Ivan Hong Jun Koh | Universidade Federal de São Paulo (UNIFESP) (original) (raw)

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Papers by Ivan Hong Jun Koh

Research paper thumbnail of Role of Procoagulant Activity (PCA) in Allograft Rejection

Procoagulant Activity in Health and Disease, 2019

Research paper thumbnail of Estudo comparativo de duas técnicas operatórias para o tratamento cirúrgico do apêndice vermiforme: por secção e por invaginação; estudo experimental em coelhos

BV UNIFESP: Teses e dissertaçõe

Research paper thumbnail of Effects of the PARP Inhibitor Olaparib on the Response of Human Peripheral Blood Leukocytes to Bacterial Challenge or Oxidative Stress

Biomolecules

Prior studies demonstrate the activation of poly-(ADP-ribose) polymerase 1 (PARP1) in various pat... more Prior studies demonstrate the activation of poly-(ADP-ribose) polymerase 1 (PARP1) in various pathophysiological conditions, including sepsis. We have assessed the effect of olaparib, a clinically used PARP1 inhibitor, on the responses of human peripheral blood leukocytes (PBMCs) obtained from healthy volunteers in response to challenging with live bacteria, bacterial lipopolysaccharide (LPS), or oxidative stress (hydrogen peroxide, H2O2). The viability of PBMCs exposed to olaparib or to the earlier generation PARP inhibitor PJ-34 (0.1–1000 µM) was monitored using Annexin V and 7-aminoactinomycin D. To evaluate the effects of olaparib on the expression of PARP1 and its effects on protein PARylation, PBMCs were stimulated with Staphylococcus aureus with or without olaparib (1–10 μM). Changes in cellular levels of nicotinamide adenine dinucleotide (NAD+) and adenosine triphosphate (ATP), as well as changes in mitochondrial membrane potential (MMP), were measured in PBMCs exposed to H2...

Research paper thumbnail of Patterns of renal and splanchnic sympathetic vasomotor activity in an animal model of survival to experimental sepsis

Brazilian Journal of Medical and Biological Research, 2022

Sepsis causes long-term disability, such as immune dysfunction, neuropsychological disorders, per... more Sepsis causes long-term disability, such as immune dysfunction, neuropsychological disorders, persistent inflammation, catabolism, and immunosuppression, leading to a high risk of death in survivors, although the contributing factors of mortality are unknown. The purpose of this experimental study in rats was to examine renal (rSNA) and splanchnic (sSNA) sympathetic nerve activity, as well as baroreflex sensitivity, in acute and chronic post-sepsis periods. The rats were divided into two groups: control group with naïve Wistar rats and sepsis group with 2-mL intravenous inoculation of Escherichia coli at 10 8 CFU/mL. Basal mean arterial pressure, heart rate, rSNA, sSNA, and baroreflex sensitivity were evaluated in all groups at the acute (6 h) and chronic periods (1 and 3 months). Basal rSNA and sSNA were significantly reduced in the surviving rats, as was their baroreflex sensitivity, for both pressor and hypotensive responses, and this effect lasted for up to 3 months. A single episode of sepsis in rats was enough to induce long-term alterations in renal and splanchnic sympathetic vasomotor nerve activity, representing a possible systemic event that needs to be elucidated. These findings showed that post-sepsis impairment of sympathetic vasomotor response may be one of the critical components in the inability of sepsis survivors to respond effectively to new etiological illness factors, thereby increasing their risk of post-sepsis morbidity.

