Displaying publications 1 - 20 of 78 in total

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  1. Ahmad AH, Ismail Z
    PMID: 22969311 MyJurnal
    The discovery that c-fos, a proto-oncogene, has a role in pain, has triggered extensive research on the consequences of c-fos expression. It has been shown that c-fos, through its protein form, FOS, leads to expression of dynorphin gene and subsequently dynorphin protein which is implicated in the development of a pain state. This mini review looks at the properties of c-fos and the consequences of its expression following noxious (painful) stimulation.
  2. Tamam S, Ahmad AH
    PMID: 28814928 MyJurnal DOI: 10.21315/mjms2017.24.3.2
    Pain is modulated by various factors, the most notable of which is emotions. Since love is an emotion, it can also modulate pain. The answer to the question of whether it enhances or reduces pain needs to be determined. A review was conducted of animal and human studies in which this enigmatic emotion and its interaction with pain was explored. Recent advances in neuroimaging have revealed similarities in brain activation relating to love and pain. At the simplest level, this interaction can be explained by the overlapping network structure in brain functional connectivity, although the explanation is considerably more complex. The effect of love can either result in increased or decreased pain perception. An explanation of the interaction between pain and love relates to the functional connectivity of the brain and to the psychological construct of the individual, as well as to his or her ability to engage resources relating to emotion regulation. In turn, this determines how a person relates to love and reacts to pain.
  3. Majid AH, Ahmad AH
    Trop Life Sci Res, 2013 Dec;24(2):91-5.
    PMID: 24575252 MyJurnal
    Nine soil samples from nine buildings infested with Coptotermes gestroi in Pulau Pinang, Malaysia, were tested for the type of soil texture. The soil texture analysis procedures used the hydrometer method. Four of nine buildings (44%) yielded loamy sand-type soil, whereas five of nine buildings (56%) contained sandy loam-type soil.
  4. Abu Tahir N, Ahmad AH
    J Med Entomol, 2013 Sep;50(5):999-1002.
    PMID: 24180104
    Effects of laterite cover soil with different characteristics on survival of buried eggs, third instar larvae, and pupae of Musca domestica (L.) were studied experimentally. Soil treatments were loose dry soil, loose wet soil, compacted dry soil, and compacted wet soil (CWS). Eggs, third instar larvae, and pupae were buried under 30 cm of the different soil treatments and placed under field conditions until adults emerged. Rearing medium was provided for eggs and larvae, and control treatments of all stages were unburied immatures placed on soil surface. Egg and pupal survival to adult were significantly affected by the cover soil treatments, but third instars were more resilient. Wet soil treatments (loose wet soil and CWS) resulted in significantly reduced pupal survival, but increased survival of eggs. However, CWS significantly reduced adult emergence from buried eggs. Though emergence of house flies buried as eggs was significantly reduced, some were able to hatch and emerging first instar larvae developed to pupation. Although cover soil does not completely prevent fly emergence, it did limit development and emergence of buried house flies.
  5. Jasmi AH, Ahmad AH
    Insects, 2011;2(4):469-74.
    PMID: 26467826 DOI: 10.3390/insects2040469
    A study was carried out to evaluate the incidence of termite attack on an Araucaria cunninghamii plantation at Teluk Bahang Forest Park (TBFP), Penang. The hilly plantation area was surveyed to determine the diversity of termite species present. Termite specimens were collected from standin Araucaria trees, underground monitoring (aggregation) stations, fallen logs, forest litter and mounds (nests). Seven species of termites were identified from 6 genera; Coptotermes curvignathus, Schedorhinotermes medioobscurus, Schedorhinotermes malaccensis, Odontotermes sarawakensis Parrhinotermes aequalis, Macrotermes malaccensis and Hospitalitermes hospitalis. A total of 289 Araucaria trees were inspected for signs of termite attack. Termite infestation of trees was determined mainly by the presence of mud on the trunk, but particularly around their butts at ground line. The most dominant termite species discovered infesting the Araucaria trees was Coptotermes curvignathus; accountable for 74% of all infestations. Schedorhinotermes medioobscurus and Odontotermes sarawakensis were commonly found infesting dead trees and/or tree stumps. Approximately 21.5% of all Araucaria trees in the plantation forest at Teluk Bahang were infested by termites.
