Displaying all 13 publications

Abstract:
Sort:
  1. Fulltext Impact of a katabatic wind event on GPS PWV measurements at Scott Base Station, Antarctica
    Suparta, W., Samah, A.A., Harper, A.R.
    ASM Science Journal, 2009;3(2):152-160.
    MyJurnal
    Katabatic winds dramatically affect the polar climate. Their activity depends on density of air and temperature in the source region. This paper presents for first time an analysis of the precipitable water vapour (PWV) variability and its relation to a katabatic event at Scott Base station, Antarctica. A significant effect in their characteristics toward calculation of a reliable user accuracy in GPS applications is addressed. Our investigations using the data between 21st and 30th of November 2002 showed that the PWV profile exhibited an irregular pattern with a maximum value of 7.38 mm (~ 6 mm on average), and was more strongly influenced by relative humidity than by wind speed activity. The dominant wind flow during this period was from the North-Northeast (blowing from the Ross Sea) with a median speed of 4.96 ms–1. The PWV was high when the temperature was between –15ºC and –11ºC. During the dates identified as a katabatic event between 21:30 UT of 28th November and 18:40 UT on 29th November, the wind blew from the Southeast-South direction (from the Ross Ice Shelf) with a maximum speed of 10.92 ms–1. The PWV increased ~1.4 mm (23%) from the mean value, indicating severe wind during this event which had pronounced effect on GPS observations.
    Matched MeSH terms: Cocaine
  2. Optimization of n-hexane reforming using Taguchi orthogonal array design
    Sinnathambi CM, Reem Ahmed Mohammed Ismail
    Sains Malaysiana, 2012;41:885-892.
    Taguchi orthogonal array design, a statistical software is applied to n-hexane reforming. The purpose is to identify the most significant process variable in reforming conditions favouring n-hexane conversion to high aromatics and isomers and low cracked and coke precursor reformate products. Actual experimental data were used for this study. Three process variables i.e. temperature, contact time and hydrogen partial pressure were investigated. From the study it was found that the contact time was the most critical operating parameter for n-hexane conversion followed by reaction temperature and hydrogen partial pressure. It was also noted that enhanced n-hexane reforming conversion can be achieved by operating the process at reaction temperature 723 K and contact time 7.1 min with a H2 partial pressure 300 kPa. For selectivity to aromatics and isomers lower contact time of 1.07 min with intermediate hydrogen partial pressure of 300 to 500 kPa operating at a reaction temperature of 723 K is most favourable.
    Matched MeSH terms: Cocaine
  3. Fulltext Progressive septal and palatal perforation secondary to intranasal cocaine abuse
    Gendeh BS, Ferguson BJ, Johnson JT, Kapadia S
    Med J Malaysia, 1998 Dec;53(4):435-8.
    PMID: 10971991
    Septal perforation from intranasal cocaine abuse is well recognised. We present a case of progressive septal as well as palatal perforation. Progression from septal perforation to palatal perforation occurred after cessation of intranasal cocaine abuse. This patient had a weakly positive cytoplasmic antineutrophilic cytoplasmic antibody (C-ANCA) but no histologic evidence of Wegener's Granulomatosis. The differential diagnosis for septal and palatal perforation is reviewed. This case represents the fifth reported case of palatal perforation secondary to cocaine abuse in the literature, and the second associated with positive C-ANCA.
    Matched MeSH terms: Cocaine-Related Disorders/complications*
  4. Butyrylcholinesterase: A Multifaceted Pharmacological Target and Tool
    Ha ZY, Mathew S, Yeong KY
    Curr Protein Pept Sci, 2020;21(1):99-109.
    PMID: 31702488 DOI: 10.2174/1389203720666191107094949
    Butyrylcholinesterase is a serine hydrolase that catalyzes the hydrolysis of esters in the body. Unlike its sister enzyme acetylcholinesterase, butyrylcholinesterase has a broad substrate scope and lower acetylcholine catalytic efficiency. The difference in tissue distribution and inhibitor sensitivity also points to its involvement external to cholinergic neurotransmission. Initial studies on butyrylcholinesterase showed that the inhibition of the enzyme led to the increment of brain acetylcholine levels. Further gene knockout studies suggested its involvement in the regulation of amyloid-beta, a brain pathogenic protein. Thus, it is an interesting target for neurological disorders such as Alzheimer's disease. The substrate scope of butyrylcholinesterase was recently found to include cocaine, as well as ghrelin, the "hunger hormone". These findings led to the development of recombinant butyrylcholinesterase mutants and viral gene therapy to combat cocaine addiction, along with in-depth studies on the significance of butyrylcholinesterase in obesity. It is observed that the pharmacological impact of butyrylcholinesterase increased in tandem with each reported finding. Not only is the enzyme now considered an important pharmacological target, it is also becoming an important tool to study the biological pathways in various diseases. Here, we review and summarize the biochemical properties of butyrylcholinesterase and its roles, as a cholinergic neurotransmitter, in various diseases, particularly neurodegenerative disorders.