Research paper thumbnail of Layered double hydroxide modulates pre-osteoblast and fibroblast performance

Research paper thumbnail of Avaliação e acompanhamento do processo inflamatório em músculos de ratos por espectroscopia Raman

Research paper thumbnail of Escherichia albertii, a novel human enteropathogen, colonizes rat enterocytes and translocates to extra-intestinal sites

PloS one, 2017

Diarrhea is the second leading cause of death of children up to five years old in the developing ... more Diarrhea is the second leading cause of death of children up to five years old in the developing countries. Among the etiological diarrheal agents are atypical enteropathogenic Escherichia coli (aEPEC), one of the diarrheagenic E. coli pathotypes that affects children and adults, even in developed countries. Currently, genotypic and biochemical approaches have helped to demonstrate that some strains classified as aEPEC are actually E. albertii, a recently recognized human enteropathogen. Studies on particular strains are necessary to explore their virulence potential in order to further understand the underlying mechanisms of E. albertii infections. Here we demonstrated for the first time that infection of fragments of rat intestinal mucosa is a useful tool to study the initial steps of E. albertii colonization. We also observed that an E. albertii strain can translocate from the intestinal lumen to Mesenteric Lymph Nodes and liver in a rat model. Based on our finding of bacterial t...

Research paper thumbnail of Can Bacterial Translocation Be a Beneficial Event?

Transplantation Proceedings, 2006

Third International Symposium on Intensive Care and Emergency Medicine for Latin America plays a ... more Third International Symposium on Intensive Care and Emergency Medicine for Latin America plays a critical role in the inflammatory response and, potentially, a polymorphism in IRAK1 may alter the immune response impacting clinical outcome. P2 Gene expression and intracellular NF-κ κB activation after HMGB1 and LPS stimuli in neutrophils from septic patients

Research paper thumbnail of Relationship between sepsis intensity, Gram-negative bacterial overgrowth and bacterial translocation in rats

Critical Care, 2008

Pseudomonas aeruginosa elastase induces IL-8 production in the lung cells via the epidermal growt... more Pseudomonas aeruginosa elastase induces IL-8 production in the lung cells via the epidermal growth factor/extracellular signal-regulated proteins/NFκ κB pathway Ali Azghani P7 Significant decrease of central venous catheterassociated bloodstream infection rates in 38 German intensive care units

Research paper thumbnail of Tetracycline prophylaxis abrogates mortality following induction of inferior vena cava sepsis

Transplantation Proceedings, 2002

Research paper thumbnail of Kidney Damage After Sepsis: A Long-term Follow-up. An Experimental Study

Research paper thumbnail of Ozone Therapy in the Prevention of Dental Plaque Formation in Dogs

This study aims to assess ozonized mineral oil ointment application as an antiplaque therapy for ... more This study aims to assess ozonized mineral oil ointment application as an antiplaque therapy for dogs. Domestic healthy dogs received dental scaling and polishing under general anesthesia. Under standard feeding and homecare during 7 days, 20 dogs were randomly placed into 2 different groups for dental treatment. The control group (CG) was given a single placebo application and the ozone group (O3G) received daily ozonized ointment application. The average age (CG = 4.4; O3G = 5.7 years old), body weight (CG = 15.7; O3G = 15.3 kg) and the gingivitis index obtained on the first day (D0) allowed initial homogeneity between the groups. The dental plaque index, including clinical and computerized analysis on the seventh day, was obtained from the buccal aspect of specific dental locations. Both analyses revealed significant statistical association between daily application of ozone and antiplaque effect. There was no evidence of toxicity during the study. These results suggest that ozon...

Research paper thumbnail of Typical and atypical enteropathogenic Escherichia coli bacterial translocation associated with tissue hypoperfusion in rats

Brazilian Journal of Medical and Biological Research, 2011

Research paper thumbnail of Evaluation of Sequential Perfusion With Euro-Collins and Belzer Solutions for Pancreas Preservation in Rats

