Complete Retinal Pigment Epithelial and Outer Retinal Atrophy in Age-Related Macular Degeneration: A Longitudinal Evaluation

PURPOSE

There is a need for robust earlier biomarkers of atrophic age-related macular degeneration (AMD) that could act as surrogate endpoints for the geographic atrophy (GA) in early interventional trials. This study sought to examine the risk of progression of complete retinal pigment epithelium and outer retinal atrophy (cRORA) to the traditional atrophic endpoint of GA on color fundus photography (CFP). This study also compared the risk of progression for cRORA to that associated with the specific OCT features that define nascent GA (nGA), a strong predictor for GA development.

METHODS

One-hundred and forty participants with bilateral large drusen at baseline underwent OCT imaging and CFP at 6-monthly intervals for up to 36 months. OCT volume scans were graded for the presence of cRORA and nGA, and CFPs were graded for the presence of GA. The association and rate of progression to GA for cRORA and nGA were examined.

RESULTS

Both cRORA and nGA were significantly associated with GA development (adjusted hazard ratio [HR], 65.7 and 76.8 respectively; both P<0.001). The probability of progression of cRORA to GA over 24-months (26%) was significantly lower than the probability for progression of nGA (38%; P=0.039).

CONCLUSIONS

This study confirmed that cRORA was a significant risk factor for developing GA, although its rate of progression was slightly lower compared to nGA. Whilst requiring replication in future studies, these findings suggest that the specific features of photoreceptor degeneration used to define nGA appear important when assessing risk of progression.

HYPERREFLECTIVE FOCI NOT SEEN AS HYPERPIGMENTARY ABNORMALITIES ON COLOR FUNDUS PHOTOGRAPHS IN AGE-RELATED MACULAR DEGENERATION

PURPOSE

To investigate the prognostic value of quantifying optical coherence tomography (OCT)-defined hyperreflective foci (HRF) that do not correspond to hyperpigmentary abnormalities (HPAs) on color fundus photographs (CFPs)-HRF (OCT+/CFP-) -when considered in addition to HPA extent, for predicting late age-related macular degeneration development. This study sought to understand the impact of HRF (OCT+/CFP-) extent on visual sensitivity.

METHODS

Two hundred eighty eyes from 140 participants with bilateral large drusen underwent imaging and microperimetry at baseline, and then 6-monthly for 3-years. The extent of HPAs on CFPs and HRF (OCT+/CFP-) on OCT was quantified at baseline. Predictive models for progression to late age-related macular degeneration, accounting for drusen volume and age, were developed using HPA extent, with and without HRF (OCT+/CFP-) extent. The association between HPA and HRF (OCT+/CFP-) extent with sector-based visual sensitivity was also evaluated.

RESULTS

Incorporating HRF (OCT+/CFP-) extent did not improve the predictive performance for late age-related macular degeneration development ( P ≥ 0.32). Increasing HPA and HRF (OCT+/CFP-) extent in each sector were independently and significantly associated with reduced sector-based visual sensitivity ( P ≤ 0.004).

CONCLUSION

The addition of HRF (OCT+/CFP-) extent to HPA extent did not improve the prediction of late age-related macular degeneration development. HRF (OCT+/CFP-) extent was also independently associated with local reductions in visual sensitivity, after accounting for HPAs.

Hyperpigmentary abnormalities in age-related macular degeneration: association with progression and impact on visual sensitivity

BACKGROUND/AIMS

To investigate the additional prognostic value of quantifying the extent of colour fundus photography (CFP)-defined hyperpigmentary abnormalities (HPAs) compared with their presence alone for predicting progression to late-stage age-related macular degeneration (AMD) and to understand their association with visual sensitivity in individuals with intermediate AMD.

METHODS

140 participants with bilateral large drusen underwent multimodal imaging and microperimetry at baseline and then every 6 months for up to 3 years. Baseline CFPs were graded for the presence of HPAs and their extent was quantified. Optical coherence tomography (OCT) scans were used to quantify drusen volume. Predictive models for progression to late AMD (including OCT signs of atrophy) were developed using either HPA presence or extent. The association between HPA extent with mean visual sensitivity (both overall and sector based) was also evaluated. All models were adjusted for the confounders of baseline age and drusen volume.

RESULTS

The predictive performance for late AMD development was not significantly different for HPA presence or extent (p=0.92). Increasing HPA extent in each sector, but not its overall extent in an eye, was associated with reduced sector-based visual sensitivity (p<0.001 and p=0.671, respectively).

CONCLUSION

In a cohort with bilateral large drusen, quantifying HPA extent did not improve the prediction of late AMD development compared with presence alone. HPA extent was associated with more local, rather than generalised, reductions in visual sensitivity. These findings suggest that quantification of HPA extent adds little to the prediction of AMD progression, but that it provides an imaging biomarker of visual dysfunction.

Age-dependent mechanical properties of tail tendons in wild-type and mimecan gene-knockout mice - A preliminary study

Mimecan, or osteoglycin, belongs to the family of small leucine-rich proteoglycans. In connective tissues mimecan is implicated in the development and maintenance of normal collagen fibrillar organization. Since collagen fibrils are responsible for tissue reinforcement, the absence of mimecan could lead to abnormal tissue mechanical properties. Here, we carried out a preliminary investigation of possible changes in the mechanical properties of tendons in mice lacking a functional mimecan gene, as a function of age. Tail tendons were dissected from mimecan gene knockout (KO) and wild type (WT) mice at ages 1, 4 and 8 months and mechanical properties evaluated using a microtensile testing equipment. Mimecan gene knockout resulted in changes in tendon elasticity- and fracture-related properties. While tendons of WT mice exhibited enhanced mechanical properties with increasing age, this trend was notably attenuated in mimecan KO tendons, with the exception of fracture strain. When genotype and age were considered as cross factors, the diminution in the mechanical properties of mimecan KO tendons was significant for yield strength, modulus and fracture strength. This effect appeared to affect the mice at 4 month old. These preliminary results suggest that mimecan may have a role in regulating age-dependent mechanical function in mouse tail tendon.

