Displaying publications 1 - 20 of 190 in total

  1. Lee YY
    PMID: 25705618 DOI: 10.3389/fmed.2014.00005
    Constipation and fecal incontinence (FI) are common complaints predominantly affecting the elderly and women. They are associated with significant morbidity and high healthcare costs. The causes are often multi-factorial and overlapping. With the advent of new technologies, we have a better understanding of their underlying pathophysiology which may involve disruption at any levels along the gut-brain-microbiota axis. Initial approach to management should always be the exclusion of secondary causes. Mild symptoms can be approached with conservative measures that may include dietary modifications, exercise, and medications. New prokinetics (e.g., prucalopride) and secretagogues (e.g., lubiprostone and linaclotide) are effective and safe in constipation. Biofeedback is the treatment of choice for dyssynergic defecation. Refractory constipation may respond to neuromodulation therapy with colectomy as the last resort especially for slow-transit constipation of neuropathic origin. Likewise, in refractory FI, less invasive approach can be tried first before progressing to more invasive surgical approach. Injectable bulking agents, sacral nerve stimulation, and SECCA procedure have modest efficacy but safe and less invasive. Surgery has equivocal efficacy but there are promising new techniques including dynamic graciloplasty, artificial bowel sphincter, and magnetic anal sphincter. Despite being challenging, there are no short of alternatives in our toolbox for the management of constipation and FI.
  2. Lee YY
    Malays J Med Sci, 2015 Jan-Feb;22(1):1-3.
    PMID: 25892944
    Obesity is a fast-emerging epidemic in the Asia-Pacific region, with numbers paralleling the rising global prevalence within the past 30 years. The landscape of gut diseases in Asia has been drastically changed by obesity. In addition to more non-specific abdominal symptoms, obesity is the cause of gastro-oesophageal reflux disease, various gastrointestinal cancers (colorectal cancer, hepatocellular carcinoma, oesophageal adenocarcinoma, gastric cardia adenocarcinoma, pancreatic cancer and gallbladder cancer) and non-alcoholic fatty liver disease. Abnormal cross-talk between the gut microbiome and the obese host seems to play a central role in the pathogenesis, but more studies are needed.
  3. Lee YY, Bhaskar S
    Case Rep Med, 2011;2011:271560.
    PMID: 22229036 DOI: 10.1155/2011/271560
    We report a 33-year-old Malay woman presented with acute left dense hemiparesis and an NIHSS score of 11/15. Computed tomography (CT) scan brain showed a massive right middle cerebral artery (MCA) territory infarct. The right internal carotid artery (ICA) and right proximal MCA were shown occluded from digital substraction angiography (DSA). Carotid dissection, carotid canal anomaly, and intercavernous communication were systematically ruled out. She had no risk factors for atherosclerosis. The connective tissue screening and thrombophilic markers were negative. However, she was anaemic on admission and subsequent investigations revealed that she had alpha-thalassemia and iron deficiency anaemia. The right ICA remained occluded from a repeat CT cerebral angiogram after one year, but otherwise she was neurologically stable. This case illustrates an unusual association between intracranial vessel occlusion with iron deficiency anaemia and alpha-thalassemia trait.
  4. Lawenko RM, Lee YY
    J Neurogastroenterol Motil, 2016 Jan 31;22(1):25-30.
    PMID: 26717929 DOI: 10.5056/jnm15151
    Gastroesophageal reflux disease (GERD) is a disease predominantly seen in the West but there is a rising trend in Asia. Ambulatory 24-hour catheter-based pH monitoring has been the de facto gold standard test for GERD that correlates symptoms with acid reflux episodes. However, drawbacks such as patients' discomfort, and catheter displacement render the test as cumbersome and error-prone. The Bravo pH wireless system is designed to be user-friendly and has an added advantage of prolonged pH monitoring. The system is comparable to the catheter-based pH monitoring system in terms of diagnostic yield and symptom-reflux association. Indications include evaluation of patients with refractory GERD symptoms and prior to anti-reflux surgery. Bravo utilizes a wireless pH-sensing capsule with a complete prepackaged system, and a data processing software. The capsule may be positioned indirectly using endoscopic or manometric landmarks or under direct endoscopic guidance. Optimal threshold cut-off values are yet to be standardized but based on available studies, for the Asian population, it may be recommended for total % time pH < 4 of 5.8 over 48 hours. Cost is a limitation but capsule placement is relatively safe although technical failures may be seen in small percentage of cases.
  5. Lee YY, McColl KE
    Dis. Esophagus, 2015 May-Jun;28(4):318-25.
