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1.
J Acoust Soc Am ; 155(6): 3794-3806, 2024 Jun 01.
Article in English | MEDLINE | ID: mdl-38864736

ABSTRACT

Defect reconstruction is essential in non-destructive testing and structural health monitoring with guided ultrasonic waves. This paper presents an algorithm for reconstructing notches in steel plates, which can be seen as artificial defects representing cracks by comparing measured results with those from a simulation model. The model contains a parameterized notch, and its geometrical parameters are to be reconstructed. While the algorithm is formulated and presented in a general notation, a special case of guided wave propagation is used to investigate one of the simplest possible simulation models that discretizes only the cross section of the steel plate. An efficient simulation model of the plate cross section is obtained by the semi-analytical scaled boundary finite element method. The reconstruction algorithm applied is gradient-based, and algorithmic differentiation calculates the gradient. The dedicated experimental setup excites nearly plane wave fronts propagating orthogonal to the notch. A scanning laser Doppler vibrometer records the velocity field at certain points on the plate surface as input to the reconstruction algorithm. Using two plates with notches of different depths, it is demonstrated that accurate geometry reconstruction is possible.

2.
J Acoust Soc Am ; 152(2): 1217, 2022 Aug.
Article in English | MEDLINE | ID: mdl-36050181

ABSTRACT

This paper considers an indirect measurement approach to reconstruct a defect in a two-dimensional waveguide model for a non-destructive ultrasonic inspection via derivative-based optimization. The propagation of the mechanical waves is simulated by the scaled boundary finite element method that builds on a semi-analytical approach. The simulated data are then fitted to given data associated with the reflected waves from a defect which is to be reconstructed. For this purpose, we apply an iteratively regularized Gauss-Newton method in combination with algorithmic differentiation to provide the required derivative information accurately and efficiently. We present numerical results for three kinds of defects, namely, a crack, delamination, and corrosion. The objective function and the properties of the reconstruction method are investigated. The examples show that the parameterization of the defect can be reconstructed efficiently as well as robustly in the presence of noise.

3.
Analyst ; 147(15): 3593-3603, 2022 Jul 22.
Article in English | MEDLINE | ID: mdl-35822546

ABSTRACT

Sterility testing is a laborious and slow process to detect contaminants present in drug products. Raman spectroscopy is a promising label-free tool to detect microorganisms and thus gaining relevance as a future alternative culture-free method for sterility testing in the pharmaceutical industry. However, reaching detection limits similar to standard procedures while keeping a high accuracy remains challenging, due to weak bacterial Raman signals. In this work, we show a new non-invasive approach focusing on detection of different bacteria in concentrations below 100 CFU per ml within drug product containers using Raman spectroscopy and multivariate data analysis. Even though Raman spectra from drug product with and without bacteria are similar, a partial least squared discriminant analysis (PLS-DA) model shows great performance to distinguish samples with bacterial contaminants in concentrations down to 10 CFU per ml. We used spiked samples with bacterial spores for model validation achieving a detection accuracy of 99%. Our results indicate the great potential of this rapid, and cost-effective approach to be used in quality control in the pharmaceutical industry.


Subject(s)
Infertility , Spectrum Analysis, Raman , Bacteria , Discriminant Analysis , Humans , Least-Squares Analysis , Multivariate Analysis , Pharmaceutical Preparations , Spectrum Analysis, Raman/methods
4.
World J Biol Psychiatry ; 22(4): 288-300, 2021 04.
Article in English | MEDLINE | ID: mdl-32657193

ABSTRACT

OBJECTIVES: The association between depressive symptomatology and endogenous testosterone levels is inconclusive. Large inter- and intra-individual testosterone differences suggest point measurements from saliva or serum to be inadequate to map basal testosterone concentrations highlighting the potential for long-term integrated testosterone levels from hair. METHODS: Using data from a prospective cohort study, a total of 578 participants (74% female) provided complete data on depressive symptomatology, clinical features, and hair samples for quantification of testosterone concentrations at baseline. Available data of three annual follow-up examinations were used for longitudinal analyses. RESULTS: Correlation analysis showed in both, men and women, hair testosterone across all the four time points not to be significantly related to depressive symptoms. Examined clinical features were not associated with testosterone levels, except for having a current diagnosis of a psychological disorder, which was associated with reduced testosterone levels in men, but not in women. Acceptable model fit for an autoregressive cross-lagged panel analysis emerged only for the female subsample suggesting inverse cross-relations for the prediction of testosterone by depressive symptomatology and vice versa. CONCLUSIONS: Findings from this study add to the literature by showing no association between long-term integrated testosterone in hair and depressive symptomatology in men and women.


