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1.
Dement Geriatr Cogn Disord ; : 1-17, 2024 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-38636474

RESUMO

INTRODUCTION: Vascular dementia (VaD), a neurocognitive impairment directly related to vascular injury, is the second most common cause of age-related dementia. Although numerous studies have investigated candidate genetic polymorphisms associated with VaD in Asia, the genetics of VaD remains unclear. METHODS: This review provides an updated meta-analysis of genetic polymorphisms associated with VaD in Asians, using the PRISMA guidelines. Published literature up to May 2021 was extracted from the PubMed, Scopus, Ovid, and EBSCOhost databases. Meta-analysis was conducted using the Open Meta analyst, Review Manager, and MedCalc® Statistical Software. Trial sequential analysis (TSA) was performed using TSA viewer software. RESULTS: A total of 46 eligible studies, comprising 23 genes and 35 single nucleotide polymorphisms, were retrieved. The meta-analysis was conducted on the following genetic polymorphisms, APOE ε2/3/4, MTHFR rs1801131, ACE rs4340 (I/D) gene polymorphism, and a PSEN1 intron 8 variant. The pooled odds ratio (ORs) revealed a significant increase in the risk of VaD in the apolipoprotein E (APOE) ε4 allelic model (OR, 1.79, p < 0.001), and the methylenetetrahydrofolate reductase (MTHFR) rs1801133 polymorphism T allele in the allelic model (OR, 1.23, p = 0.013). CONCLUSION: Our findings provide evidence that genetic polymorphisms of the APOE ε4 allele and MTHFR rs1801133 T allele increase the risk of developing VaD in Asians. However, future large-scale investigations examining particularly on South-Eastern and West-Asian populations are highly recommended.

2.
Eur Rev Med Pharmacol Sci ; 27(16): 7823-7830, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37667959

RESUMO

OBJECTIVE: COVID-19 is a febrile infectious disease caused by severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2). This virus affects several organs, including the skin. Acute telogen effluvium (TE) is a non-scarring hair loss characterized by diffuse hair shedding that begins three months after a stressful event and can last up to six months. COVID-19 infection is one of these potential stressors. Recently, there has been a reported link between increased scalp hair shedding and post-infection patients during the COVID-19 outbreak. The present work aimed to study the possible effects of COVID-19 on hair and the relationship between COVID-19 and TE and to assess the level of awareness about TE in the Asir region of Saudi Arabia. SUBJECTS AND METHODS: A questionnaire-based cross-sectional study was conducted using a pre-validated questionnaire. The study involved 561 participants from the Asir region of Saudi Arabia. Eligible participants were individuals from the Asir region who were 20 years of age or older, had previously contracted COVID-19 and had no history of TE before infection. All statistical methods used were two-tailed with an alpha level of 0.05, considering significance if the p-value was lower than or equal to 0.05. RESULTS: A total of 1,000 eligible participants completed the study questionnaire. The mean age was 32.5 ± 13.9 years, and 494 (88.1%) participants were females. In addition, 558 (99.5%) of the study participants had received the COVID-19 vaccine. A total of 411 (73.3%) participants experienced an increase in hair loss after COVID-19 infection, and 171 (30.5%) began suffering from pain when combing their hair. In addition, 182 participants (32.4%) had a family history of TE. Only 109 (10.9%) participants had a good awareness level about TE, while 452 (80.6%) had an overall poor awareness level. There was a significant relationship between the level of awareness and age, where 23.9% of the participants aged 20-29 years had a good level of awareness vs. 16.1% of others aged 40 years or older (p = 0.041). Moreover, 26.9% of participants with a family history of TE had a good awareness of TE, vs. 15.8% of those with no family history of TE (p = 0.002). In addition, significant correlations were found between increased hair loss post-COVID-19 infection and female gender (77.3% vs. 43.3%; p = 0.001) as well as suffering from pain when combing hair (86.5% vs. 65.5%; p = 0.001). CONCLUSIONS: In our study, the incidence of TE was highly related to COVID-19 infections among both sexes. However, the incidence was greater among the female population. The awareness level toward post-COVID-19 TE was poor among most of the participants in our study.


