Displaying publications 1 - 20 of 243 in total

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  1. Cellular inhibitory behavior underlying the formation of retinal direction selectivity in the starburst network
    Poznanski RR
    J Integr Neurosci, 2010 Sep;9(3):299-335.
    PMID: 21064220
    Optical imaging of dendritic calcium signals provided evidence of starburst amacrine cells exhibiting calcium bias to somatofugal motion. In contrast, it has been impractical to use a dual-patch clamp technique to record membrane potentials from both proximal dendrites and distal varicosities of starburst amacrine cells in order to unequivocally prove that they are directionally sensitive to voltage, as was first suggested almost two decades ago. This paper aims to extend the passive cable model to an active cable model of a starburst amacrine cell that is intrinsically dependent on the electrical properties of starburst amacrine cells, whose various macroscopic currents are described quantitatively. The coupling between voltage and calcium just below the membrane results in a voltage-calcium system of coupled nonlinear Volterra integral equations whose solutions must be integrated into a prescribed model for example, for a synaptic couplet of starburst amacrine cells. Networks of starburst amacrine cells play a fundamental role in the retinal circuitry underlying directional selectivity. It is suggested that the dendritic plexus of starburst amacrine cells provides the substrate for the property of directional selectivity, while directional selectivity is a property of the exclusive layerings and confinement of their interconnections within the sublaminae of the inner plexiform layer involving cone bipolar cells and directionally selective ganglion cells.
  2. Analytical solution of reaction-diffusion equations for calcium wave propagation in a starburst amacrine cell
    Poznanski RR
    J Integr Neurosci, 2010 Sep;9(3):283-97.
    PMID: 21064219
    A reaction-diffusion model is presented to encapsulate calcium-induced calcium release (CICR) as a potential mechanism for somatofugal bias of dendritic calcium movement in starburst amacrine cells. Calcium dynamics involves a simple calcium extrusion (pump) and a buffering mechanism of calcium binding proteins homogeneously distributed over the plasma membrane of the endoplasmic reticulum within starburst amacrine cells. The system of reaction-diffusion equations in the excess buffer (or low calcium concentration) approximation are reformulated as a nonlinear Volterra integral equation which is solved analytically via a regular perturbation series expansion in response to calcium feedback from a continuously and uniformly distributed calcium sources. Calculation of luminal calcium diffusion in the absence of buffering enables a wave to travel at distances of 120 μm from the soma to distal tips of a starburst amacrine cell dendrite in 100 msec, yet in the presence of discretely distributed calcium-binding proteins it is unknown whether the propagating calcium wave-front in the somatofugal direction is further impeded by endogenous buffers. If so, this would indicate CICR to be an unlikely mechanism of retinal direction selectivity in starburst amacrine cells.
  3. GC-MS Analysis of Bioactive Compounds in Ethanolic Leaf Extract of Hellenia speciosa (J.Koenig) S.R. Dutta
    R R
    Appl Biochem Biotechnol, 2022 Jan;194(1):176-186.
    PMID: 34762268 DOI: 10.1007/s12010-021-03742-2
    Hellenia speciosa (J.Koenig) S.R. Dutta is a plant species belonging to the family Costaceae. It is widely distributed in China, India, Malaysia, Indonesia, tropical, and subtropical Asia. In Ayurveda, the rhizome of this plant has been extensively used to treat fever, rash, asthma, bronchitis, and intestinal worms. The objective of the present study was to investigate the phytochemical constituents of the leaf of Hellenia speciosa using gas chromatography and mass spectroscopy analysis (GC-MS). The GC-MS analysis revealed the presence of 17 phytochemical components in the ethanolic leaf extract of Hellenia speciosa. The prevailing bioactive compounds present in Hellenia speciosa were thymol (RT-10.019; 3.59%), caryophyllene (RT-11.854; 0.62%), caryophyllene oxide (RT-13.919; 1.34%), artumerone (RT-14.795; 1.35%), hexadecanoic acid methyl ester (RT-17.536; 2.77%), 9,12-octadecanoic acid methyl ester (RT-19.163; 1.35%), squalene (RT-24.980; 1.19%), piperine (RT-25.745; 3.11%), beta tocopherol (RT-26.681; 2.88%), vitamin E (RT-27.290; 2.64%), progesterone (RT-29.608; 3.18%), caparratriene (RT-29.861; 9.72%), and testosterone (RT-30.73; 5.81%). The compounds were identified by comparing their retention time and peak area with that of the literature and by interpretation of mass spectra. The results and findings of the present study suggest that the plant leaf can be used as a valuable source in the field of herbal drug discovery. The presence of bioactive compounds justifies the use of plant leaves for treating various diseases with fewer side effects and recommended the plant of pharmaceutical importance. However, further studies are needed to undertake its bioactivity and toxicity profile.
