antibody-coated microposts. This innovative design achieves capture of viable CTCs using only 1 ml of blood and minimizes leucocyte contamination. We selected HER2 as an alternative to EpCAM-based capture, as HER2 is expressed in 90% of breast tumors and overexpressed in 30%, whereas it is absent from leucocytes. In addition, our preliminary data suggest that EpCAM can be downregulated during epithelial-to-mesenchymal transition (EMT) that often precedes dissemination of cancer cells to the circulation. HER2, on the other hand, is expressed in EMT cells further indicating its suitability for CTC capture from most of the clinically relevant BC subtypes. We tested the performance of various HER-2 antibodies using immunoblot and confocal microscopy analyses of 10 different BC cell lines with varying HER2 expression levels. Surprisingly, the antibody that provided the best dynamic range of HER2 detection in these assays, exhibited poor capture efficiency and lack of discrimination between HER2-positive and negative cell lines. Next, we tested antibody performance using flow cytometry and live-cell imaging in order to preserve the native conformation of HER2 extracellular epitope. These assays identified a different HER2 antibody that showed high capture efficiency and specificity for HER2 positive cells when applied to the GEDI microfluidic device. Currently, we are using the HER2-based GEDI to isolate CTCs from MBC patients receiving MTD-based chemotherapy. In this prospective study, we are characterizing the GEDI-captured CTCs isolated from MBC patients at baseline (before chemotherapy), during the course of therapy and at disease progression in order to gain insights into mechanisms of MTD-resistance.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2376. doi:1538-7445.AM2012-2376

Amplification and overexpression of the PSMB5 gene contributes to bortezomib resistance in retreatment of patients with multiple myeloma

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Background: The proteasome inhibitor Bortezomib is a novel anticancer drug that targets primarily the beta5 subunit (PSMB5) of the 26 S proteasome which has also demonstrated efficacy in re-treatment of almost half of relapsed Multiple Myeloma (MM) pts. Recent studies have identified qualitative and quantitative alterations at the level of PSMB5 subunit, which is located at 14q11, and cells that carry these alterations displayed a marked resistance to proteasome inhibition. We investigated the relevance of amplification and PSMB5 overexpression in the clinical outcome of pts with MM during retreatment with bortezomib. Methods: Between January and June 2008 pts with secretory MM on relapse were elegible for bortezomib re-treatment (1.3 or 1.0 mg/mq on days 1,4,8 and 11 of a 21 day cycle) if they had at least a partial remission to a bortezomib based on most recent treatment and a free interval of at least 6 months since the last dose. Bone marrow samples for morphologic analysis, mRNA expression levels of PSMB5, classical cytogenetics, FISH and in situ hybridization using a fluorescein-labeled probe to detect the amplification of PSMB5 gene, were obtained from 26 pts (16 male, 10 female mean age 64 years) before and during re-treatment with Bortezomib. Results: At the time of analyses all pts who received at least two cycles were evaluable. We identified 12 pts refractory to retreatment and five of these pts (3 males, 2 females, mean age 65 years) had a detectable amplification and overexpression of PSMB5 which interestingly appears rapidly following exposure to bortezomib and wanes with time off-therapy, even if it curiously reappeared rapidly after re-exposure to bortezomib. Conclusions: Amplification and overexpression of PSMB5 contributes to bortezomib resistance in clinical practice. These findings do highlight the susceptibility of proteasome units to genetic modifications under constant selective pressure which occur with continued treatment, furthermore, the drug resistance remains dormant but it rapidly revives upon re-exposure to bortezomib.

No significant financial relationships to disclose.

Erlotinib therapy in a patient with non-small-cell lung cancer and brain metastases

Brain metastases are a common occurrence and a major cause of mortality in non-small-cell lung cancer, with few systemic treatment options. Although targeting epidermal growth factor receptor-associated tyrosine kinase with erlotinib and gefitinib results in durable responses in some patients, the activity of these drugs against brain metastases has been poorly documented. In particular, few reports have so far reported the activity of erlotinib in this setting. Here we report the case of a male Italian smoker with an adeno-carcinoma of the lung whose lung cancer and brain metastases have both responded to erlotinib.

Prevalence of respiratory symptoms in migrant children to Italy: the results of SIDRIA-2 study

BACKGROUND

Epidemiological studies have documented large international variations in the prevalence of asthma, and 'westernization' seems to play an important role in the development of the disease. The aims of this study were to compare the prevalence of respiratory symptoms in migrant and nonmigrant children resident in Italy, and to examine the effect of length of time living in Italy.