Transplantation Proceedings, 2006

Objective. To investigate the effect of Euro-Collins and Belzer solutions in a sequential preserv... more Objective. To investigate the effect of Euro-Collins and Belzer solutions in a sequential preservation of the pancreas. Methods. Forty-five Wistar-EPM rats were divided into four groups, according to the solution used during preservation: (1) saline solution (SF): animals perfused and preserved with saline solution; (2) Euro-Collins group (C): animals perfused and preserved with Euro-Collins solution; (3) Belzer group (B): animals perfused and preserved with Belzer solution; (4) Euro-Collins/Belzer group (CB): animals perfused with equal parts of Euro-Collins and Belzer solutions sequentially and preserved with Belzer solution. After perfusion, the animals underwent pancreas resection and preservation with the respective substance at 4°C. Amylase was measured in the preservation solution after 12, 24, 36, or 48 hours. Finally, the pancreas was analyzed histologically, and a statistical analysis was performed. Results. Groups SF and C showed the highest amylase levels in the preservation solution during all periods. The levels were higher than in groups C and CB (P ϭ .05). Amylase levels were similar in groups B and CB to 24 hours (P ϭ .05). Histological analysis was significant for analysis of pancreas islet cells and edema. Groups B and CB were histologically similar (P ϭ .001) and different from groups SF and C. Conclusion. Sequential perfusion using Euro-Collins and Belzer solutions was effective for pancreas preservation in rats up to 24 hours.

Research paper thumbnail of Clearance of lethal and nonlethal concentrations of bacteria from systemic circulation

Transplantation Proceedings, 1998

Research paper thumbnail of Beneficial effect of tetracycline prophylaxis in a sepsis model mimicking portal and systemic bacterial translocation routes

Transplantation Proceedings, 2002

Research paper thumbnail of Increased bacterial clearance with portal bacterial challenge compared with systemic bacterial challenge

Transplantation Proceedings, 1998

Research paper thumbnail of The mgΔlpn mouse model for Marfan syndrome recapitulates the ocular phenotypes of the disease

Experimental Eye Research

Research paper thumbnail of Modified drug release system based on Sulindac and layered double hydroxide: An in vivo Raman investigation

Vibrational Spectroscopy, 2016

Abstract In this study, the capability of a Layered Double Hydroxide (LDH) to promote the modifie... more Abstract In this study, the capability of a Layered Double Hydroxide (LDH) to promote the modified-release of Sulindac (Sul), a non-steroid anti-inflammatory drug, was followed by Raman spectroscopy through in vitro and in vivo assays. The drug and the LDH-Sul system were pressed into pellets and their dissolution under controlled conditions was monitored in vitro for 80 h. For the in vivo assays, LDH-drug and LDH-Cl (with chloride in the interlayer space) pellets were implanted between the external and internal oblique muscles of Wistar rats. The pellets were removed after 7, 21, 28 and 35 days from implantation and up to 21 days there was an increase in the amount of intercalated carbonate ions as followed over time by Raman microscopy. The carbonate ions are from the extracellular fluid (conjunctive tissue) and replace the chloride ions between the LDH layers. The same kind of ion exchange was observed for LDH-Sulindac: ca . 50% of the drug was released in vivo after 21 days, whereas in vitro the same amount of drug was delivered within 24 h. The release kinetics was much slower in the in vivo assay due to a significantly smaller hydrodynamic interaction inside the muscle.

Research paper thumbnail of Ensaios in Vitro e in Vivo De Scaffolds De Plga Incorporados Com Óleo-Resina Do Gênero Copaifera Ssp. Para Reparação De Tecidos

A Aplicação do Conhecimento Científico nas Engenharias, 2019

Perspectives on recent advances in the understanding of the phenomena involved in the tissue repa... more Perspectives on recent advances in the understanding of the phenomena involved in the tissue repair process, has increased the demand for therapeutic alternatives as well as the analysis of efficacy and safety as the stimulation of healing. The development of tissue substitutes for the treatment of severe and extensive lesions is a challenge for regenerative medicine and tissue engineering. The aims of this research was to develop a bioactive and minimally invasive biomaterial, from poly (lactic-co-glycolic acid) PLGA, bioresorbable and approved by regulatory agencies (FDA and ANVISA), which may serve as three-dimensional cell support tissue regeneration. Fibrous matrices were produced by electrospinning technique from PLGA (50:50) solutions dissolved in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP). The scaffolds was incorporated with the Copaíba oil-resin extracted from the bark of trees (Copaifera ssp.). A natural therapeutic drug from Amazon with healing, analgesia, anti-inflammation...

