Development of pre and post-operative models to predict early recurrence of hepatocellular carcinoma after surgical resection

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The metabolic syndrome: what to treat, how to treat, what are the goals?

Metabolic syndrome is a cluster of risk factors for cardiovascular disease that include obesity, atherogenic dyslipidemia, raised blood pressure, and insulin resistance. The growing trend of obesity is associated with increased prevalence of metabolic syndrome. Optimizing diet and exercise are still the leading therapy for controlling the metabolic syndrome. Based on the current evidence, further emphasis should be placed on aggressive management of other metabolic risk factors such as high blood pressure and dyslipidemia.     

Two cases of pancreatic ductal adenocarcinoma, manifested as solid pseudopapillary tumor and intraductal papillary mucinous neoplasm]

Compared with other types of cancers, pancreatic cancer is one of the most dreadful malignancies and is fifth leading cause of cancer-related death in Korea. It is difficult to expect early diagnosis or improvement in prognosis due to lack of specific early symptoms and effective diagnostic methods. Whereas cystic neoplasm of the pancreas is a rare type of pancreatic tumor, surgical resection provides good prognosis because of its low possibility of local invasion or distant metastasis. In case of pancreatic cystic tumor, radiologic differentiation between benign and malignant lesions is crucial for the selection of appropriate treatment and the prediction of prognosis. And ductal adenocarcinoma of pancreas presenting in cystic form is an uncommon type of cystic tumor, making it extremely rare among all pancreatic malignancies. We report two cases of atypical pancreatic ductal adenocarcinoma presenting as solid pseudopapillary tumor and intraductal papillary mucinous neoplasm, respectively.     

Horseradish peroxidase‐catalysed in situ‐forming hydrogels for tissue‐engineering applications

In situ‐forming hydrogels are an attractive class of implantable biomaterials that are used for biomedical applications. These injectable hydrogels are versatile and provide a convenient platform for delivering cells and drugs via minimally invasive surgery. Although several crosslinking methods for preparing in situ forming hydrogels have been developed over the past two decades, most hydrogels are not sufficiently versatile for use in a wide variety of tissue‐engineering applications. In recent years, enzyme‐catalysed crosslinking approaches have been emerged as a new approach for developing in situ‐forming hydrogels. In particular, the horseradish peroxidase (HRP)‐catalysed crosslinking approach has received increasing interest, due to its highly improved and tunable capacity to obtain hydrogels with desirable properties. The HRP‐catalysed crosslinking reaction immediately occurs upon mixing phenol‐rich polymers with HRP and hydrogen peroxide (H₂O₂) in aqueous media. Based on this unique gel‐forming feature, recent studies have shown that various properties of formed hydrogels, such as gelation time, stiffness and degradation rate, can be easily manipulated by varying the concentrations of HRP and H₂O₂. In this review, we outline the versatile properties of HRP‐catalysed in situ‐forming hydrogels, with a brief introduction to the crosslinking mechanisms involved. In addition, the recent biomedical applications of HRP‐catalysed in situ‐forming hydrogels for tissue regeneration are described. Copyright © 2014 John Wiley & Sons, Ltd.     

Giant exciton-enhanced shift currents and direct current conduction with subbandgap photo excitations produced by many-electron interactions

Shift current is a direct current generated from nonlinear light–matter interaction in a noncentrosymmetric crystal and is considered a promising candidate for next-generation photovoltaic devices. The mechanism for shift currents in real materials is, however, still not well understood, especially if electron–hole interactions are included. Here, we employ a first-principles interacting Green’s-function approach on the Keldysh contour with real-time propagation to study photocurrents generated by nonlinear optical processes under continuous wave illumination in real materials. We demonstrate a strong direct current shift current at subbandgap excitation frequencies in monolayer GeS due to strongly bound excitons, as well as a giant excitonic enhancement in the shift current coefficients at above bandgap photon frequencies. Our results suggest that atomically thin two-dimensional materials may be promising building blocks for next-generation shift current devices.