Incomplete Retinal Pigment Epithelial and Outer Retinal Atrophy: Longitudinal Evaluation in Age-Related Macular Degeneration

PURPOSE

To examine the association between incomplete retinal pigment epithelial and outer retinal atrophy (iRORA) on OCT imaging and the subsequent risk of developing geographic atrophy (GA) defined on conventional color fundus photography (CFP) and to compare this with the specific features that define nascent GA (nGA).

DESIGN

Retrospective analysis of data from a longitudinal study.

PARTICIPANTS

A total of 280 eyes from 140 participants with bilateral large drusen without specific nGA-defining features or late age-related macular degeneration (AMD) at baseline.

METHODS

OCT imaging and CFP were performed at baseline and then at 6-month intervals for up to 36 months. Eyes that developed neovascular AMD were censored on the day it was detected. OCT volume scans were graded for the presence of iRORA and nGA separately, and CFP images were graded for the presence of GA.

MAIN OUTCOME MEASURES

Association with and variance explained in time to GA development.

RESULTS

A total of 58 eyes (21%) from 46 participants (33%) had iRORA at baseline, and a further 87 eyes (31%) developed iRORA over the follow-up period. Time-to-event analyses demonstrated that prevalent or incident iRORA was associated with an increased rate of GA development (adjusted hazard ratio [HR], 12.1; P = 0.021), as was incident nGA (adjusted HR, 78.6; P < 0.001). However, only the specific nGA features (adjusted P < 0.001), and not iRORA (adjusted P = 0.520), were associated with an increased rate of GA development when both features were included in the same multivariable model. The proportion of variance explained in the time to GA development by iRORA itself (R² = 43%) was significantly lower than explained by nGA alone (R² = 91%; P = 0.010).

CONCLUSIONS

In this cohort, iRORA is a significant risk factor for GA development, but its association with GA development appears to be accounted for by the development of the specific features that define nGA. Although requiring replication, these findings provide useful guidance on the relative utility of nGA and iRORA as risk factors for GA and as potential surrogate end points for future interventional studies in the early stages of AMD.

Cuticular Drusen in Age-Related Macular Degeneration: Association with Progression and Impact on Visual Sensitivity

PURPOSE

To determine the prognostic significance and impact on visual function of the cuticular drusen phenotype in a cohort with intermediate age-related macular degeneration (AMD).

DESIGN

Longitudinal observational study.

PARTICIPANTS

Participants aged 50 years or older, with bilateral large conventional drusen, without late AMD.

METHODS

Multimodal imaging (MMI) and microperimetry were performed at baseline, and then every 6 months for up to 3 years. Eyes were graded for the MMI-presence of cuticular drusen at baseline. Color fundus photographs were used to grade for the presence of pigmentary abnormalities. Optical coherence tomography (OCT) scans were used to calculate drusen volume. The association between cuticular drusen and progression to MMI-defined late AMD (including OCT signs of atrophy), as well as the impact on visual sensitivity were examined, with and without adjustment for the confounders of baseline age, pigmentary abnormalities and drusen volume.

MAIN OUTCOME MEASURES

Time to develop MMI-defined late AMD and change in mean visual sensitivity.

RESULTS

280 eyes from 140 participants were included, with 70 eyes from 35 (25%) individuals having cuticular drusen at baseline. Cuticular drusen were not significantly associated with an increased rate of progression to late AMD, with and without adjustment for confounders (P ≥ 0.784 for both). In an adjusted model, cuticular drusen were not associated with lower baseline visual sensitivity (P = 0.758) or with a faster rate of visual sensitivity decline (P = 0.196).

CONCLUSIONS

In a cohort with bilateral large conventional drusen, individuals with the cuticular drusen phenotype neither had a higher, nor lower, risk of developing late AMD over 3 years, and were not associated with a difference in rate of visual sensitivity decline compared to those without this phenotype. As such, individuals with this phenotype currently warrant similar monitoring strategies to those with conventional drusen.

A clinical perspective on the expanding role of artificial intelligence in age-related macular degeneration

In recent years, there has been intense development of artificial intelligence (AI) techniques, which have the potential to improve the clinical management of age-related macular degeneration (AMD) and facilitate the prevention of irreversible vision loss from this condition. Such AI techniques could be used as clinical decision support tools to: (i) improve the detection of AMD by community eye health practitioners, (ii) enhance risk stratification to enable personalised monitoring strategies for those with the early stages of AMD, and (iii) enable early detection of signs indicative of possible choroidal neovascularisation allowing triaging of patients requiring urgent review. This review discusses the latest developments in AI techniques that show promise for these tasks, as well as how they may help in the management of patients being treated for choroidal neovascularisation and in accelerating the discovery of new treatments in AMD.

Hyporeflective Cores within Drusen: Association with Progression of Age-Related Macular Degeneration and Impact on Visual Sensitivity

PURPOSE

To examine the association between hyporeflective cores within drusen (HCD) and disease progression in age-related macular degeneration (AMD) and with visual function.

