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Dive into the research topics where Hiroyuki Koami is active.

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Featured researches published by Hiroyuki Koami.


Biology of Reproduction | 2003

Expression and Functional Characterization of the Adhesion Molecule Spermatogenic Immunoglobulin Superfamily in the Mouse Testis

Tomohiko Wakayama; Hiroyuki Koami; Hiroyuki Ariga; Daisuke Kobayashi; Yoshimichi Sai; Akira Tsuji; Miyuki Yamamoto; Shoichi Iseki

Abstract Spermatogenic immunoglobulin superfamily (SgIGSF) is a mouse protein belonging to the immunoglobulin superfamily expressed in the spermatogenic cells of seminiferous tubules. We produced a specific polyclonal antibody against SgIGSF. Western blot analysis of the testes from postnatal developing mice using this antibody demonstrated multiple immunopositive bands of 80–130 kDa, which increased in number and size with the postnatal age. Enzymatic N-glycolysis caused reduction in the size of these bands to 70 kDa, indicating that SgIGSF is a glycoprotein and its glycosylation pattern and extent are developmentally regulated. Immunohistochemical analysis of the adult testis demonstrated that SgIGSF was present in the spermatogenic cells in the earlier steps of spermatogenesis and increased in amount from intermediate spermatogonia through zygotene spermatocytes but was diminished in the steps from early pachytene spermatocytes through round spermatids. After meiosis, SgIGSF reappeared in step 7 spermatids and was present in the elongating spermatids until spermiation. The immunoreactivity was localized primarily on the cell membrane. Consistent with the findings in adult testes, the analysis of the developing testes revealed that SgIGSF was expressed separately in the spermatogenic cells in earlier and later phases. Sertoli cells had no expression of SgIGSF, whereas both SgIGSF immunoprecipitated from the testis lysate and produced in COS-7 cells was shown to bind to the surface of Sertoli cells in primary culture. These results suggested that SgIGSF on the surface of spermatogenic cells binds to some membrane molecules on Sertoli cells in a heterophilic manner and thereby may play diverse roles in the spermatogenesis.


JAMA | 2017

Effect of Dexmedetomidine on Mortality and Ventilator-Free Days in Patients Requiring Mechanical Ventilation With Sepsis: A Randomized Clinical Trial.

Yu Kawazoe; Kyohei Miyamoto; Takeshi Morimoto; Tomonori Yamamoto; Akihiro Fuke; Atsunori Hashimoto; Hiroyuki Koami; Satoru Beppu; Yoichi Katayama; Makoto Itoh; Yoshinori Ohta; Hitoshi Yamamura

Importance Dexmedetomidine provides sedation for patients undergoing ventilation; however, its effects on mortality and ventilator-free days have not been well studied among patients with sepsis. Objectives To examine whether a sedation strategy with dexmedetomidine can improve clinical outcomes in patients with sepsis undergoing ventilation. Design, Setting, and Participants Open-label, multicenter randomized clinical trial conducted at 8 intensive care units in Japan from February 2013 until January 2016 among 201 consecutive adult patients with sepsis requiring mechanical ventilation for at least 24 hours. Interventions Patients were randomized to receive either sedation with dexmedetomidine (n = 100) or sedation without dexmedetomidine (control group; n = 101). Other agents used in both groups were fentanyl, propofol, and midazolam. Main Outcomes and Measures The co–primary outcomes were mortality and ventilator-free days (over a 28-day duration). Sequential Organ Failure Assessment score (days 1, 2, 4, 6, 8), sedation control, occurrence of delirium and coma, intensive care unit stay duration, renal function, inflammation, and nutrition state were assessed as secondary outcomes. Results Of the 203 screened patients, 201 were randomized. The mean age was 69 years (SD, 14 years); 63% were male. Mortality at 28 days was not significantly different in the dexmedetomidine group vs the control group (19 patients [22.8%] vs 28 patients [30.8%]; hazard ratio, 0.69; 95% CI, 0.38-1.22; P = .20). Ventilator-free days over 28 days were not significantly different between groups (dexmedetomidine group: median, 20 [interquartile range, 5-24] days; control group: median, 18 [interquartile range, 0.5-23] days; P = .20). The dexmedetomidine group had a significantly higher rate of well-controlled sedation during mechanical ventilation (range, 17%-58% vs 20%-39%; P = .01); other outcomes were not significantly different between groups. Adverse events occurred in 8 (8%) and 3 (3%) patients in the dexmedetomidine and control groups, respectively. Conclusions and Relevance Among patients requiring mechanical ventilation, the use of dexmedetomidine compared with no dexmedetomidine did not result in statistically significant improvement in mortality or ventilator-free days. However, the study may have been underpowered for mortality, and additional research may be needed to evaluate this further. Trial Registration clinicaltrials.gov Identifier: NCT01760967


