On Basing Auxiliary-Input Cryptography on NP-Hardness via Nonadaptive Black-Box Reductions

Constructing one-way functions based on NP-hardness is a central challenge in theoretical computer science. Unfortunately, Akavia et al. [Akavia et al., 2006] presented strong evidence that a nonadaptive black-box (BB) reduction is insufficient to solve this challenge. However, should we give up such a central proof technique even for an intermediate step? In this paper, we turn our eyes from standard cryptographic primitives to weaker cryptographic primitives allowed to take auxiliary-input and continue to explore the capability of nonadaptive BB reductions to base auxiliary-input primitives on NP-hardness. Specifically, we prove the followings: - if we base an auxiliary-input pseudorandom generator (AIPRG) on NP-hardness via a nonadaptive BB reduction, then the polynomial hierarchy collapses; - if we base an auxiliary-input one-way function (AIOWF) or auxiliary-input hitting set generator (AIHSG) on NP-hardness via a nonadaptive BB reduction, then an (i.o.-)one-way function also exists based on NP-hardness (via an adaptive BB reduction). These theorems extend our knowledge on nonadaptive BB reductions out of the current worst-to-average framework. The first result provides new evidence that nonadaptive BB reductions are insufficient to base AIPRG on NP-hardness. The second result also yields a weaker but still surprising consequence of nonadaptive BB reductions, i.e., a one-way function based on NP-hardness. In fact, the second result is interpreted in the following two opposite ways. Pessimistically, it shows that basing AIOWF or AIHSG on NP-hardness via nonadaptive BB reductions is harder than constructing a one-way function based on NP-hardness, which can be regarded as a negative result. Note that AIHSG is a weak primitive implied even by the hardness of learning; thus, this pessimistic view provides conceptually stronger limitations than the currently known limitations on nonadaptive BB reductions. Optimistically, it offers a new hope: breakthrough construction of auxiliary-input primitives might also provide construction standard cryptographic primitives. This optimistic view enhances the significance of further investigation on constructing auxiliary-input or other intermediate cryptographic primitives instead of standard cryptographic primitives

Analysis of Hepatic Arterial Thrombosis after Liver Transplantation: An Experience at a Single Transplantation Center

The author has experienced to practice the clinical works of cadaveric liver transplantation at a single transplantation center in Australia between 1999 and 2000. Hepatic arterial thrombosis causes higher rates of morbidity and mortality after liver transplantation. To know the associated factors, pathogenesis and patient outcome, data of 99 adult patients who underwent liver transplantation by the database for past two years were analysed. Ten patients (10%) had hepatic arterial thrombosis (HAT group). In donor demographics, brain death caused by cerebral stroke in the HAT group (90%) was significantly more than that in the non HAT group (49%) (p<0.05). The mean amount of blood transfusion in the HAT group (26665ml) was significantly greater than that in the control group (15606m1) (p<0.05). The mean hepatic arterial flow measured by Doppler flowmeter in the HAT group (214m1/min.) was lower than that in the control group (399m1/min) (p<0.01). The rate of in-hospital death or retransplantation caused by severely biliary abscess with hepatic infarction or graft failure in the HAT group (40%) tended to be higher compared to the control group (13%) (p=0.053). In conclusion, decrease of bleeding and blood transfusion, and obtaining the adequate arterial blood flow during operation were important to prevent hepatic arterial thrombosis causing higher morbidity and mortality after liver transplantation

Usefulness of vessel-sealing devices combined with crush clamping method for hepatectomy: A retrospective cohort study

Background: Blood loss during resection of the hepatic parenchyma in hepatectomy can be minimized using vessel-sealing (VS) devices. Some sealing devices were retrospectively compared to evaluate the efficacy of each device for controlling blood loss, transection time and postoperative complications in hepatectomy as a cohort study. Methods: Between 2005 and September 2012, hepatectomy was underwent in 150 patients using one of three types of LigaSure™ (Dolphin Tip Laparoscopic Instrument, Precise or Small Jaw) or the Harmonic Focus or Ace ultrasonic dissecting sealer. Results were compared to crush-clamping alone as the control method by the historical study (n=81). Results: Irrespective of the vessel-sealing device used for underlying chronic hepatitis, blood loss, blood transfusion rate, operating time and transection time were significantly reduced in the VS group compared with controls (p<0.05). Rates of postoperative bile leakage and intra-abdominal abscess formation were significantly lower in the VS group than in controls (p<0.05). Comparing devices, LigaSure Small Jaw and Harmonic Focus showed lower blood loss, shorter transection time and reduced rates of post-hepatectomy complications, in turn resulting in shorter hospital stays (p<0.05). Tendencies toward uncontrolled ascites and bile leakage were only concern with the use of Harmonic Focus. Satisfactory surgical results were achieved using the sealing device for laparoscopic hepatectomy. Conclusions: The use of energy sealing devices improves surgical results and avoids hepatectomy-related complications. Adequate use of vessel sealers is necessary for safe and rapid completion of hepatic resection

Prediction of Indocyanine Green Retention Rate at 15 Minutes by Correlated Liver Function Parameters before Hepatectomy.