Subject(s)
Depression , Testosterone , Female , Hair , Humans , Male , Prospective Studies , Saliva
5.
Sci Rep ; 10(1): 14618, 2020 09 03.
Article in English | MEDLINE | ID: mdl-32884092

ABSTRACT

The aim of this retrospective cross-sectional study was to provide an MRI-based examination framework of venous malformations (VMs) infiltrating the sciatic nerve and determine the frequency of nerve infiltration patterns and muscle involvement in correlation to the patients' quality of life. Pelvic and lower limb MR images of 378 patients with vascular malformations were examined retrospectively. Pain levels and restriction of motion were evaluated with a questionnaire. Cross-sectional areas of affected nerves were compared at standardized anatomical landmarks. Intraneural infiltration patterns and involvement of muscles surrounding the sciatic nerve were documented. Sciatic nerve infiltration occurred in 23/299 patients (7.7%) with VM. In all cases (23/23; 100%), gluteal or hamstring muscles surrounding the nerve were affected by the VM. Infiltrated nerves were enlarged and showed signal alterations (T2-hyperintensity) compared to the unaffected side. Enlarged nerve cross-sectional areas were associated with elevated pain levels. Three nerve infiltration patterns were observed: subepineurial (12/23; 52.2%), subparaneurial (6/23; 26.1%) and combined (5/23; 21.7%) infiltration. This study provides a clinically relevant assessment for sciatic nerve infiltration patterns and muscle involvement of VMs, while suggesting that VMs in gluteal and hamstring muscles require closer investigation of the sciatic nerve by the radiologist.


Subject(s)
Hamstring Muscles/diagnostic imaging , Magnetic Resonance Imaging , Sciatic Nerve/diagnostic imaging , Vascular Malformations/diagnostic imaging , Veins/diagnostic imaging , Adolescent , Adult , Child , Child, Preschool , Cross-Sectional Studies , Female , Humans , Male , Retrospective Studies , Young Adult
7.
Am J Mens Health ; 14(3): 1557988320926332, 2020.
Article in English | MEDLINE | ID: mdl-32456528

ABSTRACT

While life expectancy continues to increase, aging can bring several distinct endocrine and psychosocial changes. The study aimed to investigate the interplay between biopsychosocial factors of healthy aging in specifically healthy aging men. Ninety-seven healthy aging men were investigated at two time points spanning 4 years. Participants completed questionnaires measuring several psychosocial dimensions and gave saliva samples for hormone quantification during a laboratory appointment. The study applied a random intercept mixed-model approach. Age-related changes were found in most endocrine markers (cortisol, testosterone, dehydroepiandrosterone-sulfate, and progesterone), except for estradiol. Psychosocial measures remained stable, except for increased social support. Further, changes in endocrine and psychosocial measures were independent of each other. The results suggest that in healthy aging men, age-related endocrine changes occur, but do not necessarily determine a change in psychosocial measures. Potentially, preventive interventions can be derived from these results.


Subject(s)
Biomarkers/analysis , Men's Health , Mental Health , Adult , Aged , Androgens , Dehydroepiandrosterone Sulfate/analysis , Healthy Aging , Humans , Hydrocortisone/analysis , Longitudinal Studies , Male , Mental Health/statistics & numerical data , Middle Aged , Progesterone/analysis , Quality of Life , Surveys and Questionnaires , Testosterone/analysis
8.
J Dent Res ; 99(5): 544-551, 2020 05.
Article in English | MEDLINE | ID: mdl-32156176

ABSTRACT

The canonical Wnt/ß-catenin signaling pathway is crucial for reparative dentinogenesis following tooth damage, and the modulation of this pathway affects the rate and extent of reparative dentine formation in damaged mice molars by triggering the natural process of dentinogenesis. Pharmacological stimulation of Wnt/ß-catenin signaling activity by small-molecule GSK-3 inhibitor drugs following pulp exposure in mouse molars results in reparative dentinogenesis. The creation of similar but larger lesions in rat molars shows that the adenosine triphosphate (ATP)-competitive GSK-3 inhibitor, CHIR99021 (CHIR), and the ATP noncompetitive inhibitor, Tideglusib (TG), can equally enhance reparative dentine formation to fully repair an area of dentine damage up to 10 times larger, mimicking the size of small lesions in humans. To assess the chemical composition of this newly formed dentine and to compare its structure with surrounding native dentine and alveolar bone, Raman microspectroscopy analysis is used. We show that the newly formed dentine comprises equal carbonate to phosphate ratios and mineral to matrix ratios to that of native dentine, both being significantly different from bone. For an effective dentine repair, the activity of the drugs needs to be restricted to the region of damage. To investigate the range of drug-induced Wnt-activity within the dental pulp, RNA of short-term induced (24-h) molars is extracted from separated roots and crowns, and quantitative Axin2 expression is assayed. We show that the activation of Wnt/ß-catenin signaling is highly restricted to pulp cells in the immediate location of the damage in the coronal pulp tissue with no drug action detected in the root pulp. These results provide further evidence that this simple method of enhancement of natural reparative dentinogenesis has the potential to be translated into a clinical direct capping approach.