METHODS

Data were collected in a large cross-sectional study (SIDRIA-2) performed in 12 Italian centres, using standardized parental questionnaires. For the 29 305 subjects included in the analysis (6-7 and 13-14 years old), information about place of birth and parental nationality was available.

RESULTS

There were 1012 children (3%) born outside of Italy, mainly in East Europe. Lifetime asthma and current wheeze were generally significantly less common among children born abroad than among children born in Italy (lifetime asthma: 5.4% and 9.7% respectively, P < 0.001; current wheeze: 5.2% and 6.9%, respectively, P = 0.04). Lower risks for lifetime asthma (prevalence odds ratio, POR = 0.39; 95% CI: 0.23-0.66) and current wheeze (POR = 0.72; 95% CI: 0.47-1.10) were found for children who had lived in Italy <5 years, while migrant children who had lived in Italy for 5 years or more had risks very similar to Italian children.

CONCLUSIONS

Migrant children have a lower prevalence of asthma symptoms than children born in Italy. Prevalence increased with the number of years of living in Italy, suggesting that exposure to environmental factors may play an important role in the development of asthma in childhood.

[Surgical treatment of hydatid cysts]

Hydatidosis represents a form of helminthic zoonosis with a stronger medical, social and economic impact. It is endemic in some areas of the world including Mediterranean countries, and therefore Italy. The disease is often diagnosed in an advanced phase, due to the poor symptomatology in the early stages. The best treatment is surgery. Emergency surgery is similar to elective surgery, though in some cases is preferable only a drainage procedure until the stabilization of the genreal and local conditions of the patient allow a radical intervention. The Authors report on their five year experience of surgical treatment of compliated pulmonar hydatidosis pointing out that exeresis must be aimed at preserving pulmonar function as much as possible.

[Surgical treatment of celomic cysts]

Celomic cysts (pericardiopleural or serous cysts) are rare, as they account for about 30% of all the homoplastic disembryogenetic lesions of the mediastinum. There is not usually a characteristic symptomatology associated with this anomaly, which is, however, easily diagnosed by means of the most common radiologic techniques. The TC together with the MRI provides all the necessary data for an appropriate management of the patient. The Authors report on their five year experience of the surgical treatment of celomic cysts, pointing out that surgery must be aimed at preserving pulmonary function as much as possible. They finally maintain that the first surgical approach should be video-thoracoscopic with the aid of a minithoracotomy, if necessary.

[Combined video-thoracoscopic, surgical and endovascular treatment in a case of ascites and recurrent bilateral pleural effusion]

Among recurrent pleural effusions a role of remarkable importance is held by those combined with ascitis due to the difficulty of their treatment, even using widely tested techniques. The incidence of such pathology varies from 4% to 6% of patients suffering from cirrhotic pathology, reaching 10% in cases with advanced illnesses. Pleural effusions involve the right emithorax more frequently than the left one, but it can show up bilaterally too. Its etiopathogenesis is tied up to the direct passage of ascitic liquid into the chest and, during the past years, numerous theories have been described to explain this migration. The Authors report the case of a patient with interesting considerations for the diagnostic difficulties and the peculiarity of the treatment performed.

[Experimental results of the use of hyaluronic acid based materials (CV Seprafilm and CV Sepracoat) in postoperative pericardial adhesions]

Repeat cardiac surgical procedures are associated with increased technical difficulty and risk related to the presence of dense adhesions between the heart and the surrounding tissues. We examined the efficacy of a bioabsorbable membrane containing hyaluronic acid in the prevention of pericardial adhesions in 23 rabbits. After thoracotomy and pericardiotomy the animals were divided in three groups: Group 1 (9 animals) in which the epicardial surfaces were covered by Seprafilm membrane, Group 2 (9 animals) treated with both Seprafilm membrane and Sepracoat solution, and Group 3 (5 animals) as controls. The animals were reexplored at 10, 30 and 60 days: no intrapericardial adhesions were found in all the animals of Group 2. In 4 animals (44%) of Group 1 localized post-operative adhesions were detected, in absence of epicardial hyperplasia; in contrast, dense and diffuse adhesions were present in all the control animals. The use of the bioabsorbable membrane Seprafilm significantly reduces adhesion formation even if better results are possible with the previous intrapericardial administration of Sepracoat solution. Application of these biocompatible products could reduce the technical difficulty and risk of repeat surgical procedures.

Fibrin sealant coated stents compared with non-coated stents in a porcine carotid artery model. Preliminary study report

BACKGROUND

Balloon expandable metal stents (BEMS) are used to treat restenosis following percutaneous transluminal angioplasty (PTA) and as primary treatment. Intimal proliferation (IP) and resultant restenosis occurs in 25-50% of patients despite all preventive measures.