  4. Fulltext Torula meningitis in Malaya
    ROSS RR, DEAN D
    Br Med J, 1957 Sep 14;2(5045):627.
    PMID: 13460339
  5. Optimised and systematic suitable climate modelling confirms future longitudinal-trends for growing oil palm in Africa
    Paterson RRM
    J Environ Manage, 2021 Dec 15;300:113785.
    PMID: 34562818 DOI: 10.1016/j.jenvman.2021.113785
    Palms are iconic plants. Oil palms are very important economically and originate in Africa where they can act as a model for palms in general. The effect of future climate on the growth of oil palm will be very detrimental. Latitudinal migration of tropical crops to climate refuges may be impossible, and longitudinal migration has only been confirmed for oil palm, of all the tropical crops. The previous method to determine the longitudinal trend for oil palm used the longitudes of various countries in Africa and plotted these against the percentage suitable climate for growing oil palms in each country. An increasing longitudinal trend was observed from west to east. However, the longitudes of the countries were randomly distributed which may have introduced bias and the procedure was time consuming. The present report presents an optimised and systematic procedure that divided the regions, as presented on a map derived from a CLIMEX model, into ten equal sectors and the percentage suitable climates for growing oil palm were determined for each sector. This approach was quicker, systematic and straight forward and will be useful for management of oil palm plantations under climate change. The method confirmed and validated the trends reported in the original method although the suitability values were often lower and there was less spread of values around the trend. The values for the CSIRO MK3.0 and MIROC H models demonstrated considerable similarities to each other, contributing to validation of the method. The procedure of dividing maps equally into sectors derived from models, could be used for other crops, regions, or systems more generally, where the alternative may be a more superficial visual examination of the maps. Methods are required to mitigate the effects of climate change and stakeholders need to contribute more actively to the current climate debate with tangible actions.
  6. Fulltext Observational study on cannulation rate during ERCP at hospital alor setar
    Sivasubramaniam M, Naidu RR
    Malays J Med Sci, 2001 Jan;8(1):25-30.
    PMID: 22973152 MyJurnal
    ERCP (Endoscopic Retrograde Cholangiopancreaticography) was introduced in this hospital in late 1995. Since then, a lot of improvement have been achieved in the management of biliary tract diseases. Various general surgeons posted to this hospital have been trained in this procedure. A study was done to include all patients admitted for ERCP from August 1998 to July 1999. A total of 322 new patients with a mean of 26.9 cases a month had underwent this procedure. The duration of cannulation varied from 2 minutes to 45 minutes with a mean of 12 minutes. Cannulation rate by various surgeons differed. Overall success rate was 80%. Mortality was 0.6 % and morbidity was 0.9%. ERCP is safe and it takes at least 6 months of regular duodenoscopy before one can master the technique. Achieving 80% cannulation rate, has definitely reduced unnecessary common bile duct (CBD) explorations. During this study we have trained various surgeons in this procedure and at least 2 surgeons could be credentialled according to the guidelines provided by the Malaysian Society of Gastroenterology and Hepatology. During this study we have identified various reasons for the failure of cannulation which are useful for future training of endoscopists.
  7. Fulltext Electrospun zein nanofibers as carriers of gallic, caffeic and p-coumaric acid
    Noman R. R., Law, K. P., Neo, Y. P.
    Malaysian Journal of Medicine and Health Sciences, 2019;15(102):7-7.
