ABSTRACT
Deep brain stimulation (DBS) of the internal segment of the globus pallidus (GPi) can markedly reduce muscle rigidity in people with Parkinson's disease (PD); however, the mechanisms mediating this effect are poorly understood. Computational modeling of DBS provides a method to estimate the relative contributions of neural pathway activations to changes in outcomes. In this study, we generated patient-specific biophysical models of GPi DBS (derived from individual 7T MRI) - including pallidal efferent, putamenal efferent and internal capsule pathways - to investigate how activation of neural pathways contributed to changes in forearm rigidity in PD. Ten individuals (17 arms) were tested off medication under four conditions: off stimulation, on clinically optimized stimulation, and on stimulation specifically targeting the dorsal GPi or ventral GPi. Quantitative measures of forearm rigidity, with and without a contralateral activation maneuver, were obtained using a robotic manipulandum. Clinically optimized GPi DBS settings significantly reduced forearm rigidity (p < 0.001), which aligned with GPi efferent fiber activation. The model demonstrated that GPi efferent axons could be activated at any location along the GPi dorsal-ventral axis. These results provide evidence that rigidity reduction produced by GPi DBS is mediated by preferential activation of GPi efferents to the thalamus, likely leading to a reduction in excitability of the muscle stretch reflex via overdriving pallidofugal output.
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BACKGROUND: This study aimed to determine practical delta check limits (DCLs) for thyroid function tests (TFTs) to detect sample misidentifications across various clinical settings. METHODS: Between 2020 and 2022, 610,437 paired TFT results were collected from six university hospitals. The absolute DCL (absDCL) was determined using the 95th percentile for each clinical setting from a random 60 % of the total data. These absDCLs were then tested within and across different settings using the remaining 40 % of the data, alongside mix-up datasets for result and sample comparisons. The sensitivities of absDCL were calculated within and across groups in the mix-up datasets. RESULTS: Health screening absDCLs were notably lower than in other settings (2.58 vs. 5.93-7.08 for thyroid-stimulating hormone; 4.12 vs. 8.24-10.04 for free thyroxine; 0.49 vs. 0.82-0.91 for total triiodothyronine). The proportion of results exceeding absDCL of health screening differed from those of other clinical settings. Furthermore, sensitivity between health screening and other clinical settings was significantly different in both the result mix-up and sample mix-up datasets. CONCLUSIONS: This study determined practical DCLs for TFTs and highlighted differences in absDCLs between health screening and other settings. These findings emphasize the importance of tailored DCLs in improving the accurate reporting of TFTs.
Subject(s)
Thyroid Function Tests , Humans , Thyroid Function Tests/standards , Thyrotropin/blood , Thyrotropin/analysis , Thyroxine/blood , Thyroxine/analysis , Male , Female , Adult , Triiodothyronine/blood , Triiodothyronine/analysis , Middle Aged , Thyroid Gland/physiologyABSTRACT
Background: In recent decades, the analytical quality of clinical laboratory results has substantially increased because of collaborative efforts. To effectively utilize laboratory results in applications, such as machine learning through big data, understanding the level of harmonization for each test would be beneficial. We aimed to develop a quantitative harmonization index that reflects the harmonization status of real-world laboratory tests. Methods: We collected 2021-2022 external quality assessment (EQA) results for eight tests (HbA1c, creatinine, total cholesterol, HDL-cholesterol, triglyceride, alpha-fetoprotein [AFP], carcinoembryonic antigen [CEA], and prostate-specific antigen [PSA]). This EQA was conducted by the Korean Association of External Quality Assessment Service, using commutable materials. The total analytical error of each test was determined according to the bias% and CV% within peer groups. The values were divided by the total allowable error from biological variation (minimum, desirable, and optimal) to establish a real-world harmonization index (RWHI) at each level (minimum, desirable, and optimal). Good harmonization was arbitrarily defined as an RWHI value ≤ 1 for the three levels. Results: Total cholesterol, triglyceride, and CEA had an optimal RWHI of ≤ 1, indicating an optimal harmonization level. Tests with a desirable harmonization level included HDL-cholesterol, AFP, and PSA. Creatinine had a minimum harmonization level, and HbA1c did not reach the minimum harmonization level. Conclusions: We developed a quantitative RWHI using regional EQA data. This index may help reflect the actual harmonization level of laboratory tests in the field.
