Displaying publications 1 - 20 of 35 in total

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  1. Yaacob H
    Singapore Med J, 1991 Feb;32(1):70-2.
    PMID: 2017711
    The radiographs of fifteen Malaysian patients with presenting ameloblastoma aged between 20-55 years (average 35 years) were studied for any peculiar local features. The most common features were cortical plate expansion (80%), corticated scalloped margin (67%), multiloculation (87%), and resorption of tooth roots (47%). The latter two features are constantly found in advanced tumour stage. As pain was not a frequent complaint, many Malaysian patients seek treatment only at a very late stage after the tumours have reached large dimensions. Although ameloblastomas may be diagnosed often through radiographs, it should not be relied upon solely.
  2. Yaacob HB
    J Nihon Univ Sch Dent, 1990 Sep;32(3):187-91.
    PMID: 2230962
    The twenty-fifth reported case of squamous odontogenic tumor is presented. The patient was a 39-year-old Chinese Malaysian male. The lesion was asymptomatic and did not recur after excision. It is important to distinguish this type of lesion from squamous odontogenic tumor-like proliferation. The rest of Malassez is thought to be responsible for the histogenesis of the lesion. Better understanding will only be achieved when more cases are reported and studied.
  3. Nambiar P, Yaacob H, Menon R
    J Forensic Odontostomatol, 1996 Dec;14(2):30-3.
    PMID: 9227080
    Teeth are the most durable structures in the human body. The timing and sequence of their development, as contained in dental development charts, have been used as valid criteria for age determination. The third molars however are the last teeth to erupt and are regarded as the most variable in the dentition. Age estimation in a legal context, using developing third molars must be carefully applied otherwise justice may miscarry. A case of wrongful use of the technique is presented here.
  4. Yaacob H, Tirmzi H, Ismail K
    J Oral Med, 1983 Jan-Mar;38(1):40-2.
    PMID: 6573459
  5. Mohamad IS, Yaacob H
    Malays Fam Physician, 2018;13(3):47-48.
    PMID: 30800236 MyJurnal
    A 24-year-old man presented to the casualty department with a history of left-sided, colicky abdominal pain for one day. It was associated with an inability to pass flatus or motion within the same duration. There was no history of vomiting. On examination, the vital signs were within normal limits, and he was afebrile. His abdomen was soft, but a hard mass was palpable on the left side of his abdomen. There was no peritonitis. The bowel sounds were sluggish.
  6. Walters K, Yaacob H
    Genet Epidemiol, 2023 Apr;47(3):249-260.
    PMID: 36739616 DOI: 10.1002/gepi.22517
    Currently, the only effect size prior that is routinely implemented in a Bayesian fine-mapping multi-single-nucleotide polymorphism (SNP) analysis is the Gaussian prior. Here, we show how the Laplace prior can be deployed in Bayesian multi-SNP fine mapping studies. We compare the ranking performance of the posterior inclusion probability (PIP) using a Laplace prior with the ranking performance of the corresponding Gaussian prior and FINEMAP. Our results indicate that, for the simulation scenarios we consider here, the Laplace prior can lead to higher PIPs than either the Gaussian prior or FINEMAP, particularly for moderately sized fine-mapping studies. The Laplace prior also appears to have better worst-case scenario properties. We reanalyse the iCOGS case-control data from the CASP8 region on Chromosome 2. Even though this study has a total sample size of nearly 90,000 individuals, there are still some differences in the top few ranked SNPs if the Laplace prior is used rather than the Gaussian prior. R code to implement the Laplace (and Gaussian) prior is available at https://github.com/Kevin-walters/lapmapr.
  7. Yaacob H, Nambiar P, Naidu MD
    Malays J Pathol, 1996 Jun;18(1):1-7.
    PMID: 10879216
    Determining the racial affinity of an unknown individual from dentition for identification is indeed a difficult endeavour. However, there are certain dental characteristics which are predominant in certain racial groups and these contribute important indicators in the identification process. Inherited dental characteristics are modified by prenatal and postnatal environmental and nutritional conditions. They can also become less discernible due to admixture of the various races.
  8. Rahim ZH, Yaacob HB
    J Nihon Univ Sch Dent, 1992 Dec;34(4):273-7.
    PMID: 1283755
    Fresh samples of human whole saliva containing approximately 20-40 micrograms protein were analyzed using SDS-polyacrylamide slab gel electrophoresis systems. More than 20 protein bands were revealed by Coomassie Brilliant Blue R 250 staining. Some of the protein bands were shown to be glycoprotein-positive with PAS (periodic acid-Schiff) reagent. The protein bands with alpha-Amylase activity appeared within a molecular weight range of 120,000-180,000, which is 2 to 2.8 times higher than the normal molecular weight reported for alpha-Amylase from parotid saliva, and showed positive staining with PAS reagent. These results show that the alpha-Amylase in whole saliva appears to exist in a macromolecular form which is not dissociated in the presence of sodium dodecyl sulfate (SDS).
