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BACKGROUND: Menopausal quality of life (MenQoL) is a common concern that primary healthcare workers often encounter. Menopause has a significant impact on women's health, but studies examining its effect on the MenQoL of menopausal healthcare employees have produced conflicting results. OBJECTIVE: The aim of this study was to compare the quality of life related to menopausal status (pre-, peri-, or postmenopausal) in healthcare workers from various clinical settings in Kazakhstan. DESIGN: This was a cross-sectional study. PARTICIPANTS: In total, 222 menopausal healthcare workers (physicians, nurses/midwives, administrative staff, and cleaners) were enrolled from hospitals affiliated with the University Medical Center (UMC) in Kazakhstan. MAIN MEASURES: The outcome variable was assessed using the Menopausal Quality of Life Questionnaire (MENQOL), which evaluates MenQoL across four domains of menopausal symptoms: physical, psychological, vasomotor, and sexual. KEY RESULTS: The most frequently reported menopausal symptoms were physical ones, such as feeling tired or worn out (70.7%), followed by feeling a lack of energy (65.3%) and dry skin (64.1%). The postmenopause group had the highest mean MenQoL score in the vasomotor domain (mean 3.46 ± 1.84). There was a borderline statistical significance when comparing postmenopause and perimenopause groups in the physical domain. The pairwise comparison of mean sexual scores revealed that postmenopause women had the highest average score (3.3 ± 2.36) compared to both premenopause (mean 2.3 ± 1.82) and perimenopause (mean 2.22 ± 1.58) groups (p < 0.05). CONCLUSIONS: Menopausal status has influence on the MenQoL of healthcare workers. The study findings could have important implications for policymakers as they provide insight into the factors influencing the quality of life of menopausal healthcare employees. Creating a more menopause-friendly work environment may not only enhance the well-being of healthcare personnel but also improve their overall job satisfaction and performance.
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Personal de Salud , Menopausia , Calidad de Vida , Humanos , Estudios Transversales , Femenino , Calidad de Vida/psicología , Persona de Mediana Edad , Personal de Salud/psicología , Menopausia/psicología , Menopausia/fisiología , Adulto , Kazajstán/epidemiología , Encuestas y CuestionariosRESUMEN
The relationship between the levels of essential elements and various aspects of well-being in environmentally exposed populations still needs to be better understood. The present study aims to investigate the potential connections between serum concentrations of calcium (Ca), magnesium (Mg), and quality of life (QoL) in environmentally exposed populations in Kazakhstan. The present study involved 1881 nominally healthy individuals aged 18-52 years who were permanent residents of Abay, Borodulikha, Ust-Kamenogorsk, Kurchum, Uralsk, Aksay, and Berezovka settlements. These settlements were selected to represent different types of environmental exposure: radioactive fallout from the Semipalatinsk Nuclear Test Site (SNTS), non-ferrous metallurgy, and the condensate gas field, compared to environmentally unexposed territories. The Russian version of the SF-36 questionnaire was used to assess the participants' quality of life. Serum Ca levels were measured using colorimetry with O-cresolphthalein, and serum Mg concentrations were measured using colorimetry with xylidyl blue. Both elevated and decreased serum Ca levels were more frequently observed in the environmentally exposed populations. The prevalence of hypermagnesemia was highest among residents near the condensate gas field. Environmentally exposed populations residing near the SNTS and in Ust-Kamenogorsk exhibited lower scores in some QoL domains. In contrast, people near the condensate gas field showed comparable or even higher QoL scores than the control population. Only serum Mg demonstrated a significant association with the average QoL scores, while Ca did not show such an association. These findings have important implications for public health interventions.