    Matched MeSH terms: Cocaine/antagonists & inhibitors; Cocaine/metabolism; Cocaine-Related Disorders/drug therapy*; Cocaine-Related Disorders/genetics; Cocaine-Related Disorders/metabolism; Cocaine-Related Disorders/pathology
  5. Coca leaf and cocaine addiction--some historical notes
    Blejer-Prieto H
    Can Med Assoc J, 1965 Sep 25;93(13):700-4.
    PMID: 5318484
    Coca-leaf habituation has affected millions of Andean natives for over 400 years. In the last half-century it has also involved millions more Malayans. Coca leaf, from which cocaine and extracts for some commercial carbonated soft drinks are obtained, remains relatively unknown by the medical and allied professions elsewhere. A review of the original medical, historical and other pertinent literature of the last 350 years illustrates the origins of the use of coca leaf, its spread, the isolation of cocaine and its first uses, as well as some of the euphoric and other effects of both substances.
    Matched MeSH terms: Cocaine/adverse effects*
  6. Stress induces reinstatement of extinguished cocaine conditioned place preference by a sequential signaling via neuropeptide S, orexin, and endocannabinoid
    Chou YH, Hor CC, Lee MT, Lee HJ, Guerrini R, Calo G, et al.
    Addict Biol, 2020 Oct 19.
    PMID: 33078457 DOI: 10.1111/adb.12971
    Neurons containing neuropeptide S (NPS) and orexins are activated during stress. Previously, we reported that orexins released during stress, via orexin OX1 receptors (OX1 Rs), contribute to the reinstatement of cocaine seeking through endocannabinoid/CB1 receptor (CB1 R)-mediated dopaminergic disinhibition in the ventral tegmental area (VTA). Here, we further demonstrated that NPS released during stress is an up-stream activator of this orexin-endocannabinoid cascade in the VTA, leading to the reinstatement of cocaine seeking. Mice were trained to acquire cocaine conditioned place preference (CPP) by context-pairing cocaine injections followed by the extinction training with context-pairing saline injections. Interestingly, the extinguished cocaine CPP in mice was significantly reinstated by intracerebroventricular injection (i.c.v.) of NPS (1 nmol) in a manner prevented by intraperitoneal injection (i.p.) of SHA68 (50 mg/kg), an NPS receptor antagonist. This NPS-induced cocaine reinstatement was prevented by either i.p. or intra-VTA microinjection (i.vta.) of SB-334867 (15 mg/kg, i.p. or 15 nmol, i.vta.) and AM 251 (1.1 mg/kg, i.p. or 30 nmol, i.vta.), antagonists of OX1 Rs and CB1 Rs, respectively. Besides, NPS (1 nmol, i.c.v.) increased the number of c-Fos-containing orexin neurons in the lateral hypothalamus (LH) and increased orexin-A level in the VTA. The latter effect was blocked by SHA68. Furthermore, a 30-min restraint stress in mice reinstated extinguished cocaine CPP and was prevented by SHA68. These results suggest that NPS is released upon stress and subsequently activates LH orexin neurons to release orexins in the VTA. The released orexins then reinstate extinguished cocaine CPP via an OX1 R- and endocannabinoid-CB1 R-mediated signaling in the VTA.
    Matched MeSH terms: Cocaine
  7. Immigrant Health Study. 8. Screening for abused drugs among immigrant workers. [Abstract]
    Mustafa AM, Yap CG
    JUMMEC, 1998;3:63-64.
    Screening for drugs of abused were conducted by using Gas chromatography-Mass spectrometry (GCMS) fitted with capillary column. Urine samples supplied by Centre of Inmigrant Studies, University of Malaya were processed upon arrival and screened for the following drugs. Amphetamines, methamphetamines, aphedrine, hydroxy-amphetamines, ecstasy, benzamphetamines, codeine, morphine, heroine, cocaine and diazepam. The analysis was done using Shimadzu QP5000 Gas chromatograph-mass spectrometer by selected ion monitoring with BPX35 column, 15 m length, 0.32 ID, helium gas as carrier and quadropole mass detector at 1.60 kV electron gain. Analysis were performed using selected ion monitoring (SIM) mode and quantitations were based on area under the curve of individual standards at various concentrations. The method is sensitive to nanogram levels and are able to detect the presence of these drugs in both urine and plasma. From this study (n-100), none of the urine were found positive for the drugs screened. The major problem encountered were adulterated with water based on the clearness and the colour of the urine. Based on this suspicion we would like to suggest that the testing be done on blood samples as this would be more confirmative and quantitative.
    Matched MeSH terms: Cocaine
  8. Discriminative stimulus properties of mitragynine (kratom) in rats
    Harun N, Hassan Z, Navaratnam V, Mansor SM, Shoaib M
    Psychopharmacology (Berl), 2015 Jul;232(13):2227-38.
    PMID: 25616583 DOI: 10.1007/s00213-015-3866-5
    RATIONALE: Mitragynine (MG) is the primary active alkaloid extracted from the leaves of Mitragyna speciosa or kratom and exhibits pharmacological activities mediated by opioid receptors. The plant has been traditionally used for its opium and psychostimulant-like effects to increase work efficiency or as a substitute in the self-treatment of opiate addiction.

