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1.
J Acoust Soc Am ; 155(3): 1813-1824, 2024 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-38445988

RESUMO

This study assessed whether the effects of contralateral acoustic stimulation (CAS) are consistent with eliciting the medial olivocochlear (MOC) reflex for measurements sensitive to outer hair cell (otoacoustic emissions, OAEs), auditory-nerve (AN; compound action potential, CAP), and brainstem/cortical (envelope-following response, EFR) function. The effects of CAS were evaluated for simultaneous measurement of OAEs, CAPs, and EFRs in participants with normal hearing. Clicks were presented at 40 or 98 Hz in three ipsilateral noise conditions (no noise, 45 dB SPL, and 55 dB SPL). For the no noise condition, CAS suppressed or enhanced EFR amplitudes for 40- and 98-Hz clicks, respectively, while CAS had no significant effect on CAP amplitudes. A follow-up experiment using slower rates (4.4-22.2 Hz) assessed whether this insignificant CAS effect on CAPs was from ipsilateral MOC stimulation or AN adaptation; however, CAS effects remained insignificant despite favorable signal-to-noise ratios. CAS-related enhancements of EFR and CAP amplitudes in ipsilateral noise were not observed, contrary to the anti-masking effect of the MOC reflex. EFR and OAE suppression from CAS were not significantly correlated. Thus, the effects of CAS on EFRs may not be solely mediated by the MOC reflex and may be partially mediated by higher auditory centers.


Assuntos
Potenciais Evocados , Emissões Otoacústicas Espontâneas , Humanos , Potenciais de Ação , Estimulação Acústica , Reflexo
2.
Sci Rep ; 14(1): 5736, 2024 03 08.
Artigo em Inglês | MEDLINE | ID: mdl-38459107

RESUMO

Internal limiting membrane (ILM) peeling requires a delicate handling technique. It is also important that ophthalmologists can use the ILM forceps handle of their preference. This study objectively and subjectively evaluated the handling of the novel Finesse Reflex Handle (Reflex) in comparison with that of a conventional handle. The force required to close the forceps tips, evaluated using a digital force gauge, was significantly lesser for Reflex than for the conventional handle (3.14 ± 0.09 N vs. 3.84 ± 0.06 N, P < 0.001). Twenty-one ophthalmologists with various levels of experience answered a questionnaire after using both handles, and the total questionnaire score for Reflex was higher than that for the conventional handle (35.0 ± 3.7 vs. 30.0 ± 6.9, P = 0.01). Furthermore, the duration of experience as an ophthalmologist was negatively correlated with the vertical motion, assessed by video analysis, for the conventional handle (P = 0.02, r = - 0.50) but not for Reflex (P = 0.26). In conclusion, objective and subjective analyses revealed that compared with the conventional handle, the novel Reflex handle had more favourable handling characteristics. Most ophthalmologists preferred the handling of Reflex. Reflex may compensate for a lack of surgical experience.


Assuntos
Porcelana Dentária , Oftalmologistas , Perfurações Retinianas , Humanos , Retina , Vitrectomia/métodos , Reflexo , Estudos Retrospectivos , Membrana Basal/cirurgia , Perfurações Retinianas/cirurgia , Tomografia de Coerência Óptica
3.
Sci Rep ; 14(1): 6367, 2024 03 16.
Artigo em Inglês | MEDLINE | ID: mdl-38493201

RESUMO

Lower urinary tract (LUT) function is controlled by the central nervous system, including higher-order cognitive brain regions. The anterior cingulate cortex (ACC) is one of these regions, but the role of its activity in LUT function remains poorly understood. In the present study, we conducted optogenetic experiments to manipulate neural activity in mouse ACC while monitoring bladder pressure to elucidate how the activity of ACC regulates LUT function. Selective optogenetic stimulation of excitatory neurons in ACC induced a sharp increase in bladder pressure, whereas activation of inhibitory neurons in ACC prolonged the interval between bladder contractions. Pharmacological manipulation of ACC also altered bladder contractions, consistent with those observed in optogenetic experiments. Optogenetic mapping of the cortical area responsible for eliciting the increase in bladder pressure revealed that stimulation to ACC showed more potent effects than the neighboring motor cortical areas. These results suggest that ACC plays a crucial role in initiating the bladder pressure change and the micturition reflex. Thus, the balance between excitation and inhibition in ACC may regulate the reflex bidirectionally.


