Won-Woo Choi

Epstein–Barr virus-associated peripheral T-cell lymphoma in adults with hydroa vacciniforme-like lesions

We describe two Korean adult patients who had necrotizing papulovesicles mainly on their faces. Skin biopsy specimens showed perivascular and periadnexal infiltrate of atypical lymphoid cells with vasculitis in the dermis and subcutaneous tissue. In situ hybridization demonstrated a latent infection of Epstein–Barr virus in the majoriy of lymphoid cells in the dermis. These patients were diagnosed as having T‐cell lymphoma. Interestingly, large granular lymphocytosis was found in the peripheral blood of Case 2.

LEOPARD Syndrome with a New Association of Congenital Corneal Tumor, Choristoma

Abstract: A 5‐year‐old girl with a family history of LEOPARD syndrome had multiple lentigines on the face and trunk, hypertelorism, and growth retardation. In addition, she had congenital corneal tumors on both eyes. Histologically the tumors were choristoma. The neuroectodermal origin hypothesis of LEOPARD syndrome could explain the presence of a congenital corneal tumor in this patient. We suggest that corneal tumor may represent an unrecognized associated finding in this syndrome.

Skin Is the Frequent Site for Involvement of Peripheral T-Cell and Natural Killer Cell Lymphomas in Korea

We have studied the clinicopathological features of 19 Korean cases of peripheral T‐cell and natural killer (NK) cell lymphomas, not including mycosis fungoides. Primary cutaneous involvement was demonstrated in eight of these 19 cases, and we recognized four clinicopathologic subtypes among these eight patients: nasal type NK/T cell lymphoma, three cases; primary cutaneous CD30 positive anaplastic large cell lymphoma, two cases; subcutaneous panniculitis‐like T‐cell lymphoma, one case; lymphoma with hydroa vacciniforme‐like cutaneous lesions, two cases. We did not, however, encounter any cases of HTLV‐associated adult T‐cell lymphoma/leukemia, which is common in Taiwan and Japan. EBV‐associated lymphoma is the most prominent type of peripheral T‐cell and NK cell neoplasm involving the skin in Korea.

A new automatic cardiac output control algorithm for moving actuator total artificial heart by motor current waveform analysis.

A new automatic cardiac output control algorithm for an implantable electromechanical total artificial heart (TAH) was developed based on the analysis of motor current waveform without using any transducer. The basic control requirements of an artificial heart can be described in terms of three features: preload sensitivity, afterload insensivity, and balanced ventricular output. In previous studies, transducers were used to acquire information on the hemodynamic states for automatic cardiac output control. However, such a control system has reliability problems with the sensors. We proposed a novel sensorless automatic cardiac output control algorithm (ACOCA) providing adequate cardiac output to the time-varying physiological demand without causing right atrial collapse, which is one of the critical problems in an active filling device. In vitro tests were performed on a mock circulatory system to assess the performance of the developed algorithm and the results show that the new algorithm satisfied the basic control requirements of the cardiac output response.

Relationship Between Atrial Pressures and the Interventricular Pressure in the Moving Actuator Type Total Artificial Heart

The right and left atrial pressures are important parameters in the automatic control of a total artificial heart (TAH) within normal physiological ranges. Our TAH is composed of a moving actuator, right and left ventricles, and the interventricular space (IVS) enclosed by a semirigid housing. During operation of the TAH, the IVS volume is changed dynamically by the difference between the ejection volume of one ventricle and the inflow volume of the other. Therefore, the change in pressure of the IVS is related to both right and left atrial pressures. We measured the interventricular pressure (IVP) waveform using a pressure sensor and attempted to estimate indirectly the changes in atrial pressures. This method has the advantage that the sensor does not contact the blood directly. Furthermore, the IVP waveform has a zero baseline in each pump cycle, thus the pressure measurements are free from transducer drift problems because the peak pressure can be measured from these baseline values. From in vitro experiments, we found that the IVP waveform contained several useful parameters such as negative peak IVP value, dP/dton the initial break, and the area enclosed by the profile for each stroke, each of which are associated with the left and right atrial pressures and the filling conditions of the ventricles. The measured atrial pressures were linearly related to the negative peak value of the interventricular pressure.

Automatic Regulation of Output of an Electrohydraulic Left Ventricular Assist Device Using the Polymer Bellows Water Pressure and Motor Current

An electrohydraulically driven left ventricular assist device (LVAD) has been developed in our laboratory. Over years of in vitro and in vivo testing, a “suction” problem has been pointed out as one of the major problems related to the device mechanism. The suction problem involves collapse of the left atrium, which can be caused by excessive negative pressure generated by the active blood-filling mechanism, and can lead to damage to the atrium or an air-embolism. We have developed methods for properly controlling the assistance output, depending upon the inlet pressure conditions. Algorithms have been developed for setting an absolute limit to negative pressure and for the regulation of the diastolic velocity of the device. The regulating system is based on the estimation of left atrial pressure (LAP), using the internal pressure of the polymer bellows and the motor current as raw information indicating the status of the left atrium. The estimation is based upon direct analysis of the signal wave form, coupled with the use of fuzzy logic in determining significant parameters such as the systolic peak, diastolic peak, and diastolic integral. Results of experiments using a mock-circulation system have shown that the new control system performs satisfactorily in detecting suction. An animal experiment was conducted to verify the feasibility of the methods. In a 17-day experiment using an adult sheep with a left ventricular assist device, there was no sign of damage or suction-related problems when we used the new method for controlling the diastolic velocity depending upon the bellows water pressure. In this paper, the methods are described and the results are documented.