  6. Zakaria R, Ahmad AH, Othman Z
    Folia Biol. (Praha), 2016;62(5):181-187.
    PMID: 27978412
    Pineal melatonin biosynthesis is regulated by the circadian clock located in the suprachiasmatic nucleus of the hypothalamus. Melatonin has been found to modulate the learning and memory process in human as well as in animals. Endogenous melatonin modulates the process of newly acquired information into long-term memory, while melatonin treatment has been found to reduce memory deficits in elderly people and in various animal models. However, the mechanisms mediating the enhancing effect of melatonin on memory remain elusive. This review intends to explore the possible mechanisms by looking at previous data on the effects of melatonin treatment on memory performance in rodents.
  7. Ahmad AH, Abdul Aziz CB
    The Malaysian journal of medical sciences : MJMS, 2014 Dec;21(Spec Issue):46-54.
    PMID: 25941463 MyJurnal
    Pain, while salient, is highly subjective. A sensation perceived as painful by one person may be perceived as uncomfortable, not painful or even pleasant to others. Within the same person, pain may also be modulated according to its threat value and the context in which it is presented. Imaging techniques, such as functional magnetic resonance imaging and positron emission tomography, have identified a distributed network in the brain, the pain-relevant brain regions, that encode the sensory-discriminative aspect of pain, as well as its cognitive and affective/emotional factors. Current knowledge also implicates the prefrontal cortex as the modulatory area for pain, with its subdivisions forming the cortico-cortical pathway, an alternative pain modulatory pathway distinct from the descending modulatory pathway of pain. These findings from neuroimaging in human subjects have paved the way for the molecular mechanisms of pain modulation to be explored in animal studies.
  8. Rahman WA, Che'Rus A, Ahmad AH
    PMID: 9561615
    Until today, malaria is still one of the most important diseases in Malaysia. This is because Malaysia is located within the equatorial zone with high temperatures and humidities, usually important for the transmission of malaria. The number of malaria cases were estimated to be around 300,000 before the launching of the Malaria Eradication Program (MEP). The program was successful in reducing the numbers progressively during the 1967-1982 period. During the period 1980-1991, the highest number of malaria cases recorded for the country was 65,283 in 1989 (16,902 in Peninsular Malaysia, 47,545 in Sabah and 836 in Sarawak) whilst the lowest was 22,218 (10,069 in Peninsular Malaysia, 11,290 in Sabah and 859 in Sarawak) in 1983. In Malaysia, there are 434 species of mosquitos, representing 20 genera. Of these, 75 species are Anopheles that comprise of 2 subgenus, i.e. Anopheles and Cellia. Of the 75 species, only 9 have been reported as vectors: An. maculatus, An balabacensis, An. dirus, An. letifer An. campestris, An. sundaicus, An. donaldi, An. leucophyrus and An. flavirostris. The behavior, seasonal abundance, biting activities and breeding sites of these species are discussed.
  9. Ab Aziz CB, Ahmad AH
    PMID: 22589599 MyJurnal
    The thalamus is one of the structures that receives projections from multiple ascending pain pathways. The structure is not merely a relay centre but is involved in processing nociceptive information before transmitting the information to various parts of the cortex. The thalamic nuclei are involved in the sensory discriminative and affective motivational components of pain. Generally each group of nucleus has prominent functions in one component for example ventrobasal complex in sensory discriminative component and intralaminar nuclei in affective-motivational component. The thalamus is also part of a network that projects to the spinal cord dorsal horn and modulates ascending nociceptive information. In the animal models of neuropathic pain, changes in the biochemistry, gene expression, thalamic blood flow and response properties of thalamic neurons have been shown. These studies suggest the important contribution of the thalamus in modulating pain in normal and neuropathic pain condition.
  10. Sapaat A, Satrija F, Mahsol HH, Ahmad AH
    Trop Biomed, 2012 Dec;29(4):508-12.