Blood Coagulation & Fibrinolysis | 2015

Can rotational thromboelastometry predict septic disseminated intravascular coagulation

Hiroyuki Koami; Yuichiro Sakamoto; Miho Ohta; Akiko Goto; Showgo Narumi; Hisashi Imahase; Mayuko Yahata; Toru Miike; Takashi Iwamura; Kosuke Chris Yamada; Satoshi Inoue

Rotational thromboelastometry (ROTEM), known as point-of-care testing, has been incorporated into various kinds of postsurgical management. However, the utility of ROTEM for rapid diagnosis of sepsis-induced disseminated intravascular coagulation (DIC) has not been investigated. This retrospective study includes 13 sepsis patients who underwent ROTEM in our emergency department in 2013. All patients were divided into two groups on the basis of the presence of DIC diagnosed by the Japanese Association for Acute Medicine (JAAM) DIC score. We evaluated the demographics, clinical characteristics, laboratory data, ROTEM test and outcomes for each patient. The correlations between JAAM DIC score and significantly different parameters by univariate analysis and receiver operating characteristic (ROC) analysis were performed to assess the accuracy of the variables. There were seven and six patients in the DIC group and non-DIC group, respectively. The DIC group showed significantly longer prothrombin times, international normalized ratio of prothrombin time and clotting times (CTs) in the EXTEM test, and higher fibrinogen and fibrin degradation products and D-dimer. The CT in EXTEM test was correlated more with JAAM DIC score (r = 0.798), than the standard coagulation test. These parameters were accurate predictors in the diagnosis of septic DIC, with an AUC of 0.952, and a cut-off value of more than 46.0 s, resulting in a sensitivity of 100.0% and a specificity of 83.3%. CT in the EXTEM test was a single reliable indicator of sepsis-induced DIC diagnosed by the JAAM DIC score, and strongly associated with severity of DIC.


Yonsei Medical Journal | 2013

Studies on Therapeutic Effects and Pathological Features of an Antithrombin Preparation in Septic Disseminated Intravascular Coagulation Patients

Yuichiro Sakamoto; Satoshi Inoue; Takashi Iwamura; Tomoko Yamashita; Atsushi Nakashima; Yoichi Nishimura; Hiroyuki Koami; Hisashi Imahase; Akiko Goto; Kosuke Chris Yamada; Kunihiro Mashiko; Hiroyuki Yokota

Purpose Few reports have been made on the therapeutic effects as well as pathological features of an antithrombin preparation in patients diagnosed with septic disseminated intravascular coagulation (DIC) by the diagnostic criteria for acute DIC. Materials and Methods A total of 88 sepsis patients who had received inpatient hospital care during the period from January 2000 through December 2008 were divided into two groups, an antithrombin group and a non-antithrombin group, to study the outcomes. Furthermore, the relationship between sepsis-related factors and DIC in 44 patients was studied. Results The antithrombin group contained 34 patients, and the non-antithrombin group contained 54 patients. The outcomes were significantly better in the antithrombin group. The levels of protein C were low in DIC patients. Conclusion Our results suggest that early administration of antithrombin might improve outcomes of septic DIC patients in the diagnostic criteria for Japanese Association for Acute Medicine acute DIC.