    PMID: 24575877 DOI: 10.1111/dote.12202
    Obesity is a major reason for the recent increase in incidence of reflux disease and cancers at the distal esophagus and gastroesophageal junction (GOJ) and is mediated through a rise in the intra-abdominal pressure (IAP) but the exact mechanisms are unclear. Raised IAP from obesity and with application of waist belt produces mechanical distortion of the GOJ through formation of partial hiatus hernia. Even though there is no trans-sphincteric acid reflux, there is increased ingress of acid into the lower sphincter (intra-sphincteric reflux) as a consequence of raised IAP. In addition, short segment acid reflux is more evident in obese subjects with a belt on. Acid pocket is also enlarged in hiatus hernia, and acts as a reservoir of acid available to reflux whenever the sphincter fails. Above mechanisms may explain the common occurrence of cardiac lengthening and inflammation found in asymptomatic obese subjects. The inflamed cardia is also immunohistochemically similar to non-intestinal Barrett's mucosa, which is of etiological importance for cancers at the GOJ. Interventions that can reduce the mechanical distortion and acid exposure at the GOJ, including diet, exercise, drugs, sphincter augmentation therapy, and surgery, are clinically relevant in the treatment of gastroesophageal reflux disease but more data are needed whether if these strategies are also effective in preventing cancer. As a conclusion, raised IAP produces silent mechanical disruption of the GOJ, which may explain the high occurrence of cancers in this region and it is potentially reversible with early interventions.
  6. Lee YY, Chua AS
    J Neurogastroenterol Motil, 2013 Jul;19(3):295-300.
    PMID: 23875095 DOI: 10.5056/jnm.2013.19.3.295
    Despite being a large ethnic group within the South-East Asia, there is a paucity of reported literatures on dyspepsia in the Malay population. Recent population-based studies indicate that uninvestigated dyspepsia, based on the Rome II criteria, is reported in 12.8% and 11.6% of Malays in the urban and rural communities respectively. Organic causes of dyspepsia including upper gastrointestinal tract cancers, its precancerous lesions, and erosive diseases are uncommon which is largely due to an exceptionally low prevalence of Helicobacter pylori infection in this population. On the other hand, functional dyspepsia and irritable bowel syndrome are relatively common in the Malays than expected. Within a primary care setting, functional dyspepsia, based on the Rome III criteria, is reported in 11.9% of Malays, of which epigastric pain syndrome is found to be more common. Married Malay females are more likely to have functional dyspepsia and psychosocial alarm symptoms. Also based on the Rome III criteria, irritable bowel syndrome, commonly overlapped with functional dyspepsia, is reported in 10.9% of Malays within a community-based setting. Rather than psychosocial symptoms, red flags are most likely to be reported among the Malays with irritable bowel syndrome despite having a low yield for organic diseases. Based upon the above observations, "proton pump inhibitor test" is probably preferable than the "test and treat H. pylori" strategy in the initial management of dyspepsia among the Malays.
  7. Lee YY, Chua AS
    J Neurogastroenterol Motil, 2012 Jul;18(3):239-45.
    PMID: 22837871 DOI: 10.5056/jnm.2012.18.3.239
    The diagnosis of functional dyspepsia (FD) is challenging since it depends largely on symptoms which are often heterogeneous and overlapping. This is particularly so in Asia with many different cultures and languages. Symptom-based diagnosis of FD based on Rome III criteria has not been fully validated and it may not be suitable in some Asian populations. Clinicians often assume that investigations in FD are not rewarding and physiological tests are often not available unless in the research setting. Investigation of alarm features and role of Helicobacter pylori in FD remain controversial but experts agreed that both should be tested. Physiological tests including gastric accommodation and chemical hypersensitivity tests are underutilized in Asia and available studies were few. While experts do not recommend routine clinical use of gastric accommodation tests but they agree that these tests can be advocated if clinically indicated. Empiric therapeutic trial is not currently a diagnostic option. The pathogenesis of FD is still poorly understood and there is a substantial placebo response. As a conclusion, a diagnosis of FD is challenging especially so in the context of Asia and despite the limitations of available physiological tests experts agreed that these tests can be advocated if and when clinically indicated.
  8. Choudhary AK, Lee YY
    Nutr Neurosci, 2018 Jun;21(5):306-316.