Assuntos
Alopecia em Áreas , COVID-19 , Masculino , Humanos , Feminino , Adolescente , Adulto Jovem , Adulto , Pessoa de Meia-Idade , COVID-19/epidemiologia , Estudos Transversais , Vacinas contra COVID-19 , SARS-CoV-2 , Dor
3.
Nanotechnology ; 34(32)2023 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-37156235

RESUMO

Real-time tracking of dynamic nanoscale processes such as phase transitions by scanning probe microscopy is a challenging task, typically requiring extensive and laborious human supervision. Smart strategies to track specific regions of interest (ROI) in the system during such transformations in a fast and automated manner are necessary to study the evolution of the microscopic changes in such dynamic systems. In this work, we realize automated ROI tracking in piezoresponse force microscopy during a fast (≈0.8°C s-1) thermally stimulated ferroelectric-to-paraelectric phase transition in CuInP2S6. We use a combination of fast (1 frame per second) sparse scanning with compressed sensing image reconstruction and real-time offset correction via phase cross correlation. The applied methodology enablesin situfast and automated functional nanoscale characterization of a certain ROI during external stimulation that generates sample drift and changes local functionality.

4.
Glob Health Sci Pract ; 11(2)2023 04 28.
Artigo em Inglês | MEDLINE | ID: mdl-37116929

RESUMO

To reduce TB deaths in resource-limited settings, a differentiated care strategy can be used to triage patients with high risk of severe illness (i.e., those with very severe undernutrition, respiratory insufficiency, or inability to stand without support) at diagnosis and refer them for comprehensive assessment and inpatient care. Globally, there are few examples of implementing this type of strategy in routine program settings. Beginning in April 2022, the Indian state of Tamil Nadu implemented a differentiated care strategy called Tamil Nadu-Kasanoi Erappila Thittam (TN-KET) for all adults aged 15 years and older with drug-susceptible TB notified by public facilities. Before evaluating the impact on TB deaths, we sought to understand the retention and delays in the care cascade as well as predictors of losses. During April-June 2022, 14,961 TB patients were notified and 11,599 (78%) were triaged. Of those triaged, 1,509 (13%) were at high risk of severe illness; of these, 1,128 (75%) were comprehensively assessed at a nodal inpatient care facility. Of 993 confirmed as severely ill, 909 (92%) were admitted, with 8% unfavorable admission outcomes (4% deaths). Median admission duration was 4 days. From diagnosis, the median delay in triaging and admission of severely ill patients was 1 day each. Likelihood of triaging decreased for people with extrapulmonary TB, those diagnosed in high-notification districts or teaching hospitals, and those transferred out of district. Predictors of not being comprehensively assessed included: aged 25-34 years, able to stand without support, and diagnosis at a primary or secondary-level facility. Inability to stand without support was a predictor of unfavorable admission outcomes. To conclude, the first quarter of implementation suggests that TN-KET was feasible to implement but could be improved by addressing predictors of losses in the care cascade and increasing admission duration.


Assuntos
Desnutrição , Adulto , Humanos , Índia/epidemiologia
5.
Glob Health Action ; 16(1): 2161231, 2023 12 31.
Artigo em Inglês | MEDLINE | ID: mdl-36621943

RESUMO

Due to the workload and lack of a critical mass of trained operational researchers within their ranks, health systems and programmes may not be able to dedicate sufficient time to conducting operational research (OR). Hence, they may need the technical support of operational researchers from research/academic organisations. Additionally, there is a knowledge gap regarding implementing differentiated tuberculosis (TB) care in programme settings. In this 'how we did it' paper, we share our experience of implementing a differentiated TB care model along with an inbuilt OR component in Tamil Nadu, a southern state in India. This was a health system initiative through a collaboration of the State TB cell with the Indian Council of Medical Research institutes and the World Health Organisation country office in India. The learnings are in the form of eleven tips: four broad principles (OR on priority areas and make it a health system initiative, implement simple and holistic ideas, embed OR within routine programme settings, aim for long-term engagement), four related to strategic planning (big team of investigators, joint leadership, decentralised decision-making, working in advance) and three about implementation planning (conducting pilots, smart use of e-tools and operational research publications at frequent intervals). These may act as a guide for other Indian states, high TB burden countries that want to implement differentiated care, and for operational researchers in providing technical assistance for strengthening implementation and conducting OR in health systems and programmes (TB or other health programmes). Following these tips may increase the chances of i) an enriching engagement, ii) policy/practice change, and iii) sustainable implementation.