    MyJurnal
    Introduction: The application of nanofibers in biomedicine has gained increasing interest due to their characteristic large surface area, high porosity and chemical tunability. Electrospinning is one of the most versatile techniques for the production of uniform nanofibers. It has been used for the fabrication of extracellular matrix (ECM)-mimicking fibrous scaffolds for several decades. Electrospun fibrous scaffolds provide nanoscale to microscale fibrous structures with interconnecting pores, resembling natural ECM in tissues, and showing a high potential to facilitate the formation of artificial functional tissues. Furthermore, electrospinning demonstrated potential as a vehicle for the encapsulation of bioactive compounds such as phenolic acids, which was suggested to have significant potential to treat wounds caused by trauma, diabetes, ischemic syndromes and other pathological diseases. This study investigates the application of electrospun nanofibers as bioactive carriers of phenolic acids, where gallic, caffeic and p-coumaric acids were incorporated to zein nanofibers at different concentrations (5%, 10% and 20%). Methods: The morphology of the produced fibers were examined with scanning electron microscopy (SEM) and exhibited diameters ranging from 396 to 655 nm. Meanwhile, the interaction between the phenolic compounds and zein was examined with attenuated total reflection-Fourier transform infrared (ATR-FTIR). Results: The antioxidant activity of the fibers was determined using 1,10-diphenyl-2-picrylhydrazyl (DPPH) assay and showed that gallic and caffeic acid had retained their active properties after the incorporation to zein electrospun fibers. Conclusion: Overall, the study provides an outline on the potential of electrospinning technique to produce nanofibers that may serve as substrates in skin tissue engineering and carriers for bioactive compounds such as phenolic acids.
  8. Accuracy of intraoperative consultation for ovarian tumours: Experience in an Indonesian teaching hospital
    Fauziah D, Anggoro R R
    Malays J Pathol, 2020 Dec;42(3):409-414.
    PMID: 33361722
    BACKGROUND: Ovarian tumours are a very heterogeneous group of tumours, consisted of non-neoplastic and neoplastic lesions. Preoperative diagnoses in most conditions are inconclusive due to similar clinical, radiological and laboratory findings. Intraoperative consultation is crucial because it can provide rapid diagnosis leading to a suitable surgical management for the patients.

    OBJECTIVE: To obtain profile, accuracy and concordance rates of ovarian intraoperative consultation in Dr. Soetomo Hospital Surabaya, a teaching hospital in Indonesia.

    MATERIALS AND METHODS: Observational retrospective study, using data from archives of intraoperative consultation reports in Dr. Soetomo General Hospital Surabaya within 2012-2016 period. There were 734 cases of ovarian intraoperative consultations, all then proceed to permanent sections. Accuracy, sensitivity, and specificity rates were calculated.

    RESULTS: Overall accuracy was 89.5%. Sensitivity for benign, borderline and malignant cases were 98.49%, 71.19% and 84.01%, respectively. Specificity were 90.32%, 95.11% and 98.72%, respectively.

    CONCLUSION: Intraoperative consultation for ovarian tumours has a reliable diagnostic value in benign and malignant lesion, but lower value in borderline tumours.

  9. Associable representations as field of influence for dynamic cognitive processes
    Cacha LA, Poznanski RR
    J Integr Neurosci, 2011 Dec;10(4):423-37.
    PMID: 22262534
    In earlier models, synaptic plasticity forms the basis for cellular signaling underlying learning and memory. However, synaptic computation of learning and memory in the brain remains controversial. In this paper, we discuss ways in which synaptic plasticity remodels subcellular networks by deflecting trajectories in neuronal state-space as regulating patterns for the synthesis of dynamic continuity that form cognitive networks of associable representations through endogenous dendritic coding to consolidate memory.
  10. Intracellular capacitive effects of polarized proteins in dendrites
    Poznanski RR, Cacha LA
    J Integr Neurosci, 2012 Dec;11(4):417-37.
    PMID: 23351050 DOI: 10.1142/S0219635212500264
    Passive dendrites become active as a result of electrostatic interactions by dielectric polarization in proteins in a segment of a dendrite. The resultant nonlinear cable equation for a cylindrical volume representation of a dendritic segment is derived from Maxwell's equations under assumptions: (i) the electric field is restricted longitudinally along the cable length; (ii) extracellular isopotentiality; (iii) quasi-electrostatic conditions; (iv) isotropic membrane and homogeneous medium with constant conductivity; and (v) protein polarization contributes to intracellular capacitive effects through a well defined nonlinear capacity-voltage characteristic; (vi) intracellular resistance and capacitance in parallel are connected to the membrane in series. Under the above hypotheses, traveling wave solutions of the cable equation are obtained as propagating fronts of electrical excitation associated with capacitive charge-equalization and dispersion of continuous polarization charge densities in an Ohmic cable. The intracellular capacitative effects of polarized proteins in dendrites contribute to the conduction process.