Assuntos
Bexiga Urinária , Micção , Camundongos , Animais , Micção/fisiologia , Giro do Cíngulo/fisiologia , Optogenética , Neurônios/fisiologia , Reflexo/fisiologia
4.
Sci Rep ; 14(1): 6386, 2024 03 16.
Artigo em Inglês | MEDLINE | ID: mdl-38493261

RESUMO

Although there is no doubt from an empirical viewpoint that reflex mechanisms can contribute to tongue motor control in humans, there is limited neurophysiological evidence to support this idea. Previous results failing to observe any tonic stretch reflex in the tongue had reduced the likelihood of a reflex contribution in tongue motor control. The current study presents experimental evidence of a human tongue reflex in response to a sudden stretch while holding a posture for speech. The latency was relatively long (50 ms), which is possibly mediated through cortical-arc. The activation peak in a speech task was greater than in a non-speech task while background activation levels were similar in both tasks, and the peak amplitude in a speech task was not modulated by the additional task to react voluntarily to the perturbation. Computer simulations with a simplified linear mass-spring-damper model showed that the recorded muscle activation response is suited for the generation of tongue movement responses that were observed in a previous study with the appropriate timing when taking into account a possible physiological delay between reflex muscle activation and the corresponding force. Our results evidenced clearly that reflex mechanisms contribute to tongue posture stabilization for speech production.


Assuntos
Reflexo , Fala , Humanos , Eletromiografia , Equilíbrio Postural , Língua , Músculo Esquelético/fisiologia
5.
J Vet Intern Med ; 38(2): 1101-1110, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38339888

RESUMO

BACKGROUND: No available literature supports the claim that the patellar and withdrawal (flexor) reflexes are the only reliable segmental reflexes in dogs. OBJECTIVE: Measure intra- and interobserver agreement of 8 segmental reflexes in dogs without clinical evidence of orthopedic or neurologic disease. ANIMALS: One-hundred and one client- or staff-owned dogs between 1 and 10 years of age with no clinical evidence of orthopedic disease, myelopathy, or neuromuscular disease. METHODS: Descriptive study. The intraobserver proportion of agreement (%) of responses to selected segmental reflexes in right versus left limbs by 3 observers was calculated and reported. The interobserver agreement of 2 observers of responses to selected reflexes was estimated by calculating proportions of agreement, kappa values, and 95% confidence intervals. A segmental reflex with an acceptable agreement was defined as that with a proportion of agreement ≥90% and a Kappa value ≥0.61 in both limbs. RESULTS: The intraobserver proportion of agreement for all 3 observers was high (≥95%) for the extensor carpi radialis, withdrawal, patellar, and cranial tibial reflexes. Between observers 1 and 3 and observers 2 and 3, the interobserver proportion of agreement was high (≥ 92%) for the extensor carpi radialis (κ 0.66, not determined [ND]), withdrawal (both limbs, κ ND), patellar (κ ND), and cranial tibial reflexes (κ ND). CONCLUSIONS AND CLINICAL IMPORTANCE: The extensor carpi radialis, withdrawal, patellar, and cranial tibial reflexes had a higher proportion of agreement and kappa values between 2 observers.