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Calcio , Exposición a Riesgos Ambientales , Magnesio , Calidad de Vida , Humanos , Magnesio/sangre , Kazajstán , Adulto , Calcio/sangre , Femenino , Persona de Mediana Edad , Adolescente , Masculino , Adulto JovenRESUMEN
BACKGROUND: During the 1990-2000, Kazakhstan experienced a decline in the number of healthcare professionals working in rural areas. Since 2009, the national government has been implementing financial incentives to encourage healthcare professionals to relocate to rural areas. This study aims to investigate the temporal and spatial patterns in the distribution of the rural healthcare workforce and evaluate the impact of this incentive scheme. METHODS: Interrupted Time Series Analysis using ARIMA models and Difference in Differences analyzes were conducted to examine the impact of the incentive scheme on the density of different categories of the healthcare workforce in rural Kazakhstan in the period from 2009 to 2020. RESULTS: There was a significant increase in the number of rural healthcare professionals from 2009 to 2020 in comparison to the period from 1998 to 2008. However, this increase was less pronounced in per capita terms. Moreover, a decline in the density of internists and pediatricians was observed. There is substantial variation in the density of rural nurses and physicians across different regions of Kazakhstan. The incentive scheme introduced in 2009 by the government of Kazakhstan included a one-time allowance and housing incentive. This scheme was found to have contributed insignificantly to the observed increase in the number of rural healthcare professionals. CONCLUSION: Future research should be undertaken to examine the impact made by the incentive scheme on other medical subspecialties, particularly primary practitioners. Addressing the shortage of healthcare workers in rural areas is a complex issue that requires a multifaceted approach. Aside from financial incentives, other policies could be considered to increase relocation and improve the retention of healthcare professionals in rural areas.
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Motivación , Servicios de Salud Rural , Humanos , Kazajstán , Personal de Salud , Recursos Humanos , Atención a la SaludRESUMEN
Background: With the online proliferation of illegal substances, the Internet offers a wide variety of information on the acquisition and intake of anabolic-androgenic steroids (AAS) and other performance and image enhancing drugs. This study focuses on investigating the characteristics of the online AAS market in Central Asia. OBJECTIVES: The primary objectives of this study were to investigate the accessibility and features of the online market for AAS in Central Asia. To achieve this, we employed a netnographic approach for a systematic exploration of websites advertising and selling AAS. The study aimed to conduct a comprehensive analysis of several key aspects, including the variety of AAS products offered, the quality of health advice provided the level of product availability, the procedures involved in making purchases, and the pricing structures within this market. RESULTS: Twenty-one websites supplying AAS in Central Asia met our inclusion criteria. Using content analysis, data were gathered on AAS offerings, quality of health advice provided, availability, purchase process, and prices. Data were synthesized using descriptive statistics. Results indicate that AAS are easily accessible for purchase without valid medical prescription in the Central Asia online market. Most websites advertised the aesthetic and ergogenic benefits of AAS use without indicating the potential complications and adverse effects. CONCLUSIONS: Public health efforts to mitigate AAS use in Central Asia should consider both the online accessibility of AAS and the lack of accompanying information on potential complications as well as adverse effects associated with their use. Efforts must be intensified to curtail the proliferation of AAS and related misleading information on the Central Asian online market.
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Anabolizantes , Andrógenos , Humanos , Andrógenos/efectos adversos , Esteroides Anabólicos Androgénicos , Anabolizantes/efectos adversos , Congéneres de la Testosterona/efectos adversos , Esteroides/efectos adversos , AsiaRESUMEN
Neurodegenerative ocular disorders mostly develop with aging and present great complications in the quality of life. Glaucoma and age-related macular degeneration (ARMD) rank as the third and fourth leading causes of blindness and low vision. Oxidative stress is one factor in the pathogenesis of neurodegenerative eye disease. In addition, ocular ischemia and neuroinflammation play an important role. It can be hypothesized that the influence of antioxidants through diet or oral supplementation can counteract the harmful effects of reactive oxygen species accumulated secondary to oxidative stress, ischemia, and inflammation. A range of studies has been published over the past decades focusing on the possible adjuvant effect of antioxidants in ARMD, while there were fewer reports on the potential role of antioxidants in glaucoma. Although certain reports demonstrated positive results, others were discouraging. As there is a controversy between the studies favoring and disfavoring supplementation with different types of antioxidants, it is important to revise the existing evidence on the role of antioxidants in neurodegenerative ocular disorders with a special focus on glaucoma and ARMD.