  11. Contrast media induced transient cortical blindness
    Balasingam S, Azman RR, Nazri M
    QJM, 2016 Feb;109(2):121-2.
    PMID: 26101228 DOI: 10.1093/qjmed/hcv121
  12. Fulltext Mortality in the Department of Surgery, Alor Setar Hospital
    Lim TM, Naidu RR
    Med J Malaysia, 2001 Jun;56(2):240-2.
    PMID: 11771087
    This is a retrospective study of the annual mortality that occurred in the Department of Surgery, Alor Setar Hospital, for the years 1995 to 1997. This study looks at the number of admissions to the surgical wards and categorizes the causes of death. The annual mortality rates were 2.60, 2.89 and 3.25 per hundred admissions for the year 1995, 1996 and 1997 respectively. Head injury was the leading cause of death whilst sepsis and advanced malignancies second and third commonest causes. We hope that with the publication of these figures, we can initiate more studies to analyse similar local data.
  13. Immunomodulation by morphine and marijuana
    Yahya MD, Watson RR
    Life Sci, 1987 Dec 07;41(23):2503-10.
    PMID: 2824957
    The immunomodulatory effects of morphine and the active components of marijuana, particularly tetrahydrocannabinol, on various aspects of the host immune parameters include alterations in humoral, cell-mediated and innate immunity. Most studies have shown immunosuppressive effects due to use of these abused substances, although there are reports that they may not produce any deleterious effect and may even enhance some aspects of host immunity. They reduce resistance to cancer growth and microbial pathogens in animals.
  14. A global perspective on foreign contract labor
    Smart JE, Casco RR
    Asian Migr, 1998 Jan-Feb;1(1):8-12.
    PMID: 12281042
  15. A novel agricultural waste adsorbent for the removal of cationic dye from aqueous solutions
    Hameed BH, Krishni RR, Sata SA
    J Hazard Mater, 2009 Feb 15;162(1):305-11.
    PMID: 18573607 DOI: 10.1016/j.jhazmat.2008.05.036
    In this paper, pineapple stem (PS) waste, an agricultural waste available in large quantity in Malaysia, was utilized as low-cost adsorbent to remove basic dye (methylene blue, MB) from aqueous solution by adsorption. Batch mode experiments were conducted at 30 degrees C to study the effects of initial concentration of methylene blue, contact time and pH on dye adsorption. Equilibrium adsorption isotherms and kinetic were investigated. The experimental data were analyzed by the Langmuir and Freundlich models and the isotherm data fitted well to the Langmuir isotherm with monolayer adsorption capacity of 119.05mg/g. The kinetic data obtained at different concentrations were analyzed using a pseudo-first-order and pseudo-second-order equation and intraparticle diffusion equation. The experimental data fitted very well the pseudo-second-order kinetic model. The PS was found to be very effective adsorbent for MB adsorption.
  16. Fulltext Twisted fate of bladder catheters
    Sithasanan N, Kihne M, Naidu RR, Ramanujam TM
    Med J Malaysia, 2006 Aug;61(3):369-70.
    PMID: 17240594 MyJurnal
    Catheter knotting is a rare complication of bladder catheterisation. Retention of catheter parts resulting in calculus formation is even rarer. We report a case of a vesical calculus formed over a broken and retained supra-pubic catheter which to the best of our knowledge has yet to be reported, along with three other cases of bladder catheter knotting.
  17. The Two-Brains Hypothesis: Towards a guide for brain-brain and brain-machine interfaces
    Goodman G, Poznanski RR, Cacha L, Bercovich D
    J Integr Neurosci, 2015 Sep;14(3):281-93.