Assuntos
Doenças do Cão , Doenças da Medula Espinal , Humanos , Cães , Animais , Variações Dependentes do Observador , Reflexo , Extremidades , Doenças da Medula Espinal/veterinária , Reprodutibilidade dos Testes
7.
J Clin Virol ; 171: 105650, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38350177

RESUMO

BACKGROUND: Hepatitis Delta virus (HDV) infection is a major cause of liver-related morbidity and mortality in patients infected with HBV, with a global HDV prevalence uncertain. In France, 2 to 5 % of HBs antigen (HBsAg) carriers present anti-HDV antibodies (anti-HDV). The EASL recommends testing for anti-HDV in all HBsAg-positive patients. Since January 2022, we have systematically carried out anti-HDV serology when a positive HBsAg is discovered (new HBsAg carriers). OBJECTIVES: We evaluated the benefit of anti-HDV reflex testing after one year of practice by comparing anti-HDV and HBsAg serology data over the last six years, among the new HBsAg carriers and all the HBsAg carriers. STUDY DESIGN: HBsAg and anti-HDV were screened using the Abbott Architect HBsAg quanti kit and the DIA.PRO HDVAb kit. Serological, demographic, virological, and clinical data were analyzed. RESULTS: Implementing anti-HDV reflex testing leads to more than a 2-fold increase in diagnoses of HDV infection among all HBsAg carriers. If the anti-HDV positive rate remains stable among the new HBsAg carriers, a significant increase in the anti-HDV positive rate from 6.8 % to 10.3 % was observed considering all HBsAg carriers. Interestingly, the discovery of anti-HDV carriage increased from 3.9 % to 6.5 % in 2022, allowing earlier identification of HBV-HDV-infected patients and a fast referral to hepatologists for adequate clinical management and, in some cases, the introduction of bulevirtide-based therapy. CONCLUSIONS: Our preliminary results at one year seem promising and evaluating the cost-effectiveness of reflex tests in real life with feedback would be helpful.


Assuntos
Antígenos de Superfície da Hepatite B , Vírus Delta da Hepatite , Humanos , Anticorpos Anti-Hepatite , França/epidemiologia , Reflexo , Vírus da Hepatite B
8.
Diagn Microbiol Infect Dis ; 108(4): 116183, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38309086

RESUMO

Treatment of asymptomatic bacteriuria (ASB) is a common, but often unnecessary, practice. Our objective was to determine the impact of restrictive urinalysis reflex to culture (UARC) criteria on rate of urine cultures (UC) ordered and ASB treatment. Criteria were modified from positive leukocyte esterase, positive nitrites, or white blood cells (WBC) >10 cells to only WBC >10 cells. This pre-post study evaluated UARCs ordered in the emergency department or inpatient units. The primary outcome was the proportion of reflex UCs prevented. Secondary outcomes included the frequency of repeat UARCs and stand-alone UCs, gram-negative rod (GNR) bacteremia, and ASB treatment. In the pre-intervention, there were 4761 UARCs compared to 5420 in the post-intervention; 37.9 % and 21.4 % reflexed to UCs, a 43.5 % reduction in UCs. The rate of repeat UARCs, stand-alone UCs, and GNR bacteremia in the pre- and post-interventions were similar. ASB treatment rate was numerically lower in the post-intervention.


Assuntos
Bacteriemia , Bacteriúria , Infecções Urinárias , Humanos , Hospitais Comunitários , Urinálise , Bacteriúria/diagnóstico , Bacteriúria/tratamento farmacológico , Reflexo , Bacteriemia/diagnóstico , Bacteriemia/tratamento farmacológico , Antibacterianos/uso terapêutico , Infecções Urinárias/tratamento farmacológico
11.
J Sport Rehabil ; 33(3): 215-219, 2024 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-38198793