OBJECTIVE

to test the intra-arterial response to the insertion of a fibrin sealant (FS) coated BEMS vs an uncoated BEMS by measuring endothelization and IP.

HYPOTHESIS

that a BEMS coated with FS will lead to rapid endothelization and prevent or reduce IP.

RATIONALE

FS consists of fibrinogen and thrombin. Thrombin affects endothelial cell proliferation and reduces smooth muscle proliferation, the forerunner of IP and restenosis. Normal endothelium also releases substances that promote vascular relaxation and normal smooth muscle tone regulation.

METHODS

Thirty-40 kg pigs (EA), Palmaz-Shatz BEMS (Cordis), FS Tissucol (Baxter Immuno). Stents were uniformly coated with FS in a special mold. Both coated and uncoated stents were mounted on balloon catheters and deployed caudad in the carotid arteries via an arteriotomy. Angiograms were obtained postdeployment. All specimens were examined grossly, photographed then fixed for histology and in some cases, scanning electron microscopy (SEM).

RESULTS

Fifteen animals form this preliminary report. Sacrifice at five days as per original protocol showed insufficient stent incorporation. Thereafter 1/2 of the animals were sacrificed at 15 days and 1/2 at 30 days. PATENCY: coated stents: 6 patent, 9 thrombosed. UNCOATED: 7 patent, 8 thrombosed. Of five EA given postoperatively low molecular weight heparin (LMWH) 4 animals had patent stents 80%.

HISTOLOGY

varying degrees of IP were seen in all specimens. In general the coated stents showed a greater degree than the uncoated. STENOSIS: presacrifice angiography revealed that where the stents were patent no stenosis was present, in fact, some demonstrated mild dilatation. This was particularly the case with the coated stents.

CONCLUSIONS

Coating stents with FS is not detrimental. IP in these EA at 30 days did not produce stenosis. Postoperative LMWH appears helpful in maintaining patency in a thrombogenic experimental animal. Further study maintaining EA for 6-12 months should resolve whether the IP seen had achieved its maximum expression or would progress and produce stenosis.

Determination of polycyclic aromatic hydrocarbons in sediment using solid-phase microextraction with gas chromatography-mass spectrometry

Manual solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS) is applied for the determination of polycyclic aromatic hydrocarbons (PAHs) from natural matrix through a distilled water medium. Seven of the 16 PAH standards (naphthalene, acenaphthene, fluorene, anthracene, fluoranthene, pyrene, benzo[a]anthracene) are spiked on a marine muddy sediment. The samples, containing PAHs in the range of 10-20 ppm, are then aged at room temperature more than 10 days before analysis. The influence of the matrix, SPME adsorption time, pH, salt content, and SPME adsorption temperature are investigated. The reproducibility of the technique is less than 13% (RDS) for the first 6 considered PAHs and 28% (RDS) for benzo(a)anthracene with a fiber containing a 100-micron poly dimethylsiloxane coating. Linearity extended in the range of 5-50 picograms for PAHs direct injection, 5-70 picograms for PAHs in water, and 1-170 picograms for PAHs in sediment. The detection limit is estimated less than 1 microgram/kg of dry sample for the first 6 considered PAHs in sediment and 1.5 micrograms/kg of dry sample for benzo(a)anthracene using the selected ion monitoring mode in GC-MS. The recoveries of the considered PAHs are evaluated.

Mass spectral fragmentations of cholesterol acetate oxidation products

In this work, electron-impact mass spectroscopy (EI-MS) was employed on a wide range of sterol compounds in order to study their behaviour with regard to their functional groups. In particular, some specific mechanisms of fragmentation occurring in these substrates (i.e. retro-Diels-Alder reaction, neutral molecules eliminations, specific hydrogen migrations) were investigated. Loss of the alkyl side chain and of the D ring were observed in all cases. Finally, a classification of sterols on the basis of characteristic mass spectral fragments is suggested, and further applications to substrates with functional groups on positions other than the A and B rings is proposed.

Combined laparoendoscopic colon resection and anastomosis using the "no touch technique" and fibrin glue. An experimental study

BACKGROUND

Laparoscopic colon anastomosis are technically demanding. A new technique for colon resection and anastomosis using a combined laparoendoscopic approach is presented.

METHODS

In 10 pigs, pneumoperitoneum was induced and 5 trocars were placed. A sigmoid segment was isolated; a vein stripper was inserted from the anus, and the head was secured with a tie; the segment was intussuscepted pulling the stripper out; 4 seromuscular sutures were placed at the anastomotic site and fibrin glue was spread all around; an electrical wire loop, introduced via a colonoscope, was used to resect the intussuscepted segment that was removed from the anus.