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Bariatric surgery or weight loss surgery has been in practice for achieving significant weight loss in patients who have failed to achieve weight loss after pharmacological interventions. The rising cases of obesity are a triggering factor for more bariatric surgeries worldwide. Interestingly, sustained weight loss achieved post-bariatric surgery offers metabolic advantages, and patients show improved glucose and lipid metabolisms. Bariatric surgery is directly linked to higher incidences of vitamin, mineral, and trace element deficiencies, thus making patients susceptible to anemia, osteoporosis, and cardiomyopathy. Reduced nutrient absorption capacity, dietary changes, dietary restriction, and altered gastrointestinal tract morphology are some reasons for nutritional deficiency observed in post-bariatric surgery procedures. Micro-and-macronutrient deficiency observed in patients during the postoperative phase requires continuous monitoring of nutritional parameters. Therefore, adequate multivitamin and mineral supplements become essential to prevent/overcome micronutrient deficiencies. Bariatric surgery also raises the risk of small for gestational age (SGA) babies. Hence, a 12 - 24 months gap is recommended between bariatric surgery and pregnancy to achieve desired weight loss targets. The topic of this review is the impact of bariatric surgery procedures on vitamin and mineral absorption and the role of dietary supplements in maintaining a healthy nutritional balance during the postoperative phase.
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Cirugía Bariátrica , Desnutrición , Humanos , Cirugía Bariátrica/efectos adversos , Obesidad/cirugía , Suplementos Dietéticos , Vitaminas , Pérdida de PesoRESUMEN
Gut microbes share a symbiotic relationship with humans and perform several metabolic and physiological functions essential for human survival. It has been established in several scientific studies that obesity and other metabolic complications are always associated with disturbed gut microbiota profile, also called gut dysbiosis. In recent years, bariatric surgery has become a treatment of choice for weight loss, and it forms an important part of obesity management strategies across the globe. Interestingly, bariatric surgery has been shown to alter gut microbiota profile and synthesize short-chain fatty acids by gut microbes. In other words, gut microbes play a crucial role in better clinical outcomes associated with bariatric surgery. In addition, gut microbes are important in reducing weight and lowering the adverse events post-bariatric surgery. Therefore, several prebiotics, probiotics and postbiotics are recommended for patients who underwent bariatric surgery procedures for better clinical outcomes. The present review aims to understand the possible association between gut microbes and bariatric surgery and present scientific evidence showing the beneficial role of gut microbes in improving therapeutic outcomes of bariatric surgery.
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Cirugía Bariátrica , Microbioma Gastrointestinal , Probióticos , Humanos , Microbioma Gastrointestinal/fisiología , Obesidad/complicaciones , Prebióticos , Probióticos/uso terapéuticoRESUMEN
OBJECTIVES: This systematic review and meta-analysis is based on randomized controlled trials evaluating the effect of physical activity on weight loss in adults undergoing bariatric surgery. The study compared certain biomarkers for individuals with and without physical activity after bariatric surgery. Secondary, the study identified potential successful interventions for the target population. METHOD: PubMed, Embase, OVID, CINAHL, and Cochrane Library were searched from January 2000 to December 2020. Intervention studies on the effect of physical activity in adults after bariatric surgery were selected, included, and analyzed following the PRISMA guidelines. The primary outcome was weight loss followed by selected biomarkers. RESULTS: Two independent reviewers extracted data and conducted quality assessments. Of the 11 studies included, six reported BMI, two reported fat-free mass, three reported fat mass, two reported waist-hip ratio, and two reported waist circumference. Six studies measuring change from baseline BMI reported a significant intervention effect: SMD = -0.93 (-1.65;-0.20) with high heterogeneity of included trials (I2 = 72%). There was no significant difference between control and intervention groups for other outcomes. CONCLUSION: BMI as a measure of physical activity positively impacts the target population. Large-scale studies with better criteria and a longer evaluation follow-up may finalize pronounced outcomes.
