Calcium/calcimimetic via calcium-sensing receptor ameliorates cholera toxin-induced secretory diarrhea in mice.

BACKGROUND: Enterotoxins produce diarrhea through direct epithelial action and indirectly by activating the enteric nervous system. Calcium-sensing receptor (CaSR) inhibits both actions. The latter has been well documented in vitro but not in vivo. The hypothesis to be tested was that activating CaSR inhibits diarrhea in vivo. AIM: To determine whether CaSR agonists ameliorate secretory diarrhea evoked by cholera toxin (CTX) in mice. METHODS: CTX was given orally to C57BL/6 mice to induce diarrhea. Calcium and calcimimetic R568 were used to activate CaSR. To maximize their local intestinal actions, calcium was administered luminally via oral rehydration solution (ORS), whereas R568 was applied serosally using an intraperitoneal route. To verify that their actions resulted from the intestine, effects were also examined on Cre-lox intestine-specific CaSR knockouts. Diarrhea outcome was measured biochemically by monitoring changes in fecal Cl- or clinically by assessing stool consistency and weight loss. RESULTS: CTX induced secretory diarrhea, as evidenced by increases in fecal Cl-, stool consistency, and weight loss following CTX exposure, but did not alter CaSR, neither in content nor in function. Accordingly, calcium and R568 were each able to ameliorate diarrhea when applied to diseased intestines. Intestinal CaSR involvement is suggested by gene knockout experiments where the anti-diarrheal actions of R568 were lost in intestinal epithelial CaSR knockouts (villinCre/Casrflox/flox) and neuronal CaSR knockouts (nestinCre/Casrflox/flox). CONCLUSION: Treatment of acute secretory diarrheas remains a global challenge. Despite advances in diarrhea research, few have been made in the realm of diarrhea therapeutics. ORS therapy has remained the standard of care, although it does not halt the losses of intestinal fluid and ions caused by pathogens. There is no cost-effective therapeutic for diarrhea. This and other studies suggest that adding calcium to ORS or using calcimimetics to activate intestinal CaSR might represent a novel approach for treating secretory diarrheal diseases.

Visuospatial cognition predicts performance on an obstructed vision obstacle walking task in older adults.

Walking performance and cognitive function demonstrate strong associations in older adults, with both declining with advancing age. Walking requires the use of cognitive resources, particularly in complex environments like stepping over obstacles. A commonly implemented approach for measuring the cognitive control of walking is a dual-task walking assessment, in which walking is combined with a second task. However, dual-task assessments have shortcomings, including issues with scaling the task difficulty and controlling for task prioritization. Here we present a new assessment designed to be less susceptible to these shortcomings while still challenging cognitive control of walking: the Obstructed Vision Obstacle (OBVIO) task. During the task, participants hold a lightweight tray at waist level obstructing their view of upcoming foam blocks, which are intermittently spaced along a 10 m walkway. This forces the participants to use cognitive resources (e.g., attention and working memory) to remember the exact placement of upcoming obstacles to facilitate successful crossing. The results demonstrate that adding the obstructed vision board significantly slowed walking speed by an average of 0.26 m/s and increased the number of obstacle strikes by 8-fold in healthy older adults (n = 74). Additionally, OBVIO walking performance (a score based on both speed and number of obstacle strikes) significantly correlated with computer-based assessments of visuospatial working memory, attention, and verbal working memory. These results provide initial support that the OBVIO task is a feasible walking test that demands cognitive resources. This study lays the groundwork for using the OBVIO task in future assessment and intervention studies.

Prefrontal cortical activity during uneven terrain walking in younger and older adults.