Research paper thumbnail of Role of Procoagulant Activity (PCA) in Allograft Rejection

Procoagulant Activity in Health and Disease, 2019

Research paper thumbnail of Estudo comparativo de duas técnicas operatórias para o tratamento cirúrgico do apêndice vermiforme: por secção e por invaginação; estudo experimental em coelhos

BV UNIFESP: Teses e dissertaçõe

Research paper thumbnail of Effects of the PARP Inhibitor Olaparib on the Response of Human Peripheral Blood Leukocytes to Bacterial Challenge or Oxidative Stress

Biomolecules

Prior studies demonstrate the activation of poly-(ADP-ribose) polymerase 1 (PARP1) in various pat... more Prior studies demonstrate the activation of poly-(ADP-ribose) polymerase 1 (PARP1) in various pathophysiological conditions, including sepsis. We have assessed the effect of olaparib, a clinically used PARP1 inhibitor, on the responses of human peripheral blood leukocytes (PBMCs) obtained from healthy volunteers in response to challenging with live bacteria, bacterial lipopolysaccharide (LPS), or oxidative stress (hydrogen peroxide, H2O2). The viability of PBMCs exposed to olaparib or to the earlier generation PARP inhibitor PJ-34 (0.1–1000 µM) was monitored using Annexin V and 7-aminoactinomycin D. To evaluate the effects of olaparib on the expression of PARP1 and its effects on protein PARylation, PBMCs were stimulated with Staphylococcus aureus with or without olaparib (1–10 μM). Changes in cellular levels of nicotinamide adenine dinucleotide (NAD+) and adenosine triphosphate (ATP), as well as changes in mitochondrial membrane potential (MMP), were measured in PBMCs exposed to H2...

Research paper thumbnail of Patterns of renal and splanchnic sympathetic vasomotor activity in an animal model of survival to experimental sepsis

Brazilian Journal of Medical and Biological Research, 2022

Sepsis causes long-term disability, such as immune dysfunction, neuropsychological disorders, per... more Sepsis causes long-term disability, such as immune dysfunction, neuropsychological disorders, persistent inflammation, catabolism, and immunosuppression, leading to a high risk of death in survivors, although the contributing factors of mortality are unknown. The purpose of this experimental study in rats was to examine renal (rSNA) and splanchnic (sSNA) sympathetic nerve activity, as well as baroreflex sensitivity, in acute and chronic post-sepsis periods. The rats were divided into two groups: control group with naïve Wistar rats and sepsis group with 2-mL intravenous inoculation of Escherichia coli at 10 8 CFU/mL. Basal mean arterial pressure, heart rate, rSNA, sSNA, and baroreflex sensitivity were evaluated in all groups at the acute (6 h) and chronic periods (1 and 3 months). Basal rSNA and sSNA were significantly reduced in the surviving rats, as was their baroreflex sensitivity, for both pressor and hypotensive responses, and this effect lasted for up to 3 months. A single episode of sepsis in rats was enough to induce long-term alterations in renal and splanchnic sympathetic vasomotor nerve activity, representing a possible systemic event that needs to be elucidated. These findings showed that post-sepsis impairment of sympathetic vasomotor response may be one of the critical components in the inability of sepsis survivors to respond effectively to new etiological illness factors, thereby increasing their risk of post-sepsis morbidity.