  9. Yaacob HB, Samaranayake LP
    J Oral Pathol Med, 1989 Apr;18(4):236-9.
    PMID: 2769596
    A postal survey of 730 Malaysian dental practitioners was undertaken to assess their awareness and acceptance of the plasma derived hepatitis B vaccine. Only 32% of the 325 practitioners who responded had been vaccinated, 41% intended to be and 15% categorically refused vaccination. The main reservations about vaccine acceptance were fear of side effects including AIDS, cost of the vaccine and lack of information. Vaccine efficacy was not confirmed by serology in two-thirds of the vaccinees and two-fifths of the respondents were unaware that 5% of the vaccinees do not develop a successful antibody response after vaccination. Seventy-eight percent of dentists believed that their risk of contracting hepatitis B was high or very high while 71% recalled having received needle stick injuries in the 3 yr prior to the survey. Only 13% of respondents were aware of delta hepatitis while 63% were aware of non-A non-B hepatitis. The survey has highlighted the need for dissemination of information on hepatitis B vaccine among dentists in Malayasia.
  10. Park AW, Yaacob HB
    J Nihon Univ Sch Dent, 1991 Dec;33(4):211-43.
    PMID: 1787417
    Belief in a golden age has provided mankind with solace in times of despair and with élan during the expansive periods of history. Dreamers imagine the golden age in the remote past, in paradise lost, free from toil and grief. Optimists put their faith in the future and believe that mankind, Prometheus-like, will master the arts of life through power and knowledge. Thus, the golden age means different things to different men, but the very belief in its existence implies the conviction that perfect health and happiness are birthrights of men. Yet, in reality, complete freedom from disease and from struggle is almost incompatible with the process of living.
  11. Rahim ZH, Yaacob HB
    J Nihon Univ Sch Dent, 1991 Dec;33(4):205-10.
    PMID: 1787416
    The concentrations of calcium, phosphate, protein and nitrite in whole unstimulated saliva, and the salivary flow rate under fasting conditions (saliva collected at least after 6 h without food and water) were compared with those under control conditions (saliva collected within 30 min to 1 h after food). The flow rate of fasting saliva was half that of control (0.098 ml/min vs 0.208 ml/min) and no significant differences in the flow rate were observed between sexes. The concentration of nitrite under fasting conditions was 50% higher than that in control saliva (p less than 0.05). The protein concentration was decreased, but not significantly, under fasting conditions. The composition of fasting saliva with regard to calcium and phosphate concentrations was comparable to that of the control. No significant variations in these components between sexes were observed under either condition.
  12. Yaacob HB, Park AW
    J Nihon Univ Sch Dent, 1990 Sep;32(3):175-80.
    PMID: 2230960
    Among 350 inhabitants of two villages, 31 (8.9%) cleaned their teeth using table salt and charcoal applied to their forefinger or a Melastoma brush. As a result, all had distinct forms of abrasion cavity on the labial surfaces of their teeth. All of the above three agents are highly abrasive and injurious to both the hard and soft oral tissues. This dying practice is only popular among a very small number of persons in the older age group, and should be discouraged.
  13. Yaacob H, Karim I, Wahab A, Kamaruddin N
    PMID: 23367309 DOI: 10.1109/EMBC.2012.6347374
    Emotions are ambiguous. Many techniques have been employed to perform emotion prediction and to understand emotional elicitations. Brain signals measured using electroencephalogram (EEG) are also used in studies about emotions. Using KDE as feature extraction technique and MLP for performing supervised learning on the brain signals. It has shown that all channels in EEG can capture emotional experience. In addition it was also indicated that emotions are dynamic as represented by the level of valence and the intensity of arousal. Such findings are useful in biomedical studies, especially in dealing with emotional disorders which can results in using a two-channel EEG device for neurofeedback applications.
  14. Yadav M, Nambiar S, Khoo SP, Yaacob HB
    Arch Oral Biol, 1997 Aug;42(8):559-67.
    PMID: 9347118
    The prevalence and cellular distribution of human herpesvirus 7 (HHV-7) in archival labial salivary glands was analysed for virus-specific DNA sequences by polymerase chain reaction (PCR) and in situ hybridization signals. In addition, the cellular expression of HHV-7-encoded protein was detected by immunohistochemical staining with a virus-specific monoclonal antibody. Eleven of 20 samples were positive for the HHV-7 DNA sequence by PCR. Eighteen of 20 tissues analysed by in situ hybridization showed signals in ductal, serous and mucous cells. Some nuclei of these cells and also the myoepithelial population were positive. In immunolocalization studies, all 20 salivary glands consistently showed HHV-7-expressed protein in the cytoplasm of ductal cuboidal and columnar cells. The protein was also found in the cytoplasm of mucous and serous acinar cells that were immunopositive for HHV-7. The observations are consistent with the suggestion that the labial salivary gland is a site for virus replication, potential persistence and a source of infective HHV-7 in saliva.