Introduction: Walking in complex environments increases the cognitive demand of locomotor control; however, our understanding of the neural mechanisms contributing to walking on uneven terrain is limited. We used a novel method for altering terrain unevenness on a treadmill to investigate the association between terrain unevenness and cortical activity in the prefrontal cortex, a region known to be involved in various cognitive functions. Methods: Prefrontal cortical activity was measured with functional near infrared spectroscopy while participants walked on a novel custom-made terrain treadmill surface across four different terrains: flat, low, medium, and high levels of unevenness. The assessments were conducted in younger adults, older adults with better mobility function and older adults with worse mobility function. Mobility function was assessed using the Short Physical Performance Battery. The primary hypothesis was that increasing the unevenness of the terrain would result in greater prefrontal cortical activation in all groups. Secondary hypotheses were that heightened prefrontal cortical activation would be observed in the older groups relative to the younger group, and that prefrontal cortical activation would plateau at higher levels of terrain unevenness for the older adults with worse mobility function, as predicted by the Compensation Related Utilization of Neural Circuits Hypothesis. Results: The results revealed a significant main effect of terrain, indicating a significant increase in prefrontal cortical activation with increasing terrain unevenness during walking in all groups. A significant main effect of group revealed that prefrontal cortical activation was higher in older adults with better mobility function compared to younger adults and older adults with worse mobility function in all pooled terrains, but there was no significant difference in prefrontal cortical activation between older adults with worse mobility function and younger adults. Contrary to our hypothesis, the older group with better mobility function displayed a sustained increase in activation but the other groups did not, suggestive of neural compensation. Additional findings were that task-related increases in prefrontal cortical activation during walking were lateralized to the right hemisphere in older adults with better mobility function but were bilateral in older adults with worse mobility function and younger adults. Discussion: These findings support that compared to walking on a flat surface, walking on uneven terrain surfaces increases demand on cognitive control resources as measured by prefrontal cortical activation.

Acute Necrotizing Encephalitis Due to Influenza B in a Child: A Case Report.

Acute necrotizing encephalitis (ANE) is a rare and life-threatening form of encephalitis associated with influenza virus and other pathogens. It is characterized by a rapid onset of neurological symptoms and has been linked to a cytokine storm within the brain. We present a unique case of an eight-year-old female with influenza B-associated ANE, involving multiple brain areas including the cerebellum and brainstem and cauda equina involvement. The patient had a rapid neurological deterioration, and MRI findings revealed extensive multifocal areas of abnormal brain parenchyma and inflammation with Guillain-Barre appearance in the cauda equina. To the best of our knowledge, this is the first reported case of ANE with cauda equina involvement leading to neurological deficits. Despite treatment with oseltamivir, steroids, and intravenous immunoglobulins, the patient had poor neurological outcomes, similar to those reported in the literature.

Ca2+ fortified oral rehydration solution is effective in reducing diarrhea morbidity in cholera toxin-pretreated mice.

Diarrhea like cholera remains a leading cause of mortality and morbidity globally. Oral rehydration solution (ORS) that developed in 1970s significantly decreases diarrhea mortality; yet, it does not reduce diarrhea morbidity and its usage has reduced persistently. Patients with diarrhea lose not only monovalent ions Na+, K+, Cl- and HCO3, which are replaced via ORS, but also divalent ions Zn2+ and Ca2+, which are not routinely replaced, particularly for Ca2+. Using several in vitro technologies performed in isolated tissues, we have previously shown that Ca2+, a primary ligand that activates the Ca2+-sensing receptor, can act on intestinal epithelium and enteric nervous system and reverse cholera toxin-induced fluid secretion. In the present study, using the cholera toxin-pretreated C57BL/6 mice as a model, we show that the anti-diarrheal effect of Ca2+ can also occur in vivo. Our results raise a question of whether this divalent ion also needs to be replaced in diarrhea management. Perhaps, an ideal rehydration therapy would be solutions that contain both monovalent ions, which reduce diarrhea mortality, and divalent minerals, which reduce diarrhea morbidity.

Enhancing Locomotor Learning With Transcutaneous Spinal Electrical Stimulation and Somatosensory Augmentation: A Pilot Randomized Controlled Trial in Older Adults.

