Muscular adaptations and insulin‐like growth factor‐1 responses to resistance training are stretch‐mediated

Introduction: Modulation of muscle characteristics was attempted through altering muscle stretch during resistance training. We hypothesized that stretch would enhance muscle responses. Methods: Participants trained for 8 weeks, loading the quadriceps in a shortened (SL, 0–50° knee flexion; n = 10) or lengthened (LL, 40–90°; n = 11) position, followed by 4 weeks of detraining. Controls (CON; n = 10) were untrained. Quadriceps strength, vastus lateralis architecture, anatomical cross‐sectional area (aCSA), and serum insulin‐like growth factor‐1 (IGF‐1) were measured at weeks 0, 8, 10, and 12. Results: Increases in fascicle length (29 ± 4% vs. 14 ± 4%), distal aCSA (53 ± 12% vs. 18 ± 8%), strength (26 ± 6% vs. 7 ± 3%), and IGF‐1 (31 ± 6% vs. 7 ± 6%) were greater in LL compared with SL muscles (P < 0.05). No changes occurred in CON. Detraining decrements in strength and aCSA were greater in SL than LL muscles (P < 0.05). Conclusions: Enhanced muscle in vivo (and somewhat IGF‐1) adaptations to resistance training are concurrent with muscle stretch, which warrants its inclusion within training. Muscle Nerve 49 : 108–119, 2014     

Electrical stimulation cramp threshold frequency correlates well with the occurrence of skeletal muscle cramps

The minimum electrical stimulation frequency (HZ ) at which a muscle cramps is termed threshold frequency (TF). TF is theorized to represent one's predisposition to cramping; however, TF and cramp occurrence have never been correlated. We hypothesized that TF would be lower in individuals with a cramp history and lower on the second of two days of testing; genetics may partially explain this lower TF. Cramp TF was measured in 19 subjects with (Group 1), and 12 subjects without (Group 2), a cramp history. Group 1 had a lower TF (14.9 ± 1.3 vs. 25.5 ± 1.6 HZ ; P < 0.001) and a higher family history of cramping than Group 2 (89% vs. 27%; P < 0.001). TF was lower on day 2 (18.3 ± 0.26 HZ ) than day 1 (19.7 ± 0.25 HZ ; P = 0.03). Lower TFs are correlated with cramp history, supporting the inference that lower TFs may represent increased predisposition toward cramping. TF may be used to identify individuals at risk of cramping. Muscle Nerve 39: 364–368, 2009     

The effect of 5Hz high‐frequency rTMS over contralesional pharyngeal motor cortex in post‐stroke oropharyngeal dysphagia: a randomized controlled study

Background We sought to find the therapeutic effect of 5Hz high‐frequency repetitive transcranial magnetic stimulation (rTMS) over the unaffected pharyngeal motor cortex in post‐stroke dysphagic patients. Methods Eighteen patients with unilateral hemispheric stroke oropharyngeal dysphagia that lasted more than 1 month were randomly divided into two groups. They all performed videofluoroscopic swallowing study (VFSS) before rTMS intervention. The experimental group (EG) received 5Hz rTMS over contra‐lesional pharyngeal motor cortex for 10 min per day for 2 weeks. The control group (CG) received sham stimulation under the same condition. Videofluoroscopic swallowing study were performed again just after treatment cessation and 2 weeks afterward. The evaluation was performed using videofluoroscopic dysphagia scale (VDS) and penetration‐aspiration scale (PAS). Key Results Mean baseline VDS and PAS of EG was 33.6 ± 12.1 and 3.41 ± 2.32 respectively and the scores were reduced to 25.3 ± 9.8 and 1.93 ± 1.52 just after 2 weeks intervention (P < 0.05). This effect lasted for up to 2 weeks after treatment. However, there was no change in the CG. Baseline prevalence of aspiration, pharyngeal residue, delayed triggering of pharyngeal swallowing and abnormal pharyngeal transit time (PTT) in EG was 66.7%, 66.7%, 33.3%, and 44.4%, respectively. After rTMS, the prevalence of aspiration and pharyngeal residue was reduced to 33.3% and 33.3%, respectively. However, the prevalence of delayed triggering and abnormal PTT was not changed. Conclusions & Inferences A 5Hz high‐frequency rTMS on contra‐lesional pharyngeal motor cortex might be beneficial for post‐stroke dysphagic patients. This intervention can be used as a new treatment method in post‐stroke patients with dysphagia.     

