Cholestatic Liver Injury After Biliary Reconstruction Impairs Transplanted Islet Viability and Function

Islet autotransplantation following total pancreatectomy differs from allograft transplantation with respect to the requirement of biliary reconstruction. Although it is known that careful consideration should be given to postoperative cholestatic liver injury after biliary reconstruction, its direct effects on transplanted islets have not been completely elucidated. In this study, we developed a murine model of postoperative cholestatic liver injury after biliary reconstruction with islet autotransplantation that involved syngeneic intraportal islet transplantation into chemically induced diabetic mice and common bile duct ligation. We assessed the viability and function of the transplanted islets. The impaired viability of transplanted islets and increased blood glucose levels indicated restoration of the diabetic state after common bile duct ligation in this murine model. Furthermore, impaired islet viability and function occurred earlier in the transplanted islets than in the surrounding liver tissues, which was consistent with the faster and higher expression of oxidative stress markers in the transplanted islets. Transplanted islets may be more vulnerable to oxidative stress caused by cholestatic liver injury than the surrounding liver tissue. Therefore, patients should be intensively managed after total pancreatectomy with islet autotransplantation to preserve viability and function of the transplanted islets.

Theoretical considerations in measurement of time discrepancies between input and myocardial time-signal intensity curves in estimates of regional myocardial perfusion with first-pass contrast-enhanced MRI

The purpose of this study was to develop a method to determine time discrepancies between input and myocardial time-signal intensity (TSI) curves for accurate estimation of myocardial perfusion with first-pass contrast-enhanced MRI. Estimation of myocardial perfusion with contrast-enhanced MRI using kinetic models requires faithful recording of contrast content in the blood and myocardium. Typically, the arterial input function (AIF) is obtained by setting a region of interest in the left ventricular cavity. However, there is a small delay between the AIF and the myocardial curves, and such time discrepancies can lead to errors in flow estimation using Patlak plot analysis. In this study, the time discrepancies between the arterial TSI curve and the myocardial tissue TSI curve were estimated based on the compartment model. In the early phase after the arrival of the contrast agent in the myocardium, the relationship between rate constant K1 and the concentrations of Gd-DTPA contrast agent in the myocardium and arterial blood (LV blood) can be described by the equation K1={dCmyo(tpeak)/dt}/Ca(tpeak), where Cmyo(t) and Ca(t) are the relative concentrations of Gd-DTPA contrast agent in the myocardium and in the LV blood, respectively, and tpeak is the time corresponding to the peak of Ca(t). In the ideal case, the time corresponding to the maximum upslope of Cmyo(t), tmax, is equal to tpeak. In practice, however, there is a small difference in the arrival times of the contrast agent into the LV and into the myocardium. This difference was estimated to correspond to the difference between tpeak and tmax. The magnitudes of such time discrepancies and the effectiveness of the correction for these time discrepancies were measured in 18 subjects who underwent myocardial perfusion MRI under rest and stress conditions. The effects of the time discrepancies could be corrected effectively in the myocardial perfusion estimates.

Enhanced ultrasonography using a nano/microbubble contrast agent for islet transplantation

Recent basic and clinical studies have assessed the use of highly sensitive imaging modalities for visualizing transplanted islets. We investigated the utility of enhanced ultrasonography, combined with fluorescent acoustic liposome nano/microbubbles (FALs), for evaluating angiogenesis and the endocrine function of transplanted islets. BALB/c mice were classified into three groups: Diabetic mice that underwent syngeneic islet transplantation into the subrenal capsule and achieved normoglycemia (Tx group); those that failed to achieve normoglycemia (Tx-DM group); and those not receiving any treatment (DM group). Mice were examined by FAL-enhanced high frequency ultrasonography. The echogenicity of the islets increased rapidly within the first minute after injection of FALs and remained at a higher level in the Tx group, while small increases were observed in the other two groups. In histological assessments, fluorescently stained erythrocytes could be seen in and around the transplanted islets, indicating that the transplanted islets were enhanced by infusion of FALs via vessel networks between the engrafted islets and tissue. Furthermore, the echogenicity correlated significantly with endocrine parameters, including blood glucose (BG), serum insulin, and the BG change in the glucose tolerance test. In conclusion, the echogenicity of the islets under FAS-enhanced ultrasonosonography correlated with the endocrine status of transplanted islets.