PLOS ONE | 2017

Thromboelastometric analysis of the risk factors for return of spontaneous circulation in adult patients with out-of-hospital cardiac arrest

Hiroyuki Koami; Yuichiro Sakamoto; Ryota Sakurai; Miho Ohta; Hisashi Imahase; Mayuko Yahata; Mitsuru Umeka; Toru Miike; Futoshi Nagashima; Takashi Iwamura; Kosuke Chris Yamada; Satoshi Inoue

It is well known that coagulopathy is observed in patients with out-of-hospital cardiac arrest (OHCA). Thrombolytic therapy for those patients has been controversial until now. The purpose of this study was to identify a significant predictor for return of spontaneous circulation (ROSC) of OHCA patients in the emergency department (ED) using whole blood viscoelastic testing. Adult non-trauma OHCA patients transported to our hospital that underwent thromboelastometry (ROTEM) during cardiopulmonary resuscitation between January 2013 and December 2015 were enrolled in this study. We divided patients into two groups based on the presence or absence of ROSC, and performed statistical analysis utilizing patient characteristics, prehospital data, laboratory data, and ROTEM data. Seventy-five patients were enrolled. The ROSC group and non-ROSC group included 23 and 52 patients, respectively. The logistic regression analysis, utilizing significant parameters by univariate analysis, demonstrated that lactate level [odds ratio (OR) 0.880, 95% confidence interval (CI) 0.785–0.986, p = 0.028] and A30 of EXTEM test [OR 1.039, 95% CI 1.010–1.070, p = 0.009] were independent risk factors for ROSC. The cut-off values of lactate and A30 in EXTEM were 12.0 mmol/L and A 48.0 mm, respectively. We defined a positive prediction for ROSC if the patient presented lower lactate level (<12.0 mmol/L) and higher A30 of EXTEM (≥48.0 mm) with high specificity (94.7%) and accuracy (75.0%). The present study showed that lactate level and ROTEM parameter of clot firmness were reliable predictors of ROSC in the ED for adult patients with OHCA.


Medicine | 2016

The thromboelastometric discrepancy between septic and trauma induced disseminated intravascular coagulation diagnosed by the scoring system from the Japanese association for acute medicine

Hiroyuki Koami; Yuichiro Sakamoto; Ryota Sakurai; Miho Ohta; Hisashi Imahase; Mayuko Yahata; Mitsuru Umeka; Toru Miike; Futoshi Nagashima; Takashi Iwamura; Kosuke Chris Yamada; Satoshi Inoue

Abstract The aim of this study is to evaluate the hematological differences between septic and traumatic disseminated intravascular coagulation (DIC) using the rotational thromboelastometry (ROTEM). This retrospective study includes all sepsis or severe trauma patients transported to our emergency department who underwent ROTEM from 2013 to 2014. All patients were divided into 2 groups based on the presence of DIC diagnosed by the Japanese Association for Acute Medicine (JAAM) DIC score. We statistically analyzed the demographics, clinical characteristics, laboratory data, ROTEM findings (EXTEM and FIBTEM), and outcome. Fifty-seven patients (30 sepsis and 27 severe trauma) were included in primary analysis. Sepsis cases were significantly older and had higher systemic inflammatory response syndrome (SIRS) scores, whereas there were no significant differences in other parameters including Acute Physiology and Chronic Health Evaluation (APACHE) II score, sequential organ failure assessment (SOFA) score. Twenty-six patients (14 sepsis and 12 severe trauma) were diagnosed with DIC. The Septic DIC (S-DIC) group was significantly older and had higher DIC scores than the traumatic DIC (T-DIC) group. Hematologic examination revealed significantly higher CRP, fibrinogen, lower FDP, DD, and higher FDP/DD ratio were found in the S-DIC group in comparison with the T-DIC group. ROTEM findings showed that the A10, A20, and MCF in the FIBTEM test were significantly higher in the S-DIC group. However, no statistical differences were confirmed in the LI30, LI45, and ML in EXTEM test. The plasma fibrinogen level and fibrinogen based clot firmness in whole-blood test revealed statistical significance between septic and traumatic DIC patients.