Differential susceptibility of cortical and subcortical inhibitory neurons and astrocytes in the long term following diffuse traumatic brain injury

Long‐term diffuse traumatic brain injury (dTBI) causes neuronal hyperexcitation in supragranular layers in sensory cortex, likely through reduced inhibition. Other forms of TBI affect inhibitory interneurons in subcortical areas but it is unknown if this occurs in cortex, or in any brain area in dTBI. We investigated dTBI effects on inhibitory neurons and astrocytes in somatosensory and motor cortex, and hippocampus, 8 weeks post‐TBI. Brains were labeled with antibodies against calbindin (CB), parvalbumin (PV), calretinin (CR) and neuropeptide Y (NPY), and somatostatin (SOM) and glial fibrillary acidic protein (GFAP), a marker for astrogliosis during neurodegeneration. Despite persistent behavioral deficits in rotarod performance up to the time of brain extraction (TBI = 73.13 ± 5.23% mean ± SEM, Sham = 92.29 ± 5.56%, P < 0.01), motor cortex showed only a significant increase, in NPY neurons in supragranular layers (mean cells/mm² ± SEM, Sham = 16 ± 0.971, TBI = 25 ± 1.51, P = 0.001). In somatosensory cortex, only CR⁺ neurons showed changes, being decreased in supragranular (TBI = 19 ± 1.18, Sham = 25 ± 1.10, P < 0.01) and increased in infragranular (TBI = 28 ± 1.35, Sham = 24 ± 1.07, P < 0.05) layers. Heterogeneous changes were seen in hippocampal staining: CB⁺ decreased in dentate gyrus (TBI = 2 ± 0.382, Sham = 4 ± 0.383, P < 0.01), PV⁺ increased in CA1 (TBI = 39 ± 1.26, Sham = 33 ± 1.69, P < 0.05) and CA2/3 (TBI = 26 ± 2.10, Sham = 20 ± 1.49, P < 0.05), and CR⁺ decreased in CA1 (TBI = 10 ± 1.02, Sham = 14 ± 1.14, P < 0.05). Astrogliosis significantly increased in corpus callosum (TBI = 6.7 ± 0.69, Sham = 2.5 ± 0.38; P = 0.007). While dTBI effects on inhibitory neurons appear region‐ and type‐specific, a common feature in all cases of decrease was that changes occurred in dendrite targeting interneurons involved in neuronal integration. J. Comp. Neurol. 524:3530–3560, 2016. © 2016 Wiley Periodicals, Inc.     

Adjustments in the force–frequency relationship during passive and exercise‐induced hyperthermia

Introduction: We examined the extent to which fatiguing cycling exercise in the heat influences contractile function in modulating the force–frequency relationship. Methods: Before (∽37.0°C) and after (∽38.5°C) exercise (ExH) and passive (PaH) hyperthermia, an 8‐s train of stimulation at 10, 20, 50, and 100 Hz (2 s per frequency) and a potentiated twitch were evoked on the relaxed knee extensors using percutaneous stimulation. Results: ExH and PaH produced a decrease in the 20:50 Hz force ratio, indicative of low‐frequency fatigue (P < 0.01). This adjustment was more pronounced after ExH than PaH (P < 0.01). A rightward displacement in the force–frequency relationship occurred after ExH and PaH (P < 0.05) and was exacerbated by ExH (P < 0.05). Peak twitch force also decreased after ExH (P < 0.05). Conclusions: ExH reduces force summation due to development of skeletal muscle fatigue, exacerbating the shift in force–frequency to the right relative to PaH. Muscle Nerve 50 : 822–829, 2014     

Ingestion of transient receptor potential channel agonists attenuates exercise‐induced muscle cramps

Introduction: Exercise‐associated muscle cramping (EAMC) is a poorly understood problem that is neuromuscular in origin. Ingestion of transient receptor potential (TRP) channel agonists has been efficacious in attenuating electrically induced muscle cramps. This study examines the effect of TRP agonist ingestion on voluntarily induced EAMC and motor function. Methods: Study 1: Thirty‐nine participants completed 2 trials after ingesting TRP agonist‐containing active treatment (A), or vehicle (V) control. Cramping in the triceps surae muscle was induced via voluntary isometric contraction. Study 2: After ingesting A or V, 31 participants performed kinematic and psychomotor tests of manual dexterity. Results: A increased precramp contraction duration (A, 36.9 ± 4.1 s; V, 27.8 ± 3.1 s), decreased cramp EMG area under the curve (A, 37.3 ± 7.7 %EMG_max·s; V, 77.2 ± 17.7 %EMG_max·s), increased contraction force to produce the cramp (A, 13.8 ± 1.8 kg; V, 9.9 ± 1.6 kg), and decreased postcramp soreness (A, 4.1 ± 0.3 arbitrary units (a.u.); V, 4.7 ± 0.3 a.u.). Kinematic and psychomotor tests were not affected. Discussion: TRP agonist ingestion attenuated EAMC characteristics without affecting motor function. Muscle Nerve 56 : 379–385, 2017     