    PMID: 28198207 DOI: 10.1080/1028415X.2017.1288340
    Aspartame (α-aspartyl-l-phenylalanine-o-methyl ester), an artificial sweetener, has been linked to behavioral and cognitive problems. Possible neurophysiological symptoms include learning problems, headache, seizure, migraines, irritable moods, anxiety, depression, and insomnia. The consumption of aspartame, unlike dietary protein, can elevate the levels of phenylalanine and aspartic acid in the brain. These compounds can inhibit the synthesis and release of neurotransmitters, dopamine, norepinephrine, and serotonin, which are known regulators of neurophysiological activity. Aspartame acts as a chemical stressor by elevating plasma cortisol levels and causing the production of excess free radicals. High cortisol levels and excess free radicals may increase the brains vulnerability to oxidative stress which may have adverse effects on neurobehavioral health. We reviewed studies linking neurophysiological symptoms to aspartame usage and conclude that aspartame may be responsible for adverse neurobehavioral health outcomes. Aspartame consumption needs to be approached with caution due to the possible effects on neurobehavioral health. Whether aspartame and its metabolites are safe for general consumption is still debatable due to a lack of consistent data. More research evaluating the neurobehavioral effects of aspartame are required.
  9. Choudhary AK, Lee YY
    J Clin Neurosci, 2018 Oct;56:7-15.
    PMID: 30318075 DOI: 10.1016/j.jocn.2018.06.043
    Aspartame (NutraSweet®, Equal®) is a widely used artificial sweetener, has been reported to be accountable for neurological and behavioural disturbances in people. Upon ingestion, aspartame is hydrolyzed in gut and provides its metabolite; such as essential amino acid phenylalanine (Phy) (50%), aspartic acid (40%), and methanol (10%). Altered brain neurochemical compositions [such as dopamine (DA), norepinephrine (NE), and serotonin (5-HT)] have long been a concern and being involved in observed neurophysiological symptom (such as headaches, memory loss, mood changes, as well as depression) in aspartame consumers. Aspartames might act as chemical stressor through increasing plasma cortisol level. Aspartame consumption similarly altered gut microbiota. Taken together all this factors, we reviewed to search for convincing evidence, in what manner aspartame metabolites, stress hormones (cortisol), and gut dysbiosisis involved in altering brain neurochemical composition. We concluded that aspartame metabolite; mainly Phy and its interaction with neurotransmitter and aspartic acid by acting as excitatory neurotransmitter causes this pattern of impairments. Along with elevated cortisol and gut dysbiosis via interactions with different biogenic amine may also have additional impact to modulate neuronal signaling lead to neurobiological impairments. Hence ongoing research is instantly needed to understand the specific roles of aspartame metabolite, elevated cortisol, and gut dysbiosis with emerging neurophysiological symptom in aspartame consumers to improve healthy life in its consumers.
  10. Lee YY, Abdul Halim Z
    PeerJ Comput Sci, 2020;6:e309.
    PMID: 33816960 DOI: 10.7717/peerj-cs.309
    Stochastic computing (SC) is an alternative computing domain for ubiquitous deterministic computing whereby a single logic gate can perform the arithmetic operation by exploiting the nature of probability math. SC was proposed in the 1960s when binary computing was expensive. However, presently, SC started to regain interest after the widespread of deep learning application, specifically the convolutional neural network (CNN) algorithm due to its practicality in hardware implementation. Although not all computing functions can translate to the SC domain, several useful function blocks related to the CNN algorithm had been proposed and tested by researchers. An evolution of CNN, namely, binarised neural network, had also gained attention in the edge computing due to its compactness and computing efficiency. This study reviews various SC CNN hardware implementation methodologies. Firstly, we review the fundamental concepts of SC and the circuit structure and then compare the advantages and disadvantages amongst different SC methods. Finally, we conclude the overview of SC in CNN and make suggestions for widespread implementation.
  11. Lee YY, Erdogan A, Rao SS
    J Neurogastroenterol Motil, 2014 Oct 30;20(4):547-52.
    PMID: 25230902 DOI: 10.5056/jnm14056
    Management of chronic constipation with refractory symptoms can be challenging. Although new drugs and behavioral treat-ments have improved outcome, when they fail, there is little guidance on what to do next. At this juncture, typically most doc-tors may refer for surgical intervention although total colectomy is associated with morbidity including complications such as recurrent bacterial overgrowth. Recently, colonic manometry with sensory/tone/compliance assessment with a barostat study has been shown to be useful. Technical challenges aside, adequate preparation, and appropriate equipment and knowledge of co-lonic physiology are keys for a successful procedure. The test itself appears to be safe with little complications. Currently, colon-ic manometry is usually performed with a 6-8 solid state or water-perfused sensor probe, although high-resolution fiber-optic colonic manometry with better spatiotemporal resolutions may become available in the near future. For a test that has evolved over 3 decades, normal physiology and abnormal findings for common phenotypes of chronic constipation, especially slow transit constipation, have been well characterized only recently largely through the advent of prolonged 24-hour ambulatory colonic manometry studies. Even though the test has been largely restricted to specialized laboratories at the moment, emerg-ing new technologies and indications may facilitate its wider use in the near future.(J Neurogastroenterol Motil 2014;20:547-552).