When continuous wave light is shone on a noncentrosymmetric crystal, a direct current (DC) can arise due to a second-order optical response of the crystal. The origin of this current is interpreted to be related to the “shift” (1–4) of the intracell coordinates of the excited electron. This so-called shift current is proposed as an alternative to the photocurrent generated by traditional semiconductor p–n junctions (i.e., a junction between hole-doped [p-type] and electron-doped [n-type] semiconductors) for photovoltaic applications (5, 6). Unlike conventional photovoltaic devices, shift current is a bulk phenomenon, which does not require a p–n junction to separate the optically generated electron–hole pair for a DC. Moreover, recent studies reveal that the photocarriers in shift current can have long travel distances, which is distinct from the usual drift transport mechanism in traditional solar cells (7, 8) and makes shift current a promising candidate for efficient energy conversion.Despite many investigations over the past decade, a basic understanding of shift currents is far from complete. Most theoretical studies to date rely on the assumption of having noninteracting particles (3–6, 9–11). Given that it is well known that light-induced electron–hole pairs can form bound or resonant excitons (correlated electron–hole states), which dominate and qualitatively change the absorption features of semiconductors, electron–hole interactions or excitons are expected to play a large role in shift currents, especially for reduced dimensional systems. However, it is not straight forward to generalize existing ab initio methods [such as the ab initio GW plus Bethe-Salpeter equation (GW-BSE) approach (12)], used to understand and compute excitonic effects in linear optical absorption, to study nonlinear optical responses. Different model approaches to investigate the effects of many-electron interactions on nonlinear optical responses of materials have been proposed. For instance, a Floquet-based model Hamiltonian formalism showed that excitonic effects enhance nonlinear response (13). In the specific case of second harmonic generation, first-principles approaches have been developed and applied to real materials, for instance, by making an approximation to the full many-body perturbation theory treatment (14, 15) or to the time-dependent density function theory, in which electron interaction effects are taken into account via simplified kernels (16). A real-time formulation based on propagating the time-dependent Schrodinger equation has also been developed (17) and applied to second harmonic generation (18). For shift currents in real materials, only one recent study considered the effects of excitons on the linear optical coefficient that might influence shift currents, but these authors included only the effects of excitons on the electromagnetic field profile in a bulk sample, and the crucial process of shift current generation itself is still treated within an independent-particle picture (11). Thus, there is still no first-principles calculation and understanding of the role of many-electron interactions, particularly those due to excitons, on shift currents.Here, we show from first principles that 1) bound exciton states in the band gap can generate substantial shift currents, and 2) excitonic effects in the electron–hole continuum part of the spectrum can also greatly enhance shift currents due to the enhancement of the optical matrix elements from the coherence of the electron–hole pairs and to interexciton couplings that arose in the nonlinear responses.     

Investigation of a hemodynamic basis for syncope in hypertrophic cardiomyopathy. Use of a head-up tilt test.

BACKGROUND. Syncope and sudden death in hypertrophic cardiomyopathy may have a hemodynamic basis. The presence of a small ventricular cavity with high intracavity pressures may activate left ventricular baroreceptors and cause reflex hypotension as described in other populations with syncope. METHODS AND RESULTS. To investigate this potential mechanism of syncope in hypertrophic cardiomyopathy, we studied 17 patients with a history of syncope (syncopal), 19 without syncope (nonsyncopal), and nine normal control subjects by using a head-up tilt test. Head-up tilt at 60 degrees for 45 minutes was followed by 10-minute tilts during incremental doses of isoprenaline. Heart rate, blood pressure, and two-dimensional and Doppler echocardiography were monitored throughout. On tilting, hypertrophic cardiomyopathy patients showed a decline in mean arterial pressure of -5 +/- 6 mm Hg (p less than 0.001) compared with no change in control subjects (0.2 +/- 6 mm Hg, p = 0.9). Left ventricular outflow tract velocity decreased on tilting in control subjects (-8 +/- 6 cm/sec, p = 0.004) but increased in the syncopal and nonsyncopal patients (20 +/- 50 cm/sec, p = 0.05). Reflex hypotension with or without bradycardia, associated with syncope or presyncope, was induced in seven syncopal patients, two nonsyncopal patients, and two control subjects (p = 0.05). The early response to tilt in these subjects was characterized by maintenance of blood pressure but a greater increase in left ventricular fractional shortening than in the other subjects (10 +/- 8% versus 1 +/- 1%, p = 0.002). The onset of hypotension was associated with a trend toward further decreases in left ventricular diameters, outflow tract velocity, and transmitral flow velocities. In the remaining patients who had a negative test, transient hypotension (systolic pressure less than 100 mm Hg) occurred in seven syncopal patients and three nonsyncopal patients compared with none of the control subjects (p = 0.01). In total, hypotension was demonstrated in 82% of syncopal patients compared with 26% of nonsyncopal patients and 22% of control subjects (p = 0.001). CONCLUSIONS. Patients with hypertrophic cardiomyopathy and a history of syncope frequently display hypotension during head-up tilt. In some cases, sudden hypotension occurs and is usually associated with bradycardia and a reduced cavity size, findings compatible with activation of a ventricular baroreflex. In other cases, transient hypotension occurs and could be explained by an impairment of baroreceptor function. These mechanisms may contribute to the occurrence of syncope in daily life.     

Embolic protection device use and its association with procedural safety and long‐term outcomes following saphenous vein graft intervention: An analysis from the British Columbia Cardiac registry

• Coronary stents are commonly deployed using high pressure. However, the duration time of balloon inflation during deployment is still to be determined.
• Vallurupalli and coworkers, in this issue of CCI, show that the stent system takes an average of 33 sec to “accommodate” its pressure during in vitro deployment. In patients, the mean stent inflation time to achieve pressure stability was 104 seconds, ranging from 30 to 380 sec.
• These results challenge a rapid inflation/deflation approach for stent deployment. It is suggested that the duration of the inflation might be individualized, in a case‐by‐case approach.
• However, the findings must be interpreted with caution, as they cannot be directly extrapolated to more diverse clinical, angiographic, and interventional scenarios.