    PMID: 23202594
    The purpose of this study is to see the anthelmintic activity potential of papaya seeds against Hymenolepis diminuta in rats. The objectives of this study were: (1) to determine the effectiveness of papaya seeds on helminths especially H. diminuta in rats and (2) to determine the effective dose level on helminths in rats. Thirty six male rats from strain Sprague-Dawley were chosen as samples in this experiment. Two types of dose level were used for papaya seeds treatments such as 0.6 g kg-1 and 1.2 g kg-1. The geometric mean (GEM) was used to calculate mean for eggs per gram (EPG) before and after the treatment to be included in the reduction percentage calculation. After 21 days post treatment, necropsies were done to get the worm count and the GEM was used to calculate the efficacy percentage for the treatment. Results from this study showed that the reduction percentages in EPG for papaya seeds treatment for both doses level were very high which is 96.8% for 0.6g kg-1 dose level and 96.2% for 1.2 g kg-1 dose level. Whereas the efficacy percentage based on the worm counts for both doses level were also very high that was 90.77% for 0.6 g kg-1 dose level and 93.85% for 1.2 g kg-1.
  11. Clink DJ, Ahmad AH, Klinck H
    R Soc Open Sci, 2020 Apr;7(4):200151.
    PMID: 32431905 DOI: 10.1098/rsos.200151
    Evidence for compression, or minimization of code length, has been found across biological systems from genomes to human language and music. Two linguistic laws-Menzerath's Law (which states that longer sequences consist of shorter constituents) and Zipf's Law of abbreviation (a negative relationship between signal length and frequency of use)-are predictions of compression. It has been proposed that compression is a universal in animal communication, but there have been mixed results, particularly in reference to Zipf's Law of abbreviation. Like songbirds, male gibbons (Hylobates muelleri) engage in long solo bouts with unique combinations of notes which combine into phrases. We found strong support for Menzerath's Law as the longer a phrase, the shorter the notes. To identify phrase types, we used state-of-the-art affinity propagation clustering, and were able to predict phrase types using support vector machines with a mean accuracy of 74%. Based on unsupervised phrase type classification, we did not find support for Zipf's Law of abbreviation. Our results indicate that adherence to linguistic laws in male gibbon solos depends on the unit of analysis. We conclude that principles of compression are applicable outside of human language, but may act differently across levels of organization in biological systems.
  12. Ishadi NA, Rawi CS, Ahmad AH, Abdul NH
    Trop Life Sci Res, 2014 Dec;25(2):61-79.
    PMID: 27073600 MyJurnal
    The hemipteran (Insecta) diversity in the upper part of the Kerian River Basin was low with only 8 families and 16 genera recorded at 4 study sites from 3 rivers. Water bug composition varied among sampling sites (Kruskal-Wallis χ (2) = 0.00, p<0.05) but was not affected by wet-dry seasons (Z = 0.00, p>0.05). All recorded water parameters were weakly associated with generic abundance but the biochemical oxygen demand (BOD), chemical oxygen demand (COD), Water Quality Index (WQI) and heavy metals (zinc and manganese) showed relatively strong positive or negative relations with hemipteran diversity and richness (H' and R2). Within the ranges of measured water parameters, the WQI was negatively associated with hemipteran diversity and richness, implying the tolerance of the water bugs to the level of pollution encountered in the river basin. Based on its highest abundance and occurrence (ISI), Rhagovelia was the most important genus and along with Rheumatogonus and Paraplea, these genera were common at all study sites. In conclusion, habitat availability and suitability together with some environmental parameters influenced the abundance and composition of hemipterans in this river basin.
  13. Siran R, Ahmad AH, Abdul Aziz CB, Ismail Z
    PMID: 25218926 DOI: 10.1007/s13105-014-0356-x
    REM sleep is a crucial component of sleep. Animal studies indicate that rapid eye movement (REM) sleep deprivation elicits changes in gene expression. Down regulatory antagonist modulator (DREAM) is a protein which downregulates other gene transcriptions by binding to the downstream response element site. The aim of this study is to examine the effect of REM sleep deprivation on DREAM expression in ventrobasal thalamic nuclei (VB) of rats. Seventy-two male Sprague-Dawley rats were divided into four major groups consisting of free-moving control rats (FMC) (n = 18), 72-h REM sleep-deprived rats (REMsd) (n = 18), 72-h REM sleep-deprived rats with 72-h sleep recovery (RG) (n = 18), and tank control rats (TC) (n = 18). REM sleep deprivation was elicited using the inverted flower pot technique. DREAM expression was examined in VB by immunohistochemical, Western blot, and quantitative real-time polymerase chain reaction (qRT-PCR) studies. The DREAM-positive neuronal cells (DPN) were decreased bilaterally in the VB of rats deprived of REM sleep as well as after sleep recovery. The nuclear DREAM extractions were increased bilaterally in animals deprived of REM sleep. The DREAM messenger RNA (mRNA) levels were decreased after sleep recovery. The results demonstrated a link between DREAM expression and REM sleep deprivation as well as sleep recovery which may indicate potential involvement of DREAM in REM sleep-induced changes in gene expression, specifically in nociceptive processing.