This study investigated locomotor learning of a complex terrain walking task in older adults, when combined with two adjuvant interventions: transcutaneous spinal direct current stimulation (tsDCS) to increase lumbar spinal cord excitability, and textured shoe insoles to increase somatosensory feedback to the spinal cord. The spinal cord has a crucial contribution to control of walking, and is a novel therapeutic target for rehabilitation of older adults. The complex terrain task involved walking a 10-meter course consisting of nine obstacles and three sections of compliant (soft) walking surface. Twenty-three participants were randomly assigned to one of the following groups: sham tsDCS and smooth insoles (sham/smooth; control group), sham tsDCS and textured insoles (sham/textured), active tsDCS and smooth insoles (active/smooth), and active tsDCS and textured insoles (active/textured). The first objective was to assess the feasibility, tolerability, and safety of the interventions. The second objective was to assess preliminary efficacy for increasing locomotor learning, as defined by retention of gains in walking speed between a baseline visit of task practice, and a subsequent follow-up visit. Variability of the center of mass while walking over the course was also evaluated. The change in executive control of walking (prefrontal cortical activity) between the baseline and follow-up visits was measured with functional near infrared spectroscopy. The study results demonstrated feasibility based on enrollment and retention of participants, tolerability based on self-report, and safety based on absence of adverse events. Preliminary efficacy was supported based on trends showing larger gains in walking speed and more pronounced reductions in mediolateral center of mass variability at the follow-up visit in the groups randomized to active tsDCS or textured insoles. These data justify future larger studies to further assess dosing and efficacy of these intervention approaches. In conclusion, rehabilitation interventions that target spinal control of walking present a potential opportunity for enhancing walking function in older adults.

A Self-Limited Childhood Epilepsy as Co-Incidental in Cerebral Palsy.

BACKGROUND: Cerebral palsy is the most frequent motor disability in childhood and is associated with a higher incidence of seizure disorders. In many instances, it is recognized that motor difficulties, as well as seizures, are from the same underlying brain lesion. However, self-limited childhood epilepsies, being a common group of epilepsy syndromes, would be expected to occur in patients with cerebral palsy merely on chance association and be unrelated to the structural brain imaging abnormality causing the motor impairment. Differential diagnosis in this case is important determining the long-term prognosis and need for anticonvulsant treatment. CASE PRESENTATION: Here, we report two patients with cerebral palsy combined with epilepsy, whose age at onset, seizure semiology and electroclinical features were similar to children with self-limited childhood-specific seizure disorders (childhood epilepsy with centrotemporal spikes and Panayiotopoulos syndrome). CONCLUSION: These cases highlight the importance of comprehensive differential diagnosis of seizures in cerebral palsy. Co-existence of age-dependent focal epilepsies with an underlying brain pathology as white matter injury, not affecting the cerebral cortex, might take place in the case of children with impaired motor skills. With health systems increasingly utilizing clinical pathways, it is important to consider the possibility of a self-limited childhood epilepsy and avoid aggressive and unnecessary medication treatment in children with cerebral palsy.

Comparative assessment of health-related quality of life with and without anticonvulsant therapy in patients with childhood epilepsy with centrotemporal spikes.

OBJECTIVE: To estimate anti-seizure medication (ASM) treatment burden and its effects on health-related quality of life (HRQOL) in new-onset childhood epilepsy with centrotemporal spikes (CECTS) using different treatment approaches in Kazakhstan. METHODS: Forty-three patients were followed prospectively during 2015 to 2020 for at least 2 years. Patients were divided into three groups: (1) history of ≤3 seizures (n = 32); (2) ≥4 seizures (n = 6); (3) cerebral palsy coexisting with CECTS (n = 5). The first group was subdivided into treated (n = 8) and observed (n = 24) subgroups. The shortened Quality of Life in Childhood Epilepsy Questionnaire (QOLCE-55) was completed by parents after 6 months of follow-up. RESULTS: At the end of the study, all children had a sustained remission from seizures for at least 2 years. Differences were identified in emotional, social, and physical subscales between patients in the low seizure frequency group. Signs of low self-esteem, anxiety, depression, limited social interaction owing to pharmacotherapy, painful medical procedures, and stigma were reasons for decreased HRQOL in the treated subgroup. Overall HRQOL in treated (89.2 ± 5.2) patients was significantly decreased compared with observed children with low seizure frequency (98.0 ± 3.0). CONCLUSION: ASM therapy does not necessarily improve and may decrease HRQOL in children with low seizure frequency CECTS.