Assuntos
Pesquisa Biomédica , Tuberculose , Humanos , Índia , Tuberculose/prevenção & controle , Programas Governamentais , Organizações
6.
J Hosp Infect ; 127: 1-6, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35671861

RESUMO

BACKGROUND: The COVID-19 (SARS-CoV-2) pandemic has increased infection control vigilance across several modes of patient contact. However, it is unknown whether hygiene pertaining to stethoscopes, which carry the potential for pathogenic contamination, has also shifted accordingly. AIM: To characterize pandemic-related changes in stethoscope hygiene. METHODS: We surveyed healthcare providers at three major medical centres. Questions quantitatively (Likert scale and frequency) assessed stethoscope hygiene beliefs and practices with two components: before and during COVID-19. Participants were grouped based on performance of optimal stethoscope hygiene (after every patient) before and during COVID-19. Groups were compared using χ2 and analysis of variance (ANOVA). FINDINGS: Of the 515 (10%) who completed the survey, 55 were excluded (N = 460). Optimal hygiene increased from 27.4% to 55.0% (P < 0.001). There were significant increases in Likert scores for all questions pertaining to knowledge of stethoscope contamination (P < 0.001). Belief in stethoscope contamination increased (P < 0.001) despite no change in perceived hygiene education. Resident physicians were less likely compared with attending physicians and nurses to have adopted optimal hygiene during COVID-19 (P < 0.001). CONCLUSION: Despite a positive shift in stethoscope hygiene during COVID-19, optimal hygiene was still only performed by around half of providers. Educational interventions, particularly targeting early-career providers, are encouraged.


Assuntos
COVID-19 , Estetoscópios , COVID-19/prevenção & controle , Estudos Transversais , Desinfecção , Humanos , Higiene , SARS-CoV-2
7.
Nanomaterials (Basel) ; 10(1)2020 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-31963431

RESUMO

Nb2O5/graphene nanocomposites without any surfactant are synthesized by an in situ microwave irradiation technique. Structural and morphological studies revealed that the prepared composites were composed of Nb2O5 nanoparticles intercalated into the graphene sheet. The thermal stability of graphene oxide, Nb2O5, and Nb2O5/graphene nanocomposite was studied by the TGA. The electrochemical properties are assessed by cyclic voltammetry, chronopotentiometry and electrochemical impedance spectroscopy analyses. The specific capacitance of Nb2O5/graphene nanocomposites is greater (633 Fg-1) than pure Nb2O5 nanoparticles (221 Fg-1) and graphene (290 Fg-1) at a current density of 1 Ag-1. The long-term cyclic measurement confirms higher cyclic stability of the nanocomposite with capacitance retention of 99.3% after 5000 cycles without performance degradation. The composites exhibit higher electrochemical conductivity and allow effective ions and charge transport over the entire electrode surface with aqueous electrolyte. The electrochemical study suggests that Nb2O5/graphene nanocomposites have the potential to be an effective electrode for superior performance supercapacitor applications.

8.
Arch Gerontol Geriatr ; 81: 240-244, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30669017

RESUMO

BACKGROUND: Physical and pathological changes associated with advancing age affect sexual behaviours of the elderly. The aim of this study was to explore the impact of gender on sexual problems and perceptions among the urban Malay elderly. METHODS: A cross-sectional study was conducted among 160 Malaysian elderly participants aged 60 years and older who live in Kuala Lumpur. Twelve neighbourhood associations were randomly selected using multi-stage cluster sampling. Data was collected using standardized and validated questionnaire by face-to-face interview technique with which was conducted by trained interviewers. RESULTS: Mean age of the participants was 65.33 (5.87) year old with majority were still married. Female (55.7%) reported more sexual problems as evidenced by the higher proportion of those with lacked interest in having sex (72.5%), find sex is unpleasant (34.8%) and unable to come to orgasm (55.1%). Gender was found to have significant impact on every model obtained in the analysis for both sexual problems and perceptions. Female elderly were 10.6 times more likely to have sexual problem compared to male elderly (OR = 10.64, P < 0.001, 95% CI 3.61, 31.35) and 033 less likely to have good sexual perception (OR = 0.33, P = 0.027, 95% CI 0.12, 0.88). CONCLUSION: Gender is a crucial factor towards sexual problem and perceptions among older persons. Older women were reported to have more sexual problems and poor sexual perceptions, reflecting the needs for sexual awareness and education to improve the perceptions and sexuality in later life.


