MyMedR

Fulltext 2-[Carbamo-thio-yl(2-hy-droxy-eth-yl)amino]-ethyl benzoate: crystal structure, Hirshfeld surface analysis and computational study

Tan SL, Tiekink ERT

Acta Crystallogr E Crystallogr Commun, 2020 Jun 01;76(Pt 6):933-939.

PMID: 32523767 DOI: 10.1107/S2056989020006829

The title di-substituted thio-urea, C12H16N2O3S, has the hy-droxy-lethyl and ethyl benzoate substituents bound to the same amine-N atom, and is twisted, having a (+)syn-clinal conformation with the Namine-C-C-O(hydroxyl, carbon-yl) torsion angles of 49.39 (13) and 59.09 (12)°, respectively; the dihedral angle between the almost planar CN2S core and the pendent benzene ring is 69.26 (4)°. In the crystal, supra-molecular layers propagating in the ac plane are formed via a combination of hydroxyl-O-H⋯S(thione), amine-N-H⋯O(hydroxyl, carbon-yl) hydrogen-bonds. The layers stack along the b axis with inter-digitation of the benzene rings allowing the formation of π-π stacking [inter-centroid separation = 3.8722 (7) Å] and parallel C=O⋯π inter-actions. A computational chemistry study shows the conventional hydrogen bonding in the crystal leads to significant electrostatic stabilization but dispersion terms are also apparent, notably through the inter-actions involving the benzene residue.

Fulltext Crystal structure, Hirshfeld surface analysis and computational study of the 1:2 co-crystal formed between N,N'-bis-[(pyridin-4-yl)meth-yl]ethanedi-amide and 3-chloro-benzoic acid

Tan SL, Tiekink ERT

Acta Crystallogr E Crystallogr Commun, 2020 Jun 01;76(Pt 6):870-876.

PMID: 32523755 DOI: 10.1107/S2056989020006568

The asymmetric unit of the title 1:2 co-crystal, C14H14N4O2·2C7H5ClO2, comprises a half-mol-ecule of oxalamide (4 LH2), being located about a centre of inversion, and a mol-ecule of3-chloro-benzoic acid (3-ClBA) in a general position. From symmetry, the 4 LH2 mol-ecule has a (+)anti-periplanar conformation with the 4-pyridyl residues lying to either side of the central, planar C2N2O2 chromophore with the dihedral angle between the core and pyridyl ring being 74.69 (11)°; intra-molecular amide-N-H⋯O(amide) hydrogen bonds are noted. The 3-ClBA mol-ecule exhibits a small twist as seen in the C6/CO2 dihedral angle of 8.731 (12)°. In the mol-ecular packing, three-mol-ecule aggregates are formed via carb-oxy-lic acid-O-H⋯N(pyrid-yl) hydrogen bonding. These are connected into a supra-molecular tape along [111] through amide-N-H⋯O(carbon-yl) hydrogen bonding. Additional points of contact between mol-ecules include pyridyl and benzoic acid-C-H⋯O(amide), methyl-ene-C-H⋯O(carbon-yl) and C-Cl⋯π(pyrid-yl) inter-actions so a three-dimensional architecture results. The contributions to the calculated Hirshfeld surface are dominated by H⋯H (28.5%), H⋯O/O⋯H (23.2%), H⋯C/C⋯H (23.3%), H⋯Cl/Cl⋯H (10.0%) and C⋯Cl/C⋯Cl (6.2%) contacts. Computational chemistry confirms the C-Cl⋯π inter-action is weak, and the importance of both electrostatic and dispersion terms in sustaining the mol-ecular packing despite the strong electrostatic term provided by the carb-oxy-lic acid-O-H⋯N(pyrid-yl) hydrogen bonds.

Fulltext 2,2'-(Disulfanedi-yl)di-benzoic acid N,N-di-methyl-formamide monosolvate: crystal structure, Hirshfeld surface analysis and computational study

Tan SL, Tiekink ERT

Acta Crystallogr E Crystallogr Commun, 2020 Jul 01;76(Pt 7):1150-1157.