DESIGN

Longitudinal observational study.

PARTICIPANTS

280 eyes from 140 participants with bilateral large drusen, without late AMD.

METHODS

Multimodal imaging (MMI) and microperimetry were performed at baseline, and then every 6 months for up to 3 years. Baseline optical coherence tomography (OCT) scans were graded for the presence of HCD and used to calculate drusen volume. The total area of the drusenoid lesions containing hyporeflective cores (HCD extent) on color fundus photographs (CFPs) was calculated. CFPs were also graded for the presence of pigmentary abnormalities. The association between HCD extent with progression to late AMD (including OCT signs of atrophy) and visual sensitivity measured by microperimetry at baseline and its rate of change over time was evaluated, with and without adjustment for confounders of drusen volume, pigmentary abnormalities, and age.

MAIN OUTCOME MEASURES

Time to develop late AMD and visual sensitivity.

RESULTS

Twenty (7%) eyes from 12 (9%) individuals were found to have HCD at baseline, which was associated with a non-significantly increased rate of progression to late AMD (unadjusted P = 0.050). HCD extent was significantly associated with an increased rate of progression to late AMD (unadjusted P = 0.034) and lower visual sensitivity at baseline (unadjusted P < 0.001). However, these associations were no longer significant (P ≥ 0.264 for both) after adjusting for known risk factors for AMD progression. HCD extent was also not associated with a faster rate of visual sensitivity decline prior to the development of late AMD, with or without adjustment (P ≥ 0.674 for both). Increasing age and larger drusen volume was associated with HCD extent (P ≤ 0.041).

CONCLUSIONS

In a cohort with bilateral large drusen, HCD presence and extent was not independently associated with an increased rate of progression to late AMD over 3 years, nor with lower visual sensitivity or an increased rate of visual sensitivity decline prior to the development of late AMD, after adjusting for known risk factors of disease progression.

Post-process optimization of 3D printed poly(lactic-co-glycolic acid) dental implant scaffold for enhanced structure and mechanical properties: effects of sonication duration and power

We described a technique of a post-process stage to partially remove the poly(vinyl alcohol) (PVA) binder in Poly(lactic-co-glycolic acid) (PLGA) dental scaffolds. The scaffolds were exposed to ultrasonic waves while immersed in an ethanol/acetone solvent mixture that possessed both polar and nonpolar properties. A factorial experiment was conducted in which the scaffolds were treated to three levels of sonication power (p_W): 0, 20% (22 W) and 40% (44 W), and soaking duration (t): 5, 15, and 30 min. The treated scaffolds were characterized by FT-IR, optical microscopy, and mechanical (compressive) testing. FT-IR revealed that the amount of PVA decreased with increasing p_W and t. Two-way ANOVA revealed that increasing p_W and t, respectively, resulted in increasing scaffold surface area to volume (SVR). Sonication and solvent caused structural damage (i.e., unevenness) on the scaffold surface, but the damage was minimal at 20% p_W and 30 min. The optimal values of p_W and t resulting in enhanced fracture strength, strain and toughness were 20% and 30 min, respectively, which corroborated the findings of minimal structural damage. However, sonication had no significant effects on the scaffold stiffness. Mechanistic analysis of the effects of sonication predicted that the ultrasonic energy absorbed by the scaffold was sufficient to disrupt the van Der Waals bonds between the PVA and PLGA but not high enough to disrupt the covalent bonds within the PLGA. This technique is promising as it can partially remove the PVA from the scaffold, and mitigate problematic issues down the line, such as thermal degradation during sterilization, and undue delay/variability in biodegradation.

Dataset on mechanical properties of damaged fibre composite laminates with drilled vent-holes for resin-injection repair procedure

This dataset comprises the mechanical properties of pristine and barely visible impact damaged (BVID) carbon fibre reinforced epoxy composite (CFRP) laminates. The mechanical dataset describes the compressive strength, compressive strain at fracture, strain energy density for resilience and strain energy density to fracture of the CFRP laminates with different number of vent holes (namely 4, 5 and 6) in the respective pristine and BVID states. The vent holes were created in the laminate to facilitate the resin-injection repair process. The mechanical properties were determined from in-plane compression test of the CFRP laminates. Structure-related dataset, namely infrared thermographs and ultrasonic C-scan images of BVID and other damage features induced by mechanical drilling, are included for completeness.

The equilibrium and fixed-bed study of malachite green adsorption on chitosan hydrogels

Chitosan hydrogel beads were prepared by a precipitation process, and were used to investigate the adsorption of malachite green (MG) oxalate under various conditions. It was found that adsorption equilibrium was most sensitive to the pH value at pH <8 while fixed bed breakthrough kinetics presented asymmetric S-shaped profiles which could not be adequately described by conventional models such as Adams-Bohart and Yoon-Nelson. The possible reasons were discussed and an improved Adams-Bohart model was proposed to better describe the changes in mass transfer mechanisms during adsorption.