Thrombosis Research | 2017

The efficacy and associated bleeding complications of recombinant antithrombin supplementation among intensive care unit patients

Hiroyuki Koami; Yuichiro Sakamoto; Ryota Sakurai; Miho Ohta; Hisashi Imahase; Mayuko Yahata; Mitsuru Umeka; Toru Miike; Futoshi Nagashima; Takashi Iwamura; Kosuke Chris Yamada; Satoshi Inoue

INTRODUCTION The aim of this study was to evaluate the efficacy and complications of recombinant antithrombin (rAT) supplementation for adult patients with disseminated intravascular coagulation (DIC) compared with conventional plasma derived AT (pAT) treatment in the intensive care unit. MATERIALS AND METHODS This study was performed in a single national university hospital in Japan. Adult patients from April 2015 to March 2016 with DIC were divided into two groups based on the type of AT agent used: the pAT group (n=24) and the rAT group (n=21). Patient demographics, medical history, diagnosis, blood tests, various clinical scores, AT activity, complications, and clinical outcome were collected and analyzed retrospectively. RESULTS Significantly higher SIRS and APACHEII scores were confirmed in the rAT group than the pAT group. The initial dose of AT was significantly higher in the rAT group than in the pAT group. ATIII values before and after initial supplementation and during their ten-day clinical course were statistically similar between two groups. During the same period, 10 bleeding adverse events were found and there was no significant difference between both groups. Significantly more cases of the rAT group were administered with recombinant thrombomodulin concomitantly than those of the pAT group. Despite significantly more severe patients in rAT group, the clinical outcomes were the same in each group. CONCLUSIONS Compared with pAT, the supplementation of rAT indicates clinical effectiveness without increasing the risk of bleeding complications in adult DIC patients with low AT activity.


Journal of Nippon Medical School | 2016

Utility of Measurement of Serum Lactate in Diagnosis of Coagulopathy Associated with Peripheral Circulatory Insufficiency: Retrospective Evaluation Using Thromboelastometry from a Single Center in Japan.

Hiroyuki Koami; Yuichiro Sakamoto; Ryota Sakurai; Miho Ohta; Akiko Goto; Hisashi Imahase; Mayuko Yahata; Mitsuru Umeka; Toru Miike; Futoshi Nagashima; Takashi Iwamura; Kosuke Chris Yamada; Satoshi Inoue

Recently, serum lactate level rather than systolic blood pressure (sBP) has been widely used to diagnose peripheral circulatory insufficiency, which often leads to coagulopathy with systemic inflammation. However, most of the reported disorders were examined by plasma samples. The aim of this study was to evaluate the utility of serum lactate for detecting coagulopathy with circulatory failure by using thromboelastometry as well as standard coagulation test. 192 adult patients transported to our hospital between January 2013 and September 2014 were enrolled in this retrospective study. The sBP, serum lactate and thromboelastometry (ROTEM(®)) were measured in these patients in the emergency department. All patients were divided into three groups based on serum lactate levels: (1) the severe group (≥4 mmol/L, n=41); (2) the mild group (<4 mmol/L and ≥2 mmol/L, n=59); and (3) the normal group (<2 mmol/L, n=92). Patients in the severe group were of a significantly younger age but had lower pH and poor outcome. SBP was significantly lower and heart rates were higher in the severe group than in the other groups. Prolonged PT-INR and APTT were statistically confirmed in the severe group. ROTEM findings in the severe group revealed significantly lower alpha angle, shortened Lysis Onset Time and significantly more cases exhibited hyperfibrinolysis. The same analysis with the cut-off level of sBP at 90 mmHg showed no significant difference in ROTEM findings between the two groups. Abnormal serum lactate levels (≥4.0 mmol/L) properly reflected peripheral circulatory insufficiency and were more closely associated with coagulopathy such as hyperfibrinolysis and hypocoagulability than sBP.


Blood Coagulation & Fibrinolysis | 2016

Utility of rotational thromboelastometry for the diagnosis of asymptomatic hyperfibrinolysis secondary to anaphylaxis.