PMID: 32695471 DOI: 10.1107/S2056989020008257

The title 1:1 solvate, C14H10O4S2·C3H7NO, features a twisted mol-ecule of 2,2'-di-thiodi-benzoic acid (DTBA), with the central C-S-S-C torsion angle being -88.57 (6)°, and a mol-ecule of di-methyl-formamide (DMF). The carb-oxy-lic acid groups are, respectively, close to co-planar and twisted with respect to the benzene rings to which they are connected as seen in the CO2/C6 torsion angles of 1.03 (19) and 7.4 (2)°. Intra-molecular, hypervalent S←O inter-actions are noted [S⋯O = 2.6140 (9) and 2.6827 (9) Å]. In the crystal, four-mol-ecule aggregates are formed via DTBA-O-H⋯O(DMF) and DTBA-O-H⋯O(DTBA) hydrogen bonding, the latter via an eight-membered {⋯OHCO}2 homosynthon. These are linked into supra-molecular layers parallel to (011) via benzene-C-H⋯O(DTBA) and DTBA-C=O⋯π(benzene) inter-actions, with the connections between these, giving rise to a three-dimensional architecture, being of the type benzene-C-H⋯π(benzene). An analysis of the calculated Hirshfeld surfaces indicates, in addition to the aforementioned inter-molecular contacts, the presence of stabilizing inter-actions between a benzene ring and a quasi-π-system defined by O-H⋯O hydrogen bonds between a DTBA dimer, i.e. the eight-membered {⋯OCOH}2 ring system, and between a benzene ring and a quasi-π(OCOH⋯OCH) system arising from the DTBA-O-H⋯O(DMF) hydrogen bond. The inter-centroid separations are 3.65 and 3.49 Å, respectively.

Fulltext Potency of Selected Berries, Grapes, and Citrus Fruit as Neuroprotective Agents

Tan SJ, Ismail IS

Evid Based Complement Alternat Med, 2020;2020:3582947.

PMID: 32565853 DOI: 10.1155/2020/3582947

A healthy diet should nourish the brain with essential nutrients, including bioactive compounds, for normal brain functioning and to protect it from the negative effects of inflammation and oxidative stress. In this review, a concise summation of the protective effects of selected fruits, namely, berries, grapes, and citrus fruits, against neurological disorder is presented. The focus is on the neuroprotective potential of these fruits against neurodegenerative and mental disorders. The fruits selection was based on the vast reported pharmacological studies on their neuroprotection efficacies. Hence, the respective knowledge and limitations are discussed based on the biological and pharmacological evidence compiled from the previously reported laboratory, epidemiology, and intervention trials.

Midurethral sling surgery for stress urinary incontinence: an Asian perspective footnote from the Pan-Asia meeting

Lo TS, Tan YL

Int Urogynecol J, 2021 03;32(3):473-476.

PMID: 32676691 DOI: 10.1007/s00192-020-04416-z

Fulltext Oxidative Stress, Diet and Prostate Cancer

Tan BL, Norhaizan ME

World J Mens Health, 2021 Apr;39(2):195-207.

PMID: 32648373 DOI: 10.5534/wjmh.200014

Prostate cancer has become the second leading cancer in men worldwide. Androgen plays an important role in normal functioning, development, and differentiation of the prostate, and thus is considered to be the most powerful candidate that mediates reactive oxygen species (ROS) balance in the prostate. The elevation of ROS has been associated with the progression and development of this disease. Conventional therapy has shown a high cure rate in patients with localized prostate cancer. Despite the patients respond favorably initially, this therapy fails to response in the advanced stage of the diseases even in the absence of androgens. Indeed, the onset and progression of prostate cancer could be prevented by changing dietary habits. Much information indicates that oxidative stress and prostate cancer can be modulated by dietary components rich in antioxidants. While there is substantial evidence to suggest an association between prostate cancer risk and ROS-mediated oxidative stress; therefore, the interactions and mechanisms of this phenomenon are worth to discuss further. This review aimed to discuss the mechanisms of action of oxidative stress involved in the progression of prostate cancer. We also highlighted how some of the vital dietary components dampen or exacerbate inflammation, oxidative stress, and prostate cancer. Overall, the reported information would provide a useful approach to the prevention of prostate cancer.

Fulltext Intervention to reduce childhood undernutrition: a systematic review

Tan ECH, Manah AM

Borneo Journal of Medical Sciences, 2018;12(101):7-8.

MyJurnal

hildhood undernutrition while being a preventable condition remains a major public health issue because it contributes to the mortality and morbidity of children globally. Intervention to improve the nutritional status of children includes supplementary feeding, fortified foods, cash transfers and nutritional education.
Keywords:

Effect of diarrhoea on Tacrolimus trough level in a post liver transplant patient

Tan ST, Yoong BK

Med J Malaysia, 2020 11;75(6):734-735.