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Cirugía Bariátrica , Obesidad , Adulto , Humanos , Ejercicio Físico , Pérdida de Peso , BiomarcadoresRESUMEN
Prostate disorders are commonplace in medicine, especially in older men, with prostatitis, benign prostatic hyperplasia, and prostate cancer being the most abundant pathologies. The complexity of this organ, however, turns treatment into a challenge. In this review, we aim to provide insight into the efficacy of alternative treatments, which are not normally used in conventional medicine, with a particular focus on nutrients. In order to understand why and how nutrition can be beneficial in diseases of the prostate, we give an overview of the known characteristics and features of this organ. Then, we provide a summary of the most prevalent prostate illnesses. Finally, we propose nutrition-based treatment in each of these prostate problems, based on in-depth research concerning its effects in this context, with an emphasis on surgery. Overall, we plead for an upgrade of this form of alternative treatment to a fully recognized mode of therapy for the prostate.
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Hiperplasia Prostática , Neoplasias de la Próstata , Prostatitis , Masculino , Humanos , Anciano , Próstata/cirugía , Próstata/patología , Neoplasias de la Próstata/cirugía , Hiperplasia Prostática/cirugía , Hiperplasia Prostática/patología , Prostatitis/patología , Prostatitis/terapiaRESUMEN
A novel fiber laser structure, to the best of our knowledge, based on an erbium-doped fiber ring (EDFR) and a silica microbottle resonator (MBR) is proposed and investigated experimentally. Two fiber laser samples based on MBRs with different geometries and diameters of 200 and 150 µm are fabricated, and their performance is studied experimentally. Periodic whispering gallery mode spectra of the MBRs are dependent on the position of the fiber taper used for coupling of light into the MBR, and this dependence is explored to achieve lasing at different wavelengths by moving the light coupling point along the axis of the microbottle incorporated into the proposed EDFR-MBR system. The influences of the pump laser power and light polarization on the system performance and laser stability are also investigated. Single-mode lasing with a maximum optical signal-to-noise ratio of 32 dB is demonstrated.
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Today, optical sensors are the subject of a very significant number of studies and applications [...].
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Capillary fiber (CF) has been extensively investigated in a singlemode fiber (SMF)-CF-SMF (SCS) sensing structure since multiple light guiding mechanisms can be easily excited by simply tuning the air core diameter (cladding diameter) and length of the CF. Understanding the light guiding principles in an SCS structure is essential for improved implementation of a CF based fiber sensor. In this work, light guiding principles in a relatively large air core diameter (≥ 20 µm) and long length of CF (> 1 mm) are investigated theoretically and experimentally. It is found that both multimode interference (MMI) and Anti-Resonant Reflecting Optical Waveguide (ARROW) light guiding mechanisms are excited in the SCS structure in the transmission configuration. However, MMI dips are not observed in the spectrum for the air core diameters of CF smaller than 50 µm in the experiment due to large transmission loss in small air core CFs. Further experimental results demonstrate that a CF with a bigger air core diameter shows a higher sensitivity to curvature, and the highest sensitivity of -16.15 nm/m-1 is achieved when an CF-100 was used. In addition, a SMF-CF-20-CF-30-SMF (SCCS) structure is proposed for high sensitivity bi-direction liquid level measurement for the first time, to the best of our knowledge. Two types of ARROW dips (Dip-20 and Dip-30) are simultaneously excited in transmission, hence both liquid level and liquid flow direction can be detected by tracing the dip strength changes of Dip-20 and Dip-30, respectively.