Assuntos
Comportamento Sexual , Idoso , Estudos Transversais , Feminino , Humanos , Malásia , Masculino , Pessoa de Meia-Idade , Percepção , Caracteres Sexuais , Comportamento Sexual/estatística & dados numéricos , Inquéritos e Questionários , População Urbana
9.
Adv Struct Chem Imaging ; 4(1): 6, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29755927

RESUMO

Many spectral responses in materials science, physics, and chemistry experiments can be characterized as resulting from the superposition of a number of more basic individual spectra. In this context, unmixing is defined as the problem of determining the individual spectra, given measurements of multiple spectra that are spatially resolved across samples, as well as the determination of the corresponding abundance maps indicating the local weighting of each individual spectrum. Matrix factorization is a popular linear unmixing technique that considers that the mixture model between the individual spectra and the spatial maps is linear. Here, we present a tutorial paper targeted at domain scientists to introduce linear unmixing techniques, to facilitate greater understanding of spectroscopic imaging data. We detail a matrix factorization framework that can incorporate different domain information through various parameters of the matrix factorization method. We demonstrate many domain-specific examples to explain the expressivity of the matrix factorization framework and show how the appropriate use of domain-specific constraints such as non-negativity and sum-to-one abundance result in physically meaningful spectral decompositions that are more readily interpretable. Our aim is not only to explain the off-the-shelf available tools, but to add additional constraints when ready-made algorithms are unavailable for the task. All examples use the scalable open source implementation from https://github.com/ramkikannan/nmflibrary that can run from small laptops to supercomputers, creating a user-wide platform for rapid dissemination and adoption across scientific disciplines.

10.
Nat Commun ; 9(1): 513, 2018 02 06.
Artigo em Inglês | MEDLINE | ID: mdl-29410417

RESUMO

Spectroscopic measurements of current-voltage curves in scanning probe microscopy is the earliest and one of the most common methods for characterizing local energy-dependent electronic properties, providing insight into superconductive, semiconductor, and memristive behaviors. However, the quasistatic nature of these measurements renders them extremely slow. Here, we demonstrate a fundamentally new approach for dynamic spectroscopic current imaging via full information capture and Bayesian inference. This general-mode I-V method allows three orders of magnitude faster measurement rates than presently possible. The technique is demonstrated by acquiring I-V curves in ferroelectric nanocapacitors, yielding >100,000 I-V curves in <20 min. This allows detection of switching currents in the nanoscale capacitors, as well as determination of the dielectric constant. These experiments show the potential for the use of full information capture and Bayesian inference toward extracting physics from rapid I-V measurements, and can be used for transport measurements in both atomic force and scanning tunneling microscopy.

11.
Med J Malaysia ; 72(1): 7-11, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-28255133

RESUMO

INTRODUCTION: Internet is important to university students, especially for medical students who use it to search for literature and relevant information. However, some of the users are experiencing a gradual loss of the ability to reduce the duration and frequency of their internet activities, despite the negative consequences. The literature on internet usage among Malaysian medical students is limited. This study aims to determine the prevalence and factors associated with internet usage among medical students in a public university in Malaysia. METHODS: This cross-sectional study was performed among all the medical students (Year 1-5). Students were assessed on their internet activities using the internet addiction questionnaires (IAT). A Multiple Logistic Regression was used for data analysis. RESULTS: The study was conducted among 426 students. The study population consisted of 156 males (36.6%) and 270 females (63.4%). The mean age was 21.6 ±1.5 years. Ethnicity distribution among the students was: Malays (55.6%), Chinese (34.7%), Indians (7.3%) and others (2.3%). According to the IAT, 36.9% of the study sample was addicted to the internet. Using the multivariate logistic regression analysis, we have found that the use of internet access for entertainment purposes (odds ratio [OR] 3.5, 95% confidence interval [CI] 1.05-12.00), male students (OR 1.8, 95% CI 1.01-3.21) and increasing frequency of internet usage were associated with internet addiction (OR 1.4, 95% CI 1.09- 1.67). CONCLUSION: Internet addiction is a relatively frequent phenomenon among medical students. The predictors of internet addiction were male students using it for surfing and entertainment purposes.