  14. Al-Rahbi B, Zakaria R, Othman Z, Hassan A, Ahmad AH
    ScientificWorldJournal, 2014;2014:310821.
    PMID: 24550703 DOI: 10.1155/2014/310821
    A possible interaction between glucocorticoids and estrogen-induced increases in brain-derived-neurotrophic factor (BDNF) expression in enhancing depressive-like behaviour has been documented. Here we evaluated the effects of Tualang honey, a phytoestrogen, and 17 β -estradiol (E2) on the depressive-like behaviour, stress hormones, and BDNF concentration in stressed ovariectomised (OVX) rats. The animals were divided into six groups: (i) nonstressed sham-operated control, (ii) stressed sham-operated control, (iii) nonstressed OVX, (iv) stressed OVX, (v) stressed OVX treated with E2 (20  μg daily, sc), and (vi) stressed OVX treated with Tualang honey (0.2 g/kg body weight daily, orally). Two months after surgery, the animals were subjected to social instability stress procedure followed by forced swimming test. Struggling time, immobility time, and swimming time were scored. Serum adrenocorticotropic hormone (ACTH) and corticosterone levels, and the BDNF concentration were determined using commercially available ELISA kits. Stressed OVX rats displayed increased depressive-like behaviour with significantly increased serum ACTH and corticosterone levels, while the BDNF concentration was significantly decreased compared to other experimental groups. These changes were notably reversed by both E2 and Tualang honey. In conclusion, both Tualang honey and E2 mediate antidepressive-like effects in stressed OVX rats, possibly acting via restoration of hypothalamic-pituitary-adrenal axis and enhancement of the BDNF concentration.
  15. Dom NC, Ahmad AH, Latif ZA, Ismail R
    Trans R Soc Trop Med Hyg, 2013 Nov;107(11):715-22.
    PMID: 24062522 DOI: 10.1093/trstmh/trt073
    Dengue has emerged as one of the major public health problems in Malaysia. The Ministry of Health, Malaysia, is committed in monitoring and controlling this disease for many years. The objective of this study is to analyze the dengue outbreak pattern on a monthly basis in Subang Jaya in terms of their spatial dissemination and hotspot identification.
  16. Srinivasan V, Mohamed M, Zakaria R, Ahmad AH
    Infect Disord Drug Targets, 2012 Oct;12(5):371-9.
    PMID: 23082960
    Malaria, one of the most deadly diseases of our time affects more than 200 million people across the globe and is responsible for about one million deaths annually. Until recently Plasmodium falciparum has been the main cause for malarial infection in human beings but now Plasmodium knowlesi from Malaysia remains as one of the most virulent parasite spreading fast not only in Malaysia but in different parts of the world. Hence there is urgent need for the global fight to control malaria. Global malaria eradication program by use of insecticide spraying has resulted in good response in the past. Treatment of malaria infected patients with anti-malarial drugs has helped to eliminate malarial infections successfully but with increased resistance displayed by malarial parasites to these drugs there is resurgence of malaria caused both by drug resistance as well as by infection caused by new malarial species like Plasmodium knowlesi. With recent advances on molecular studies on malarial parasites it is now clear that the pineal hormone melatonin acts as a cue for growth and development of Plasmodium falciparum. Same may be true for Plasmodium knowlesi also. Hence treatment modalities that can effectively block the action of melatonin on Plasmodium species during night time by way of using either bright light therapy or use of melatonin receptor blocking can be considered as useful approaches for eliminating malarial infection in man.