RESUMO

CONTEXT: Latency is a reliable temporal metric used to evaluate sensorimotor integration of the fibularis longus (FL) and fibularis brevis (FB) during lateral ankle sprain perturbations. Currently, no clinical recommendations exist to select appropriate thresholds to evaluate the closed-loop reflex response of the lateral ankle musculature. The purpose of this study was to assess threshold value on latency of the FL and FB during an unanticipated inversion perturbation that simulates the mechanism of a lateral ankle sprain. DESIGN: Descriptive laboratory study. METHODS: Twenty healthy adults with no history of lateral ankle sprain injury completed an unanticipated single-leg drop landing onto a 25° laterally inclined force platform from a height of 30 cm. Surface electromyography recorded muscle activity data from the FL and FB during the inversion perturbation. Latency was identified at points where muscle activity exceeded 2, 5, and 10 SD above the average muscle activity 200 milliseconds prior to foot contact, and compared across threshold value using a 1-way analysis of variance (P < .05). RESULTS: The 2 SD threshold was significantly shorter than both 5 SD and 10 SD thresholds for the FL (P < .01) and FB (P < .01). Likewise, the 5 SD threshold was significantly shorter than the 10 SD thresholds for FL (P = .004) and FB (P = .003). CONCLUSIONS: More sensitive thresholds results in a shorter closed-loop reflexive response compared to the more rigorous thresholds. We recommend that selection of the appropriate threshold to identify latency of the lateral ankle musculature should be based on the device used to simulate a lateral ankle sprain and the ankle inversion velocity produced during the ankle inversion perturbation.


Assuntos
Traumatismos do Tornozelo , Tornozelo , Adulto , Humanos , Extremidade Inferior , Articulação do Tornozelo , Reflexo
12.
J Appl Physiol (1985) ; 136(3): 492-508, 2024 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-38205553

RESUMO

Insufficient hydration is prevalent among free living adults. This study investigated whether hypohydration alters 1) renal functional reserve, 2) the renal hemodynamic response to the exercise pressor reflex, and 3) urine-concentrating ability during oral protein loading. In a block-randomized crossover design, 22 healthy young adults (11 females and 11 males) underwent 24-h fluid deprivation (Hypohydrated) or 24-h normal fluid consumption (Euhydrated). Renal functional reserve was assessed by oral protein loading. Renal hemodynamics during the exercise pressor reflex were assessed via Doppler ultrasound. Urine-concentrating ability was assessed via free water clearance. Creatinine clearance did not differ at 150 min postprotein consumption between conditions [Hypohydrated: 246 mL/min, 95% confidence interval (CI): 212-280; Euhydrated: 231 mL/min, 95% CI: 196-265, P = 0.2691] despite an elevated baseline in Hypohydrated (261 mL/min, 95% CI: 218-303 vs. 143 mL/min, 95% CI: 118-168, P < 0.0001). Renal artery vascular resistance was not different at baseline (P = 0.9290), but increases were attenuated in Hypohydrated versus Euhydrated at the end of handgrip (0.5 mmHg/cm/s, 95% CI: 0.4-0.7 vs. 0.8 mmHg/cm/s 95% CI: 0.6-1.1, P = 0.0203) and end occlusion (0.2 mmHg/cm/s, 95% CI: 0.1-0.3 vs. 0.4 mmHg/cm/s 95% CI: 0.3-0.6, P = 0.0127). There were no differences between conditions in free water clearance at 150 min postprotein (P = 0.3489). These data indicate that hypohydration 1) engages renal functional reserve and attenuates the ability to further increase creatinine clearance, 2) attenuates increases in renal artery vascular resistance to the exercise pressor reflex, and 3) does not further enhance nor impair urine-concentrating ability during oral protein loading.NEW & NOTEWORTHY Insufficient hydration is prevalent among free living adults. This study found that hypohydration induced by 24-h fluid deprivation engaged renal functional reserve and that oral protein loading did not further increase creatinine clearance. Hypohydration also attenuated the ability to increase renal vascular resistance during the exercise pressor reflex. In addition, hypohydration neither enhanced nor impaired urine-concentrating ability during oral protein loading. These data support the importance of mitigating hypohydration in free living adults.