Assuntos
Comportamento Aditivo/epidemiologia , Internet/estatística & dados numéricos , Estudantes de Medicina/psicologia , Comportamento Aditivo/etiologia , Estudos Transversais , Feminino , Humanos , Modelos Logísticos , Malásia/epidemiologia , Masculino , Prevalência , Fatores de Risco , Estudantes de Medicina/estatística & dados numéricos , Adulto Jovem
12.
Nat Commun ; 7: 12712, 2016 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-27581797

RESUMO

The strong coupling between antiferromagnetism and ferroelectricity at room temperature found in BiFeO3 generates high expectations for the design and development of technological devices with novel functionalities. However, the multi-domain nature of the material tends to nullify the properties of interest and complicates the thorough understanding of the mechanisms that are responsible for those properties. Here we report the realization of a BiFeO3 material in thin film form with single-domain behaviour in both its magnetism and ferroelectricity: the entire film shows its antiferromagnetic axis aligned along the crystallographic b axis and its ferroelectric polarization along the c axis. With this we are able to reveal that the canted ferromagnetic moment due to the Dzyaloshinskii-Moriya interaction is parallel to the a axis. Furthermore, by fabricating a Co/BiFeO3 heterostructure, we demonstrate that the ferromagnetic moment of the Co film does couple directly to the canted moment of BiFeO3.

13.
Genet Mol Res ; 15(2)2016 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-27173202

RESUMO

Type 2 diabetes mellitus (T2DM) is believed to be associated with excessive production of reactive oxygen species. Glutathione S-transferase (GST) polymorphisms result in decreased or absent enzyme activity and altered oxidative stress, and have been associated with cardiovascular disease (CVD). The present study assessed the effect of GST polymorphisms on the risk of developing T2DM in individuals of Malaysian Malay ethnicity. A total of 287 subjects, consisting of 87 T2DM and 64 CVD/T2DM patients, as well as 136 healthy gender- and age-matched controls were genotyped for selected polymorphisms to evaluate associations with T2DM susceptibility. Genomic DNA was extracted using commercially available kits, and GSTM1, GSTT1, and α-globin sequences were amplified by multiplex polymerase chain reaction. Biochemical parameters were measured with a Hitachi autoanalyzer. The Fisher exact test, the chi-square statistic, and means ± standard deviations were calculated using the SPSS software. Overall, we observed no significant differences regarding genotype and allele frequencies between each group (P = 0.224 and 0.199, respectively). However, in the combined analysis of genotypes and blood measurements, fasting plasma glucose, HbA1c, and triglyceride levels, followed by age, body mass index, waist-hip ratio, systolic blood pressure, and history of T2DM significantly differed according to GST polymorphism (P ˂ 0.05). Genetically induced absence of the GSTT1 enzyme is an independent and powerful predictor of premature vascular morbidity and death in individuals with T2DM, and might be triggered by cigarette smoking's oxidative effects. These polymorphisms could be screened in other ethnicities within Malaysia to determine further possible risk factors.


Assuntos
Doenças Cardiovasculares/genética , Diabetes Mellitus Tipo 2/genética , Glutationa Transferase/genética , Polimorfismo de Nucleotídeo Único , Alelos , Doenças Cardiovasculares/complicações , Estudos de Casos e Controles , Diabetes Mellitus Tipo 2/complicações , Feminino , Genótipo , Humanos , Malásia , Masculino , alfa-Globinas/genética
14.
Nat Mater ; 15(5): 549-56, 2016 05.
Artigo em Inglês | MEDLINE | ID: mdl-26878312