Research paper thumbnail of Layered double hydroxide modulates pre-osteoblast and fibroblast performance

Research paper thumbnail of Avaliação e acompanhamento do processo inflamatório em músculos de ratos por espectroscopia Raman

Research paper thumbnail of Escherichia albertii, a novel human enteropathogen, colonizes rat enterocytes and translocates to extra-intestinal sites

PloS one, 2017

Diarrhea is the second leading cause of death of children up to five years old in the developing ... more Diarrhea is the second leading cause of death of children up to five years old in the developing countries. Among the etiological diarrheal agents are atypical enteropathogenic Escherichia coli (aEPEC), one of the diarrheagenic E. coli pathotypes that affects children and adults, even in developed countries. Currently, genotypic and biochemical approaches have helped to demonstrate that some strains classified as aEPEC are actually E. albertii, a recently recognized human enteropathogen. Studies on particular strains are necessary to explore their virulence potential in order to further understand the underlying mechanisms of E. albertii infections. Here we demonstrated for the first time that infection of fragments of rat intestinal mucosa is a useful tool to study the initial steps of E. albertii colonization. We also observed that an E. albertii strain can translocate from the intestinal lumen to Mesenteric Lymph Nodes and liver in a rat model. Based on our finding of bacterial t...

Research paper thumbnail of Can Bacterial Translocation Be a Beneficial Event?

Transplantation Proceedings, 2006

Third International Symposium on Intensive Care and Emergency Medicine for Latin America plays a ... more Third International Symposium on Intensive Care and Emergency Medicine for Latin America plays a critical role in the inflammatory response and, potentially, a polymorphism in IRAK1 may alter the immune response impacting clinical outcome. P2 Gene expression and intracellular NF-κ κB activation after HMGB1 and LPS stimuli in neutrophils from septic patients

Research paper thumbnail of Relationship between sepsis intensity, Gram-negative bacterial overgrowth and bacterial translocation in rats

Critical Care, 2008

Pseudomonas aeruginosa elastase induces IL-8 production in the lung cells via the epidermal growt... more Pseudomonas aeruginosa elastase induces IL-8 production in the lung cells via the epidermal growth factor/extracellular signal-regulated proteins/NFκ κB pathway Ali Azghani P7 Significant decrease of central venous catheterassociated bloodstream infection rates in 38 German intensive care units

Research paper thumbnail of Tetracycline prophylaxis abrogates mortality following induction of inferior vena cava sepsis

Transplantation Proceedings, 2002

Research paper thumbnail of Kidney Damage After Sepsis: A Long-term Follow-up. An Experimental Study

Research paper thumbnail of Ozone Therapy in the Prevention of Dental Plaque Formation in Dogs

This study aims to assess ozonized mineral oil ointment application as an antiplaque therapy for ... more This study aims to assess ozonized mineral oil ointment application as an antiplaque therapy for dogs. Domestic healthy dogs received dental scaling and polishing under general anesthesia. Under standard feeding and homecare during 7 days, 20 dogs were randomly placed into 2 different groups for dental treatment. The control group (CG) was given a single placebo application and the ozone group (O3G) received daily ozonized ointment application. The average age (CG = 4.4; O3G = 5.7 years old), body weight (CG = 15.7; O3G = 15.3 kg) and the gingivitis index obtained on the first day (D0) allowed initial homogeneity between the groups. The dental plaque index, including clinical and computerized analysis on the seventh day, was obtained from the buccal aspect of specific dental locations. Both analyses revealed significant statistical association between daily application of ozone and antiplaque effect. There was no evidence of toxicity during the study. These results suggest that ozon...

Research paper thumbnail of Typical and atypical enteropathogenic Escherichia coli bacterial translocation associated with tissue hypoperfusion in rats

Brazilian Journal of Medical and Biological Research, 2011

Research paper thumbnail of Evaluation of Sequential Perfusion With Euro-Collins and Belzer Solutions for Pancreas Preservation in Rats