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Rodent studies demonstrated specialized sodium chloride (NaCl) sensing neurons in the circumventricular organs, which mediate changes in sympathetic nerve activity, arginine vasopressin, thirst, and blood pressure. However, the neural pathways involved in NaCl sensing in the human brain are incompletely understood. The purpose of this pilot study was to determine if acute hypernatremia alters the functional connectivity of NaCl-sensing regions of the brain in healthy young adults. Resting-state fMRI scans were acquired in 13 participants at baseline and during a 30 min hypertonic saline infusion (HSI). We used a seed-based approach to analyze the data, focusing on the subfornical organ (SFO) and the organum vasculosum of the lamina terminalis (OVLT) as regions of interest (ROIs). Blood chemistry and perceived thirst were assessed pre- and post-infusion. As expected, serum sodium increased from pre- to post-infusion in the HSI group. The primary finding of this pilot study was that the functional connectivity between the SFO and a cluster within the OVLT increased from baseline to the late-phase of the HSI. Bidirectional connectivity changes were found with cortical regions, with some regions showing increased connectivity with sodium-sensing regions while others showed decreased connectivity. Furthermore, the functional connectivity between the SFO and the posterior cingulate cortex (a control ROI) did not change from baseline to the late-phase of the HSI. This finding indicates a distinct response within the NaCl sensing network in the human brain specifically related to acute hypernatremia that will need to be replicated in large-scale studies.
Subject(s)
Hypernatremia , Magnetic Resonance Imaging , Humans , Pilot Projects , Hypernatremia/physiopathology , Male , Female , Adult , Young Adult , Saline Solution, Hypertonic/pharmacology , Brain/diagnostic imaging , Brain/physiopathology , Neural Pathways/physiopathology , Neural Pathways/diagnostic imaging , Subfornical Organ/drug effects , Subfornical Organ/physiology , Organum Vasculosum/physiology , Organum Vasculosum/physiopathology , Thirst/physiology , Sodium Chloride/administration & dosage , Sodium Chloride/pharmacologyABSTRACT
Background: Research shows that individuals with Parkinson's disease (PD) who have a postural instability and gait difficulties (PIGD) subtype have a faster disease progression compared to those with a tremor dominant (TD) subtype. Nevertheless, our understanding of the structural brain changes contributing to these clinical differences remains limited, primarily because many brain imaging techniques are only capable of detecting changes in the later stages of the disease. Objective: Free water (FW) has emerged as a robust progression marker in several studies, showing increased values in the posterior substantia nigra that predict symptom worsening. Here, we examined longitudinal FW changes in TD and PIGD across multiple brain regions. Methods: Participants were TD and PIGD enrolled in the Parkinson's Progression Marker Initiative (PPMI) study who underwent diffusion MRI at baseline and 2 years later. FW changes were quantified for regions of interest (ROI) within the basal ganglia, thalamus, brainstem, and cerebellum. Results: Baseline FW in all ROIs did not differ between groups. Over 2 years, PIGD had a greater percentage increase in FW in the putamen, globus pallidus, and cerebellar lobule V. A logistic regression model incorporating percent change in motor scores and FW in these brain regions achieved 91.4% accuracy in discriminating TD and PIGD, surpassing models based solely on clinical measures (74.3%) or imaging (76.1%). Conclusion: The results further suggest the use of FW to study disease progression in PD and provide insight into the differential course of brain changes in early-stage PD subtypes.