PMID: 33219186

Tacrolimus, which bonds to an immunophilin, FK506 binding protein (FKBP) has emerged as one of the most widely used immunosuppressant post solid organ transplantation. It offers excellent patient survival rates post-transplantation and a lesser number of acute rejections as compared to cyclosporine. Tacrolimus has a narrow therapeutic window with overexposure leading to acute and chronic forms of nephrotoxicity. Remarkably few data have been published on the overexposure to tacrolimus following mild diarrhoea in post-transplant patients who received treatment with tacrolimus. We observed a post-liver transplant patient with increased trough level of tacrolimus during severe diarrhoea with no complications following a timely adjustment on the dose of tacrolimus.

Fulltext Viruses join the circular RNA world

Tan KE, Lim YY

FEBS J, 2021 08;288(15):4488-4502.

PMID: 33236482 DOI: 10.1111/febs.15639

Circular RNAs (circRNAs) are a recently discovered class of noncoding RNAs found in many species across the eukaryotic kingdom. These intriguing RNA species are formed through a unique mechanism that is known as back splicing in which the 5' and 3' termini are covalently joined. Recent research has revealed that viruses also encode a repertoire of circRNAs. Some of these viral circRNAs are abundantly expressed and are reported to play a role in disease pathogenesis. A growing number of studies also indicate that host circRNAs are involved in immune responses against virus infections with either an antiviral or proviral role. In this review, we briefly introduce circRNA, its biogenesis, and mechanism of action. We go on to summarize the latest research on the expression, regulation, and functions of viral and host-encoded circRNAs during the host-virus interaction, with the aim of highlighting the potential of viral and host circRNAs as a suitable target for diagnostic biomarker development and therapeutic treatment of viral-associated diseases. We conclude by discussing the current limitations in knowledge and significance of elucidating the roles of circRNAs in host-virus interactions, as well as future directions for this emerging field.

Hamatopeduncularia Yamaguti, 1953 (Monogenea: Ancylodiscoididae) from catfish off Peninsular Malaysia: Description of two new species and insights on the genus

Soo OYM, Tan WB

Parasitol Int, 2021 Apr;81:102282.

PMID: 33444771 DOI: 10.1016/j.parint.2021.102282

Hamatopeduncularia longiangusticirrata sp. nov. and H. petalumvaginata sp. nov. were collected from Arius maculatus and Nemapteryx caelata, respectively from Tanjung Karang, Peninsular Malaysia. Morphological and molecular investigations were carried out to ascertain the identity of the new species. The two new species differ from previously described Hamatopeduncularia species in the morphology of the male and female reproductive organs. Hamatopeduncularia longiangusticirrata sp. nov. possesses a long penis similar to H. elongata, H. longicopulatrix, H. brisbanensis, H. major and H. petalumvaginata sp. nov., but differs in having a thread-like tapering distal end and can be distinguished from H. brisbanensis and H. major in not having an accessory piece. Hamatopeduncularia longiangusticirrata sp. nov. is also unique in having an ornamented penis initial and a vaginal tube surrounded by fine hair-like structures. Hamatopeduncularia petalumvaginata sp. nov. possesses a simple penis without an accessory piece and a petaloid vaginal opening that resembles the arrangement of petals on a flower. Maximum likelihood trees were constructed from partial 28S and 18S rDNA sequences of the two new species and other ancylodiscoidids to reveal a strongly supported monophyletic branch consisting of the two new species for both markers. According to Lim's classification in 1996 of Hamatopeduncularia species penis type, H. petalumvaginata sp. nov. has been classified within the elegans-type and H. longiangusticirrata sp. nov. is proposed as the longiangusticirrata-type.

Simple high-performance liquid chromatographic method for simultaneous determination of fusidic Acid and betamethasone dipropionate in a cream formulation

Peh KK, Tan YT

Int J Pharm Compd, 2000 May-Jun;4(3):229-31.