Assuntos
Força da Mão , Reflexo , Feminino , Masculino , Adulto Jovem , Humanos , Creatinina , Hemodinâmica , Água
13.
J Appl Physiol (1985) ; 136(2): 385-398, 2024 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-38174374

RESUMO

We investigated the locomotor muscle metaboreflex control of ventilation, circulation, and dyspnea in patients with chronic obstructive pulmonary disease (COPD). Ten patients [forced expiratory volume in 1 second (FEV1; means ± SD) = 43 ± 17% predicted] and nine age- and sex-matched controls underwent 1) cycling exercise followed by postexercise circulatory occlusion (PECO) to activate the metaboreflex or free circulatory flow to inactivate it, 2) cold pressor test to interpret whether any altered reflex response was specific to the metaboreflex arc, and 3) muscle biopsy to explore the metaboreflex arc afferent side. We measured airflow, dyspnea, heart rate, arterial pressure, muscle blood flow, and vascular conductance during reflexes activation. In addition, we measured fiber types, glutathione redox balance, and metaboreceptor-related mRNAs in the vastus lateralis. Metaboreflex activation increased ventilation versus free flow in patients (∼15%, P < 0.020) but not in controls (P > 0.450). In contrast, metaboreflex activation did not change dyspnea in patients (P = 1.000) but increased it in controls (∼100%, P < 0.001). Other metaboreflex-induced responses were similar between groups. Cold receptor activation increased ventilation similarly in both groups (P = 0.46). Patients had greater type II skeletal myocyte percentage (14%, P = 0.010), lower glutathione ratio (-34%, P = 0.015), and lower nerve growth factor (NGF) mRNA expression (-60%, P = 0.031) than controls. Therefore, COPD altered the locomotor muscle metaboreflex control of ventilation. It increased type II myocyte percentage and elicited redox imbalance, potentially producing more muscle metaboreceptor stimuli. Moreover, it decreased NGF expression, suggesting a downregulation of metabolically sensitive muscle afferents.NEW & NOTEWORTHY This study's integrative physiology approach provides evidence for a specific alteration in locomotor muscle metaboreflex control of ventilation in patients with COPD. Furthermore, molecular analyses of a skeletal muscle biopsy suggest that the amount of muscle metaboreceptor stimuli derived from type II skeletal myocytes and redox imbalance overcame a downregulation of metabolically sensitive muscle afferents.


Assuntos
Fator de Crescimento Neural , Doença Pulmonar Obstrutiva Crônica , Humanos , Fator de Crescimento Neural/metabolismo , Reflexo/fisiologia , Músculo Esquelético/fisiologia , Dispneia , Glutationa/metabolismo , Pressão Sanguínea/fisiologia
14.
Brain Res ; 1828: 148773, 2024 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-38244757

RESUMO

Childhood is a period of construction of the organism, during which interactions with the environment and regular physical activity are necessary for the maturation of the neuronal networks. An atypical sensorimotor activity during childhood (due to bed-rest or neurodevelopmental disorders) impacts the development of the neuromuscular system. A model of sensorimotor restriction (SMR) developed in rats has shown that casting pups' hind limbs from postnatal day 1 (P1) to P28 induced a severe perturbation of motor behavior, due to muscle weakness as well as disturbances within the central nervous system. In the present study, our objective was to determine whether SMR affects the early postnatal ontogenesis. We explored the neuromuscular development through the determination of the age for achievement of the main neurodevelopmental reflexes, which represent reliable indicators of neurological and behavioral development. We also evaluated the maturation of postural control. Our results demonstrate that SMR induces a delay in the motor development, illustrated by a several days delay in the acquisition of a mature posture and in the acquisition reflexes: hind limb grasping, righting, hind limb placing, cliff avoidance, negative geotaxis. In conclusion, impaired physical activity and low interactions with environment during early development result in altered maturation of the nervous system.