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BACKGROUND: Despite the high vaccination coverage rate, in-hospital transmission of measles continues to occur in South Korea. We present a measles outbreak in which two healthcare workers (HCWs) with presumptive evidence of measles immunity were infected by a patient with typical measles at a single hospital in South Korea. This facilitated the evaluation of measles seroprevalence in all HCWs. METHODS: In 2018, suspected patients and contacts exposed during a measles outbreak were investigated based on their medical histories and vaccination status. Cases were confirmed by the detection of measles-specific immunoglobulin M or RNA. After the measles outbreak in 2018, measles IgG testing was conducted on a total of 972 HCWs for point-prevalence, including those exposed to the measles. In addition, we have routinely performed measles IgG tests on newly employed HCWs within one week of their hire date since 2019. The measles vaccine was administered to HCWs who tested negative or equivocally negative for IgG antibodies. RESULTS: An index patient who returned from China with fever and rash was diagnosed with measles at a hospital in Korea. Two additional HCWs were revealed as measles cases: one was vaccinated with the two-dose measles-mumps-rubella (MMR) vaccine, and the other, who was born in 1967, was presumed to have immunity from natural infection in South Korea. All three patients harbored the same D8 genotype. No additional measles cases were identified among the 964 contacts of secondary patients. A total of 2310 HCWs, including those tested during the 2018 outbreak, underwent measles IgG tests. The average age at the time of the test was 32.6 years, and 74.3% were female. The overall seropositivity of measles was 88.9% (95% confidence interval, 87.5-90.1). Although the birth cohorts between 1985 and 1994 were presumed to have received the measles-rubella (MR) catch-up vaccination in 2001, 175 (89.3%) HCWs were born after 1985 among the 195 seronegative cases. CONCLUSION: Despite high population immunity, imported measles transmission occurred among HCWs with presumed immunity. This report underscores the importance of understanding the prevalence of measles susceptibility among newly employed HCWs. This is important for policymaking regarding hospital-wide vaccinations to prevent the spread of vaccine-preventable diseases.
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AIMS: To explore whether gait and/or balance disturbances are associated with the onset of Alzheimer's dementia (AD) among older adults with amnestic mild cognitive impairment (MCI). DESIGN: This study employed a longitudinal retrospective cohort design. METHODS: We obtained data from the National Alzheimer's Coordinating Center's Uniform Data Set collected from 35 National Institute on Aging Alzheimer's Disease Research Centers between September 2005 and December 2021. The mean age of participants (n = 2692) was 74.5 years with women making up 47.2% of the sample. Risk of incident AD according to baseline gait and/or balance disturbances as measured using the Postural Instability and Gait Disturbance Score, a subscale of the Unified Parkinson's Disease Rating Scale Motor Score, was examined by the Cox proportional hazards regression models adjusting for baseline demographics, medical conditions and study sites. The mean follow-up duration was 4.0 years. RESULTS: Among all the participants, the presence or the severity of gait and/or balance disturbances was associated with an increased risk of AD. The presence or the severity of gait and/or balance disturbances was associated with a higher risk of Alzheimer's dementia among the subgroups of female and male participants. CONCLUSION: Gait and/or balance disturbances may increase the risk of developing AD, regardless of sex. IMPACT: Gait and/or balance disturbances among community-dwelling older adults with amnestic MCI may need to be frequently assessed by nurses to identify potential risk factors for cognitive decline. NO PATIENT OR PUBLIC CONTRIBUTION: Given the secondary analysis, patients, service users, caregivers or members of the public were not directly involved in this study.
