Evaluation of the Effect of Perfluorohexane Sulfonate on the Proliferation of Human Liver Cells

Perfluorohexane sulfonate (PFHxS) is a widely detected replacement for legacy long-chain perfluoroalkyl substances (PFAS) in the environment and human blood samples. Its potential toxicity led to its recent classification as a globally regulated persistent organic pollutant. Although animal studies have shown a positive association between PFHxS levels and hepatic steatosis and hepatocellular hypertrophy, the link with liver toxicity, including end-stage liver cancer, remains inconclusive. In this study, we examined the effects of PFHxS on the proliferation of Hep3B (human hepatocellular carcinoma) and SK-Hep1 (human liver sinusoidal endothelial cells). Cells were exposed to different PFHxS concentrations for 24-48 h to assess viability and 12-14 days to measure colony formation. The viability of both cell lines increased at PFHxS concentrations <200 μM, decreased at >400 μM, and was highest at 50 μM. Colony formation increased at <300 μM and decreased at 500 μM PFHxS. Consistent with the effect on cell proliferation, PFHxS increased the expression of proliferating cell nuclear antigen (PCNA) and cell-cycle molecules (CDK2, CDK4, cyclin E, and cyclin D1). In summary, PFHxS exhibited a biphasic effect on liver cell proliferation, promoting survival and proliferation at lower concentrations and being cytotoxic at higher concentrations. This suggests that PFHxS, especially at lower concentrations, might be associated with HCC development and progression.

High Levels of Hyaluronic Acid Synthase-2 Mediate NRF2-Driven Chemoresistance in Breast Cancer Cells

Hyaluronic acid (HA), a ligand of CD44, accumulates in some types of tumors and is responsible for tumor progression. The nuclear factor erythroid 2-like 2 (NRF2) regulates cytoprotective genes and drug transporters, which promotes therapy resistance in tumors. Previously, we showed that high levels of CD44 are associated with NRF2 activation in cancer stem like-cells. Herein, we demonstrate that HA production was increased in doxorubicin-resistant breast cancer MCF7 cells (MCF7-DR) via the upregulation of HA synthase-2 (HAS2). HA incubation increased NRF2, aldo-keto reductase 1C1 (AKR1C1), and multidrug resistance gene 1 (MDR1) levels. Silencing of HAS2 or CD44 suppressed NRF2 signaling in MCF7-DR, which was accompanied by increased doxorubicin sensitivity. The treatment with a HAS2 inhibitor, 4-methylumbelliferone (4-MU), decreased NRF2, AKR1C1, and MDR1 levels in MCF7-DR. Subsequently, 4-MU treatment inhibited sphere formation and doxorubicin resistance in MCF7-DR. The Cancer Genome Atlas (TCGA) data analysis across 32 types of tumors indicates the amplification of HAS2 gene is a common genetic alteration and is negatively correlated with the overall survival rate. In addition, high HAS2 mRNA levels are associated with increased NRF2 signaling and poor clinical outcome in breast cancer patients. Collectively, these indicate that HAS2 elevation contributes to chemoresistance and sphere formation capacity of drug-resistant MCF7 cells by activating CD44/NRF2 signaling, suggesting a potential benefit of HAS2 inhibition.

Perfluorohexane sulfonate induces memory impairment and downregulation of neuroproteins via NMDA receptor-mediated PKC-ERK/AMPK signaling pathway

Perfluorohexane sulfonate (PFHxS) is a widely used industrial chemical detected in human umbilical cord blood and breast milk, and has been suggested to exhibit developmental neurotoxicity. Previous studies on mice reported that neonatal exposure to PFHxS altered neuroprotein levels in the developing brain, and caused behavioral toxicity and cognitive dysfunction in the mature brain. However, the underlying mechanisms responsible for PFHxS-induced neuroprotein dysregulation are poorly understood. In this study, we examined the effect of neonatal exposure to PFHxS on memory function using an in vivo mice model. Furthermore, we examined the levels of growth associated protein-43 (GAP-43) and calcium/calmodulin dependent protein kinase II (CaMKII) (biomarkers of neuronal development) and the involved signaling pathways using differentiated neuronal PC12 cells. PFHxS decreased cell viability, GAP-43 and CaMKII levels, and neurite formation. These effects were mediated by the NMDA receptor, PKC-α, PKC-δ, AMPK and ERK pathways. MK801, an NMDA receptor antagonist, reduced the activation of PKC-α, PKC-δ, ERK and AMPK. The activation of ERK was suppressed by pharmacological and knockdown inhibition of PKC-α and -δ. Interestingly, the AMPK pathway was selectively inhibited by inhibiting PKC-δ but not PKC-ɑ. Consistent with PFHxS-induced neuronal death, and GAP-43 and CaMKII downregulation, neonatal exposure to PFHxS caused significant memory impairment in adult mice. Collectively, these results demonstrate that PFHxS induces persistent developmental neurotoxicity, as well as GAP-43 and CaMKII downregulation via the NMDA receptor-mediated PKCs (α and δ)-ERK/AMPK pathways.