Assuntos
Transtornos do Neurodesenvolvimento , Reflexo , Humanos , Ratos , Animais , Neurônios , Equilíbrio Postural , Sistema Nervoso Central , Animais Recém-Nascidos
15.
Am J Physiol Gastrointest Liver Physiol ; 326(3): G318-G329, 2024 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-38226423

RESUMO

The external carotid artery (ECA) plays a major role in supplying blood to the head and neck. Although impeded blood flow in the ECA is expected to affect orofacial functions, few studies have shown how blood flow obstruction in the ECA contributes to impairment of these functions, including chewing and swallowing. This study was performed to investigate the effects of ECA ligation (ECAL) on immediate and long-term changes in masticatory and swallowing functions as well as the jaw-opening reflex evoked in the digastric muscle. The experiments were carried out using male Sprague-Dawley rats. In the acute experiment, the digastric reflex evoked by low-threshold electrical stimulation of the inferior alveolar nerve and the swallow reflex, identified by digastric and thyrohyoid electromyographic (EMG) bursts, were compared between before and 1 h after ECAL. The chronic experiment was conducted on freely moving rats. EMGs of the masseter, digastric, and thyrohyoid muscles were chronically recorded. The long-term effects of ECAL on behavior and muscle histology were compared between rats with an intact ECA and rats with ECAL. In the acute experiment, the peak amplitude of the digastric reflex on the ECAL side was significantly decreased 1 h after ECAL. In the chronic experiment, although most parameters of the masticatory and swallowing EMGs were not significantly different between the groups, the results suggest wide variation of the effect of ECAL on the muscles. Blood supply compensation from collaterals of the internal carotid artery may be permanent in some animals.NEW & NOTEWORTHY The inhibitory effect of unilateral external carotid artery ligation (ECAL) on the ipsilateral digastric reflex was small but evident. Most parameters of masticatory and swallowing muscle activity were not significantly different after ECAL. Wide variation was noted in the effect of ECAL on the ipsilateral muscle activity. Blood supply compensation from collaterals of the internal carotid artery may occur in response to the impaired blood flow.


Assuntos
Artéria Carótida Externa , Reflexo , Ratos , Animais , Masculino , Ratos Sprague-Dawley , Eletromiografia , Reflexo/fisiologia , Mastigação/fisiologia
16.
J Appl Lab Med ; 9(1): 28-40, 2024 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-38167774

RESUMO

BACKGROUND: Molecular biomarker analysis is standard of care in advanced nonsmall cell lung cancer (NSCLC). Pathologist-driven reflex testing protocols are one approach to initiating this analysis. Two years after insourcing genomic analysis at our institution, a reflex testing protocol for advanced NSCLC was initiated. METHODS: A retrospective review of the records of 578 NSCLC biopsies was performed to assess the impact of 3 genomic testing workflows (send-out, in-house clinician-ordered, and in-house reflex) on time to initiation of molecular testing [initiation time (IT)], reporting time (RT), proportion of test failures, and test ordering practices. The proportion of test failures by test methodology was also assessed. RESULTS: IT was lowest for reflex protocol orders (mean weekdays: 30.0 send-out, 27.4 in-house clinician-ordered, 0.95 reflex). Test failure was highest for send-out testing (31.7% vs. 10% each for in-house clinician-ordered and reflex). RT remained consistent across the 3 workflows (mean weekdays: 11.1 send-out, 11.9 in-house clinician-ordered, and 11.4 reflex). Guideline-congruent molecular testing increased upon insourcing genomic analysis and again upon implementing reflex testing with a reduction in nonbiomarker informed care (58.8% send-out, 19.5% in-house clinician-ordered, 11.5% reflex). CONCLUSIONS: Implementation of reflex in-house genomic analysis for advanced NSCLC ensured consistency in RT and significantly decreased IT and proportion of test failures. Insourcing genomic analysis and thoughtful care pathway design improve equitable access to molecular biomarker analysis and mitigate nonbiomarker informed cancer care in NSCLC.