RESULTS

All animals but one survived until sacrifice at 30, 60, 90, and 120 days. Macroscopically, the anastomosis appeared well healed; microscopically, after 90 days, there was a complete restitutio ad integrum of the intestinal wall.

CONCLUSIONS

This technique is feasible and quick; it could be used clinically in small tumors not removable endoscopically.

Hepatic uptake and intestinal absorption of bile acids in the rabbit

The existence of transporters for bile acids (BA) in liver and intestine has been well documented, but information is still needed as to their respective transport capacity. In the present investigation, we compared the hepatic and intestinal transport rates for BA, using perfused livers and intestines. The livers and intestines were separately perfused and dose-response curves (0.25-10 mM) for tauroursodeoxycholate, taurocholate and taurodeoxycholate were obtained. The intestinal and mesenteric concentration and bile acid pattern were also evaluated in six non-fasting rabbits. Taurocholic, tauroursodeoxycholic and taurodeoxycholic acid ileal absorption showed saturation kinetics in the intestine as in the liver; the maximal uptake velocity for each bile acid in the liver was tenfold higher than the respective maximal transport velocity in the intestine; the Km values obtained in the liver were of the same order of magnitude, i.e. in the millimolar range. Taurocholic, tauroursodeoxycholic and taurodeoxycholic acid transport differences in the liver paralleled those in the intestine. Although the intestine was not homogeneously filled, the bile acid concentration in the ileal content fell into the range of the Km for the three studied bile acids, while the portal blood total bile acid concentration was inferior to the observed Kms of liver uptake. Therefore, both the hepatic and intestinal systems do not operate at their maximal transport rates at the prevailing concentrations in portal blood and luminal content, and the hepatic transport occurs at its highest efficiency (below the Km values) in physiological conditions.

The effects of heparin and dietary fish oil on embolic events and the microcirculation downstream from a small-artery repair

In recent studies we demonstrated that platelet emboli induced by arterial injury impair the microcirculation. The present study was performed to determine if heparin or dietary cod liver oil reduces the incidence of emboli following the same arterial injury and, in turn, whether these agents prevent the associated decrease in microcirculatory blood flow. The cremaster muscle of 29 male Sprague-Dawley rats was isolated on a single neurovascular bundle consisting of the iliac artery and vein and the genitofemoral nerve. Emboli were generated by a thrombogenic injury of the iliac artery, and their number and their subsequent effect on capillary perfusion in the downstream microcirculation were measured. Nine animals received heparin (10-unit IV bolus plus 10 units/hour IV infusion), 10 were fed cod liver oil (10 percent by weight of food) for 3 weeks prior to the experiment, and 9 animals receiving no treatment served as controls. The number of emboli was significantly reduced in the heparin group, but there was no accompanying improvement in capillary perfusion. In contrast, in the cod liver oil group, the number of emboli was not reduced, but there was significant improvement in capillary perfusion. These findings suggest that the harmful effect that platelet emboli have on the microcirculation is probably biochemical in nature (vasoconstriction) rather than related to simple mechanical obstruction to flow.

Bile acid active and passive ileal transport in the rabbit: effect of luminal stirring

The intestinal absorption of bile acids (BA) with different chemical structure has been evaluated in the rabbit, after intestinal infusion of different concentrations (0.25-30 mM) of BA, by mesenteric blood sampling. Cholic (CA), chenodeoxycholic (CDCA), ursodeoxycholic (UDCA) acid, free and taurine (T-) conjugated, together with glycocholic (GCA) acid and deoxycholic acid (DCA) were studied. The apparent uptake parameters were calculated. All conjugated BA showed active transport (T max, nmol min-1 cm-1 int.), with Tmax values in the following order: TCA > TUDCA > TCDCA; unconjugated BA showed passive uptake, with values in the following order: DCA > CDCA > UDCA > CA. GCA and CA showed both passive uptake and active transport. For all BA studied the % uptake in the ileal segment considered was less than 10%, BA uptake being thus limited by transport and/or diffusion kinetics, rather than by flow velocity. The liquid resistance to BA radial diffusion inside the lumen was evaluated, and the infusate-to-blood uptake parameters corrected for it, in order to get the uptake parameters from the epithelium-to-liquid interface to mesenteric blood: the apparent Km decreased, passive uptake coefficient increased, while Tmax was unchanged. The passive component of the uptake, corrected for the luminal resistance, correlated with the BA hydrophobicity (r = 0.963; P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)