Dataset on structure and mechanical properties of electrospun polyacrylonitrile nanofibrous mesh reinforced by halloysite nanotubes

The mechanical properties of electrospun polyacrylonitrile (PAN)-based membranes for ultrafiltration, such as oil–water separation and heavy metals from water, are often characterised in the dry state but little is known about the membrane properties in the hydrated state. This dataset comprised mechanical properties and structure-related properties of electrospun PAN-based membranes. The mechanical dataset described the yield strength and strain, stiffness, resilience energy, fracture strength, strain at fracture and fracture toughness of electrospun neat PAN and halloysite nanotube (HNT) reinforced PAN membranes in both hydrated and dry states. The data related to the hydrated state were derived from direct measurements of the mechanical properties of the PAN-based membrane using a novel environmental micromechanical tester. The structure-related dataset comprised electron micrographs and quantitative measurements (fibre diameter and pore diameter) derived from the micrographs. For further interpretation and discussion of the dataset, the reader is referred to the research data article, “Direct measurement of the elasticity and fracture properties of electrospun polyacrylonitrile/halloysite fibrous mesh in water” (Govindasamy et al., 2014).

Hepatitis B virus infection among children of hepatitis B surface antigen positive mothers in a Malaysian hospital

INTRODUCTION

There have been no published data on the transmission of hepatitis B virus (HBV) infection among children of hepatitis B surface antigen (HBsAg) positive mothers in Malaysia.

METHODS

This is a cross-sectional study of all the children of HBsAg-positive mothers who delivered at the University of Malaya Medical Centre between 1993 and 2000.

RESULTS

A total of 60 HBsAg-positive mothers and their 154 children participated in the study. HBsAg was detected in four children (2.6%) while IgG antibody to the hepatitis B core antigen (anti-HBc IgG) was detected in seventeen children (11.0%). The mother's age at childbirth was significantly lower in the children with detectable HBsAg (22.5±6.1 years vs. 29.7±4.5 years, p=0.043) and anti-HBc IgG (26.6±6.1 years vs. 30.0±4.3 years, p=0.004). Children born in the 1980s were significantly more likely to have detectable HBsAg (18.8% vs. 0.7%, p=0.004) and anti-HBc IgG (37.5% vs. 8.0%, p=0.000) compared with those born later. All children with detectable HBsAg were born via spontaneous vaginal delivery, and hepatitis B immunoglobulin was either not given or the administration status was unknown. The majority of mothers with chronic HBV infection (70.4%) were not under any regular follow-up for their chronic HBV infection and the main reason was the lack of awareness of the need to do so (47.4%).

CONCLUSION

Transmission of HBV infection among children of HBsAg-positive mothers in Malaysia is low. However, attention needs to be given to the high rate of HBsAgpositive mothers who are not on any regular follow-up.

Resolving the viscoelasticity and anisotropy dependence of the mechanical properties of skin from a porcine model

The mechanical response of skin to external loads is influenced by anisotropy and viscoelasticity of the tissue, but the underlying mechanisms remain unclear. Here, we report a study of the main effects of tissue orientation (TO, which is linked to anisotropy) and strain rate (SR, a measure of viscoelasticity), as well as the interaction effects between the two factors, on the tensile properties of skin from a porcine model. Tensile testing to rupture of porcine skin tissue was conducted to evaluate the sensitivity of the tissue modulus of elasticity (E) and fracture-related properties, namely maximum stress (σU) and strain (εU) at σU, to varying SR and TO. Specimens were excised from the abdominal skin in two orientations, namely parallel (P) and right angle (R) to the torso midline. Each TO was investigated at three SR levels, namely 0.007-0.015 s(-1) (low), 0.040 s(-1) (mid) and 0.065 s(-1) (high). Two-factor analysis of variance revealed that the respective parameters responded differently to varying SR and TO. Significant changes in the σU were observed with different TOs but not with SR. The εU decreased significantly with increasing SR, but no significant variation was observed for different TOs. Significant changes in E were observed with different TOs; E increased significantly with increasing SR. More importantly, the respective mechanical parameters were not significantly influenced by interactions between SR and TO. These findings suggest that the trends associated with the changes in the skin mechanical properties may be attributed partly to differences in the anisotropy and viscoelasticity but not through any interaction between viscoelasticity and anisotropy.

An updated Asia Pacific Consensus Recommendations on colorectal cancer screening

OBJECTIVE

Since the publication of the first Asia Pacific Consensus on Colorectal Cancer (CRC) in 2008, there are substantial advancements in the science and experience of implementing CRC screening. The Asia Pacific Working Group aimed to provide an updated set of consensus recommendations.

DESIGN

Members from 14 Asian regions gathered to seek consensus using other national and international guidelines, and recent relevant literature published from 2008 to 2013. A modified Delphi process was adopted to develop the statements.

RESULTS

Age range for CRC screening is defined as 50-75 years. Advancing age, male, family history of CRC, smoking and obesity are confirmed risk factors for CRC and advanced neoplasia. A risk-stratified scoring system is recommended for selecting high-risk patients for colonoscopy. Quantitative faecal immunochemical test (FIT) instead of guaiac-based faecal occult blood test (gFOBT) is preferred for average-risk subjects. Ancillary methods in colonoscopy, with the exception of chromoendoscopy, have not proven to be superior to high-definition white light endoscopy in identifying adenoma. Quality of colonoscopy should be upheld and quality assurance programme should be in place to audit every aspects of CRC screening. Serrated adenoma is recognised as a risk for interval cancer. There is no consensus on the recruitment of trained endoscopy nurses for CRC screening.

CONCLUSIONS

Based on recent data on CRC screening, an updated list of recommendations on CRC screening is prepared. These consensus statements will further enhance the implementation of CRC screening in the Asia Pacific region.