  15. Hanapiah F, Yaacob H, Ghani KS, Hussin AS
    J Nihon Univ Sch Dent, 1993 Sep;35(3):171-4.
    PMID: 8246038
    Histiocytosis X is a rare disorder with no particular predilection for race, age or sex. Since its discovery by Hand in 1893, the etiology has remained unknown, although viruses, bacteria and genetic factors have been implicated. Familial occurrence of this disease is very rare, and only a handful of such cases have been reported. The present study adds further evidence to support the influence of genetic factors in the etiology of histiocytosis X.
  16. Walters K, Cox A, Yaacob H
    Genet Epidemiol, 2021 Jun;45(4):386-401.
    PMID: 33410201 DOI: 10.1002/gepi.22375
    The Gaussian distribution is usually the default causal single-nucleotide polymorphism (SNP) effect size prior in Bayesian population-based fine-mapping association studies, but a recent study showed that the heavier-tailed Laplace prior distribution provided a better fit to breast cancer top hits identified in genome-wide association studies. We investigate the utility of the Laplace prior as an effect size prior in univariate fine-mapping studies. We consider ranking SNPs using Bayes factors and other summaries of the effect size posterior distribution, the effect of prior choice on credible set size based on the posterior probability of causality, and on the noteworthiness of SNPs in univariate analyses. Across a wide range of fine-mapping scenarios the Laplace prior generally leads to larger 90% credible sets than the Gaussian prior. These larger credible sets for the Laplace prior are due to relatively high prior mass around zero which can yield many noncausal SNPs with relatively large Bayes factors. If using conventional credible sets, the Gaussian prior generally yields a better trade off between including the causal SNP with high probability and keeping the set size reasonable. Interestingly when using the less well utilised measure of noteworthiness, the Laplace prior performs well, leading to causal SNPs being declared noteworthy with high probability, whilst generally declaring fewer than 5% of noncausal SNPs as being noteworthy. In contrast, the Gaussian prior leads to the causal SNP being declared noteworthy with very low probability.
  17. Walters K, Cox A, Yaacob H
    Genet Epidemiol, 2019 Sep;43(6):675-689.
    PMID: 31286571 DOI: 10.1002/gepi.22212
    The default causal single-nucleotide polymorphism (SNP) effect size prior in Bayesian fine-mapping studies is usually the Normal distribution. This choice is often based on computational convenience, rather than evidence that it is the most suitable prior distribution. The choice of prior is important because previous studies have shown considerable sensitivity of causal SNP Bayes factors to the form of the prior. In some well-studied diseases there are now considerable numbers of genome-wide association study (GWAS) top hits along with estimates of the number of yet-to-be-discovered causal SNPs. We show how the effect sizes of the top hits and estimates of the number of yet-to-be-discovered causal SNPs can be used to choose between the Laplace and Normal priors, to estimate the prior parameters and to quantify the uncertainty in this estimation. The methodology can readily be applied to other priors. We show that the top hits available from breast cancer GWAS provide overwhelming support for the Laplace over the Normal prior, which has important consequences for variant prioritisation. This work in this paper enables practitioners to derive more objective priors than are currently being used and could lead to prioritisation of different variants.
  18. Malek SN, Shin SK, Wahab NA, Yaacob H
    Molecules, 2009;14(5):1713-24.
    PMID: 19471192 DOI: 10.3390/molecules14051713
    Dihydroactinidiolide (1) and a mixture of sterols [campesterol (2), stigmasterol (3) and beta-sitosterol (4)], together with the previously isolated individual compounds beta-sitosterol (4), 2,4-di-tert-butylphenol (5), alpha-tocopherol (6), phytol (7) were isolated from the active ethyl acetate fraction of Pereskia bleo (Kunth) DC. (Cactaceae) leaves. Cytotoxic activities of the above mentioned compounds against five human carcinoma cell lines, namely the human nasopharyngeal epidermoid carcinoma cell line (KB), human cervical carcinoma cell line (CasKi), human colon carcinoma cell line (HCT 116), human hormone-dependent breast carcinoma cell line (MCF7) and human lung carcinoma cell line (A549); and non-cancer human fibroblast cell line (MRC-5) were investigated. Compound 5 possessed very remarkable cytotoxic activity against KB cells, with an IC(50 )value of 0.81microg/mL. This is the first report on the cytotoxic activities of the compounds isolated from Pereskia bleo.
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