Subject(s)
Regeneration , Animals , Dental Pulp , Dental Pulp Capping , Dentin , Dentin, Secondary , Dentinogenesis , Glycogen Synthase Kinase 3 , Mice , Rats
9.
Neurosci Biobehav Rev ; 114: 232-270, 2020 07.
Article in English | MEDLINE | ID: mdl-32088345

ABSTRACT

It is debated as to whether major depressive disorder (MDD) and the burnout syndrome represent different aspects of the same syndrome or whether they reflect separate entities. A dysregulation of the hypothalamus-pituitary-adrenal-axis has been related to both conditions separately. Dissecting the pathophysiology of the conditions and describing differences and similarities with regard to stress physiological systems might further clarify whether underlying etiological models of these syndromes differ. A systematic literature search including MDD and the burnout syndrome and peripheral cortisol measures was performed and resulted in 190 studies for inclusion in the qualitative synthesis. For MDD, findings suggest a general state of hypercortisolism and glucocorticoid resistance reflected by increased basal cortisol levels, reduced reactivity to psychosocial stress and a reduced cortisol suppression in pharmacological challenge tests. For the burnout syndrome, two central factors limit further conclusions: i) there is not a sufficient amount of studies examining the burnout syndrome and different cortisol secretion patterns to provide an evidence base, ii) the burnout syndrome is assessed heterogeneously reflecting imprecision of the measured constructs. Large prospective cohort studies examining both conditions in parallel rigorously controlling for confounders are required to further elucidate the differences and similarities of the HPA axis in MDD and the burnout syndrome.


Subject(s)
Depressive Disorder, Major , Hydrocortisone , Burnout, Psychological , Humans , Hypothalamo-Hypophyseal System , Pituitary-Adrenal System , Prospective Studies
10.
Anaesthesist ; 69(1): 20-36, 2020 01.
Article in German | MEDLINE | ID: mdl-31820017

ABSTRACT

The current article is a summary of the 2018 revised S3 guideline on screening, diagnosis, therapy, and follow-up of the abdominal aortic aneurysm (AAA) from an anesthesiological point of view. It is the only interdisciplinary guideline that describes in particular the perioperative anesthesiological and intensive care management.


Subject(s)
Anesthesia/standards , Aortic Aneurysm, Abdominal/surgery , Anesthesiology , Aortic Aneurysm, Abdominal/diagnosis , Critical Care/standards , Guidelines as Topic , Humans , Perioperative Care/standards , Vascular Surgical Procedures/standards
11.
Psychoneuroendocrinology ; 109: 104382, 2019 11.
Article in English | MEDLINE | ID: mdl-31374371

ABSTRACT

Depressive and anxiety disorders substantially contribute to the global burden of disease, particularly in poor countries. Higher prevalence rates for both disorders among women indicate sex hormones may be integrated in the pathophysiology of these disorders. The Kshetriya Gramin Financial Services study surveyed a random sample of 4160 households across 876 villages in rural Tamil Nadu, India. An interviewer-administered questionnaire was conducted to quantify depressive (K6-D) and anxiety (K6-A) symptoms. Alongside, hair samples for sex hormone profiling were collected from a subsample of 2105 women aged 18-85 years. Importantly, 5.9%, 14.8%, and 46.3% of samples contained non-detectable hormone levels for dehydroepiandrosterone, progesterone, and testosterone, respectively. Our primary analysis imputes values for the non-detectable sample and we check robustness of results when non-detectable values are dropped. In this cohort of women from rural India, higher depressive symptomatology is associated with lower levels of dehydroepiandrosterone and higher depressive and anxiety symptoms are associated with higher levels of testosterone. Progesterone shows no clear association with either depressive or anxiety symptoms. These results support a potential protective effect of higher endogenous dehydroepiandrosterone levels. An important caveat on the potential negative effect of hair testosterone levels on women's mental health is that the testosterone analysis is sensitive to how non-detectable values are treated.


