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 (pW): 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 pW and t. Two-way ANOVA revealed that increasing pW 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% pW and 30 min. The optimal values of pW 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.

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.

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.

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.

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.

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.

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.

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.

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.

Dataset on open/blind hole-hole interaction in barely visible impact damaged composite laminates.

This dataset contains the mechanical properties and structural characteristics with images of the carbon fibre reinforced epoxy composite (CFRP) laminates with open/blind holes. The mechanical dataset are the fracture strength, strain at fracture, strain energy density for resilience, strain energy density to fracture and stiffness of the CFRP laminates for different setups (namely 1 hole, 2 holes parallel to applied load, and 2 holes normal to applied load) from pristine and barely visible impact damage (BVID) specimens, determine from in-plane compression test. The structural-related dataset include thermographs, images of BVID specimens, drilling-induced damage BVID specimens and video clips of crack propagation during in-plane compression testing.

The cag PAI is intact and functional but HP0521 varies significantly in Helicobacter pylori isolates from Malaysia and Singapore.

Helicobacter pylori-related disease is at least partially attributable to the genotype of the infecting strain, particularly the presence of specific virulence factors. We investigated the prevalence of a novel combination of H. pylori virulence factors, including the cag pathogenicity island (PAI), and their association with severe disease in isolates from the three major ethnicities in Malaysia and Singapore, and evaluated whether the cag PAI was intact and functional in vitro. Polymerase chain reaction (PCR) was used to detect dupA, cagA, cagE, cagT, cagL and babA, and to type vacA, the EPIYA motifs, HP0521 alleles and oipA ON status in 159 H. pylori clinical isolates. Twenty-two strains were investigated for IL-8 induction and CagA translocation in vitro. The prevalence of cagA, cagE, cagL, cagT, babA, oipA ON and vacA s1 and i1 was >85%, irrespective of the disease state or ethnicity. The prevalence of dupA and the predominant HP0521 allele and EPIYA motif varied significantly with ethnicity (p < 0.05). A high prevalence of an intact cag PAI was found in all ethnic groups; however, no association was observed between any virulence factor and disease state. The novel association between the HP0521 alleles, EPIYA motifs and host ethnicity indicates that further studies to determine the function of this gene are important.

Antibiotic prophylaxis tailored to local organisms reduces percutaneous gastrostomy site infection.

BACKGROUND: Current recommendations for the choice of antibiotic prophylaxis prior to percutaneous endoscopic gastrostomy (PEG) insertion may not be suitable in all situations. AIMS: We sought to review the microbiology of PEG-wound infections at our institution locally and observe PEG infection rates following a change in antibiotic policy. METHODS: A retrospective clinical and microbiological review of all PEG-wound infections resulted in a change in the choice of antibiotic. A further review was conducted 2 years later to examine the effect of this change. RESULTS: PEG-wound infection was detected in 33/103 (32.0%) patients between January 2002 and May 2004 with either second generation cephalosporins or co-amoxiclav antibiotic prophylaxis, with the commonest organisms being Pseudomonas aeruginosa (16.7%), Klebsiella species (9.9%) and methicillin-resistant Staphylococcus aureus (5.3%). Microbiological data revealed high levels of resistance to cefuroxime (60.7%) and co-amoxiclav (51%). A change of prophylaxis to cefoperazone (during the period June 2004-May 2006) resulted in a reduction of PEG-wound infections to 17/90 (18.9%) patients that required PEG tube insertion (p = 0.04). Together with a reduction in P. aeruginosa infections (18.4-10%, p = 0.10), a lower incidence of pyrexia (10.7% vs. 3.3%, p = 0.05), lower antibiotic administration (20.4% vs. 11.1%, p = 0.08) and lower rate of PEG removal (23.2% vs. 10.2%, p = 0.018) were noted following prophylaxis change. CONCLUSIONS: Antibiotic prophylaxis for PEG should be tailored to local organisms as this approach reduces the incidence and severity of peri-stomal PEG infections.

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.

Cost-effectiveness of and satisfaction with a Helicobacter pylori "test and treat" strategy compared with prompt endoscopy in young Asians with dyspepsia.

OBJECTIVE: To compare a Helicobacter pylori "test and treat" strategy with prompt endoscopy in young Asians with dyspepsia. METHODS: A randomised, prospective study was carried out on uninvestigated dyspeptics aged <45 years in a single (academic) primary care centre. Patients were randomised to either a [(13)C]urea breath test (UBT) or prompt endoscopy (oesophagogastroduodenoscopy (OGD) and followed-up for 12 months. RESULTS: 432 patients (mean (SD) age 30 (8) years, male 46%, ethnicity: Malays 33.3%, Chinese 30.6%, Indians 34.7%) were randomised to UBT (n = 222) or OGD (n = 210). 387 (89.6%) patients completed the study. At 12 months, there was no difference in symptom change (measured by the Leeds Dyspepsia Questionnaire) between the two groups, but more patients were very satisfied (40.0% vs 21.6%, p<0.0001) in the OGD group. More additional endoscopy was performed in the UBT group (25 vs 10, p = 0.03), but medication consumption was higher in the OGD group (proton pump inhibitor 3.6 (8.8) vs 2.0 (7.5) weeks, p<0.001; H2 receptor antagonist 5.3 (9.7) vs 3.9 (9.2) weeks, p = 0.017; prokinetics 1.4 (4.7) vs 0.4 (2.5) weeks, p<0.001) and no differences in medical consultation were noted. The median cost of the initial prompt endoscopy approach at 12 months was significantly higher than a "test and treat" strategy (US$179.05 vs US$87.10, p<0.0001). CONCLUSION: A H. pylori "test and treat" strategy is more cost-effective but less satisfying than prompt endoscopy in the management of young Asian patients with uncomplicated dyspepsia.

Asia Pacific consensus recommendations for colorectal cancer screening.

Colorectal cancer (CRC) is rapidly increasing in Asia, but screening guidelines are lacking. Through reviewing the literature and regional data, and using the modified Delphi process, the Asia Pacific Working Group on Colorectal Cancer and international experts launch consensus recommendations aiming to improve the awareness of healthcare providers of the changing epidemiology and screening tests available. The incidence, anatomical distribution and mortality of CRC among Asian populations are not different compared with Western countries. There is a trend of proximal migration of colonic polyps. Flat or depressed lesions are not uncommon. Screening for CRC should be started at the age of 50 years. Male gender, smoking, obesity and family history are risk factors for colorectal neoplasia. Faecal occult blood test (FOBT, guaiac-based and immunochemical tests), flexible sigmoidoscopy and colonoscopy are recommended for CRC screening. Double-contrast barium enema and CT colonography are not preferred. In resource-limited countries, FOBT is the first choice for CRC screening. Polyps 5-9 mm in diameter should be removed endoscopically and, following a negative colonoscopy, a repeat examination should be performed in 10 years. Screening for CRC should be a national health priority in most Asian countries. Studies on barriers to CRC screening, education for the public and engagement of primary care physicians should be undertaken. There is no consensus on whether nurses should be trained to perform endoscopic procedures for screening of colorectal neoplasia.

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.