Assuntos
Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , Humanos , Carcinoma Pulmonar de Células não Pequenas/diagnóstico , Carcinoma Pulmonar de Células não Pequenas/genética , Carcinoma Pulmonar de Células não Pequenas/patologia , Neoplasias Pulmonares/diagnóstico , Neoplasias Pulmonares/genética , Genômica , Reflexo , Biomarcadores
17.
Am J Physiol Gastrointest Liver Physiol ; 326(4): G360-G373, 2024 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-38226653

RESUMO

To investigate noxious stimulation-responsive neural circuits that could influence the gut, we recorded from intestinally directed (efferent) nerve filaments dissected from mesenteric nerves close to the small intestine in anesthetized rats. These exhibited baseline multiunit activity that was almost unaffected by vagotomy (VagX) and reduced only slightly by cutting the splanchnic nerves. The activity was halved by hexamethonium (Hex) treatment. When an adjacent gut segment received an intraluminal stimulus 2,4,6-trinitrobenzenesulfonate (TNBS) in 30% ethanol, mesenteric efferent nerve activity increased for more than 1 h. The increased activity was almost unaffected by bilateral vagotomy or splanchnic nerve section, indicating a lack of central nervous involvement, but it was 60% reduced by hexamethonium. Spike sorting discriminated efferent single and predominantly single-unit spike trains that responded to TNBS, were unaffected by splachnectomy but were silenced by hexamethonium. After noxious stimulation of one segment, the adjacent segment showed no evidence of suppression of gut motility or vasoconstriction. We conclude that luminal application of a noxious stimulus to the small intestine activates an entirely peripheral, intestinointestinal reflex pathway. This pathway involves enteric intestinofugal neurons that excite postganglionic sympathetic neurons via a nicotinic synapse. We suggest that the final sympathetic efferent neurons that respond to a tissue damaging stimulus are distinct from vasoconstrictor, secretomotor, and motility inhibiting neurons.NEW & NOTEWORTHY An intraluminal noxious chemical stimulus applied to one segment of small intestine increased mesenteric efferent nerve activity to an adjacent segment. This was identified as a peripheral ganglionic reflex that did not require vagal or spinal connections. Hexamethonium blocked most, but not all, ongoing and reflex mesenteric efferent activity. The prevertebral sympathetic efferent neurons that are activated likely affect inflammatory and immune functions of other gut segments.


Assuntos
Reflexo , Nervos Esplâncnicos , Ratos , Animais , Hexametônio/farmacologia , Reflexo/fisiologia , Vagotomia , Nervo Vago/fisiologia , Sistema Nervoso Simpático/fisiologia
18.
PLoS Comput Biol ; 20(1): e1011771, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38241215

RESUMO

Humans can generate and sustain a wide range of walking velocities while optimizing their energy efficiency. Understanding the intricate mechanisms governing human walking will contribute to the engineering applications such as energy-efficient biped robots and walking assistive devices. Reflex-based control mechanisms, which generate motor patterns in response to sensory feedback, have shown promise in generating human-like walking in musculoskeletal models. However, the precise regulation of velocity remains a major challenge. This limitation makes it difficult to identify the essential reflex circuits for energy-efficient walking. To explore the reflex control mechanism and gain a better understanding of its energy-efficient maintenance mechanism, we extend the reflex-based control system to enable controlled walking velocities based on target speeds. We developed a novel performance-weighted least squares (PWLS) method to design a parameter modulator that optimizes walking efficiency while maintaining target velocity for the reflex-based bipedal system. We have successfully generated walking gaits from 0.7 to 1.6 m/s in a two-dimensional musculoskeletal model based on an input target velocity in the simulation environment. Our detailed analysis of the parameter modulator in a reflex-based system revealed two key reflex circuits that have a significant impact on energy efficiency. Furthermore, this finding was confirmed to be not influenced by setting parameters, i.e., leg length, sensory time delay, and weight coefficients in the objective cost function. These findings provide a powerful tool for exploring the neural bases of locomotion control while shedding light on the intricate mechanisms underlying human walking and hold significant potential for practical engineering applications.