Subject(s)
Alzheimer Disease , Cognitive Dysfunction , Humans , Male , Female , Aged , Alzheimer Disease/complications , Retrospective Studies , Cognitive Dysfunction/psychology , Longitudinal Studies , Gait , Disease ProgressionABSTRACT
BACKGROUND: Clinical laboratory tests are inevitably affected by various factors. Therefore, when comparing consecutive test results, it is crucial to consider the inherent uncertainty of the test. Clinical laboratories use reference change value (RCV) to determine a significant change between 2 results. Whereas the criteria for the interpretation of consecutive results by clinicians are not well known. We investigated the clinician's interpretation of a clinically significant change in consecutive laboratory test results and compared them to RCV. METHODS: We performed a questionnaire survey on clinicians, which comprised 2 scenarios with 22 laboratory test items suggesting initial test results. Clinicians were asked to choose a result showing clinically significant change. RCV of the analytes from EFLM database were collected. RESULTS: We received 290 valid questionnaire responses. Clinicians' opinions on clinically significant change was inconsistent between clinicians and scenarios, and was generally larger than RCV. Clinicians commented that they were not familiar with the variability of the laboratory tests. CONCLUSIONS: Clinicians' opinions on clinically significant changes were more prominent than RCV. Meanwhile, they tended to neglect the analytical and biological variation. Laboratories should properly guide clinicians on the RCV of tests for better decision-making on patients' clinical states.
Subject(s)
Clinical Laboratory Services , Laboratories , Humans , Clinical Laboratory Techniques , Uncertainty , Reference ValuesABSTRACT
Background: The quality of laboratory test results is crucial for accurate clinical diagnosis and treatment. Pre-analytical errors account for approximately 60%-70% of all laboratory test errors. Laboratory test results may be largely impacted by pre-analytical phase management. However, primary care clinics currently do not have pre-analytical quality management audit systems. We aimed to understand the current status of pre-analytical quality management in laboratory medicine in Korean primary care clinics. Methods: Questionnaires were designed to focus on essential components of the pre-analytical process of primary care clinics. An online survey platform was used to administer the survey to internal medicine or family medicine physicians in primary care clinics. Results: A total of 141 physicians provided a complete response to the questionnaire. In 65.2% of the clinics, patient information was hand-labeled rather than barcoded on the specimen bottles; 14.2% of clinics displayed only one piece of patient information (name or identification number), and 19.9% of clinics displayed two pieces of information. Centrifuges were not available in 29.1% of the clinics. Institutions carrying out the National Health Screening Program (NHSP) used more barcode system and had more centrifuges than institutions that did not carrying out the NHSP. Conclusions: Pre-analytical quality management is inadequate in many primary clinics. We suggest implementation of a mandatory management system, allowing for a pre-analytical quality management to be carried out in primary care clinics.
Subject(s)
Laboratories , Humans , Republic of KoreaABSTRACT
BACKGROUND: Despite the significant impact of lower limb symptoms on everyday life activities in Parkinson's disease (PD), knowledge of the neural correlates of lower limb deficits is limited. OBJECTIVE: We ran an fMRI study to investigate the neural correlates of lower limb movements in individuals with and without PD. METHODS: Participants included 24 PD and 21 older adults who were scanned while performing a precisely controlled isometric force generation task by dorsiflexing their ankle. A novel MRI-compatible ankle dorsiflexion device that limits head motion during motor tasks was used. The PD were tested on their more affected side, whereas the side in controls was randomized. Importantly, PD were tested in the off-state, following overnight withdrawal from antiparkinsonian medication. RESULTS: The foot task revealed extensive functional brain changes in PD compared to controls, with reduced fMRI signal during ankle dorsiflexion within the contralateral putamen and M1 foot area, and ipsilateral cerebellum. The activity of M1 foot area was negatively correlated with the severity of foot symptoms based on the Movement Disorder Society-Sponsored Revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS-III). CONCLUSION: Overall, current findings provide new evidence of brain changes underlying motor symptoms in PD. Our results suggest that pathophysiology of lower limb symptoms in PD appears to involve both the cortico-basal ganglia and cortico-cerebellar motor circuits.