Vitamins are Indeed Vital Amines: A Discussion of 3 Deficiencies With Neurologic Manifestations.

Optimal functioning of the human nervous system depends on a constant supply of nutrients, vitamins, and minerals. In the developed world, nutritional deficiencies are relatively rare and infrequently present with neurologic manifestations. These neurologic disorders can be mistaken for inflammatory and/or autoimmune phenomena. This manuscript describes 2 pediatric cases with neurologic signs/symptoms arising from vitamin deficiencies-(1) optic neuropathy and (2) Wernicke encephalopathy associated with a Guillain-Barre-like pattern of weakness. The 2 cases and the subsequent discussion of vitamin A, B1, and B12 deficiencies underscore the value of taking a thorough dietary history and emphasize risk factors for these 3 nutritional deficiencies.

Online educational curriculum in pediatric epilepsy: A pilot study.

ABSTRACT: Recent projections suggest that increasing numbers of nurse practitioners (NPs) and physician assistants (PAs) will be needed to meet the increasing need for pediatric neurology expertise. This pilot study assessed feasibility and preliminary effectiveness of an online curriculum designed to impact knowledge, skills, attitudes, and behaviors of NPs/PAs treating patients with pediatric epilepsy. Ten-session online curriculum was developed using previous experience and published recommendations to improve knowledge, electroencephalogram (EEG) skills, attitudes, and behaviors related to treating patients with pediatric epilepsy. Participants were NPs and PAs recruited from regional pediatric neurology practices. Three successive 10-week courses were provided. Attendance and completion were used to assess feasibility. Knowledge, EEG skills, attitudes, and behaviors were evaluated using pretest versus posttest questionnaires and compared analytically using a paired t-test and McNemar test. Twenty-nine NPs/PAs started the course, with typical attendance ∼85%. Twenty-two participants (76%) completed the course. Completers showed significant improvements in medication knowledge (premedication: mean = 74.6, SD = 16.4; postmedication: mean: 88.3, SD = 14.0; p = .001), EEG skills (premedication: mean = 44.8, SD = 24.4; postmedication: mean: 77.3, SD = 19.8; p < .001), and several measures of attitude and behavior. This pilot study shows feasibility and potential educational benefit of a 10-hour online course on pediatric epilepsy and may provide a convenient and effective option for continuing education for hard-to-reach students.

Risk Factors for Seizures and Epilepsy in Children With Congenital Heart Disease.

OBJECTIVES: To identify potential risk factors for pre- and postoperative seizures and epilepsy in children with congenital heart disease. METHODS: Retrospective cohort study of neonates and infants <3 months of age with congenital heart disease who underwent cardiopulmonary bypass from November 24, 2006, until June 1, 2015. Children with seizures were classified based on time of occurrence into early preoperative, early postoperative, and late postoperative. Children with recurring seizures 30 days after cardiac surgery met criteria for epilepsy. RESULTS: 247 patients completed follow-up; 2.4% had seizures early preoperation and 1.6% early postoperation. Late postoperative epilepsy occurred in 5.3% of the cohort. The majority of seizures in the late postoperative epilepsy group started after 1 year of age (mean 1.53 years, range = 0.18-4.7 years). One of the 13 patients with epilepsy had a seizure during their intensive care unit hospitalization. Potential risk factors for seizures included brain injury (P < .001), high-risk surgery (Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery score ≥3, P = .024), and low birth weight (P < .04). Infants with stroke were more likely to develop epilepsy (P = .04). Presence of seizures was associated with increased length of stay (P < .001). CONCLUSIONS: Our study suggests an association between children with congenital heart disease diagnosed with stroke in the neonatal/infancy period and the development of epilepsy. These children may not have prior early pre- and postoperative seizures. Risk factors for seizures include brain injury, high-risk surgery, and lower birth weight. Seizures were associated with an increased length of stay but did not necessarily lead to subsequent epilepsy.

A Cross-species Model of Dual-Task Walking in Young and Older Humans and Rats.