  17. Srinivasan V, Ahmad AH, Mohamed M, Zakaria R
    PMID: 22537380
    Malaria remains a global health problem affecting more than 515 million people all over the world including Malaysia. It is on the rise, even within unknown regions that previous to this were free of malaria. Although malaria eradication programs carried out by vector control programs are still effective, anti-malarial drugs are also used extensively for curtailing this disease. But resistance to the use of anti-malarial drugs is also increasing on a daily basis. With an increased understanding of mechanisms that cause growth, differentiation and development of malarial parasites in rodents and humans, new avenues of therapeutic approaches for controlling the growth, synchronization and development of malarial parasites are essential. Within this context, the recent discoveries related to IP3 interconnected signalling pathways, the release of Ca2+ from intracellular stores of Plasmodium, ubiquitin protease systems as a signalling pathway, and melatonin influencing the growth and differentiation of malarial parasites by its effects on these signalling pathways have opened new therapeutic avenues for arresting the growth and differentiation of malarial parasites. Indeed, the use of melatonin antagonist, luzindole, has inhibited the melatonin's effect on these signalling pathways and thereby has effectively reduced the growth and differentiation of malarial parasites. As Plasmodium has effective sensors which detect the nocturnal plasma melatonin concentrations, suppression of plasma melatonin levels with the use of bright light during the night or by anti-melatonergic drugs and by using anti-kinase drugs will help in eradicating malaria on a global level. A number of patients have been admitted with regards to the control and management of malarial growth. Patents related to the discovery of serpentine receptors on Plasmodium, essential for modulating intra parasitic melatonin levels, procedures for effective delivery of bright light to suppress plasma melatonin levels and thereby arresting the growth and elimination of malarial parasites from the blood of the host are all cited in the paper. The purpose of the paper is to highlight the importance of melatonin acting as a cue for Plasmodium faciparum growth and to discuss the ways of curbing the effects of melatonin on Plasmodium growth and for arresting its life cycle, as a method of eliminating the parasite from the host.
  18. Thevan K, Ahmad AH, Rawi CS, Singh B
    J Forensic Sci, 2010 Nov;55(6):1656-8.
    PMID: 20579228 DOI: 10.1111/j.1556-4029.2010.01485.x
    In estimating the postmortem interval (PMI) using maggots obtained during autopsy, the forensic entomologist makes decisions regarding the effects of low-temperature storage of the body on the insects. In this case report, a corpse was found in an abandoned house in the residential area of Bukit Mertajam, Penang, Malaysia. The maggots were found to be alive inside the mouth of the deceased although the corpse had been in the morgue cooler for 12 days. The maggots were reared and identified as Chrysomya megacephala (Fabricius). The emerged adult flies were kept as a stock colony, and the duration of development under the indoor fluctuating temperature regime was studied. The total duration of developmental process of this species was 9.5 ± 0.5 days, and the PMI estimated was 3.2 ± 0.6 days. This case report demonstrates the survival of Ch. megacephala maggots for 12 days and their growth inside the morgue cooler.
  19. Maimusa HA, Ahmad AH, Kassim NF, Rahim J
    J. Am. Mosq. Control Assoc., 2016 Mar;32(1):1-11.
    PMID: 27105211 DOI: 10.2987/moco-32-01-1-11.1
    The life table developmental attributes of laboratory colonies of wild strains of Aedes albopictus and Aedes aegypti were analyzed and compared based on the age-stage, two-sex life table. Findings inclusive in this study are: adult preoviposition periods, total preoviposition period, mean intrinsic rate of increase (r), mean finite rate of increase (λ), net reproductive rates (R0), and mean generation time (T). The total preadult development time was 9.47 days for Ae. albopictus and 8.76 days for Ae. aegypti. The life expectancy was 19.01 days for Ae. albopictus and 19.94 days for Ae. aegypti. Mortality occurred mostly during the adult stage. The mean development time for each stage insignificantly correlated with temperature for Ae. albopictus (r  =  -0.208, P > 0.05) and (r  =  -0.312, P > 0.05) for Ae. aegypti. The population parameters suggest that Ae. albopictus and Ae. aegypti populations are r-strategists characterized by a high r, a large R0, and short T. This present study provides the first report to compare the life parameters of Ae. albopictus and Ae. aegypti strains from Penang island, Malaysia.
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