Perfluorooctane sulfonate and bisphenol A induce a similar level of mast cell activation via a common signaling pathway, Fyn-Lyn-Syk activation

Perfluoroalkyl compounds (PFCs) as food contaminants are widely distributed persistent organic pollutants (POPs) and have been suggested to induce immune dysfunction. However, their effects on immune function are not conclusive. Mast cells play a central role in allergic and non-allergic inflammatory responses. Therefore, we have examined the effects of PFCs (PFHxS, PFOA, PFOS) on mast cell-mediated inflammatory responses using in vitro mouse bone marrow-derived mast cells (BMMCs) and human mast cells (HMC-1) and in vivo mice model. The effects of PFCs were compared with those of bisphenol A (BPA), a well-studied environmental pollutant. Among PFCs tested, PFOS had the highest effects. Both PFOS and BPA increased degranulation and production of inflammatory eicosanoids in mast cells at a similar level, which subsequently led to increased skin edema and serum LTC₄ and PGD₂ in mice. Both PFOS and BPA increased not only downstream signaling (PLCγ1, AKT, ERK), but also upstream signaling (Fyn, Lyn, Syk/LAT) in mast cells. Taken together, PFOS and BPA induce mast cell-mediated inflammatory responses via a common signaling pathways. Our results may help establish the scientific basis for understanding the etiology of mast cell-mediated inflammatory responses and improve the immune dysfunction risk assessment for emerging POPs such as PFCs.

Acrylamide and its metabolite induce neurotoxicity via modulation of protein kinase C and AMP-activated protein kinase pathways

Acrylamide is known as a neurotoxicant found in commonly consumed food as well as in human body. However, the underlying mechanisms involved in neurotoxicity by acrylamide and its metabolite, glycidamide remain largely unknown. In this study, we have examined the interplay between CYP2E1, AMPK, ERK and PKC in acrylamide-induced neurotoxicity associated with autophagy in PC12 cells. Acrylamide-induced cell death was mediated by CYP2E1 expression and the activation of ERK, PKC-ɑ and PKC-δ, whereas AMPK knockdown exacerbated the acrylamide-induced neurotoxic effects. PKC-ɑ, but not PKC-δ, plays an upstream regulator of ERK and AMPK. Moreover, AMPK activation suppressed ERK, and CYP2E1 and AMPK bilaterally inhibit each other. Furthermore, acrylamide increased autophagy with impaired autophagic flux, evidenced by the increased beclin-1, LC3-II and p62 protein. Acrylamide-induced neuronal death was ameliorated by 3-methyladenine, an autophagy inhibitor, whereas neuronal death was exacerbated by chloroquine, a lysosomal inhibitor. Interestingly, PKC-δ siRNA, but not PKC-ɑ siRNA, dramatically reduced acrylamide-induced beclin-1 and LC3-II levels, whereas AMPK siRNA further increased beclin-1, LC3-II and p62 protein levels. Glycidamide, a major metabolite, mimicked acrylamide only with a higher potency. Taken together, acrylamide- and glycidamide-induced neurotoxicity may involve cytotoxic autophagy, which is mediated by interplay between PKCs and AMPK pathways.