Subject(s)
Parkinson Disease , Aged , Humans , Antiparkinson Agents/therapeutic use , Basal Ganglia , Lower Extremity/diagnostic imaging , Magnetic Resonance Imaging/methods , Movement/physiologyABSTRACT
BACKGROUND: Much of our understanding of the deficits in force control in Parkinson's disease (PD) relies on findings in the upper extremity. Currently, there is a paucity of data pertaining to the effect of PD on lower limb force control. OBJECTIVE: The purpose of this study was to concurrently evaluate upper- and lower-limb force control in early-stage PD and a group of age- and gender-matched healthy controls. METHODS: Twenty individuals with PD and twenty-one healthy older adults participated in this study. Participants performed two visually guided, submaximal (15% of maximum voluntary contractions) isometric force tasks: a pinch grip task and an ankle dorsiflexion task. PD were tested on their more affected side and after overnight withdrawal from antiparkinsonian medication. The tested side in controls was randomized. Differences in force control capacity were assessed by manipulating speed-based and variability-based task parameters. RESULTS: Compared with controls, PD demonstrated slower rates of force development and force relaxation during the foot task, and a slower rate of relaxation during the hand task. Force variability was similar across groups but greater in the foot than in the hand in both PD and controls. Lower limb rate control deficits were greater in PD with more severe symptoms based on the Hoehn and Yahr stage. CONCLUSIONS: Together, these results provide quantitative evidence of an impaired capacity in PD to produce submaximal and rapid force across multiple effectors. Moreover, results suggest that force control deficits in the lower limb may become more severe with disease progression.
Subject(s)
Ankle , Hand Strength , Parkinson Disease , Aged , Humans , Foot , Lower Extremity , Parkinson Disease/physiopathology , Case-Control Studies , HandABSTRACT
Background: National reference standards for anti-HIV-1 antibody are needed to evaluate the performance and maintain the quality control of anti-HIV-1 antibody assays. The aim of this study was to prepare a mixed-titer performance panel and assess its suitability as a national reference standard for anti-HIV-1 antibody according to stability, collaboration, and other studies. Methods: Nineteen serum samples from different HIV patients were obtained, along with 15 units of fresh frozen plasma samples with negative anti-HIV-1 antibody results. Ten anti-HIV-1 antibody-positive candidate standards and two negative candidate standards were prepared based on the reactivity in the Alinity i HIV Ag/Ab combo assay (Abbott Laboratories, Wiesbaden, Germany). A collaborative study was conducted across eight laboratories using five anti-HIV-1 antibody assays. Real-time and accelerated stability were evaluated to assess the long-term stability. Results: In the collaborative study, results of all five anti-HIV-1 antibody assays were positive for all 10 candidate standards prepared using HIV patient samples. The CV of each assay for every candidate standard was within 10%, except for one assay result. No real-time and accelerated stability change trend was observed at -70°C or -20°C, supporting that the reference standards were maintained in a stable state at -70°C for long-term storage. Conclusions: The overall results suggest that the 12 candidate standards could serve as national reference standards for anti-HIV-1 antibody.
Subject(s)
HIV Infections , HIV-1 , Humans , HIV Infections/diagnosis , Reference Standards , Quality ControlABSTRACT
OBJECTIVES: Recently, the linearity evaluation protocol by the Clinical & Laboratory Standards Institute (CLSI) has been revised from EP6-A to EP6-ED2, with the statistical method of interpreting linearity evaluation data being changed from polynomial regression to weighted least squares linear regression (WLS). We analyzed and compared the analytical measurement range (AMR) verification results according to the present and prior linearity evaluation guidelines. METHODS: The verification of AMR of clinical chemistry tests was performed using five samples with two replicates in three different laboratories. After analyzing the same evaluation data in each laboratory by the polynomial regression analysis and WLS methods, results were compared to determine whether linearity was verified across the five sample concentrations. In addition, whether the 90% confidence interval of deviation from linearity by WLS was included in the allowable deviation from linearity (ADL) was compared. RESULTS: A linearity of 42.3-56.8% of the chemistry items was verified by polynomial regression analysis in three laboratories. For analysis of the same data by WLS, a linearity of 63.5-78.3% of the test items was verified where the deviation from linearity of all five samples was within the ADL criteria, and the cases where the 90% confidence interval of all deviation from linearity overlapped the ADL was 78.8-91.3%. CONCLUSIONS: Interpreting AMR verification data by the WLS method according to the newly revised CLSI document EP6-ED2 could reduce laboratory workload, enabling efficient laboratory practice.