Assuntos
Sistema Musculoesquelético , Caminhada , Humanos , Caminhada/fisiologia , Marcha/fisiologia , Locomoção , Reflexo/fisiologia , Fenômenos Biomecânicos
19.
Sci Rep ; 14(1): 236, 2024 01 02.
Artigo em Inglês | MEDLINE | ID: mdl-38168485

RESUMO

The optokinetic reflex (OKR) serves as a vital index for visual system development in early life, commonly observed within the first six months post-birth in humans. Zebrafish larvae offer a robust and convenient model for OKR studies due to their rapid development and manageable size. Existing OKR assays often involve cumbersome setups and offer limited portability. In this study, we present an innovative OKR assay that leverages the flexible screen of the Samsung Galaxy Z Flip to optimize setup and portability. We conducted paired slow-phase velocity measurements in 5-day post-fertilization (dpf) zebrafish larvae (n = 15), using both the novel flip-phone-based assay and a traditional liquid-crystal display (LCD) arena. Utilizing Bland-Altman plots, we assessed the agreement between the two methods. Both assays were efficacious in eliciting OKR, with eye movement analysis indicating high tracking precision in the flip-phone-based assay. No statistically significant difference was observed in slow-phase velocities between the two assays (p = 0.40). Our findings underscore the feasibility and non-inferiority of the flip-phone-based approach, offering streamlined assembly, enhanced portability, and the potential for cost-effective alternatives. This study contributes to the evolution of OKR assay methodologies, aligning them with emerging research paradigms.


Assuntos
Nistagmo Optocinético , Peixe-Zebra , Animais , Humanos , Reflexo
20.
Europace ; 26(2)2024 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-38262617

RESUMO

AIMS: Systolic blood pressure (SBP) drops recorded by 24-h ambulatory blood pressure (BP) monitoring (ABPM) identify patients with susceptibility to reflex syncope and orthostatic intolerance. We tested the hypothesis that treatments aimed to increase BP (reassurance, education, and lifestyle measures plus pharmacological strategies) can reduce SBP drops. METHODS AND RESULTS: This was a multicentre, observational proof-of-concept study performed in patients with reflex syncope and/or orthostatic intolerance and with SBP drops on a screening ABPM. Among 144 eligible patients, 111 underwent a second ABPM on average 2.5 months after start of treatment. Overall, mean 24-h SBP increased from 114.1 ± 12.1 to 121.4 ± 14.5 mmHg (P < 0.0001). The number of SBP drops <90 and <100 mmHg decreased by 61%, 46% during daytime, and by 48% and 37% during 24-h period, respectively (P < 0.0001 for all). The dose-response relationship between difference in 24-h average SBP increase and reduction in number of SBP drops reached a plateau around ∼15 mmHg increase of 24-h SBP. The reduction in SBP drop rate was consistent and significant in patients who underwent deprescription of hypotensive medications (n = 44) and in patients who received BP-rising drugs (n = 67). CONCLUSION: In patients with reflex syncope and/or orthostatic intolerance, an increase in average 24-h SBP, regardless of the implemented strategy, significantly reduced the number of SBP drops and symptom burden. A 13 mmHg increase in 24-h SBP appears to represent the optimal goal for aborting the maximal number of SBP drops, representing a possible target for future interventions. ClincalTrials.gov identifier: NCT05729724.


Assuntos
Hipertensão , Hipotensão , Intolerância Ortostática , Síncope Vasovagal , Humanos , Anti-Hipertensivos/uso terapêutico , Pressão Sanguínea , Monitorização Ambulatorial da Pressão Arterial , Hipertensão/tratamento farmacológico , Intolerância Ortostática/diagnóstico , Intolerância Ortostática/tratamento farmacológico , Reflexo , Síncope Vasovagal/diagnóstico , Síncope Vasovagal/prevenção & controle , Estudo de Prova de Conceito
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