    OBJECTIVES: The present study was performed to investigate the discriminative stimulus effects of MG in rats. The pharmacological mechanism of MG action and its derivative, 7-hydroxymitragynine (7-HMG) with a specific focus on opioid receptor involvement was examined in rats trained to discriminate morphine from vehicle. In order to study the dual actions of MG, the effect of cocaine substitution to the MG discriminative stimulus was also performed in MG-trained rats.

    METHODS: Male Sprague Dawley rats were trained to discriminate MG from vehicle in a two-lever drug discrimination procedure under a tandem variable-interval (VI 60') fixed-ratio (FR 10) schedule of food reinforcement.

    RESULTS: Rats acquired the MG discrimination (15.0 mg/kg, i.p.) which was similar to the acquisition of morphine discrimination (5.0 mg/kg, i.p.) in another group of rats. MG substituted fully to the morphine discriminative stimulus in a dose-dependent manner, suggesting pharmacological similarities between the two drugs. The administration of 7-HMG derivative in 3.0 mg/kg (i.p.) dose engendered full generalisation to the morphine discriminative stimulus. In addition, the MG stimulus also partially generalised to cocaine (10.0 mg/kg, i.p.) stimulus.

    CONCLUSION: The present study demonstrates that the discriminative stimulus effect of MG possesses both opioid- and psychostimulant-like subjective effects.

    Matched MeSH terms: Cocaine/pharmacology
  9. Fulltext Integrating HIV pre-exposure prophylaxis and harm reduction among men who have sex with men and transgender women to address intersecting harms associated with stimulant use: a modelling study
    Bórquez A, Rich K, Farrell M, Degenhardt L, McKetin R, Tran LT, et al.
    J Int AIDS Soc, 2020 Jun;23 Suppl 1(Suppl 1):e25495.
    PMID: 32562365 DOI: 10.1002/jia2.25495
    INTRODUCTION: Among men who have sex with men (MSM) and transgender women (TW), stimulant use is high and has been associated with an increased risk of HIV infection, suicide and cardiovascular disease (CVD) mortality. We used epidemic modelling to investigate these intersecting health harms among MSM/TW in Lima, Peru and assess whether they could be mitigated by prioritizing HIV pre-exposure prophylaxis (PrEP) and harm reduction interventions among MSM/TW who use stimulants.

    METHODS: We adapted a dynamic model of HIV transmission among MSM/TW in Lima to incorporate stimulant use and increased HIV risk, suicide and CVD mortality. Among 6% to 24% of MSM/TW using stimulants (mostly cocaine), we modelled an increased risk of unprotected anal sex (RR = 1.35 [95%CI: 1.17 to 1.57]) obtained from local data, and increased risk of suicide (SMR = 6.26 [95%CI: 2.84 to 13.80]) and CVD (SMR = 1.83 [95%CI: 0.39 to 8.57]) mortality associated with cocaine use based on a global systematic review. We estimated the proportion of health harms occurring among MSM/TW who use stimulants in the next year (01-2020/01-2021). We also investigated the 10-year impact (01-2020/01-2030) of: (1) PrEP prioritization for stimulant-using MSM/TW compared to random allocation, and (2) integrating PrEP with a theoretical intervention halving stimulant-associated risk.