Association between EGF and VEGF functional polymorphisms and sporadic colorectal cancer in the Malaysian population

Growth factors are polypeptides that are critical for the initiation, progression, and metastasis of cancer. Most tumor cells are capable of synthesizing particular growth factors leading to constitutive pathway activation in these cells through autocrine signaling. Epidermal growth factor (EGF) is a potent mitogenic peptide that exerts direct effects on the proliferation and differentiation of tumor cells in carcinogenesis. By contrast, vascular endothelial growth factor (VEGF) is vital for the invasion and metastasis of neoplasms through the formation of new blood vessels from mature endothelial cells. In this study, we investigated the association between functional polymorphisms of both the EGF and VEGF genes and colorectal cancer (CRC) susceptibility. A total of 130 CRC patients and 212 healthy controls were recruited for this case-control study. Genotyping of genetic variants was conducted via real-time polymerase chain reaction (PCR) amplification with allele-specific TaqMan probes. None of the genotypes of the EGF +61 A>G and VEGF +936 C>T variants was significantly associated with CRC susceptibility among the Malaysian subjects evaluated (P > 0.05). The observed frequency distributions of the EGF +61 A>G polymorphism genotypes showed ethnic heterogeneity, which was not the case for the VEGF +936 C>T genotypes. In conclusion, no positive correlation between these functional polymorphisms and CRC risk was found in this Malaysian population. Studies of the EGF and VEGF genes and CRC susceptibility are scarce, and the results reported thus far differ from one population to another. Hence, more replication studies are warranted before any firm conclusions can be made.

NOD2/CARD15 variants in Malaysian patients with sporadic colorectal cancer

Colorectal cancer (CRC) is one of the most common types of cancer in both developed and developing countries. This disease is triggered by and progresses via the sequential accumulation of multiple genetic alterations. In addition, the interaction between low-penetrance genes and environmental factors can also increase the risk of developing CRC. Since inflammatory bowel diseases (IBDs) are one of the predisposing factors for CRC, IBD-related genes might, to a certain extent, be associated with cancer initiation. The nucleotide oligomerization domain 2/caspase activating recruitment domain 15 gene (NOD2/CARD15) is the most well-established gene to be associated with increased susceptibility to Crohn's disease. Thus, various studies have been performed to investigate the potential contribution of this gene to CRC risk. In this study, we aimed to determine the frequency of the Arg702Trp, Gly908Arg, 3020insC, Pro268Ser, and JW1 variants of NOD2/CARD15, and to investigate their association with CRC susceptibility. A total of 130 CRC patients and 212 healthy controls were recruited for this study. Subsequently, real-time polymerase chain reaction with TaqMan was performed for the genotyping of these NOD2/ CARD15 variants. None of the NOD2/CARD15 variants was statistically associated to CRC susceptibility in our Malaysian population. Our findings were remarkably similar to those of other Asian cohorts, which indicated that these NOD2/CARD15 variants exhibit genetic heterogeneity between Caucasian and Asian populations.

Hypericin-photodynamic therapy leads to interleukin-6 secretion by HepG2 cells and their apoptosis via recruitment of BH3 interacting-domain death agonist and caspases

Photodynamic therapy (PDT) has emerged as a capable therapeutic modality for the treatment of cancer. PDT is a targeted cancer therapy that reportedly leads to tumor cell apoptosis and/or necrosis by facilitating the secretion of certain pro-inflammatory cytokines and expression of multiple apoptotic mediators in the tumor microenvironment. In addition, PDT also triggers oxidative stress that directs tumor cell killing and activation of inflammatory responses. However, the cellular and molecular mechanisms underlying the role of PDT in facilitating tumor cell apoptosis remain ambiguous. Here, we investigated the ability of PDT in association with hypericin (HY) to induce tumor cell apoptosis by facilitating the induction of reactive oxygen species (ROS) and secretion of Th1/Th2/Th17 cytokines in human hepatocellular liver carcinoma cell line (HepG2) cells. To discover if any apoptotic mediators were implicated in the enhancement of cell death of HY-PDT-treated tumor cells, selected gene profiling in response to HY-PDT treatment was implemented. Experimental results showed that interleukin (IL)-6 was significantly increased in all HY-PDT-treated cells, especially in 1 μg/ml HY-PDT, resulting in cell death. In addition, quantitative real-time PCR analysis revealed that the expression of apoptotic genes, such as BH3-interacting-domain death agonist (BID), cytochrome complex (CYT-C) and caspases (CASP3, 6, 7, 8 and 9) was remarkably higher in HY-PDT-treated HepG2 cells than the untreated HepG2 cells, entailing that tumor destruction of immune-mediated cell death occurs only in PDT-treated tumor cells. Hence, we showed that HY-PDT treatment induces apoptosis in HepG2 cells by facilitating cytotoxic ROS, and potentially recruits IL-6 and apoptosis mediators, providing additional hints for the existence of alternative mechanisms of anti-tumor immunity in hepatocellular carcinoma, which contribute to long-term suppression of tumor growth following PDT.

Helicobacter pylori infection in chronic immune thrombocytopenic purpura patients in Malaysia

INTRODUCTION

Helicobacter Pylori has been implicated with a possible link to immune thrombocytopenia purpura (ITP) and studies have shown contradicting results in platelet recovery after eradication of H pylori infection.

OBJECTIVES

To determine the prevalence of H pylori infection in adult ITP patients in Malaysia and to examine the effect of eradication of H pylori infection in these patients.