    PMID: 26477360 DOI: 10.1142/S0219635215500235
    Great advances have been made in signaling information on brain activity in individuals, or passing between an individual and a computer or robot. These include recording of natural activity using implants under the scalp or by external means or the reverse feeding of such data into the brain. In one recent example, noninvasive transcranial magnetic stimulation (TMS) allowed feeding of digitalized information into the central nervous system (CNS). Thus, noninvasive electroencephalography (EEG) recordings of motor signals at the scalp, representing specific motor intention of hand moving in individual humans, were fed as repetitive transcranial magnetic stimulation (rTMS) at a maximum intensity of 2.0[Formula: see text]T through a circular magnetic coil placed flush on each of the heads of subjects present at a different location. The TMS was said to induce an electric current influencing axons of the motor cortex causing the intended hand movement: the first example of the transfer of motor intention and its expression, between the brains of two remote humans. However, to date the mechanisms involved, not least that relating to the participation of magnetic induction, remain unclear. In general, in animal biology, magnetic fields are usually the poor relation of neuronal current: generally "unseen" and if apparent, disregarded or just given a nod. Niels Bohr searched for a biological parallel to complementary phenomena of physics. Pertinently, the two-brains hypothesis (TBH) proposed recently that advanced animals, especially man, have two brains i.e., the animal CNS evolved as two fundamentally different though interdependent, complementary organs: one electro-ionic (tangible, known and accessible), and the other, electromagnetic (intangible and difficult to access) - a stable, structured and functional 3D compendium of variously induced interacting electro-magnetic (EM) fields. Research on the CNS in health and disease progresses including that on brain-brain, brain-computer and brain-robot engineering. As they grow even closer, these disciplines involve their own unique complexities, including direction by the laws of inductive physics. So the novel TBH hypothesis has wide fundamental implications, including those related to TMS. These require rethinking and renewed research engaging the fully complementary equivalence of mutual magnetic and electric field induction in the CNS and, within this context, a new mathematics of the brain to decipher higher cognitive operations not possible with current brain-brain and brain-machine interfaces. Bohr may now rest.
  18. Fulltext Management of gastroschisis in a peripheral hospital setting
    Naidu RR, Lee FH, Teh KH
    Med J Malaysia, 1996 Dec;51(4):444-6.
    PMID: 10968031
    Ten patients (5 males and 5 females) with gastroschisis were treated in Alor Setar Hospital from January 1989 to December 1993. Two patients had associated congenital anomalies. Primary closure was possible in 9 patient while the other patient had stage closure. All patients received prophylactic antibiotics, 9 patients were ventilated electively in the post-operative period and 7 patients received parenteral nutrition. There were 9 survivors. Complications especially wound infection and breakdown were seen in 7 patients. The average hospital stay was 36 days.
  19. Venous congestion from brachiocephalic vein stenosis mimicking sclerotic vertebral lesions
    Ab Mumin N, Azman RR, Chan WY
    Med J Malaysia, 2019 Jun;74(3):240-242.
    PMID: 31256183
    In central venous obstruction, vertebral marrow enhancement (VME) may be seen secondary to collateral venous flow via the vertebral venous plexus.1 There are only sporadic case reports on pseudolesions due to collateral enhancement mimicking sclerotic osseous metastasis. This abnormal vertebral enhancement may lead to erroneous diagnosis of sclerotic metastases or suspicious bone lesion which affect the management and prognosis. We describe a case of brachiocephalic vein obstruction-related vertebral body pseudolesions as identified in contrast-enhanced computed tomography (CECT) scan.
  20. Fulltext An Incidental Detection of Popliteal Vein Aneurysm during Labeled Leukocyte Scintigraphy
    Hassan HA, Nazri M, Azman RR
    World J Nucl Med, 2012 May;11(2):81-3.
    PMID: 23372443 DOI: 10.4103/1450-1147.103421
    Technetium (99mTc) exametazime (hexamethylpropyleneamine oxime, HMPAO) labeled leukocyte scintigraphy is mainly used to exclude occult infection in our institution. On review of previously published article, no case of popliteal venous aneurysm was ever diagnosed and detected on labeled leukocyte scintigraphy. We present a rare case of popliteal venous aneurysm which was detected on labeled leukocyte scintigraphy and was further confirmed with single-photon emission computed tomography and computed tomography fusion.
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