Vitamin D metabolism in hypophosphatemic vitamin D-resistant rickets

Plasma levels of 1,25-(OH)2-D were low in children with hypophosphatemic vitamin D-resistant rickets (HVDRR), but increased after very large doses of 1 alpha-OH-D3. These results suggest that the metabolism of 1,25-(OH)2-D is accelerated in HVDRR. In addition, the lower level of plasma 1,25-(OH)2-D in untreated HVDRR was correlated with the lower level of serum phosphate and renal threshold phosphate concentration (TmP/GFR). The administration of 1 alpha-OH-D3 to the patients with HVDRR could enhance the renal threshold phosphate concentration.

A quantitative high resolution voxel-wise assessment of myocardial blood flow from contrast-enhanced first-pass magnetic resonance perfusion imaging: microsphere validation in a magnetic resonance compatible free beating explanted pig heart model

AIMS

To assess the feasibility of high-resolution quantitative cardiovascular magnetic resonance (CMR) voxel-wise perfusion imaging using clinical 1.5 and 3 T sequences and to validate it using fluorescently labelled microspheres in combination with a state of the art imaging cryomicrotome in a novel, isolated blood-perfused MR-compatible free beating pig heart model without respiratory motion.

METHODS AND RESULTS

MR perfusion imaging was performed in pig hearts at 1.5 (n = 4) and 3 T (n = 4). Images were acquired at physiological flow ('rest'), reduced flow ('ischaemia'), and during adenosine-induced hyperaemia ('stress') in control and coronary occlusion conditions. Fluorescently labelled microspheres and known coronary myocardial blood flow represented the reference standards for quantitative perfusion validation. For the comparison with microspheres, the LV was divided into 48 segments based on a subdivision of the 16 AHA segments into subendocardial, midmyocardial, and subepicardial subsegments. Perfusion quantification of the time-signal intensity curves was performed using a Fermi function deconvolution. High-resolution quantitative voxel-wise perfusion assessment was able to distinguish between occluded and remote myocardium (P < 0.001) and between rest, ischaemia, and stress perfusion conditions at 1.5 T (P < 0.001) and at 3 T (P < 0.001). CMR-MBF estimates correlated well with the microspheres at the AHA segmental level at 1.5 T (r = 0.94, P < 0.001) and at 3 T (r = 0.96, P < 0.001) and at the subendocardial, midmyocardial, and subepicardial level at 1.5 T (r = 0.93, r = 0.9, r = 0.88, P < 0.001, respectively) and at 3 T (r = 0.91, r = 0.95, r = 0.84, P < 0.001, respectively).

CONCLUSION

CMR-derived voxel-wise quantitative blood flow assessment is feasible and very accurate compared with microspheres. This technique is suitable for both clinically used field strengths and may provide the tools to assess extent and severity of myocardial ischaemia.

Magnetic resonance of coronary arteries: assessment of luminal narrowing and blood flow in the coronary arteries

The assessment of luminal narrowing and altered blood flow in the coronary artery is challenging because of the small size of the vessel and the complex motion caused by cardiac contraction and respiration. Free-breathing, whole-heart coronary magnetic resonance angiography (MRA) has been introduced as a method that can provide visualization of all 3 major coronary arteries within a single 3-dimensional acquisition, either by using 1.5 T steady-state free precession or 3 T gradient-echo sequences. Recent studies have indicated that coronary MRA has sufficient diagnostic accuracy for excluding coronary artery disease (CAD) in patients with suspected CAD. Furthermore, coronary MRA can provide risk stratification for future cardiac events. In addition to the morphologic assessment of the coronary artery, phase-contrast cine MR imaging has unique advantages because it allows for measurement of blood flow and flow reserve in the coronary arteries. Comprehensive assessment of the morphology and blood flow in the coronary artery has a great potential in noninvasive detection of physiologically significant CAD that requires revascularization. The aim of this review is to provide an update on current technical improvements in coronary MRA and MR flow measurement of coronary arteries.