RESUMO

Domains and domain walls are critical in determining the response of ferroelectrics, and the ability to controllably create, annihilate, or move domains is essential to enable a range of next-generation devices. Whereas electric-field control has been demonstrated for ferroelectric 180° domain walls, similar control of ferroelastic domains has not been achieved. Here, using controlled composition and strain gradients, we demonstrate deterministic control of ferroelastic domains that are rendered highly mobile in a controlled and reversible manner. Through a combination of thin-film growth, transmission-electron-microscopy-based nanobeam diffraction and nanoscale band-excitation switching spectroscopy, we show that strain gradients in compositionally graded PbZr1-xTixO3 heterostructures stabilize needle-like ferroelastic domains that terminate inside the film. These needle-like domains are highly labile in the out-of-plane direction under applied electric fields, producing a locally enhanced piezoresponse. This work demonstrates the efficacy of novel modes of epitaxy in providing new modalities of domain engineering and potential for as-yet-unrealized nanoscale functional devices.

15.
Nat Commun ; 6: 8985, 2015 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-26597483

RESUMO

Elastic anomalies are signatures of phase transitions in condensed matters and have traditionally been studied using various techniques spanning from neutron scattering to static mechanical testing. Here, using band-excitation elastic/piezoresponse spectroscopy, we probed sub-MHz elastic dynamics of a tip bias-induced rhombohedral-tetragonal phase transition of strained (001)-BiFeO3 (rhombohedral) ferroelectric thin films from ∼10(3) nm(3) sample volumes. Near this transition, we observed that the Young's modulus intrinsically softens by over 30% coinciding with two- to three-fold enhancement of local piezoresponse. Coupled with phase-field modelling, we also addressed the influence of polarization switching and mesoscopic structural heterogeneities (for example, domain walls) on the kinetics of this phase transition, thereby providing fresh insights into the morphotropic phase boundary in ferroelectrics. Furthermore, the giant electrically tunable elastic stiffness and corresponding electromechanical properties observed here suggest potential applications of BiFeO3 in next-generation frequency-agile electroacoustic devices, based on the utilization of the soft modes underlying successive ferroelectric phase transitions.

16.
Nanoscale ; 7(47): 20089-94, 2015 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-26568116

RESUMO

Variable temperature band-excitation atomic force microscopy in conjunction with I-V spectroscopy was used to investigate the crystalline superionic proton conductor CsHSO4 during proton exchange induced by a Pt-coated conductive scanning probe. At a sample temperature of 150 °C and under an applied bias <1 V, reduction currents of up to 1 nA were observed. Simultaneously, we show that the electrochemical reactions are accompanied by a reversible decrease in the elastic modulus of CsHSO4, as seen by a contact resonance shift, and find evidence for superplasticity during scanning. These effects were not observed in the room-temperature phase of CsHSO4 or in the case of catalytically inactive conductive probes, proving the utility of this technique for monitoring electrochemical processes on the nanoscale, as well as the use of local contact stiffness as a sensitive indicator of electrochemical reactions.

17.
Andrologia ; 47(2): 168-77, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24528375

RESUMO

Azoospermia factor region (AZF) deletions (AZFa, AZFb, AZFc and AZFd) in the Y chromosome were analysed in male infertility subjects in various populations with conflicting results. This study comprised of 54 infertile males and 63 fertile controls, and the frequency of AZFa, AZFb, AZFc and AZFd deletions were determined using conventional polymerase chain reaction (PCR) as well as real-time PCR-high resolution melting analysis-based methods. The results of this study showed that, three of 54 cases (5.55%) had AZF (a, b and c) deletions (two had AZFc and one had AZFa deletions). Four cases were found to have AZFd deletions (7.4%) with two of them being associated with AZFc deletions (P = 0.028). The frequency of AZF (a, b and c) deletions in Malaysian infertile male subjects was found to be comparable with other populations. AZFd deletions were found to be significant (P < 0.05) in male infertility and it may be associated with other types of AZF deletions.