METHOD

50 ITP adult patients from haematology clinics were recruited. A 13C urea breath test for H. pylori infection was performed in all patients. Those with H. pylori infection were treated with standard eradication regimen. Platelet counts were monitored regularly after eradication therapy to assess response. Complete response (CR) was defined as the achievement of platelet counts of >150x10(9)/L within 3 months after eradication therapy and partial response (PR) was defined as platelet count above 50x10(9)/L and/or at least doubling the baseline count.

RESULT

The median age of patients recruited was 50 years. The majority of patients were female (76%). Chinese was the largest ethnic groups (56%) followed by Malays (28%) and Indians (16%). 11 of the 50 patients (22%) were found to have H. pylori infection and all but one had eradication therapy. Overall, some response was observed in 3 patients (30%) with a CR seen in 2 patients and PR in one patient. However, all these patients had a drop in their platelet counts at 6th month follow up.

CONCLUSION

The prevalence of H. pylori infection is relatively low in our adult ITP patients (22%) and by eradicating the infection did not have any sustained effect in the platelet recovery.

Increased fracture risk and osteoporosis not associated with vitamin D levels in Malaysian patients with inflammatory bowel disease

INTRODUCTION

Osteoporosis and osteopenia are well-recognized complications of inflammatory bowel disease. Previous studies have suggested that vitamin D deficiency is an important risk factor for the development of osteoporosis. We hypothesized that low vitamin D levels is the main reason for reduced bone mineral density in patients with inflammatory bowel disease. We aimed to study its potential role in Malaysia, which is a tropical country with 3 large ethnic groups. We also sought to examine the relationship between fracture risk and bone mineral density in this group.

METHODOLOGY

Relevant history as well as 25-hydroxycholecalciferol (vitamin D) levels and bone mineral density were obtained. Normal, inadequate, and low vitamin D levels were defined as 61-160 nmol/L (24-64 ng/mL), 30-60 nmol/L (12-24 ng/mL), and less than 30 nmol/L (<12 ng/mL), respectively.

RESULTS

Seventy-two patients were recruited. The prevalence of osteopenia and osteoporosis, respectively, were 58% and 17% in the spine and 51% and 14% in the hip. Mean vitamin D level in the group was low at 45.12 ± 17.4 nmol/L (18.05 ± 6.96 ng/mL), but there was no significant association between bone mineral density and vitamin D level. Twelve patients (16.7%) had a fragility fracture after the diagnosis of inflammatory bowel disease. The cumulative fracture incidence was 10% at 5 years and 35% at 10 years. There was a statistically significant association between osteoporosis of hip and a history of fracture (odds ratio 5.889; 95% confidence interval 1.41-24.53, P = .009).

CONCLUSION

Osteoporosis is prevalent among Malaysian patients with inflammatory bowel disease and is associated with a 6-fold increased risk of fractures. Most inflammatory bowel disease patients had inadequate or low vitamin D levels, but there was no association between vitamin D levels and BMD.

Stool patterns of Malaysian adults with functional constipation: association with diet and physical activity

INTRODUCTION

Diet and lifestyle modification is commonly used in constipation management. As there is a dearth of studies on this topic in Malaysia, we aim to elucidate the relations between stool patterns, dietary intake and physical activity levels among adults with functional constipation.

METHODS

From a database collected via surveys at public events, a convenience sample of 100 adults diagnosed with Rome II-defined functional constipation was enrolled in this cross-sectional study. After severity assessment using the Chinese Constipation Questionnaire, subjects completed 2-week bowel movement diaries to determine stool frequency, consistency and output. Dietary intake and physical activity levels were assessed twice using three-day 24-hour diet recalls and International Physical Activity Questionnaire, respectively. Ninety subjects who completed the study were included in the analysis.

RESULTS

Mean weekly stool frequency was 3.9 +/- 1.9 times, consistency score was 2.6 +/- 0.6 (range 1.0-4.0), output was 11.0 +/- 6.3 balls (40 mm diameter) and severity score was 10.3 +/- 3.3 (range 5.0-22.0). Mean daily dietary intakes were: energy 1,719 +/- 427kcal, dietary fibre 15.0 +/- 4.9g and fluid 2.5 +/- 0.8L. The majority of subjects were physically inactive. Stool frequency and output were positively associated with dietary fibre (r(s) = 0.278, P < 0.01; r(s) = 0.226, P < 0.05) and fluid intake (r(s) = 0.257, P < 0.05; OR = 3.571, 95% CI [1.202-10.609]). Constipation severity was associated with higher physical activity levels (OR = 2.467, 95% CI [1.054-5.777]).

CONCLUSION

Insufficient intake of dietary fibre and fluid are associated with aggravated constipation symptoms. Further studies are necessary to confirm usefulness of dietary intervention in treatment of constipation as dietary factors alone may not influence overall severity and stool consistency, an integral element of constipation.

Lack of association between TYK2 and STAT3 genes and Crohn's disease in the Malaysian population

This study aimed to investigate the potential association of TYK2 and STAT3 genes with the susceptibility to Crohn's disease (CD) among Malaysians. DNA samples were obtained from 80 CD patients and 100 healthy controls. Polymerase chain reaction-restriction fragment length polymorphism methods were employed for genotyping, followed by statistical analysis. In our current study, none of the single nucleotide polymorphisms of either TYK2 or STAT3 was statistically associated with the susceptibility to CD in our local population (P > 0.05). In contrast, there was a statistically significant association between the G/G homozygotes of the STAT3 rs2293152 and the healthy control group (χ(2) = 6.229, P < 0.05). In conclusion, our study does not support the role of the TYK2 and STAT3 genes influencing CD susceptibility.