PMID: 23986007

A simple and selective high-performance liquid chromatography (HPLC) method using ultraviolet detection was developed for simultaneous determination of fusidic acid and betamethasone dipropionate in a cream formulation. A Supelcosil LC18 column was used for chromatographic separation. The mobile phase consisted of acetonitrile and 0.01 M disodium hydrogen orthophosphate (70:30, % v/v) adjusted to pH 6 with glacial acetic acid. Analysis was run at a flow rate of 1.0 mL/minute with the detector operating at 235 nm. The standard calibration curve was linear over a concentration range of 0.3 to 1.2 mg/mL for fusidic acid and 9.6 to 38.4 micrograms/mL for betamethasone dipropionate. The average recovery values for fusidic acid and betamethasone dipropionate were almost 100%. The within-run and between-run coefficient of variation and percent error values for the two drugs were all less than 2% and +/- 3%, respectively.

Fulltext A unique case of tetrodotoxin poisoning

Loke YK, Tan MH

Med J Malaysia, 1997 Jun;52(2):172-4.

PMID: 10968077

A 69-year-old lady who was referred by her general practitioner with a diagnosis of food poisoning developed cardiorespiratory arrest shortly after arriving at the Casualty Department. Cardiac output was successfully restored with resuscitation but she had to be mechanically ventilated due to the absence of any spontaneous respiratory effort. Assessment 24 hours after admission, showed fixed and dilated pupils with brain stem areflexia. Her family was told that the prognosis was hopeless. Surprisingly, her condition rapidly improved a day later and she eventually had a good recovery. Her condition was actually due to severe tetrodotoxin poisoning after eating roe of the puffer fish and it was fortunate that appropriate aggressive resuscitation was instituted to revive the patient from her critical state.

Fulltext Unilateral pulmonary agenesis: an unusual cause of respiratory distress in the newborn

Tan KK, Chin CN

Singapore Med J, 1996 Dec;37(6):668-9.

PMID: 9104074

Unilateral pulmonary agenesis is a rare disorder and is an unusual cause of respiratory distress in the newborn. It is often associated with other congenital abnormalities, as documented in about 200 cases of unilateral pulmonary agenesis in the current literature. The onset and mode of presentation are highly variable, from asymptomatic cases discovered incidentally to symptomatic cases diagnosed in early infancy. We report a newborn infant with right pulmonary agenesis associated with facial and skeletal abnormalities who presented with respiratory distress. Unilateral pulmonary agenesis should be considered in the differential diagnosis of respiratory distress in the newborn, particularly when there are other associated congenital abnormalities.

Unusual ritual burns of the hand

Tay YG, Tan KK

Burns, 1996 Aug;22(5):409-12.

PMID: 8962663

Six hands from five patients were seen with full-thickness burns following a ritual practice between June 1993 and June 1994. Three hands were treated with excision and medium-thickness split-skin grafts, one patient was treated with a medium-thickness split skin graft taken from the instep of the foot. The first patient with bilateral burns of the palms refused surgery and returned 3 months later with contractures of the palms. The results of the treated hands are presented.

Epidemiology of chronic (perennial) rhinitis in Singapore: prevalence estimates, demographic variation and clinical allergic presentation

Ng TP, Tan WC

Ann Acad Med Singap, 1994 Jan;23(1):83-8.

PMID: 8185279

We conducted a population-based study involving a stratified cluster disproportionate random sample of 2868 adults aged 20 to 74 years selected from five housing estates (Yishun, Toa Payoh, Jurong East, Geylang/Eunos and Bukit Merah). Chronic rhinitis was defined as the usual presence of symptoms of blocked or running nose, apart from colds or the flu, lasting for more than a year. Allergic rhinitis was considered to be present if these symptoms were associated with conjunctivitis or recognisable provocation by commonly known allergens, namely house dust, dogs, cats, birds, pollen, or medicines. The estimated general population prevalence of chronic rhinitis was 10.8% (95% confidence interval (CI) 8.8-12.7). Higher prevalences were noted in males, in younger adults, in Indians and Chinese, in those with higher socio-economic status, and in Toa Payoh, Jurong East and Geylang/Eunos. The prevalence of allergic rhinitis was 5.5% (95% CI 4.5-6.5). The most common 'allergenic' factor in allergic rhinitis was house dust (73%); provocation by birds, cats or dogs (5%), grass or tree pollens (5%), and medicine (5%) was less common but likely to have been under-recognised. Provocation by change in temperature (54%) and early in the morning (64%) was equally frequent in both 'allergic' and 'non-allergic' rhinitis; cigarette smoke, petrol and diesel fumes, food and work environment were less common (4-12%). Allergic rhinitis was highly significantly associated with asthma (13.9% in allergic rhinitis, 4.4% in non-allergic rhinitis, and 2.2% in non-rhinitic subjects).