Hiroyuki Koami; Yuichiro Sakamoto; Takashi Furukawa; Hisashi Imahase; Takashi Iwamura; Satoshi Inoue

We present a case of hyperfibrinolysis induced by oxaliplatin-derived anaphylactic shock, which was diagnosed with rotational thromboelastometry (ROTEM). A 57-year-old male patient underwent a second course of oxaliplatin (126 mg/m/course)-based chemotherapy for stage IV metastatic rectal cancer. Two minutes after the infusion of oxaliplatin, the patient lost consciousness and developed generalized urticarial lesions, followed by hemodynamic instability and respiratory insufficiency. He was diagnosed anaphylactic shock and transported to emergency department (ED) after intramuscular injection of 0.2 mg of adrenaline, an intravenous injection of 100 mg of hydrocortisone, and 500 mg of methylprednisolone. After arriving in the ED, the patient remained in shock and early resuscitation with administration of 5 mg of D-chlorpheniramine maleate and 20 mg of famotidine was performed. He recovered from his state of shock 30 min after the resuscitation. ROTEM findings showed fulminant hyperfibrinolysis with minimal changes in standard coagulation tests (SCTs) and no remarkable coagulopathy. Seven hours after the attack, he became asymptomatic and follow-up ROTEM revealed values within normal limits with the exception of sustained slight abnormalities of SCTs. He was discharged the next day without any signs of spontaneous bleeding and has continued his outpatient chemotherapy uneventfully. A review of the literature on anaphylaxis-induced hyperfibrinolysis and a discussion of the mechanism between anaphylactic shock and hyperfibrinolysis were performed. Although administration of tissue-type plasminogen activator can play a vital role in anaphylactic shock-induced hyperfibrinolysis, early effective resuscitation is imperative to prevent severe hemorrhagic complications. Therefore, ROTEM is a useful tool that can detect these dynamic changes faster and more accurately than SCTs.


Yonsei Medical Journal | 2014

Usefulness of the Endotoxin Activity Assay to Evaluate the Degree of Lung Injury

Yuichiro Sakamoto; Satoshi Inoue; Takashi Iwamura; Tomoko Yamashita; Atsushi Nakashima; Hiroyuki Koami; Toru Miike; Mayuko Yahata; Hisashi Imahase; Akiko Goto; Showgo Narumi; Miho Ohta; Chris-Kosuke Yamada

Purpose It has been reported that the Pulse Contour Cardiac Output (PiCCO) is very useful mainly in the field of intensive care and treatment to grasp the pathophysiological conditions of pulmonary edema because of its capability of obtaining data such as Pulmonary Vascular Permeability Index (PVPI) and Extra Vascular Lung Water (EVLW). Furthermore, a high degree of usability of various markers has been reported for better understanding of the pathological conditions in cases with septicemia. Materials and Methods The correlation between the cardiorespiratory status based upon the PiCCO monitor (EVLW and PVPI) and inflammatory markers including C reactive protein, procalcitonin (PC), and Endotoxin Activity Assay (EAA) were evaluated in 11 severe cases that required treatment with a respirator in an intensive care unit. Results The EAA values were significantly higher in patients with abnormal EVLW at 0.46±0.20 compared to the normal EVLW group at 0.21±0.19 (p=0.0064). In a similar fashion, patients with abnormal PVPI values tended to have higher PC levels at 18.9±21.8 compared to normal PVPI cases at 2.4±2.2 (p=0.0676). On the other hand, PVPI was significantly higher in the abnormal EAA group at 3.55±0.48 in comparison with the normal EAA group at 1.99±0.68 (p=0.0029). The abnormal EAA group tended to have higher PVPI values than the normal EAA group. Conclusion The EAA is a measurement method designed to estimate the activity of endotoxins in the whole blood. Our results suggest that the EAA value, which had the greatest correlation with lung disorders diagnosed by the PiCCO monitoring, reflects inflammatory reactions predominantly in the lungs.

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Satoshi Inoue

Saitama Medical University

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