Assuntos
Azoospermia/genética , Deleção Cromossômica , Cromossomos Humanos Y/genética , Infertilidade Masculina/etnologia , Infertilidade Masculina/genética , Adulto , Estudos de Casos e Controles , Testes Genéticos , Genótipo , Humanos , Infertilidade Masculina/epidemiologia , Malásia/epidemiologia , Masculino , Fenótipo , Reação em Cadeia da Polimerase/métodos , Fatores de Risco
18.
Nat Commun ; 5: 4971, 2014 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-25233288

RESUMO

Ferroelectrics have been used as memory storage devices, with an upper bound on the total possible memory levels generally dictated by the number of degenerate states allowed by the symmetry of the ferroelectric phase. Here, we introduce a new concept for storage wherein the polarization can be rotated arbitrarily, effectively decoupling it from the crystallographic symmetry of the ferroelectric phase on the mesoscale. By using a Bi5Ti3FeO15-CoFe2O4 film and via Band-Excitation Piezoresponse Force Microscopy, we show the ability to arbitrarily rotate polarization, create a spectrum of switched states, and suggest the reason for polarization rotation is an abundance of sub-50 nm nanodomains. Transmission electron microscopy-based strain mapping confirms significant local strain undulations imparted on the matrix by the CoFe2O4 inclusions, which causes significant local disorder. These experiments point to controlled tuning of polarization rotation in a standard ferroelectric, and hence the potential to greatly extend the attainable densities for ferroelectric memories.

19.
Genet Mol Res ; 13(2): 2939-48, 2014 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-24782128

RESUMO

The sympathetic nervous system plays a major role in blood pressure regulation. Beta 2 (ß2) adrenoceptor gene polymorphisms have been associated with hypertension in different populations with conflicting results. We examined the association of three common polymorphisms, Arg16Gly, Gln27Glu, and Thr164Ile, of the ß2 adrenoceptor gene in Malaysian hypertensive subjects. A total of 160 hypertensive and control subjects were recruited. Systolic blood pressure (SBP), diastolic blood pressure (DBP), and anthropometric measurements were obtained from each subject. Biochemical analyses of lipid profiles were conducted with an autoanalyzer. DNA samples were extracted from blood and buccal cells. Genotyping was accomplished with polymerase chain reaction-restriction fragment length polymorphism. SBP, DBP, body mass index, and biochemical factors all differed significantly between case and control subjects (P < 0.05). The genotype frequencies of Arg16Arg, Arg16Gly, and Gly16Gly were 22.5, 70, and 7.5% among cases and 33.1, 63.1, and 3.8% among controls, respectively. The genotype frequencies of Gln27Gln, Gln27Glu, and Glu27Glu among cases were 41.1, 50, and 1.9% compared to 77.5, 20.6, and 1.9% among controls, respectively. In this study, the Gln27Glu polymorphism was significantly associated with Malaysian hypertensive subjects (P < 0.05). Therefore, the Gln27Glu polymorphism of the ß2 adrenoceptor could be a risk factor associated with hypertension among Malaysians.


Assuntos
Pressão Sanguínea/genética , Estudos de Associação Genética , Hipertensão/genética , Receptores Adrenérgicos beta 2/genética , Adulto , Povo Asiático , Feminino , Genótipo , Humanos , Hipertensão/patologia , Malásia , Masculino , Pessoa de Meia-Idade , Polimorfismo Genético , Polimorfismo de Nucleotídeo Único/genética , Fatores de Risco
20.
Annu Rev Phys Chem ; 65: 519-36, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24689800

RESUMO

Field confinement at the junction between a biased scanning probe microscope's tip and solid surface enables local probing of various bias-induced transformations, such as polarization switching, ionic motion, and electrochemical reactions. The nanoscale size of the biased region, smaller or comparable to that of features such as grain boundaries and dislocations, potentially allows for the study of kinetics and thermodynamics at the level of a single defect. In contrast to classical statistically averaged approaches, this approach allows one to link structure to functionality and deterministically decipher associated mesoscopic and atomistic mechanisms. Furthermore, responses measured as a function of frequency and bias can serve as a fingerprint of local material functionality, allowing for local recognition imaging of inorganic and biological systems. This article reviews current progress in multidimensional scanning probe microscopy techniques based on band excitation time and voltage spectroscopies, including discussions on data acquisition, dimensionality reduction, and visualization, along with future challenges and opportunities for the field.


Assuntos
Microscopia de Varredura por Sonda/métodos , Desenho de Equipamento , Processamento de Imagem Assistida por Computador/instrumentação , Processamento de Imagem Assistida por Computador/métodos , Microscopia Acústica/instrumentação , Microscopia Acústica/métodos , Microscopia de Varredura por Sonda/instrumentação
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