Subject(s)
Anxiety/metabolism , Depression/metabolism , Gonadal Steroid Hormones/analysis , Adult , Aged , Aged, 80 and over , Androgens/analysis , Anxiety Disorders/metabolism , Cohort Studies , Dehydroepiandrosterone/analysis , Dehydroepiandrosterone Sulfate/analysis , Depression/epidemiology , Depressive Disorder/metabolism , Estradiol/analysis , Female , Hair/chemistry , Humans , Middle Aged , Progesterone/analysis , Rural Population , Sex Hormone-Binding Globulin/analysis , Testosterone/analysis , Women's Health
12.
Biol Psychol ; 146: 107730, 2019 09.
Article in English | MEDLINE | ID: mdl-31326436

ABSTRACT

BACKGROUND: Infidelity in romantic relationships is a common, but severe issue often causing breakup and severe psychological impairment. Higher levels of testosterone are related to mating-behavior, sexual desire, and infidelity in men with sexual dysfunctions. Previous studies, have insufficiently addressed the potential role of testosterone in infidelity in healthy men. METHODS: A sample of 224 middle-aged self-reporting healthy men being currently in a relationship completed questionnaires on relationship characteristics, infidelity, and provided overnight-fasting saliva samples for testosterone quantification. RESULTS: In the sample, 37.5% men answered having been unfaithful in the current relationship, while 29% were identified as fulfilling criteria for a sexual dysfunction. Adjusting for covariates, a significant positive association for the frequency of unfaithful behavior and testosterone levels emerged. Subsample analysis indicates a positive association between testosterone and infidelity only to be present in men without sexual dysfunction. CONCLUSION: Unfaithful behavior in males is associated with higher testosterone levels.


Subject(s)
Interpersonal Relations , Sexual Behavior/physiology , Testosterone/metabolism , Adult , Aged , Female , Humans , Libido , Male , Marriage , Middle Aged , Saliva/chemistry , Social Desirability
13.
Clin Implant Dent Relat Res ; 21(4): 766-774, 2019 Aug.
Article in English | MEDLINE | ID: mdl-31062517

ABSTRACT

BACKGROUND: Immediate provisionalization reduces chair time and improves patient comfort. PURPOSE: To analyze immediate functional loading vs nonfunctional loading with restorations in the posterior mandible for marginal bone defects, implant success/survival, and patient satisfaction. MATERIALS AND METHODS: A randomized controlled clinical trial was designed to assess these parameters based on 20 adult patients who underwent implant surgery, followed by immediate delivery of screw-retained or cemented single or splinted restorations in full occlusal contact or in infraocclusion (test and control group). A questionnaire with visual analog scales was used to assess patient satisfaction. RESULTS: Following 36-month data were evaluable for 9 patients (21 implants) in the study group (immediate functional loading) and for 10 patients (31 implants) in the control group (immediate nonfunctional loading). One implant in the control group was lost, hence the overall implant survival and success rate was 98.2%. Marginal bone defects were consistent with previous studies and comparable in both groups. Periotest values did not significantly change from baseline and the 12-month follow-up (Friedmann test). Patient satisfaction was high and did not involve any significant intergroup differences (Mann-Whitney U-test). CONCLUSIONS: Both types of immediate provisional restorations are viable in selected patients. Larger randomized controlled trials are needed to establish immediate functional loading as a standard treatment for partially edentulous jaws.


Subject(s)
Alveolar Bone Loss , Dental Implants , Immediate Dental Implant Loading , Adult , Dental Implantation, Endosseous , Dental Prosthesis, Implant-Supported , Follow-Up Studies , Humans , Patient-Centered Care , Pilot Projects , Prospective Studies , Treatment Outcome
15.
Psychophysiology ; 56(5): e13328, 2019 05.
Article in English | MEDLINE | ID: mdl-30623451