Quantitative assessment of magnetic resonance derived myocardial perfusion measurements using advanced techniques: microsphere validation in an explanted pig heart system

BACKGROUND

Cardiovascular Magnetic Resonance (CMR) myocardial perfusion imaging has the potential to evolve into a method allowing full quantification of myocardial blood flow (MBF) in clinical routine. Multiple quantification pathways have been proposed. However at present it remains unclear which algorithm is the most accurate. An isolated perfused, magnetic resonance (MR) compatible pig heart model allows very accurate titration of MBF and in combination with high-resolution assessment of fluorescently-labeled microspheres represents a near optimal platform for validation. We sought to investigate which algorithm is most suited to quantify myocardial perfusion by CMR at 1.5 and 3 Tesla using state of the art CMR perfusion techniques and quantification algorithms.

METHODS

First-pass perfusion CMR was performed in an MR compatible blood perfused pig heart model. We acquired perfusion images at physiological flow ("rest"), reduced flow ("ischaemia") and during adenosine-induced hyperaemia ("hyperaemia") as well as during coronary occlusion. Perfusion CMR was performed at 1.5 Tesla (n = 4 animals) and at 3 Tesla (n = 4 animals). Fluorescently-labeled microspheres and externally controlled coronary blood flow served as reference standards for comparison of different quantification strategies, namely Fermi function deconvolution (Fermi), autoregressive moving average modelling (ARMA), exponential basis deconvolution (Exponential) and B-spline basis deconvolution (B-spline).

RESULTS

All CMR derived MBF estimates significantly correlated with microsphere results. The best correlation was achieved with Fermi function deconvolution both at 1.5 Tesla (r = 0.93, p < 0.001) and at 3 Tesla (r = 0.9, p < 0.001). Fermi correlated significantly better with the microspheres than all other methods at 3 Tesla (p < 0.002). B-spline performed worse than Fermi and Exponential at 1.5 Tesla and showed the weakest correlation to microspheres (r = 0.74, p < 0.001). All other comparisons were not significant. At 3 Tesla exponential deconvolution performed worst (r = 0.49, p < 0.001).

CONCLUSIONS

CMR derived quantitative blood flow estimates correlate with true myocardial blood flow in a controlled animal model. Amongst the different techniques, Fermi function deconvolution was the most accurate technique at both field strengths. Perfusion CMR based on Fermi function deconvolution may therefore emerge as a useful clinical tool providing accurate quantitative blood flow assessment.

Longitudinal spin Seebeck effect: from fundamentals to applications

The spin Seebeck effect refers to the generation of spin voltage as a result of a temperature gradient in ferromagnetic or ferrimagnetic materials. When a conductor is attached to a magnet under a temperature gradient, the thermally generated spin voltage in the magnet injects a spin current into the conductor, which in turn produces electric voltage owing to the spin-orbit interaction. The spin Seebeck effect is of increasing importance in spintronics, since it enables direct generation of a spin current from heat and appears in a variety of magnets ranging from metals and semiconductors to insulators. Recent studies on the spin Seebeck effect have been conducted mainly in paramagnetic metal/ferrimagnetic insulator junction systems in the longitudinal configuration in which a spin current flowing parallel to the temperature gradient is measured. This 'longitudinal spin Seebeck effect' (LSSE) has been observed in various sample systems and exclusively established by separating the spin-current contribution from extrinsic artefacts, such as conventional thermoelectric and magnetic proximity effects. The LSSE in insulators also provides a novel and versatile pathway to thermoelectric generation in combination of the inverse spin-Hall effects. In this paper, we review basic experiments on the LSSE and discuss its potential thermoelectric applications with several demonstrations.

Development of polyvinyl alcohol bioartificial pancreas with rat islets and mesenchymal stem cells

To improve the function of the polyvinyl alcohol (PVA) bioartificial pancreas, we focused on bone marrow-derived mesenchymal stem cells (MSCs). We examined whether the function of PVA-encapsulated rat islets could be improved by coencapsulation with syngeneic MSCs. We macroencapsulated 1,500 rat islet equivalents (IEQ) with or without 1 × 10(6) MSCs with the use of 3% PVA solution before implantation intraperitoneally into diabetic BALB/c mice. We evaluated the function of the device in vitro (the residual rate, viability, and insulin-releasing function of the islets) and in vivo assessments (blood glucose and serum C-peptide changes after transplantation and glucose tolerance test). Although cultured islets also were destroyed, the shapes of the islets cocultured with MSCs were preserved but not different from encapsulated islets without MSCs. At 96 hours after culture the residual rates of islet recovery among those cocultured with versus without MSCs were 66% versus 39.5%, respectively, (P = .03). On the other hand, there was no significant difference between encapsulated islets with versus without MSCs. Furthermore, the stimulation index of the islets was improved by coculture with MSCs (2.6 ± 0.6 vs 1.4 ± 0.1; P = .03), but no beneficial effects were observed between islets encapsulated with versus without MSCs. The viability of islets cocultured with MSCs was significantly better than that without MSCs (84.2 ± 2.5 vs 73.3 ± 0.9; P = .037), but MSCs did not improve the viability of encapsulated islets. There were no significant differences in blood glucose or serum C-peptide between islets encapsulated with versus without MSCs. The histologic findings showed many degenerative islets and MSCs soon after transplantation. In conclusion, further studies are necessary to develop a novel PVA bioartificial pancreas that can be used with MSCs.