Co-inheritance of variants/mutations in Malaysian patients with Crohn's disease

Crohn's disease is a chronic, relapsing inflammatory bowel disease; it affects the mucosa and deeper layers of the digestive wall. Two Crohn's disease patients who carried the JW1 variant and two patients who carried the SNP5 variant were investigated for other co-inherited polymorphisms that could influence Crohn's disease development. Based on the sequencing results, a homozygous 5'-UTR-59 G to A variant in exon 1 (SNP6) was observed in a patient who carried SNP5, while a heterozygous SNP6 variant was detected in the other patient who carried SNP5. No other associated mutations or polymorphisms were detected in the two patients who carried the JW1 variant of the CARD15/NOD2 gene.

Bimodal collagen fibril diameter distributions direct age-related variations in tendon resilience and resistance to rupture

Scaling relationships have been formulated to investigate the influence of collagen fibril diameter (D) on age-related variations in the strain energy density of tendon. Transmission electron microscopy was used to quantify D in tail tendon from 1.7- to 35.3-mo-old (C57BL/6) male mice. Frequency histograms of D for all age groups were modeled as two normally distributed subpopulations with smaller (D(D1)) and larger (D(D2)) mean Ds, respectively. Both D(D1) and D(D2) increase from 1.6 to 4.0 mo but decrease thereafter. From tensile tests to rupture, two strain energy densities were calculated: 1) u(E) [from initial loading until the yield stress (σ(Y))], which contributes primarily to tendon resilience, and 2) u(F) [from σ(Y) through the maximum stress (σ(U)) until rupture], which relates primarily to resistance of the tendons to rupture. As measured by the normalized strain energy densities u(E)/σ(Y) and u(F)/σ(U), both the resilience and resistance to rupture increase with increasing age and peak at 23.0 and 4.0 mo, respectively, before decreasing thereafter. Multiple regression analysis reveals that increases in u(E)/σ(Y) (resilience energy) are associated with decreases in D(D1) and increases in D(D2), whereas u(F)/σ(U) (rupture energy) is associated with increases in D(D1) alone. These findings support a model where age-related variations in tendon resilience and resistance to rupture can be directed by subtle changes in the bimodal distribution of Ds.

Asia-Pacific Working Group consensus on non-variceal upper gastrointestinal bleeding

Upper gastrointestinal bleeding (UGIB), especially peptic ulcer bleeding, remains one of the most important cause of hospitalisation and mortality world wide. In Asia, with a high prevalence of Helicobacter pylori infection, a potential difference in drug metabolism, and a difference in clinical management of UGIB due to variable socioeconomic environments, it is considered necessary to re-examine the International Consensus of Non-variceal Upper Gastrointestinal Bleeding with emphasis on data generated from the region. The working group, which comprised experts from 12 countries from Asia, recommended the use of the Blatchford score for selection of patients who require endoscopic intervention and which would allow early discharge of patients at low risk. Patients' comorbid conditions should be included in risk assessment. A pre-endoscopy proton pump inhibitor (PPI) is recommended as a stop-gap treatment when endoscopy within 24 h is not available. An adherent clot on a peptic ulcer should be treated with endoscopy combined with a PPI if the clot cannot be removed. Routine repeated endoscopy is not recommended. High-dose intravenous and oral PPIs are recommended but low-dose intravenous PPIs should be avoided. COX-2 selective non-steroidal anti-inflammatory drugs combined with a PPI are recommended for patients with very high risk of UGIB. Aspirin should be resumed soon after stabilisation and clopidogrel alone is no safer than aspirin plus a PPI. When dual antiplatelet agents are used, prophylactic use of a PPI reduces the risk of adverse gastrointestinal events.

Elasticity, thermal stability and bioactivity of polyhedral oligomeric silsesquioxanes reinforced chitosan-based microfibres

A wet-spinning approach was used to extrude ribbon-like micrometer-thick fibres comprising chitosan with 1, 3, 5, 7 and 9% (w/w) polyhedral oligomeric silsesquioxanes (POSS). ANOVA reveals significant variations in the maximum stress (σ), stiffness (E), elastic energy storage (u') and fracture toughness (u) of the microfibres with respect to POSS concentration: σ, u' and u peak at 7% (w/w) but POSS concentration has no effect on E. Scanning electron microscopy of the ruptured microfibres reveals fracture and detachment of POSS precipitates from the chitosan matrix. Bioactivity test using simulated body fluids reveals a net gain in mass (by day 4) and grossly distorted morphology caused by apatite deposition on the microfibre surface. Fourier transform infrared spectroscopy reveals that chitin is partially deacetylated into chitosan and it further shows the presence of POSS in the microfibres. Thermogravimetric analysis shows that the microfibres are thermally stable up to 240°C in a nitrogen atmosphere.

World Gastroenterology Organization Practice Guidelines for the diagnosis and management of IBD in 2010

Inflammatory bowel disease (IBD) represents a group of idiopathic, chronic, inflammatory intestinal conditions. Its two main disease categories are: Crohn's disease (CD) and ulcerative colitis (UC), which feature both overlapping and distinct clinical and pathological features. While these diseases have, in the past, been most evident in the developed world, their prevalence in the developing world has been gradually increasing in recent decades. This poses unique issues in diagnosis and management which have been scarcely addressed in the literature or in extant guidelines. Depending on the nature of the complaints, investigations to diagnose either form of IBD or to assess disease activity will vary and will also be influenced by geographic variations in other conditions that might mimic IBD. Similarly, therapy varies depending on the phenotype of the disease being treated and available resources. The World Gastroenterology Organization has, accordingly, developed guidelines for diagnosing and treating IBD using a cascade approach to account for variability in resources in countries around the world.