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The construction of multiple light guidance mechanisms in a hollow-core fiber (HCF) structure is a popular way to realize the simultaneous measurement of multiple parameters. In this work, a partial coating method to excite multiple anti-resonant light guidance mechanisms (ARLGMs) in an HCF structure for the simultaneous measurement of multiple parameters is proposed. As an example, a double ARLGM based on a partially polyimide (PI)-coated HCF structure for the simultaneous measurement of relative humidity (RH) and temperature is demonstrated theoretically and experimentally. The dip (dip II) produced by the PI-coated HCF section shifts linearly with surrounding RH changes with a sensitivity of circa 58.6 ± 0.77 pm/%RH, while the dip (dip I) produced by the bare HCF section (with an air coating layer) is insensitive to RH changes. In addition, both types of dips have linear responses to temperature variations, with similar sensitivities of â¼ 17 pm/°C. Hence, the proposed sensor structure can be used as an RH sensor that is also capable of compensating for local temperature fluctuations. More importantly, the simultaneous measurement of multiple parameters (such as biomarkers) is possible using the proposed method provided the proper sensing materials are partially coated onto the HCF surface.
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Coenzyme Q10 (CoQ10) is an essential component of the electron transport chain. It also acts as an antioxidant in cellular membranes. It can be endogenously produced in all cells by a specialized mitochondrial pathway. CoQ10 deficiency, which can result from aging or insufficient enzyme function, has been considered to increase oxidative stress. Some drugs, including statins and bisphosphonates, often used by older individuals, can interfere with enzymes responsible for endogenous CoQ10 synthesis. Oral supplementation with high doses of CoQ10 can increase both its circulating and intracellular levels and several clinical trials observed that its administration provided beneficial effects on different disorders such as cardiovascular disease and inflammation which have been associated with low CoQ10 levels and high oxidative stress. Moreover, CoQ10 has been suggested as a promising therapeutic agent to prevent and slow the progression of other diseases including metabolic syndrome and type 2 diabetes, neurodegenerative and male infertility. However, there is still a need for further studies and well-designed clinical trials involving a large number of participants undergoing longer treatments to assess the benefits of CoQ10 for these disorders.
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BACKGROUND: Despite ample international knowledge on cost-effectiveness of total knee arthroplasty (TKA), it has never been a subject of investigation in Kazakhstan or other post-Soviet economies. Our study aimed to carry-out the cost-utility analysis of TKA alone and in comparison with post-surgical rehabilitation and conservative treatment at health care facilities of Kazakhstan. METHODS: Two hundred and forty four patients with knee osteoarthritis (KOA) who underwent TKA in orthopedic departments of Almaty, Nur-Sultan and Semey hospitals between January 1, 2019 and September 30, 2019 were followed-up for 12 months. The health-related quality of life was measured by the EQ-5D utility and Western Ontario and McMaster Universities Osteoarthritis Index was used to measure the patients' health status. The costs were estimated from the view of health care provider. We calculated the cost per QALY, the Cost-Utility Ratio and the Incremental Cost-Effectiveness Ratio. RESULTS: At the time of 12-month follow-up patients who received TKA alone or with the course of rehabilitation showed benefit over patients from the group of conservative treatment in terms of overall health status. Mean QALY gained at 12 months constituted 1.66 for the group that received TKA with rehabilitation, 1.48 for the group that received TKA alone and 0.24 for the group that received conservative treatment. Mean cost per QALY gained was USD 30 795.75 for KOA patients under conservative treatment, USD 6 323.69 for KOA patients subjected to TKA and USD 2 670.32 for KOA patients with rehabilitation course after TKA. CONCLUSION: Both TKA and TKA with rehabilitation could be considered as highly cost-effective interventions. The data obtained could be of interest for policy makers, medical professionals and KOA patients.