ABSTRACT

The ratio between the length of the second (index) and the fourth (ring) finger (2D4D) is a putative biomarker of prenatal testosterone (T) exposure, with higher exposure leading to a smaller ratio. 2D4D has further been linked to mental and somatic disorders. Healthy male Swiss recruits (N = 245; Mage = 20.30 years) underwent a psychosocial stress test. Mood and salivary alpha-amylase (sAA) were assessed before and after the stress test, while heart rate (HR) and heart rate variability (HRV) were measured continuously. Additionally, 2D4D (right: R2D4D; left: L2D4D) was determined and divided into quartile groups. Correlation analysis showed no associations between R/L2D4D and outcome measures. Comparing calculated quartiles for R2D4D, subjects in the lowest R2D4D quartile expressed trendwise (p < 0.10) lower positive and higher negative affect, significantly elevated sAA activity (p < 0.05), but no HR and HRV differences at baseline as compared to subjects in the upper three quartiles. With regard to acute stress, subjects in the lowest as compared to subjects in the upper three R2D4D quartiles showed a higher increase of negative affect and a stronger cardiac response (p < 0.05), but no alterations in positive affect and sAA activity. Young healthy men in the lowest R2D4D quartile revealed a more negative affect and increased physiological activity at baseline and in response to acute stress. An exposure to high levels of prenatal T might constitute a risk factor potentially increasing vulnerability to stress-related disorders in men.


Subject(s)
Affect/physiology , Autonomic Nervous System , Fingers/anatomy & histology , Heart Rate/physiology , Prenatal Exposure Delayed Effects , Salivary alpha-Amylases/metabolism , Stress, Psychological , Testosterone , Adult , Autonomic Nervous System/metabolism , Autonomic Nervous System/physiopathology , Female , Humans , Male , Pregnancy , Prenatal Exposure Delayed Effects/metabolism , Prenatal Exposure Delayed Effects/physiopathology , Stress, Psychological/metabolism , Stress, Psychological/physiopathology , Young Adult
16.
Andrology ; 6(6): 896-902, 2018 11.
Article in English | MEDLINE | ID: mdl-29993200

ABSTRACT

In males, age-related decline in free testosterone (T) and dehydroepiandrosterone (DHEA) by 2-3% per year has been reported. Estradiol (E2) and progesterone (P) seem to decrease as well, but to a lesser extent. Lower sex steroid levels in men have been related to physical and mental symptoms. Low birthweight and left-/mixed-handedness (L/MH) are indicators of an adverse fetal environment during pregnancy, and both have been linked to morbidity in later life. The aim of this study is to examine the relationship between lower birthweight as well as L/MH and age-related sex steroid decline. In a cross-sectional study design, saliva samples were collected under standardized conditions from healthy men for subsequent steroid hormone analysis using standard luminescence immunoassays. T (M = 67.57 pg/mL), DHEA (M = 247.91 pg/mL), E2 (M = 1.29 pg/mL), and P (M = 28.20 pg/mL) have been quantified leading to a final sample of 256 men providing complete data on sex hormones (MAge =57.8; SDAge  = 10.8). Information on participants' birthweight was obtained from birth reports (N = 134), and participants were asked about their handedness (right-handed, left-handed, mixed-handed) (N = 256). Multivariate-adjusted linear regression models relating each sex hormone individually and the principal component of declining steroid hormones (DSH)-an integrated hormonal parameter-with handedness and birthweight did not identify significant associations except for handedness and E2. Moderation analysis using robust regression accounting for bias due to influential data points detected a significant association between age and DSH for handedness (ß = -0.0314, p = 0.040) but only a trend for birthweight (ß = 0.0309, p = 0.073). For lower birthweight, a trend toward intensified age-related sex steroid decline in men was observed, while for L/MH, a significant association with intensified age-related sex steroid decline was identified. These results indicate that L/MH and potentially also lower birthweight might be considered as early risk factors for endocrine health in later life.


Subject(s)
Aging/metabolism , Birth Weight , Functional Laterality , Gonadal Steroid Hormones/analysis , Men's Health , Saliva/chemistry , Adult , Age Factors , Aged , Cross-Sectional Studies , Down-Regulation , Health Status , Humans , Infant, Newborn , Male , Middle Aged , Risk Factors
17.
Complement Ther Med ; 36: 68-72, 2018 Feb.
Article in English | MEDLINE | ID: mdl-29458935