Transplantation Proceedings, 2006

Objective. To investigate the effect of Euro-Collins and Belzer solutions in a sequential preserv... more Objective. To investigate the effect of Euro-Collins and Belzer solutions in a sequential preservation of the pancreas. Methods. Forty-five Wistar-EPM rats were divided into four groups, according to the solution used during preservation: (1) saline solution (SF): animals perfused and preserved with saline solution; (2) Euro-Collins group (C): animals perfused and preserved with Euro-Collins solution; (3) Belzer group (B): animals perfused and preserved with Belzer solution; (4) Euro-Collins/Belzer group (CB): animals perfused with equal parts of Euro-Collins and Belzer solutions sequentially and preserved with Belzer solution. After perfusion, the animals underwent pancreas resection and preservation with the respective substance at 4°C. Amylase was measured in the preservation solution after 12, 24, 36, or 48 hours. Finally, the pancreas was analyzed histologically, and a statistical analysis was performed. Results. Groups SF and C showed the highest amylase levels in the preservation solution during all periods. The levels were higher than in groups C and CB (P ϭ .05). Amylase levels were similar in groups B and CB to 24 hours (P ϭ .05). Histological analysis was significant for analysis of pancreas islet cells and edema. Groups B and CB were histologically similar (P ϭ .001) and different from groups SF and C. Conclusion. Sequential perfusion using Euro-Collins and Belzer solutions was effective for pancreas preservation in rats up to 24 hours.

Research paper thumbnail of Clearance of lethal and nonlethal concentrations of bacteria from systemic circulation

Transplantation Proceedings, 1998

Research paper thumbnail of Beneficial effect of tetracycline prophylaxis in a sepsis model mimicking portal and systemic bacterial translocation routes

Transplantation Proceedings, 2002

Research paper thumbnail of Increased bacterial clearance with portal bacterial challenge compared with systemic bacterial challenge

Transplantation Proceedings, 1998

Research paper thumbnail of The mgΔlpn mouse model for Marfan syndrome recapitulates the ocular phenotypes of the disease

Experimental Eye Research

Research paper thumbnail of Modified drug release system based on Sulindac and layered double hydroxide: An in vivo Raman investigation

Vibrational Spectroscopy, 2016

Abstract In this study, the capability of a Layered Double Hydroxide (LDH) to promote the modifie... more Abstract In this study, the capability of a Layered Double Hydroxide (LDH) to promote the modified-release of Sulindac (Sul), a non-steroid anti-inflammatory drug, was followed by Raman spectroscopy through in vitro and in vivo assays. The drug and the LDH-Sul system were pressed into pellets and their dissolution under controlled conditions was monitored in vitro for 80 h. For the in vivo assays, LDH-drug and LDH-Cl (with chloride in the interlayer space) pellets were implanted between the external and internal oblique muscles of Wistar rats. The pellets were removed after 7, 21, 28 and 35 days from implantation and up to 21 days there was an increase in the amount of intercalated carbonate ions as followed over time by Raman microscopy. The carbonate ions are from the extracellular fluid (conjunctive tissue) and replace the chloride ions between the LDH layers. The same kind of ion exchange was observed for LDH-Sulindac: ca . 50% of the drug was released in vivo after 21 days, whereas in vitro the same amount of drug was delivered within 24 h. The release kinetics was much slower in the in vivo assay due to a significantly smaller hydrodynamic interaction inside the muscle.

Research paper thumbnail of Ensaios in Vitro e in Vivo De Scaffolds De Plga Incorporados Com Óleo-Resina Do Gênero Copaifera Ssp. Para Reparação De Tecidos

A Aplicação do Conhecimento Científico nas Engenharias, 2019

Perspectives on recent advances in the understanding of the phenomena involved in the tissue repa... more Perspectives on recent advances in the understanding of the phenomena involved in the tissue repair process, has increased the demand for therapeutic alternatives as well as the analysis of efficacy and safety as the stimulation of healing. The development of tissue substitutes for the treatment of severe and extensive lesions is a challenge for regenerative medicine and tissue engineering. The aims of this research was to develop a bioactive and minimally invasive biomaterial, from poly (lactic-co-glycolic acid) PLGA, bioresorbable and approved by regulatory agencies (FDA and ANVISA), which may serve as three-dimensional cell support tissue regeneration. Fibrous matrices were produced by electrospinning technique from PLGA (50:50) solutions dissolved in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP). The scaffolds was incorporated with the Copaíba oil-resin extracted from the bark of trees (Copaifera ssp.). A natural therapeutic drug from Amazon with healing, analgesia, anti-inflammation...