Yukihiro Yokoyama

Bio: Yukihiro Yokoyama is an academic researcher from Nagoya University. The author has contributed to research in topics: Hepatectomy & Bile duct. The author has an hindex of 43, co-authored 319 publications receiving 8835 citations. Previous affiliations of Yukihiro Yokoyama include University of North Carolina at Chapel Hill & University of North Carolina at Charlotte.

Evolution of surgical treatment for perihilar cholangiocarcinoma: a single-center 34-year review of 574 consecutive resections.

Abstract: Objective:To review our 34-year experience with 574 consecutive resections for perihilar cholangiocarcinoma and to evaluate the progress made in surgical treatment of this disease.Background:Few studies have reported improved surgical outcomes for perihilar cholangiocarcinoma; therefore, it is still

Post-hepatectomy haemorrhage: a definition and grading by the International Study Group of Liver Surgery (ISGLS)

Abstract: Background A standardized definition of post-hepatectomy haemorrhage (PHH) has not yet been established. Methods An international study group of hepatobiliary surgeons from high-volume centres was convened and a definition of PHH was developed together with a grading of severity considering the impact on patients' clinical management. Results The definition of PHH varies strongly within the hepatic surgery literature. PHH is defined as a drop in haemoglobin level >3 g/dl post-operatively compared with the post-operative baseline level and/or any post-operative transfusion of packed red blood cells (PRBC) for a falling haemoglobin and/or the need for radiological intervention (such as embolization) and/or re-laparotomy to stop bleeding. Evidence of intra-abdominal bleeding should be obtained by imaging or blood loss via the abdominal drains if present. Transfusion of up to two units of PRBC is considered as being Grade A PHH. Grade B PHH requires transfusion of more than two units of PRBC, whereas the need for invasive re-intervention such as embolization and/ or re-laparotomy defines Grade C PHH. Conclusion The proposed definition and grading of severity of PHH enables valid comparisons of results from different studies. It is easily applicable in clinical routine and should be applied in future trials to standardize reporting of complications. A proposed international definition and grading of severity of post hepatectomy haemorrhage which may enable better comparison of outcomes from future published studies

Incidence of and risk factors for incisional hernia after abdominal surgery

Abstract: Background Few larger studies have estimated the incidence of incisional hernia (IH) after abdominal surgery. Methods Patients who had abdominal surgery between November 2009 and February 2011 were included in the study. The incidence rate and risk factors for IH were monitored for at least 180 days. Results A total of 4305 consecutive patients were registered. Of these, 378 were excluded because of failure to complete follow-up and 3927 patients were analysed. IH was diagnosed in 318 patients. The estimated incidence rates for IH were 5·2 per cent at 12 months and 10·3 per cent at 24 months. In multivariable analysis, wound classification III and IV (hazard ratio (HR) 2·26, 95 per cent confidence interval 1·52 to 3·35), body mass index of 25 kg/m2 or higher (HR 1·76, 1·35 to 2·30), midline incision (HR 1·74, 1·28 to 2·38), incisional surgical-site infection (I-SSI) (HR 1·68, 1·24 to 2·28), preoperative chemotherapy (HR 1·61, 1·08 to 2·37), blood transfusion (HR 1·46, 1·04 to 2·05), increasing age by 10-year interval (HR 1·30, 1·16 to 1·45), female sex (HR 1·26, 1·01 to 1·59) and thickness of subcutaneous tissue for every 1-cm increase (HR 1·18, 1·03 to 1·35) were identified as independent risk factors. Compared with superficial I-SSI, deep I-SSI was more strongly associated with the development of IH. Conclusion Although there are several risk factors for IH, reducing I-SSI is an important step in the prevention of IH. Registration number: UMIN000004723 (University Hospital Medical Information Network, http://www.umin.ac.jp/ctr/index.htm).

The complex role of estrogens in inflammation

Abstract: There is still an unresolved paradox with respect to the immunomodulating role of estrogens. On one side, we recognize inhibition of bone resorption and suppression of inflammation in several animal models of chronic inflammatory diseases. On the other hand, we realize the immunosupportive role of estrogens in trauma/sepsis and the proinflammatory effects in some chronic autoimmune diseases in humans. This review examines possible causes for this paradox. This review delineates how the effects of estrogens are dependent on criteria such as: 1) the immune stimulus (foreign antigens or autoantigens) and subsequent antigen-specific immune responses (e.g., T cell inhibited by estrogens vs. activation of B cell); 2) the cell types involved during different phases of the disease; 3) the target organ with its specific microenvironment; 4) timing of 17beta-estradiol administration in relation to the disease course (and the reproductive status of a woman); 5) the concentration of estrogens; 6) the variability in expression of estrogen receptor alpha and beta depending on the microenvironment and the cell type; and 7) intracellular metabolism of estrogens leading to important biologically active metabolites with quite different anti- and proinflammatory function. Also mentioned are systemic supersystems such as the hypothalamic-pituitary-adrenal axis, the sensory nervous system, and the sympathetic nervous system and how they are influenced by estrogens. This review reinforces the concept that estrogens have antiinflammatory but also proinflammatory roles depending on above-mentioned criteria. It also explains that a uniform concept as to the action of estrogens cannot be found for all inflammatory diseases due to the enormous variable responses of immune and repair systems.

Pharmacological and Clinical Aspects of Heme Oxygenase

Abstract: This review is intended to stimulate interest in the effect of increased expression of heme oxygenase-1 (HO-1) protein and increased levels of HO activity on normal and pathological states. The HO system includes the heme catabolic pathway, comprising HO and biliverdin reductase, and the products of heme degradation, carbon monoxide (CO), iron, and biliverdin/bilirubin. The role of the HO system in diabetes, inflammation, heart disease, hypertension, neurological disorders, transplantation, endotoxemia and other pathologies is a burgeoning area of research. This review focuses on the clinical potential of increased levels of HO-1 protein and HO activity to ameliorate tissue injury. The use of pharmacological and genetic probes to manipulate HO, leading to new insights into the complex relationship of the HO system with biological and pathological phenomena under investigation, is reviewed. This information is critical in both drug development and the implementation of clinical approaches to moderate and to alleviate the numerous chronic disorders in humans affected by perturbations in the HO system.