Epidemiology of Helicobacter pylori infection in Malaysia--observations in a multiracial Asian population

Observations of racial differences in the prevalence of Helicobacter pylori in Malaysia have been intriguing. The Indians and Chinese consistently have a higher prevalence compared to the Malays. The racial cohort theory has been proposed to explain these differences where transmission and perpetuation of infection takes place within a racial group rather than between races, races being separate owing to the low rate of interracial marriages. Studies have demonstrated distinctive bacterial strains between races. Phylogenetic studies have shown that H. pylori isolates amongst Chinese and Indians are distinctive while Malays have Indian and other strains suggesting a more recent acquisition of the bacterium from Indians. H. pylori is recognized as the major causative factor in peptic ulcer disease and gastric cancer. Despite the high prevalence of H. pylori, Indians have a relatively low prevalence of peptic ulcer disease and a low incidence of gastric cancer. This paradox with regards to gastric cancer has been termed the "Indian enigma". Bacterial strain differences between races may be putative but this observation may also indicate gastroprotective environmental factors or a lower genetic susceptibility to develop cancer in the Indians.

Demography and clinical course of ulcerative colitis in a multiracial Asian population: a nationwide study from Malaysia

OBJECTIVE

To establish the clinical course of ulcerative colitis (UC) in the Malaysian population, comparing the three major ethnic groups: Malay, Chinese and Indian.

METHODS

Patients who were diagnosed with UC from seven major medical referral centers in Malaysia were recruited. Their baseline characteristics, and the extent of the disease, its clinical course and complications were recorded.

RESULTS

A total of 118 patients was included. The extent of disease was as follows: proctitis alone in 22 (18.6%), sigmoid colon in 23 (19.5%), descending colon in 16 (13.6%), transverse colon in 11 (9.3%), ascending colon and pancolitis 46 (39%). Most patients had chronic intermittent disease. Extra-intestinal complications were seen in 27 (22.9%) patients and fulminant colitis was seen in four (3.4%). None developed colorectal cancer. The overall cumulative colectomy rates at 1, 5 and 10 years were 3.4% (CI: 0.9-8.5), 5.9% (CI: 1.9-13.2) and 15.6% (CI: 6.5-29.4), respectively. There was a higher prevalence of extra-intestinal manifestations and a trend towards more extensive disease among Indian patients. However, no significant differences were seen in the age of onset, the severity of disease (fulminant colitis, refractory disease) and the colectomy rate.

CONCLUSION

As in developed countries, most of our patients have a remitting and relapsing pattern of disease but the clinical course appears to be milder, with lower rates of colectomies. There are differences in clinical presentation among the three major ethnic groups, with Indians having a higher prevalence of extra-intestinal manifestations and a trend towards more extensive disease.

Changing epidemiology of Helicobacter pylori in Asia

As in developed societies, the prevalence of Helicobacter pylori has declined rapidly in Asia. This has been shown in both seroprevalence-based and endoscopy-based studies. While the decline in the incidence of gastric cancer has now been observed, a decrease in peptic ulcer disease has not been so clearly evident. This apparent paradox can be explained by an increase in non-H. pylori associated ulcers - such as those related to non-steroidal anti-inflammatory drugs or idiopathic ulcers. The increase of gastroesophageal reflux disease in Asia has been widely observed and commented on and its relationship to the decline in H. pylori speculated upon. However there have been few conclusive studies from Asia on this subject. While the improved diagnosis and elimination of H. pylori has contributed to its decline, a more basic change involving large segments of the Asian population must be responsible. An improvement in hygiene and living conditions that results from more affluent Asian societies is thought to be a possible cause.

Ageing changes in the tensile properties of tendons: influence of collagen fibril volume fraction

Connective tissues are biological composites comprising of collagen fibrils embedded in (and reinforcing) the hydrated proteoglycan-rich (PG) gel within the extracellular matrices (ECMs). Age-related changes to the mechanical properties of tissues are often associated with changes to the structure of the ECM, namely, fibril diameter. However, quantitative attempts to correlate fibril diameter to mechanical properties have yielded inconclusive evidence. Here, we described a novel approach that was based on the rule of mixtures for fiber composites to evaluate the dependence of age-related changes in tendon tensile strength (sigma) and stiffness (E) on the collagen fibril cross-sectional area fraction (rho), which is related to the fibril volume fraction. Tail tendons from C57BL6 mice from age groups 1.6-35.3 months old were stretched to failure to determine sigma and E. Parallel measurements of rho as a function of age were made using transmission electron microscopy. Mathematical models (rule of mixtures) of fibrils reinforcing a PG gel in tendons were used to investigate the influence of rho on ageing changes in sigma and E. The magnitudes of sigma, E, and rho increased rapidly from 1.6 months to 4.0 months (P-values <0.05) before reaching a constant (age independent) from 4.0 months to 29.0 months (P-values >0.05); this trend continued for E and rho (P-values >0.05) from 29.0 months to 35.3 months, but not for sigma, which decreased gradually (P-values <0.05). Linear regression analysis revealed that age-related changes in sigma and E correlated positively to rho (P-values <0.05). Collagen fibril cross-sectional area fraction rho is a significant predictor of ageing changes in sigma and E in the tail tendons of C57BL6 mice.