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Bariatric surgery is an effective option for managing obesity and has gained general acceptance among patients in recent years. Generally, despite the high caloric intake, a bad nutritional habit of obese people results in the deficiency of several vitamins, minerals, and trace elements essential for body metabolism and normal physiological processes. Additionally, the current bariatric surgical approaches such as sleeve gastrectomy (SG), Roux-en-Y-gastric bypass (RYGB), laparoscopic adjustable gastric banding (LAGB), and jejunoileal bypass (JIB) can cause or exacerbate these deficiencies. Based on several reports, it appears that the various bariatric surgical procedures affect nutrient absorption differently. Being purely restrictive, LAGB and SG affect the absorption of iron, selenium, and vitamin B12, while RYGB, JIB, and biliopancreatic diversion have a more profound impact on the absorption of essential vitamins, minerals, and trace elements. Nutritional deficiencies in vitamins, minerals, and trace elements may follow bariatric surgery and are associated with clinical manifestations and diseases, including anemia, ataxia, hair loss, and Wernicke encephalopathy. The present review summarizes some of the major vitamin and micronutrient deficiencies associated with bariatric surgery, particularly those presented post-surgically. To avoid any adverse consequences of vitamin and trace element deficiency, proper monitoring and tests are recommended at any stage, from pre- to post-surgery (periodical check-up), followed by specific and individual nutritional supplementation treatments and a proper healthy diet.
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Cirugía Bariátrica , Derivación Gástrica , Desnutrición , Obesidad Mórbida , Derivación Gástrica/efectos adversos , Humanos , Micronutrientes , Obesidad Mórbida/cirugía , VitaminasRESUMEN
Methylmercury (MeHg) is a global environmental pollutant with neurotoxic effects. Exposure to MeHg via consumption of seafood and fish can severely impact fetal neurobehavioral development even when MeHg levels in maternal blood are as low as about 5 µg/L, which the mother tolerates well. Persistent motor dysfunctions and cognitive deficits may result from trans-placental exposure. The present review summarizes current knowledge on the mechanisms of MeHg toxicity during the period of nervous system development. Although cerebellar Purkinje cells are MeHg targets, the actions of MeHg on thiol components in the neuronal cytoskeleton as well as on mitochondrial enzymes and induction of disturbances of glutamate signaling can impair extra-cerebellar functions, also at levels well tolerated by adult individuals. Numerous herbal substances possess neuroprotective effects, predominantly represented by natural polyphenolic molecules that might be utilized to develop natural drugs to alleviate neurotoxicity symptoms caused by MeHg or other Hg compounds.
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Contaminantes Ambientales , Mercurio , Compuestos de Metilmercurio , Fármacos Neuroprotectores , Síndromes de Neurotoxicidad , Animales , Femenino , Embarazo , Compuestos de Metilmercurio/toxicidad , Fármacos Neuroprotectores/farmacología , Fármacos Neuroprotectores/uso terapéutico , Placenta , Síndromes de Neurotoxicidad/etiología , Síndromes de Neurotoxicidad/prevención & control , Contaminantes Ambientales/toxicidad , Fitoquímicos , Compuestos de Sulfhidrilo , GlutamatosRESUMEN
Background: The asthma burden is growing worldwide, and this is predisposed by environmental and occupational exposures as well as individual risk factors. This study was aimed at a comparison of diagnostic accuracy of spirometry and peak expiratory flow rate (PEFR) in asthma screening of adult patients with lung function abnormalities that present at the level of primary care. Methods: This study was conducted in Shymkent city, South Kazakhstan, the third most populous city of the country with developed industries and high rates of pulmonary diseases. Four hundred and ninety-five adult patients with lung function abnormalities were enrolled in the study and underwent two screening tests (spirometry and PEFR). The diagnosis of asthma was verified by a qualified pulmonologist after performance of screening tests and was based on symptoms, medical history, and laboratory and lung function tests. Results: The sensitivity of spirometry was 0.97 and that of PEFR was 0.95 (p = 0.721), whereas the specificity of spirometry was 0.37 and that of PEFR was 0.28 (p = 0.227). Both tests yielded the same results for the positive predictive value (0.98). The negative predictive value was significantly higher for spirometry versus PEFR (0.23 versus 0.08; p = 0.006). The positive and negative likelihood ratios of the two tests also differed significantly (p = 0.001 and p = 0.006, respectively), whereas the overall accuracy was comparable between the two tests (0.96 for spirometry and 0.94 for PEFR; p = 0.748). Conclusion: Ambulatory PEFR monitoring is non-inferior to the monitoring of the forced expiratory volume in 1 second and could be used for screening purposes on equal grounds with spirometry.