    RESULTS: MSM/TW in Lima will experience high HIV incidence, suicide mortality and CVD mortality (1.6/100 py, and 0.018/100 py, 0.13/100 py respectively) in 2020. Despite stimulant using MSM/TW comprising an estimated 9.5% (95%CI: 7.8 to 11.5) of all MSM/TW, in the next year, 11% 95%CI (i.e. 2.5% to 97.5% percentile) 10% to 13%) of new HIV infections, 39% (95%CI: 18% to 60%) of suicides and 15% (95%CI: 3% to 44%) of CVD deaths could occur among this group. Scaling up PrEP among all stimulant using MSM/TW could prevent 19% (95%CI: 11% to 31%) more HIV infections over 10 years compared to random allocation. Integrating PrEP and an intervention to halve stimulant-associated risks could reduce new HIV infections by 20% (95%CI: 10% to 37%), suicide deaths by 14% (95%CI: 5% to 27%) and CVD deaths by 3% (95%CI: 0% to 16%) over a decade.

    CONCLUSIONS: MSM/TW who use stimulants experience a disproportionate burden of health harms. Prioritizing PrEP based on stimulant use, in addition to sexual behaviour/gender identity criteria, could increase its impact. Integrated substance use, harm reduction, mental health and HIV care among MSM/TW is needed.