Cilostazol protects hepatocytes against alcohol-induced apoptosis via activation of AMPK pathway

Alcoholic liver disease (ALD) is a worldwide health problem and hepatocyte apoptosis has been associated with the development/progression of ALD. However, no definite effective pharmacotherapy for ALD is currently available. Cilostazol, a selective type III phosphodiesterase inhibitor has been shown to protect hepatocytes from ethanol-induced apoptosis. In the present study, the underlying mechanisms for the protective effects of cilostazol were examined. Primary rat hepatocytes were treated with ethanol in the presence or absence of cilostazol. Cell viability and intracellular cAMP were measured. Apoptosis was detected by Hoechst staining, TUNEL assay, and caspase-3 activity assay. The roles of cAMP and AMP-activated protein kinase (AMPK) pathways in the action of CTZ were explored using pharmacological inhibitors and siRNAs. Liver from mice received ethanol (5 g/kg body weight) by oral gavage following cilostazol treatment intraperitoneally was obtained for measurement of apoptosis and activation of AMPK pathway. Cilostazol inhibited ethanol-induced hepatocyte apoptosis and potentiated the increases in cAMP level induced by forskolin. However, the anti-apoptotic effect of cilostazol was not reversed by an inhibitor of adenylyl cyclase. Interestingly, cilostazol activated AMPK and increased the level of LC3-II, a marker of autophagy. The inhibition of AMPK abolished the effects of cilostazol on LC3-II expression and apoptosis. Moreover, the inhibition of LKB1 and CaMKK2, upstream kinases of AMPK, dampened cilostazol-inhibited apoptosis as well as AMPK activation. In conclusion, cilostazol protected hepatocytes from apoptosis induced by ethanol mainly via AMPK pathway which is regulated by both LKB1 and CaMKK2. Our results suggest that cilostazol may have potential as a promising therapeutic drug for treatment of ALD.

Carotid intima media thickness and high sensitivity C-reactive protein as markers of cardiovascular risk in a malaysian population

INTRODUCTION

Carotid intima media thickness (CIMT) being a cost effective and easily performed technique is useful in the detection of subclinical atherosclerosis and has been shown to be a prognosticator of cardiovascular events. The primary objective of this study was to obtain the distribution of CIMT measurements, highly sensitive C reactive protein (hs-CRP) and assessing health awareness and attitudes of the Malaysian population at cardiovascular disease (CVD) risk and not receiving lipid lowering agents. Secondarily the study sought to assess the significance of the relationship between these measurements against various patient characteristics.

METHODS

Measurements of CIMT are obtained by ultrasonography of 12 sites within the common carotid artery was recorded for 123 subjects from a single centre tertiary hospital of Malaysia who had two or more CVD risk factors but were not receiving lipid lowering therapy. CVD risk factors and lipid and glucose profiles were analyzed with respect to distribution of CIMT and high-sensitivity Creactive protein (hs-CRP) values.

RESULTS

The mean-max CIMT was 0.916±0.129mm (minimum 0.630mm, maximum 1.28mm) and the mean-mean CIMT was 0.743±0.110mm (minimum 0.482mm, maximum 1.050mm) and mean hs-CRP was 0.191mg/dL (minimum 0.030mg/dL, maximum 5.440mg/dL). Multivariate analyses confirmed a significant association between increasing CIMT and increasing age, total and low density lipoprotein cholesterol while log-transformed hs-CRP levels showed significant association with increasing body mass index, waist circumference, high blood glucose and triglyceride levels. Our patients had good health awareness on CVD.

CONCLUSION

Newly defined CIMT measurements and hs-CRP levels may be useful adjunctive tools to screen for atherosclerosis in the Malaysian population. It may help in refining risk stratification on top of traditional clinical assessment.

Radiation-induced eye lens changes and risk for cataract in interventional cardiology

BACKGROUND

Recent studies have reported a significant increase in eye lens opacities among staff in the cardiac catheterization laboratory but indicated further studies are needed to confirm the findings.

OBJECTIVE

To evaluate the prevalence of opacities in eyes of cardiologists, radiographers and nurses working in interventional cardiology.

METHODS

The eyes of 52 staff in interventional cardiology facilities and 34 age- and sex-matched unexposed controls were screened in a cardiology conference held in Kuala Lumpur by dilated slit-lamp examination, and posterior lens changes were graded. Individual cumulative lens X-ray exposures were calculated from responses to a questionnaire in terms of workload and working practice.

RESULTS

The prevalence of posterior lens opacities among interventional cardiologists was 53%, while in nurses and radiographers it was 45%. Corresponding relative risks were 2.6 (95% CI: 1.2-5.4) and 2.2 (95% CI: 0.98-4.9), for interventional cardiologists and support staff, respectively.