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Asma , Adulto , Asma/diagnóstico , Estudios de Seguimiento , Volumen Espiratorio Forzado , Humanos , Ápice del Flujo Espiratorio , Atención Primaria de Salud , Pruebas de Función Respiratoria , EspirometríaRESUMEN
The issue of radiation exposure as a potential cause of cerebrovascular disease raises many concerns. The aim of the present study was to investigate the epidemiology of stroke and transient ischemic attacks (TIA) along with the associated risk factors among the population of East Kazakhstan exposed to ionising radiation from the former Semipalatinsk Nuclear Test Site (SNTS) in comparison with the unexposed population of the same region. This 5-year retrospective cross-sectional study included the data on 10,970 patients, of whom the majority (62.3%) suffered from ischemic stroke, 11.7% had hemorrhagic stroke and the remaining 26.0% had TIA. At the moment when stroke/TIA happened, exposed patients were younger than the unexposed (mean age 63 years versus 64 years, p < 0.001) and showed higher rates of nearly all associated comorbidities, which commonly were more severe. Besides, exposed patients showed a higher risk of stroke lethality in contrast with the unexposed. The observed features might indicate that people residing in the vicinity of the SNTS are vulnerable to cerebrovascular disease and thus, this study contributes to timely recognition of this public health problem. In addition, a longitudinal study has to be envisaged to clarify whether there is any cause-effect relationship between exposure to radiation from the SNTS and the development of stroke or transient ischemic attacks.
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Ataque Isquémico Transitorio , Accidente Cerebrovascular , Estudios Transversales , Humanos , Ataque Isquémico Transitorio/epidemiología , Ataque Isquémico Transitorio/etiología , Kazajstán/epidemiología , Estudios Longitudinales , Persona de Mediana Edad , Estudios Retrospectivos , Accidente Cerebrovascular/epidemiología , Accidente Cerebrovascular/etiologíaRESUMEN
A novel micron-range displacement sensor based on a whispering-gallery mode (WGM) microcapillary resonator filled with a nematic liquid crystal (LC) and a magnetic nanoparticle- coated fiber half-taper is proposed and experimentally demonstrated. In the proposed device, the tip of a fiber half-taper coated with a thin layer of magnetic nanoparticles (MNPs) moves inside the LC-filled microcapillary resonator along its axis. The input end of the fiber half-taper is connected to a pump laser source and due to the thermo-optic effect within the MNPs, the fiber tip acts as point heat source increasing the temperature of the LC material in its vicinity. An increase in the LC temperature leads to a decrease in its effective refractive index, which in turn causes spectral shift of the WGM resonances monitored in the transmission spectrum of the coupling fiber. The spectral shift of the WGMs is proportional to the displacement of the MNP-coated tip with respect to the microcapillary's light coupling point. The sensor's operation is simulated considering heat transfer in the microcapillary filled with a LC material having a negative thermo-optic coefficient. The simulations are in a good agreement with the WGMs spectral shift observed experimentally. A sensitivity to displacement of 15.44 pm/µm and a response time of 260 ms were demonstrated for the proposed sensor. The device also shows good reversibility and repeatability of response. The proposed micro-displacement sensor has potential applications in micro-manufacturing, precision measurement and medical instruments.