Indocyanine green retention rate at 15 min (ICGR15) is a useful marker of liver function in deciding on the extent of hepatectomy. To determine ICGR15 regardless of liver condition, we sought to establish a formula for converted ICGR15 based on conventional blood tests and technetium-99 m galactosyl human serum albumin ((99m)Tc-GSA) scintigraphy

Resection of Segments 4, 5 and 8 for a Cystic Liver Tumor Using the Double Liver Hanging Maneuver

To achieve complete anatomic central hepatectomy for a large tumor compressing surrounding vessels, transection by an anterior approach is preferred but a skillful technique is necessary. We propose the modified technique of Belghiti's liver hanging maneuver (LHM). The case was a 77-year-old female with a 6-cm liver cystic tumor in the central liver compressing hilar vessels and the right hepatic vein. At the hepatic hilum, the spaces between Glisson's pedicle and hepatic parenchyma were dissected, which were (1) the space between the right anterior and posterior Glisson pedicles and (2) the space adjacent to the umbilical Glisson pedicle. Two tubes were repositioned in each space and ‘double LHM’ was possible at the two resected planes of segments 4, 5 and 8. Cut planes were easily and adequately obtained and the compressed vessels were secured. Double LHM is a useful surgical technique for hepatectomy for a large tumor located in the central liver

Expression of Keratinocyte Growth Factor and Its Receptor in Rat Tracheal Cartilage: Possible Involvement in Wound Healing of the Damaged Cartilage

Keratinocyte growth factor (KGF) is involved in the development and regeneration of a variety of tissues. To clarify the role of KGF in cartilage wound healing, we examined the expression of KGF and its receptor (KGFR) immunohistochemically in the wound healing area of rat tracheal cartilage, and the direct effect of recombinant KGF on the proliferation and differentiation of primary cultures of rat chondrocytes. KGF was found in the cytoplasm of both chondrocytes and perichondrial cells. On the other hand, KGFR was detected only in the plasma membrane of chondrocytes. Although the expression of KGF was similar in the cartilage and perichondrial area before and after injury, KGFR expression was induced after injury and limited to proliferating chondrocytes. The staining pattern of KGF and KGFR was same in the mature and the immature rat tracheal cartilage. Moreover, in vitro experiments using primary cultured chondrocytes revealed that KGF at 200 ng/ml significantly increased the number of chondrocytes (~1.5-fold), and significantly reduced acid mucopolysaccharide production. These results indicate that KGF stimulates chondrocyte proliferation, suggesting that KGF could therapeutically modulate the wound healing process in the tracheal cartilage

Prediction of portal pressure from intraoperative ultrasonography

BackgroundPortal hypertension is a major risk factor for hepatic failure or bleeding in patients who have undergone hepatectomy, but it cannot be measured indirectly. We attempted to evaluate the intraoperative ultrasonography parameters that correlate with portal pressure (PP) in patients undergoing hepatectomy.MethodsWe examined 30 patients in whom PP was directly measured during surgery. The background liver conditions included chronic viral liver disease in seven patients, chemotherapy-associated steatohepatitis in four patients, fatty liver in one patient, hepatolithiasis in one patient, obstructive jaundice in one patient, and a normal liver in 16 patients. A multivariate logistic analysis and linear regression analysis were conducted to develop a predictive formula for PP.ResultsThe mean PP was 10.4 ± 4.1 mm Hg. The PP tended to be increased in patients with chronic viral hepatitis. A univariate analysis identified the association of the six following parameters with PP: the platelet count and the maximum (max), minimum (min), endo-diastolic, peak-systolic, and mean velocity in the portal vein (PV) flow. Using multiple linear regression analysis, the predictive formula using the PV max and min was as follows: Y (estimated PP) = 18.235?0.120 × (PV max.[m/s])?0.364 × (PV min). The calculated PP (10.44 ± 2.61 mm Hg) was nearly the same as the actual PP (10.43 ± 4.07 mm Hg). However, there was no significant relationship between the calculated PP and the intraoperative blood loss and post hepatectomy morbidity.ConclusionsThis formula, which uses ultrasonographic Doppler flow parameters, appears to be useful for predicting PP