CONCLUSIONS

This study confirms a statistically significant increase in radiation-associated posterior lens changes in the eyes of interventional cardiology staff.

New oral anticoagulants for venous thromboembolism (VTE) prophylaxis

Venous thromboembolism is a rising concern in Asia especially among patients after surgery where this complication is readily preventable. Despite the availability of several treatment options, the acceptance of prophylaxis and usage of these methods remain low. A possible explanation to this behavior is the limitations attached to the available treatment options: narrow therapeutic window of warfarin and parenteral administration of low molecular weight as well as unfractionated heparins. Newer agents have been researched and introduced to overcome these limitations in the hope of improving the adaptation towards post surgical thromboprophylaxis. Dabigatran and rivaroxaban are two such new agents that are promising in view of efficacy and ease of administration.

Cardiovascular diagnostics mining on Borneo island: from labour-intensive to prototype

Mining for medical data poses different challenges compared with mining other types of data. The wide range of imaging modalities of medical data leads to data integration and compatibility issues. The analysis of imaging modalities is further complicated by the different format and attributes used by the different imaging equipment by different vendors. Human factors such as interest of adapting data mining into diagnosis and planning process raised the difficulty of engaging the users into the development of a practical and useful data miner. Requirement engineering technique prototyping further enhanced the engagement of users towards the data-miner. Data from different equipment and different vendors are also merged for efficient data analysis and subsequently charting and reporting. We have also successfully engaged the medical doctors into believing the data miner's capability after they reviewed and walkthrough the prototype.

Acute coronary syndrome (ACS) registry--leading the charge for National Cardiovascular Disease (NCVD) Database

Coronary artery disease is one of the most rampant non-communicable diseases in the world. It begins indolently as a fatty streak in the lining of the artery that soon progresses to narrow the coronary arteries and impair myocardial perfusion. Often the atherosclerotic plaque ruptures and causes sudden thrombotic occlusion and acute ST-elevation myocardial infarction (STEMI), non-ST-elevation MI (NSTEMI) or unstable angina (UA). This phenomenon is called acute coronary syndrome (ACS) and is the leading cause of death not only in Malaysia but also globally. In order for us to tackle this threat to the health of our nation we must arm ourselves with reliable and accurate information to assess current burden of disease resources available and success of current strategies. The acute coronary syndrome (ACS) registry is the flagship of the National Cardiovascular Disease Database (NCVD) and is the result of the dedicated and untiring efforts of doctors and nurses in both public and private medical institutions and hospitals around the country, ably guided and supported by the National Heart Association, the National Heart Foundation, the Clinical Research Centre and the Ministry of Health of Malaysia. Analyses of data collected throughout 2006 from 3422 patients with ACS admitted to the 12 tertiary cardiac centres and general hospitals spanning nine states in Malaysia in this first report has already revealed surprising results. Mean age of patients was 59 years while the most consistent risk factor for STEMI was active smoking. Utilization of medications was high generally. Thirty-day mortality for STEMI was 11%, for NSTEMI 8% and UA 4%. Thrombolysis (for STEMI only) reduced in-hospital and 30-day mortality by nearly 50%. Percutaneous coronary intervention or PCI also reduced 30-day mortality for patients with non-ST elevation MI and unstable angina. The strongest determinants of mortality appears to be Killip Class and age of the patient. Fewer women received thrombolysis or underwent PCI on same admission although women make up 25% of the cohort.

The foundation of NCVD PCI Registry: the Malaysia's first multi-centre interventional cardiology project

The National Cardiovascular Database for Percutaneous Coronary Intervention (NCVD PCI) Registry is the first multicentre interventional cardiology project, involving the main cardiac centres in the country. The ultimate goal of NCVD PCI is to provide a contemporary appraisal of PCI in Malaysia. This article introduces the foundation, the aims, methodology, database collection and preliminary results of the first six-month database.

Managing congestive heart failure in a general hospital in Malaysia. Are we keeping pace with evidence?