Subject(s)
Clinical Chemistry Tests , Laboratories , Humans , Least-Squares Analysis , Linear Models , Reference StandardsABSTRACT
People with Parkinson's disease who have elevated muscle activity during rapid eye movement sleep (REM sleep without atonia) typically have a worse motor and cognitive impairment compared with those with normal muscle atonia during rapid eye movement sleep. This study used tract-based spatial statistics to compare diffusion MRI measures of fractional anisotropy, radial, mean and axial diffusivity (measures of axonal microstructure based on the directionality of water diffusion) in white matter tracts between people with Parkinson's disease with and without rapid eye movement sleep without atonia and controls and their relationship to measures of motor and cognitive function. Thirty-eight individuals with mild-to-moderate Parkinson's disease and 21 matched control subjects underwent ultra-high field MRI (7â T), quantitative motor assessments of gait and bradykinesia and neuropsychological testing. The Parkinson's disease cohort was separated post hoc into those with and without elevated chin or leg muscle activity during rapid eye movement sleep based on polysomnography findings. Fractional anisotropy was significantly higher, and diffusivity significantly lower, in regions of the corpus callosum, projection and association white matter pathways in the Parkinson's group with normal rapid eye movement sleep muscle tone compared with controls, and in a subset of pathways relative to the Parkinson's disease group with rapid eye movement sleep without atonia. The Parkinson's disease group with elevated rapid eye movement sleep muscle tone showed significant impairments in the gait and upper arm speed compared with controls and significantly worse scores in specific cognitive domains (executive function, visuospatial memory) compared with the Parkinson's disease group with normal rapid eye movement sleep muscle tone. Regression analyses showed that gait speed and step length in the Parkinson's disease cohort were predicted by measures of fractional anisotropy of the anterior corona radiata, whereas elbow flexion velocity was predicted by fractional anisotropy of the superior corona radiata. Visuospatial memory task performance was predicted by the radial diffusivity of the posterior corona radiata. These findings show that people with mild-to-moderate severity of Parkinson's disease who have normal muscle tone during rapid eye movement sleep demonstrate compensatory-like adaptations in axonal microstructure that are associated with preserved motor and cognitive function, but these adaptations are reduced or absent in those with increased rapid eye movement sleep motor tone.
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BACKGROUND: The interest in Clostridioides difficile infection (CDI) has increased, and the choice of assays became wider since the first national survey in Korea on CDI diagnosis in 2015. We conducted a survey of the domestic CDI assays with more varied questions to understand the current situation in Korea. METHODS: In April 2018, about 50 questions on the current status of CDI assays and details on implementation and perceptions were written, and a survey questionnaire was administered to laboratory medicine specialists in 200 institutions. RESULTS: One-hundred and fifty institutions responded to the questionnaire, of which 90 (60.0%) including one commercial laboratory, performed CDI assays. The toxin AB enzyme immunoassay (toxin AB EIA), nucleic acid amplification test (NAAT), and C. difficile culture, glutamate dehydrogenase assay, alone or in combination with other assays, were used in 75 (84.3%), 52 (58.4%), 35 (36.0%), and 23 (25.8%), respectively, and 65 (73.0%) institutions performed a combination of two or more assays. The sensitivity of toxin AB EIA was more negatively perceived, and that on specificity was more positively perceived. The perception of sensitivity and specificity of NAAT was mostly positive. Perception on the algorithm test projected it as useful but in need of countermeasures. Sixty-three (73.3%) institutions responded that they performed surveillance on CDI. CONCLUSION: This study provides useful evidence on the current status of CDI laboratory diagnosis in Korea as well as on items that require improvement and is thought to aid in standardizing and improving the CDI laboratory diagnosis in Korea.