Introduction: Dual-task walking is common in daily life but becomes more difficult with aging. Little is known about the neurobiological mechanisms affecting competing cognitive demands. Translational studies with human and animal models are needed to address this gap. This pilot study investigated the feasibility of implementing a novel cross-species dual-task model in humans and rats and aimed to establish preliminary evidence that the model induces a dual-task cost. Methods: Young and older humans and rats performed an object discrimination task (OD), a baseline task of typical walking (baseline), an alternation turning task on a Figure 8 walking course (Alt), and a dual-task combining object discrimination with the alternation task (AltOD). Primary behavioral assessments including walking speed and correct selections for object discrimination and turning direction. In humans, left prefrontal cortex activity was measured with functional near-infrared spectroscopy (fNIRS). Results: Human subjects generally performed well on all tasks, but the older adults exhibited a trend for a slowing of walking speed immediately before the turning decision for Alt and AltOD compared to baseline. Older adults also had heightened prefrontal activity relative to young adults for the Alt and AltOD tasks. Older rodents required more training than young rodents to learn the alternation task. When tested on AltOD with and without a 15-s delay between trials, older rodents exhibited a substantial performance deficit for the delayed version on the initial day of testing. Old rats, however, did not show a significant slowing in walking speed with increasing task demand, as was evident in the young rats. Discussion: This study demonstrates the feasibility and challenges associated with implementing a cross-species dual-task model. While there was preliminary evidence of dual-task cost in both humans and rats, the magnitude of effects was small and not consistent across species. This is likely due to the relative ease of each task in humans and the walking component in rats not being sufficiently challenging. Future versions of this test should make the cognitive tasks more challenging and the motor task in rats more complex.

Calcimimetic R568 inhibits tetrodotoxin-sensitive colonic electrolyte secretion and reduces c-fos expression in myenteric neurons.

AIMS: Calcium-sensing receptor (CaSR) is expressed on neurons of both submucosal and myenteric plexuses of the enteric nervous system (ENS) and the CaSR agonist R568 inhibited Cl- secretion in intestine. The purpose of this study was to localize the primary site of action of R568 in the ENS and to explore how CaSR regulates secretion through the ENS. MATERIALS AND METHODS: Two preparations of rat proximal and distal colon were used. The full-thickness preparation contained both the submucosal and myenteric plexuses, whereas for the "stripped" preparation the myenteric plexus with the muscle layers was removed. Both preparations were mounted onto Ussing chambers and Cl- secretory responses were compared by measuring changes in short circuit current (Isc). Two tissue-specific CaSR knockouts (i.e., neuron-specific vs. enterocyte-specific) were generated to compare the effect of R568 on expression of c-fos protein in myenteric neurons by immunocytochemistry. KEY FINDINGS: In full-thickness colons, tetrodotoxin (TTX) inhibited Isc, both in proximal and distal colons. A nearly identical inhibition was produced by R568. However, in stripped preparations, while the effect of TTX on Isc largely remained, the effect of R568 was nearly completely eliminated. In keeping with this, R568 reduced c-fos protein expression only in myenteric neurons of wild type mice and mutant mice that contained CaSR in neurons (i.e., villinCre/Casrflox/flox mice), but not in myenteric neurons of nestinCre/Casrflox/flox mice in which neuronal cell CaSR was eliminated. SIGNIFICANCE: These results indicate that R568 exerts its anti-secretory effects predominantly via CaSR-mediated inhibition of neuronal activity in the myenteric plexus.

Bumetanide increases Cl--dependent short-circuit current in late distal colon: Evidence for the presence of active electrogenic Cl- absorption.