Arrhythmogenic right ventricular cardiomyopathy in a 20-year-old woman with systemic sclerosis

A 20-year-old Japanese woman with systemic sclerosis was evaluated for the progressive aggravation of chest pain, palpitations and dyspnea. Cardiac magnetic resonance imaging revealed diffuse wall thinning, segmental dyskinesis and late gadolinium enhancement of the right ventricular (RV) myocardium. Cardiac catheterization demonstrated no pulmonary hypertension. 24-hour electrocardiography monitoring showed non-sustained ventricular tachycardia (VT). Pulseless VT was induced via programmed ventricular stimulation. An endomyocardial biopsy of the right side of the interventricular septum was performed, the histological specimen of which demonstrated massive myocardial atrophy and fibro-fatty replacement with predominant fibrotic changes. The patient was ultimately diagnosed with arrhythmogenic RV cardiomyopathy.

Abstract P1-13-15: Risk of late recurrence of hormone receptor positive breast cancer in cases with no recurrent disease at five years after surgery

Background: Among women who take 2-5 years of adjuvant endocrine therapy, more than half of all recurrences of hormone receptor (HR) positive breast cancer occur after the first 5 years. Data from large clinical trials including ATLAS, aTTom,MA17 and NSABP B-30 support extending tamoxifen or aromatase inhibitor beyond 5 year for women with HR positive breast cancer. For decision making according to extending endocrine therapy, the information of the risk of late recurrence is quietly important.

Patients and methods: In order to determine ten year disease free survival (DFS) rates, we reviewed medical records and database of patients who were treated at National Kyushu Cancer Center between 1990 and 2001. Among seven hundred fifty seven patients with HR positive breast cancer, 550 received tamoxifen for 2-5 years. Eighty eight patients had recurrence within five years after surgery, and 13 were not followed, with 83.5% of 5-year DFS after surgery. Remaining four hundred twenty six had no recurrence at the time of 5 years after surgery. To evaluate the risk of late recurrence, we analyzed the long-term results in association with clinicopathological factors for these 426 patients.

Results: Four hundred twenty six patients had 87.1% of 10-year DFS rate. According to lymph node metastasis (N), ten year DFS rates were 91.4% for 275 N-negative and 80.0% for 155 N-positive cases (P = 0.0037). As for the number of lymph node metastasis, 10-year DFS rates were 82.5%, 74.2%, and 79.1% for N1-3, N4-9, N&gt;9, respectively. Tumor size was correlated with the prognosis, and 10-year DFS rates were 91.5% for 167 T1 (≤2 cm), 86.9% for T2 (2-5 cm), and 67.9% for T3 (&gt;5cm) (P = 0.0334). There were no significant differences between grade and prognosis, and 10-year DFS rates of grade 1, 2 and 3 were 88.9%, 89.8%, and 96.8%, respectively (p = 0.3914). Considering the age at 5 years after surgery, no significant differences were observed as for late recurrence. Ten-year DFS rates of 96 cases of age under 50, 227 between 50 and 65, 113 over 65 was 89.4%, 85.1%, and 86.0%, respectively. Ten-year DFS rates of N-negative and N-positive were 94.3% and 81.2%, 88.1% and 80.1%, and 90.4% and 76.7% for these age criteria, respectively.

Conclusion: Patients with HR positive breast cancer require optimal information for decision making whether to receive extending endocrine therapy or not. Our data demonstrated the risk of late recurrence in relation to clinic-pathological factors, which may support the consideration about extending endocrine therapy. Relatively high risks of late recurrence with over 10% of 10 year DFS rates are there in cases with N-positive or T2-3 HR positive breast cancer.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-13-15.