Subject(s)
Clinical Laboratory Techniques/methods , Clostridioides difficile/isolation & purification , Clostridium Infections/diagnosis , Clostridium Infections/epidemiology , Health Surveys , Humans , Population Surveillance , Republic of KoreaABSTRACT
BACKGROUND: An external cue can markedly improve gait initiation in people with Parkinson's disease (PD) and is often used to overcome freezing of gait (FOG). It is unknown if the effects of external cueing are comparable if the imperative stimulus is triggered by the person receiving the cue (self-triggered) or an external source. OBJECTIVE: Two experiments were conducted to compare the effects of self- versus externally triggered cueing on anticipatory postural adjustments (APAs) during gait initiation in people with PD. METHODS: In experiment 1, 10 individuals with PD and FOG initiated gait without a cue or in response to a stimulus triggered by the experimenter or by the participant. Experiment 2 compared self- versus externally triggered cueing across three groups: healthy young adults (nâ=â16), healthy older adults (nâ=â11), and a group with PD (nâ=â10). RESULTS: Experiment 1: Externally triggered cues significantly increased APA magnitudes compared to uncued stepping, but not when the same cue was self-triggered. Experiment 2: APAs were not significantly improved with a self-triggered cue compared to un-cued stepping in both the PD and healthy older adult groups, but the young adults showed a significant facilitation of APA magnitude. CONCLUSION: The effectiveness of an external cue on gait initiation in people with PD and older adults is critically dependent upon whether the source of the trigger is endogenous (self-produced) or exogenous (externally-generated). These results may explain why cueing interventions that rely upon self-triggering of the stimulus are often ineffective in people with PD.
Subject(s)
Gait Disorders, Neurologic , Parkinson Disease , Aged , Cognition , Cues , Gait/physiology , Gait Disorders, Neurologic/etiology , Humans , Parkinson Disease/complications , Young AdultABSTRACT
This review aimed to evaluate the effects of multi-domain interventions on cognition among individuals without dementia. Multi-domain interventions refer to those combining any single preventive measure such as physical activity, cognitive training, and/or nutrition to prevent dementia. Seventeen studies were included (n = 10,056 total participants; mean age = 73 years), eight of which were rated as strong in quality while the other nine showed moderate quality. The standardized mean difference (SMD; d) was used to calculate the effect size for each included study. Multi-domain interventions consisting of physical activity, cognitive training, cardioprotective nutrition, and/or cardiovascular health education exerted beneficial effects on global cognition, episodic memory, and/or executive function with very small to moderate effect sizes (0.16-0.77). Nurses may consider combining these components to potentially stave off dementia. Future research is warranted to identify the optimal multi-domain intervention components that can induce clinically significant beneficial effects on cognition.
Subject(s)
Dementia , Memory, Episodic , Humans , Aged , Cognition , Executive Function , Exercise , Dementia/therapyABSTRACT
Increasing the toughness of poly(lactic acid) (PLA), i.e., simultaneously increasing both the tensile strength and ductility, remains a major challenge. In this study, fully bio-based PLA blends with polydecalactone (PDL)-grafted cellulose copolymer (CgPD) were prepared and comprehensively analyzed to enhance the toughness of the PLA matrix. The blends were found by FT-IR and solid-state 1H NMR to be physically intact and miscible at the sub-twenty-nanometer scale. The WXRD and DSC analyses indicated that the addition of the alkyl-branched CgPD imparts a more structurally disordered PLA mesophase state to the prepared PLA_CgPD bio-blends. UTM analysis was used to characterize the macroscopic mechanical properties of the PLA_CgPD bio-blends. Both the tensile strength and elongation properties were simultaneously improved with the addition of 1 wt% CgPD loading amount to PLA (PLA_CgPD1). This study experimentally demonstrates that the enhanced mechanical properties of PLA_CgPD1 are closely related to the existence of more ordered PLA mesophases induced by the introduction of an optimal amount of CgPD into the PLA matrix.