Mammalian colonic epithelia consist of cells that are capable of both absorbing and secreting Cl-. The present studies employing Ussing chamber technique identified two opposing short-circuit current (Isc) responses to basolateral bumetanide in rat distal colon. Apart from the transepithelial Cl--secretory Isc in early distal colon that was inhibited by bumetanide, bumetanide also stimulated Isc in late distal colon that had not previously been identified. Since bumetanide inhibits basolateral Na+-K+-2Cl- cotransporter (NKCC) in crypt cells and basolateral K+-Cl- cotransporter (KCC) in surface epithelium, we proposed this stimulatory Isc could represent a KCC-mediated Cl- absorptive current. In support of this hypothesis, ion substitution experiments established Cl- dependency of this absorptive Isc and transport inhibitor studies demonstrated the involvement of an apical Cl- conductance. Current distribution and RNA sequencing analyses revealed that this Cl- absorptive Isc is closely associated with epithelial Na+ channel (ENaC) but is not dependent on ENaC activity. Thus, inhibition of ENaC by 10 µM amiloride or benzamil neither altered the direction nor its activity. Physiological studies suggested that this Cl- absorptive Isc senses dietary Cl- content; thus when dietary Cl- was low, Cl- absorptive Isc was up-regulated. In contrast, when dietary Cl- was increased, Cl- absorptive Isc was down-regulated. We conclude that an active Cl- extrusion mechanism exists in ENaC-expressing late distal colon and likely operates in parallel with ENaC to facilitate NaCl absorption.

Diet Redux: Outcomes from Reattempting Dietary Therapy for Epilepsy.

The outcome for patients attempting dietary therapy for epilepsy a second time is unknown. Twenty-six subjects treated with the ketogenic diet as children who then began either the ketogenic diet or a Modified Atkins Diet (MAD) at least 6 months later were evaluated. The mean age at the first diet trial was 5.6 years and at the second diet trial was 11.5 years. Most restarted dietary therapy because of persistent seizures (65%) or recurrence after seizure freedom (19%). Overall, 77% had a ≥50% seizure reduction with the first diet, and 50% with the second diet, P = .04. Individual subject responses were largely similar, with 14 (54%) having identical seizure reduction both times, 9 worse (35%) with the second attempt, and 3 (16%) improved. The second diet trial was more likely to lead to >50% seizure reduction if the first trial was started at a later age (7.4 vs 3.9 years, P = .04).

The ketogenic diet in pharmacoresistant childhood epilepsy.

Available pharmacologic treatments for seizures are limited in their efficacy. For a patient with seizures, pharmacologic treatment with available anticonvulsant medications leads to seizure control in <70% of patients. Surgical resection can lead to control in a select subset of patients but still leaves a significant number of patients with uncontrolled seizures. The ketogenic diet and related diets have proven to be useful in pharmacoresistant childhood epilepsy.

ADCY5-related dyskinesia: Broader spectrum and genotype-phenotype correlations.

OBJECTIVE: To investigate the clinical spectrum and distinguishing features of adenylate cyclase 5 (ADCY5)-related dyskinesia and genotype-phenotype relationship. METHODS: We analyzed ADCY5 in patients with choreiform or dystonic movements by exome or targeted sequencing. Suspected mosaicism was confirmed by allele-specific amplification. We evaluated clinical features in our 50 new and previously reported cases. RESULTS: We identified 3 new families and 12 new sporadic cases with ADCY5 mutations. These mutations cause a mixed hyperkinetic disorder that includes dystonia, chorea, and myoclonus, often with facial involvement. The movements are sometimes painful and show episodic worsening on a fluctuating background. Many patients have axial hypotonia. In 2 unrelated families, a p.A726T mutation in the first cytoplasmic domain (C1) causes a relatively mild disorder of prominent facial and hand dystonia and chorea. Mutations p.R418W or p.R418Q in C1, de novo in 13 individuals and inherited in 1, produce a moderate to severe disorder with axial hypotonia, limb hypertonia, paroxysmal nocturnal or diurnal dyskinesia, chorea, myoclonus, and intermittent facial dyskinesia. Somatic mosaicism is usually associated with a less severe phenotype. In one family, a p.M1029K mutation in the C2 domain causes severe dystonia, hypotonia, and chorea. The progenitor, whose childhood-onset episodic movement disorder almost disappeared in adulthood, was mosaic for the mutation. CONCLUSIONS: ADCY5-related dyskinesia is a childhood-onset disorder with a wide range of hyperkinetic abnormal movements. Genotype-specific correlations and mosaicism play important roles in the phenotypic variability. Recurrent mutations suggest particular functional importance of residues 418 and 726 in disease pathogenesis.