    Matched MeSH terms: Cocaine/pharmacology
  10. Neuropsychiatric implications of transient receptor potential vanilloid (TRPV) channels in the reward system
    Singh R, Bansal Y, Parhar I, Kuhad A, Soga T
    Neurochem Int, 2019 12;131:104545.
    PMID: 31494132 DOI: 10.1016/j.neuint.2019.104545
    Neuropsychiatric disorders (NPDs) exert a devastating impact on an individual's personal and social well-being, encompassing various conditions and brain anomalies that influence affect, cognition, and behavior. Because the pathophysiology of NPDs is multifactorial, the precise mechanisms underlying the development of such disorders remain unclear, representing a unique challenge in current neuropsychopharmacotherapy. Transient receptor potential vanilloid (TRPV) type channels are a family of ligand-gated ion channels that mainly include sensory receptors that respond to thermal, mechanical and chemical stimuli. TRPV channels are abundantly present in dopaminergic neurons, thus playing a pivotal role in the modulation of the reward system and in pathophysiology of diseases such as stress, anxiety, depression, schizophrenia, neurodegenerative disorders and substance abuse/addiction. Recent evidence has highlighted TRPV channels as potential targets for understanding modulation of the reward system and various forms of addiction (opioids, cocaine, amphetamines, alcohol, nicotine, cannabis). In this review, we discuss the distribution, physiological roles, ligands and therapeutic importance of TRPV channels with regard to NPDs and addiction biology.
    Matched MeSH terms: Cocaine
  11. Fulltext Pharmacotherapy for comorbid adult attention-deficit hyperactivity disorder and stimulant dependence: a systematic review
    Woon, L.S., Hazli Z., Gan, L.L.Y.
    International Medical Journal Malaysia, 2018;17(2):149-161.
    MyJurnal
    Comorbid adult attention-deficit hyperactivity disorder (ADHD) and stimulant dependence is widely recognized, but efficacy of pharmacotherapy in this patient population is not well established. We aimed to review whether pharmacotherapy is efficacious in reducing ADHD symptoms and stimulant use in comorbid adult ADHD and stimulant use disorder. English articles until June 2017 were systematically searched in electronic databases (MEDLINE and PsycINFO), an online clinical trials register (ClinicalTrial.gov), and through hand-search of article references. Randomized, double-blind, placebo-controlled trials that studied efficacy of pharmacotherapy in adults with comorbid ADHD and stimulant dependence were included. Two reviewers assessed studies for inclusion and extracted data; disagreements were resolved by consensus. Study outcomes included were changes in ADHD symptom severity, substance abstinence, treatment retention rates and safety. From the 1394 records identified, five trials (n=358) were included. Four studies involved methylphenidate; in another study extended-release mixed amphetamine were used. The comorbid stimulant was cocaine in three studies, and amphetamines in the rest. All were short-term studies involving predominantly young male adults conducted in outpatient settings. There is early promising but mixed evidence for therapeutic efficacy in improving ADHD symptoms. Stimulant medications did not worsen stimulant dependence or adverse effects of stimulant medications. Side effects were mild and tolerable. High attrition rates and small sample size limited the generalizability of findings. Current limited evidence suggests that stimulant treatment for comorbid adult ADHD and stimulant dependence is feasible. Welldesigned trials with adequate power are needed for more robust evidence on ADHD and stimulant use outcomes.
    Matched MeSH terms: Cocaine
  12. Fulltext Amphetamine type stimulant (ATS) induced psychosis: A rising problems in Malaysia
    Ahmad, H.S.
    Malaysian Journal of Psychiatry, 2008;17(2):1-4.
    MyJurnal
    The past decade has seen a marked increase in the popularity of ATS use, particularly methamphetamine, within East Asia,and the Pacific region. In Malaysia, the National Anti Drug Agency has identified 8,870 addicts (from January till August 2008) out of which 1,126 was ATS dependence. During the same period, the police have arrested 46,388 people under the Dangerous Drug Act 1952. They also has seize 283kg of syabu, 545kg of ecstacy powder, 66194 tablets of esctacy pills and 222,376 tablets of yaba pills from Jan till August this year. The occurrence of psychosis arising from the use of ATS was first reported in the late 1930's. With growing ATS use, particularly methamphetamine, ATS-induced psychosis has become a major impact on public health.Symptoms of ATS-induced psychosis: Methamphetamine use produces a variety of effects, ranging from irritability, to physical aggression, hyperawareness, hypervigilance, and psychomotor agitation. Repeated or high-dose use of the stimulant can cause drug-induced psychosis resembling paranoid schizophrenia, characterized by hallucinations, delusions and thought disorders. When used in long term, methamphetamine may lead to development of psychiatric symptoms due to dopamine depletion in the striatum. The most common lifetime psychotic symptoms among methamphetamine psychotic patients - as reported in a cross-country study involving Australia, Japan, the Philippines and Thailand - are persecutory delusion, auditory hallucinations, strange or unusual beliefs and thought reading. Those patients were also reported to suffer from impaired speech, psychomotor retardation, depression and anxiety. An ATS psychosis can be distinguished from primary psychotic disorders by time. In ATS-induced psychosis symptoms usually resolve after the drug is discontinued. If symptoms do not resolve within 2 weeks after cessation of stimulant use, a primary psychiatric disorder should be suspected. When compared with other stimulants, such as cocaine, psychosis is induced more commonly by ATS, possibly due to the longer duration of action produced by amphetamines.For example, while smoking cocaine produces a high that lasts for 20-30 minutes, smoking methamphetamine produces a high that lasts 8-24 hours. Other symptoms of ATS-induced psychosis reported include affective blunting,(6) violent behavior, and self-mutilation and self-injurious behavior.
    Matched MeSH terms: Cocaine
  13. Orexin-mediated restoration of hippocampal synaptic potentiation in mice with established cocaine-conditioned place preference
    Lu GL, Lee MT, Chiou LC
    Addict Biol, 2019 11;24(6):1153-1166.
    PMID: 30276922 DOI: 10.1111/adb.12672
    Orexins (also called hypocretins) are implicated in reward and addiction, but little is known about their role(s) in the association between hippocampal synaptic plasticity and drug preference. Previously, we found that exogenous orexin via OX1 and OX2 receptors can impair low frequency stimulation-induced depotentiation, i.e. restoring potentiation of excitatory synaptic transmission (re-potentiation) in mouse hippocampal slices. Here, we found this re-potentiation in hippocampal slices from mice that had acquired conditioned place preference (CPP) to cocaine. Both 10 and 20 mg/kg of cocaine induced similar magnitudes of CPP in mice and re-potentiation in their hippocampal slices, but differed in their susceptibility to TCS1102, a dual (OX1 and OX2 ) orexin receptor antagonist. TCS1102 significantly attenuated CPP and hippocampal re-potentiation induced by cocaine at 10 mg/kg but not at 20 mg/kg. Nonetheless, SCH23390, an antagonist of dopamine D1-like receptors (D1-likeRs), inhibited the effects induced by both doses of cocaine. SKF38393, a D1-likeR-selective agonist, also induced hippocampal re-potentiation in vitro. Interestingly, this effect was attenuated by TCS1102. Conversely, SCH23390 prevented orexin A-induced hippocampal re-potentiation. These results suggest that endogenous orexins are released in mice during cocaine-CPP acquisition, which sustains potentiated hippocampal transmission via OX1 /OX2 receptors and may contribute to the addiction memory of cocaine. This effect of endogenous orexins, however, may be substituted by dopamine that may dominate hippocampal re-potentiation and CPP via D1-likeRs when the reinforcing effect of cocaine is high.
    Matched MeSH terms: Cocaine/administration & dosage*
Related Terms
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links