Fulltext Resection of large primary chest wall chondrosarcoma with reconstruction: 2 case reports

Wong PS, Tan GP

Med J Malaysia, 2000 Dec;55(4):516-9.

PMID: 11221168

We report two cases of large chest wall primary chondrosarcoma, one of the sternum and the other of the lateral chest wall. Both were treated by radical resection and reconstruction using marlex mesh and methyl methacrylate "sandwich" prosthesis and pedicled latissiumus dorsi flap.

Oral biopsy turnaround time: 20-year experience of the Department of Oral Pathology, Oral Medicine and Periodontology, Faculty of Dentistry, University of Malaya

Siar CH, Tan BH

J Oral Sci, 2000 Dec;42(4):205-10.

PMID: 11269378

The turnaround time (TAT) for oral biopsies received for histological examination by the Department of Oral Pathology, Oral Medicine and Periodontology, Faculty of Dentistry, University of Malaya, for the years 1978, 1988 and 1998 was evaluated. For the three years studied, TATs for 61, 233 and 463 specimens were retrospectively analysed. Testing intervals, that is, from the dates the surgeons procured the specimens, the laboratories accessioned them and until the pathologists signed off the diagnoses, were used to calculate TAT. The performance level of the respective pathologists, the growth of tissue diagnostic services and the possible variables that influence TAT were also evaluated. As prompt diagnosis means prompt treatment, which in turn has a bearing on prognosis, the TAT pertinent to oral malignant tumors was emphasized. The mean TAT, its mode and median fell significantly in 1998 compared with the previous 2 years; it was lower for soft tissue than for hard tissue specimens, and lower for malignant, than for non-malignant specimens. The progression of tissue diagnostic services is up to a satisfactory level, as 88.89 % of biopsies could render diagnoses within a fair period of time in 1998.

Fulltext An unusual case of Wegener's granulomatosis

Loke YK, Tan MH

Med J Malaysia, 1998 Mar;53(1):107-9.

PMID: 10968148

A 35-year-old Malay man underwent treatment for uveitis of the right eye in 1992 but developed marked visual impairment in the affected eye after he failed to attend follow-up. Two years later, he complained of difficulty swallowing and was found to have left sided X and XI cranial nerve palsies. Chest radiograph showed a cavitating lesion in the lower zone of the right lung field. Inflammation and perforation of the nasal septum was found on examination of his upper respiratory tract. Punch biopsies taken from that area showed chronic inflammatory change and necrotizing vasculities. The patient was diagnosed as having Wegener's granulomatosis and made a very good recovery with immunosuppressive therapy.

Sociobiological risk factors for spontaneous abortion in Malaysia

Tan NH, Yahya A, Adeeb N

J Obstet Gynaecol (Tokyo 1995), 1995 Aug;21(4):313-8.

PMID: 8775898

OBJECTIVE: To evaluate the risk factors of spontaneous abortion.

METHODS: A case-control study was conducted by interviewing 350 women who were admitted to the university gynaecological unit for spontaneous abortion and 350 women who delivered normally at the university obstetric unit. Odds ratios, as the estimators of relative risks, were calculated.

RESULTS: The relative risk for spontaneous abortion among women in the age-group 30 to 39 years was 1.61 and among women above 40 years of age was 3.68 when compared to those below 30 years of age. In relation to career women, the relative risk of spontaneous abortion for housewives was 0.45. Ethnic group, parity, subfertility, previous induced abortion, ectopic pregnancy, contraception and menarcheal age did not influence the risk of spontaneous abortion.

CONCLUSION: Increasing age and a woman's career are significant risk factors of spontaneous abortion.

Do fertility intentions predict subsequent behavior? Evidence from Peninsular Malaysia

Tan PC, Tey NP

Stud Fam Plann, 1994 Jul-Aug;25(4):222-31.

PMID: 7985216 DOI: 10.2307/2137905

Data from the 1984 Malaysian Population and Family Survey were matched with birth registration records for 1985-87 to determine the accuracy of statements regarding desired family size that were reported in a household survey in predicting subsequent reproductive behavior. The findings of this study were that stated fertility intention provides fairly accurate forecasts of fertility behavior in the subsequent period. In other words, whether a woman has another child is predicted closely by whether she wanted an additional child. Informational, educational, and motivational activities of family planning programs would, therefore, have greater success in reducing family size if fertility intentions were taken into account.

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