Evidence-based heart failure management now includes beta-blockers and spironolactone in addition to diuretics and angiotensin-converting enzyme inhibitors. We aim to determine if these recommendations had been applied in practice for acute and chronic stable heart failure, and what difficulties there might be. Data from 80 consecutive patients hospitalized for decompensated heart failure ('acute') between May and July 2003 were analyzed at admission, upon discharge and at 12 weeks follow-up; along with 74 cardiology clinic out-patients with stable congestive heart failure ('chronic'- no decompensation or admission in previous six months). Less than half of study patients with prior left ventricular dysfunction were on ACE-inhibitors (47%), diuretics (39%), ATII antagonists, spironolactone or digoxin (5% each). All 'acute' patients were commenced on diuretics and ACE-inhibitors in hospital. Six patients died or transferred to another center. Compliance with clinic appointment at 12 weeks was 85% despite telephone reminders. Drug prescription at 12 weeks was significantly lower for diuretics and ACE-inhibitors compared to prescription at discharge (all p < 0.05) but higher compared to patients with chronic HF. Diuretics and ACE inhibitors remain under-utilized for patients with recurrent heart failure. Use of spironolactone and beta-blocker is slow due to limited medical experience and funding. Clinic non-attendance is significant and due to patient factors.

Feasibility and accuracy of 64-row MDCT coronary imaging from a centre with early experience: a review and comparison with established centres

The accuracy of multi-detector computed tomographic (MDCI) coronary angiography (CTA) is dependant on image quality as well as the experience of the operator. Established centers have reported negative predictive values of over 95%. The aim of our study was to investigate the accuracy and feasibility of CTA for the assessment of haemodynamically significant coronary stenosis in a center with very early experience (<6 months) utilizing the improved spatial and temporal resolutions of the latest generation 64-row MDCI scanner. One hundred and twenty eight patients (93 male, 35 female; mean age 56.2 +/- 9.5 years) with suspected or known coronary artery disease underwent both CIA and conventional coronary angiographv (CCA). The sensitivity, specificity, positive (PPV) and negative (NPV) predictive values for stenoses > or =50% by CIA compared to CCA were 70%, 97%, 70% and 97% respectively. Evaluation of main and proximal segments in patients with good quality images (78% of patients) produced values of 94%, 95%, 74% and 99% respectively. The improved spatial and temporal resolutions of 64-row MJ) CT provided a high negative predictive value in assessing significant coronary artery stenosis even in a centre with very early experience. However, new centers embarking on CTA might not be able to reproduce the results reported by more experienced centers.

Early diagnosis of traumatic aortic valve rupture in ICU patients using transoesophageal echocardiography

A case is presented of a 60-year-old man who sustained spinal and chest wall injuries following a collision between his glider and an aeroplane. The severity of his injuries required him to be managed with bilateral underwater seal drains, cervical spine stabilisation and sedation with mechanical ventilation. Due to the severity of his chest trauma, a transoesophageal echocardiograph was performed which revealed a partial dehiscence and prolapse of the left coronary cusp of the aortic valve with mild to moderate aortic regurgitation. Despite conservative treatment, severe cardiac failure developed six days later requiring aortic valve replacement. After a prolonged stay in the Intensive Care Unit during which the patient developed acute respiratory distress syndrome, methicillin resistant Staphylococcus aureus pneumonia and Enterobacter septicaemia, the patient was discharged, returning to his pre-admission lifestyle. In patients with complex and severe chest trauma, transoesophageal echocardiography is of great benefit, not only in allowing good image quality, compared with transthoracic echocardiography, but having a greater reliability and accuracy in diagnosing cardiac and mediastinal trauma in complex monitoring environments.

Xenotransplantation: A potential solution to the critical organ donor shortage

The success of allotransplantation as a treatment for end-stage organ failure has resulted in the need for an increasing number of organ donors. Attempts to meet this need include the use of organs from living related and unrelated donors, financial or other incentives for the donor family, and even the reuse of transplanted organs. Despite these initiatives, the supply of organs for transplantation still falls far short of the demand, as evidenced by longer waiting times for transplantation and decreasing transplantation rates. Even if Canada were able to increase its organ donor rate to that of Spain (40 to 50/million), where organ donation is governed by 'presumed consent' legislation, this would not alleviate the problem of donor shortage. Interest in xenotransplantation stems from the need to overcome this increasingly severe shortage of human organs. Indeed, some argue that xenotransplantation is the only potential way of addressing this shortage. As immunological barriers to xenotransplantation are better understood, those hurdles are being addressed through genetic engineering of donor animals and the development of new drug therapies. However, before xenotransplantation can be fully implemented, both the scientific/medical communities and the general public must seriously consider and attempt to resolve the many complex ethical, social and economic issues that it presents.