ABSTRACT

BACKGROUND: Higher age is associated to a variety of physical and mental disorders. Age-related changes in steroid secretion have been suggested to be an underlying mechanism leading to frailty, depression, and sexual dysfunction. However, Tai chi qigong and similar forms of exercise have been shown to improve a great variety of health-related parameters in older individuals. METHODS: We examined 56 self-reporting healthy men actively practicing Tai chi qigong and/or self-defense Kung-fu and 55 age-matched self-reporting healthy controls. Saliva samples were obtained in a standardized procedure for subsequent quantification of circulating testosterone and cortisol levels. In addition, depressive symptoms, life satisfaction, and sexual health were assessesd via self-report questionnaires. RESULTS: Age was negatively associated with testosterone, while no association emerged for cortisol. Tai chi qigong and/or self-defense Kung-fu training was neither associated with testosterone nor cortisol. More weekly Tai chi qigong and/or self-defense Kung-fu training (4 or more times per week) was instead associated with a lower CT-ratio, less depressive symptoms, and higher life satisfaction compared to individuals, who trained only one to three times per week. More years of Tai chi qigong and/or self-defense Kung-fu training were associated with less depressive symptoms and higher life satisfaction but not with the CT-ratio. No significant associations emerged for Tai chi qigong and/or self-defense Kung-fu training and sexual health. When compared to the age-matched controls, there is a significant effect of Tai chi, qigong and/or self-defense Kung-fu on the CT-ratio. Contrast analyses revealed a significantly lower CT-ratio for the high training load group in contrast to the low training load group. Further, in contrast to the control group, the low training load group exhibits a significantly higher CT-ratio. For depression, contrast analyses revealed a significantly lower level of depression in the high training load group compared to the control group. CONCLUSION: The results indicate that Tai chi qigong and/or self-defense Kung-fu training is beneficially associated with steroid secretion patterns and mental health in aging men, when training is performed with a frequency of 4 or more trainings per week. However, the high frequency training and control group show similar steroid secretion patterns suggesting an inverted U-shaped association between Tai chi qigong and/or self-defense Kung-fu training frequency and the CT-ratio in aging men. More research is needed to elucidate the underlying mechanism of this association. Still, Tai chi qigong and/or self-defense Kung-fu training provides a promising prevention strategy against age-related physical and mental deterioration in aging men.


Subject(s)
Aging/physiology , Personal Satisfaction , Qigong/psychology , Quality of Life , Tai Ji/psychology , Aged , Case-Control Studies , Depression/therapy , Humans , Hydrocortisone/analysis , Male , Middle Aged , Saliva/chemistry , Testosterone/analysis
18.
Front Neuroanat ; 11: 89, 2017.
Article in English | MEDLINE | ID: mdl-29081738

ABSTRACT

Handedness is one of the most recognized lateralized behavior in humans. Usually, it is associated with manual superiority regarding performance proficiency. For instance, more than 90% of the human population is considered more skilled with the right hand, which is controlled by the left hemisphere, than with the left. However, during the performance of bimanual tasks, the two hands usually assume asymmetric roles, with one hand acting on objects while the other provides support, stabilizing the object. Traditionally, the role of the two hands is viewed as fixed. However, several studies support an alternate view with flexible assignments for the two hands depending on the task. The supporting role of the hand depends on a closed loop pathway based on proprioceptive inputs from the periphery. The circuit's efferent arm courses through the dorsal corticospinal tract (dCST) in rodents and terminate on spinal cord interneurons which modulate the excitability of motoneurons in the ventral horn. In the present work, we developed an experimental model of unilateral lesion targeting the cervical dCST with microinjections of the vasoconstrictor endothelin-1 (ET-1) to evaluate the degree of flexibility of forelimb assignment during a food manipulation task. Our results show that just 3 days after unilateral corticospinal tract (CST) injury in the cervical region, rats display severe motor impairment of the ipsilateral forepaw together with a remarkable reversal of motor assignment between the forelimbs.

20.
Chem Sci ; 8(5): 4100-4107, 2017 May 01.
Article in English | MEDLINE | ID: mdl-28580123

ABSTRACT

Functional DNA nanotechnology creates increasingly complex behaviors useful for sensing, actuation or computation, as enabled via the integration of dynamic and responsive structural DNA motifs. However, temporally controlled and dynamic DNA structures with programmable lifetimes, that are able to operate autonomously and self-revert to the starting state are challenging to achieve due to tedious and very system-specific sequence design. Here, we present a straightforward concept to program transient lifetimes into DNA duplexes based on the pH-sensitive DNA i-motif switch. We integrate the i-motif switch with an internal, non-linear pH-resetting function using a rationally designed chemical reaction framework, by which the switch autonomously undergoes a complete "off-on-off"-cycle without the use of additional external triggers. The lifetime of the activated "on"-state (i.e. the hybridized state) can be systematically programmed over several hours. The system can be readily implemented into hybrid DNA structures on larger length scales. Focusing on autonomous materials, we demonstrate temporal control of transient fluorescence signals and temporary aggregation of gold nanoparticles.

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