  12. Lee YY, Erdogan A, Rao SS
    J Neurogastroenterol Motil, 2014 Apr 30;20(2):265-70.
    PMID: 24840380 DOI: 10.5056/jnm.2014.20.2.265
    Assessment of transit through the gastrointestinal tract provides useful information regarding gut physiology and patho-physiology. Although several methods are available, each has distinct advantages and limitations. Recently, an ingestible wire-less motility capsule (WMC), similar to capsule video endoscopy, has become available that offers a less-invasive, standardized, radiation-free and office-based test. The capsule has 3 sensors for measurement of pH, pressure and temperature, and collec-tively the information provided by these sensors is used to measure gastric emptying time, small bowel transit time, colonic transit time and whole gut transit time. Current approved indications for the test include the evaluation of gastric emptying in gastroparesis, colonic transit in constipation and evaluation of generalised dysmotility. Rare capsule retention and malfunc-tion are known limitations and some patients may experience difficulty with swallowing the capsule. The use of WMC has been validated for the assessment of gastrointestinal transit. The normal range for transit time includes the following: gastric empty-ing (2-5 hours), small bowel transit (2-6 hours), colonic transit (10-59 hours) and whole gut transit (10-73 hours). Besides avoiding the use of multiple endoscopic, radiologic and functional gastrointestinal tests, WMC can provide new diagnoses, leads to a change in management decision and help to direct further focused work-ups in patients with suspected disordered motility. In conclusion, WMC represents a significant advance in the assessment of segmental and whole gut transit and mo-tility, and could prove to be an indispensable diagnostic tool for gastrointestinal physicians worldwide.
  13. Lee YY, Mahendra Raj S, Graham DY
    Helicobacter, 2013 Oct;18(5):338-46.
    PMID: 23607896 DOI: 10.1111/hel.12058
    Helicobacter pylori (H. pylori) infection is etiologically associated with gastric cancer and peptic ulcer diseases which are both important public health burdens which could be largely eliminated by H. pylori eradication. However, some investigators urge caution based on the hypothesis that eradication of H. pylori may result in an increase in the incidence of gastroesophageal reflux disease, esophageal adenocarcinoma, and childhood asthma. The ethnic Malays of northeastern Peninsular Malaysia have long had a low prevalence of H. pylori infection and, as expected, the incidence of gastric cancer and its precursor lesions is exceptionally low. The availability of a population with a low H. pylori prevalence and generally poor sanitation allows separation of H. pylori from the hygiene hypothesis and direct testing of whether absence of H. pylori is associated with untoward consequence. Contrary to predictions, in Malays, erosive esophagitis, Barrett's esophagus, distal esophageal cancers, and childhood asthma are all of low incidence. This suggests that H. pylori is not protective rather the presence of H. pylori infection is likely a surrogate for poor hygiene and not an important source of antigens involved in the hygiene hypothesis. Helicobacter pylori in Malays is related to transmission from H. pylori-infected non-Malay immigrants. The factors responsible for low H. pylori acquisition, transmission, and burden of H. pylori infection in Malays remain unclear and likely involves a combination of environmental, host (gene polymorphisms), and strain virulence factors. Based on evidence from this population, absence of H. pylori infection is more likely to be boon than a bane.
  14. Lee YY, Tang TK, Lai OM
    J Food Sci, 2012 Aug;77(8):R137-44.
    PMID: 22748075 DOI: 10.1111/j.1750-3841.2012.02793.x
    Medium- and long-chain triacylglycerol (MLCT) is a modified lipid containing medium- chain (C6-C12) and long-chain fatty acids (C14-C24) in the same triacylglycerol (TAG) molecule. It can be produced either through enzymatic (with 1,3 specific or nonspecific enzyme) or chemical methods. The specialty of this structured lipid is that it is metabolized differently compared to conventional fats and oils, which can lead to a reduction of fat accumulation in the body. Therefore, it can be used for obesity management. It also contains nutritional properties that can be used to treat metabolic problems. This review will discuss on the health benefits of MLCT, its production methods especially via enzymatic processes and its applications in food industries.
Contact Us

Please provide feedback to Administrator (tengcl@gmail.com)

External Links