BsmI vitamin D receptor’s polymorphism and bone mineral density in men and premenopausal women on long‐term antiepileptic therapy

Background: Utilization of antiepileptic drugs (AEDs) has long been associated with bone deleterious effects. Furthermore, the BsmI restriction fragment polymorphism of the vitamin D receptor (VDR) has been associated with reduced bone mineral density (BMD), mostly in postmenopausal women. This study evaluates the association between bone metabolism of patients with epilepsy and the BsmI VDR’s polymorphism in chronic users of AEDs. Methods: This study evaluated 73 long‐term users of antiepileptic drug monotherapy, in a cross‐sectional design. Fasting blood samples were obtained to estimate the circulating serum levels of calcium, magnesium, phosphorus, parathormone, 25hydroxyvitamin D as well as the VDR’s genotype. Bone mineral density at the lumbar spine was measured with Dual Energy X‐Ray Absorptiometry. Results: Bone mineral density was significantly associated with the genotype of VDR (mean BMD: Bb genotype 1.056 ± 0.126 g/cm²; BB genotype 1.059 ± 0.113 g/cm²; bb genotype 1.179 ± 0.120 g/cm²; P < 0.05). Additionally, the presence of at least one B allele was significantly associated with lower bone mineral density (B allele present: BMD = 1.057 ± 0.12 g/cm², B allele absent: BMD = 1.179 ± 0.119 g/cm²; P < 0.01). Patients with at least one B allele had lower serum levels of 25hydroxyvitamin D when compared with bb patients (22.61 ng/ml vs. 33.27 ng/ml, P < 0.05), whilst they tended to have higher levels of parathyroid hormone. Discussion: Vitamin D receptor polymorphism is associated with lower bone mass in patients with epilepsy. This effect might be mediated through the vitamin D‐parathormone pathway.     

Validation of ACB in vitro and in vivo as a biomagnetic method for measuring stomach contraction

Background The aim of this study was to validate a biomagnetic method (alternate current biosusceptometry, ACB) for monitoring gastric wall contractions in rats. Methods In vitro data were obtained to establish the relationship between ACB and the strain‐gauge (SG) signal amplitude. In vivo experiments were performed in pentobarbital‐anesthetized rats with SG and magnetic markers previously implanted under the gastric serosa or after ingestion of magnetic material. Gastric motility was quantified from the tracing amplitudes and frequency profiles obtained by Fast Fourier Transform. Key Results The correlation between in vitro signal amplitudes was strong (R = 0.989). The temporal cross‐correlation coefficient between the ACB and SG signal amplitude was higher (P < 0.0001) in the postprandial (88.3 ± 9.1 V) than in the fasting state (31.0 ± 16.9 V). Irregular signal profiles, low contraction amplitudes, and smaller signal‐to‐noise ratios explained the poor correlation between techniques for fasting‐state recordings. When a magnetic material was ingested, there was also strong correlation in the frequency and signal amplitude and a small phase‐difference between the techniques. The contraction frequencies using ACB were 0.068 ± 0.007 Hz (postprandial) and 0.058 ± 0.007 Hz (fasting) (P < 0.002) and those using SG were 0.066 ± 0.006 Hz (postprandial) and 0.059 ± 0.008 Hz (fasting) (P < 0.005). Conclusions & Inferences In summary, ACB is reliable for monitoring gastric wall contractions using both implanted and ingested magnetic materials, and may serve as an accurate and sensitive technique for gastrointestinal motility studies.     

Normal values of median nerve cross‐sectional area obtained by ultrasound along its course in the arm with electrophysiological correlations,in 100 Asian subjects

Introduction: The objective of this study is to obtain normative cross‐sectional area (CSA) values for median nerve by ultrasound at predetermined sites and correlate them with electrophysiological variables in healthy Asian subjects. Methods: The median nerve was examined ultrasonographically in 100 healthy volunteers, mean age 39 years (range, 18–75 years). CSA of the median nerve was measured at wrist, mid‐forearm, mid‐arm, and axilla. All subjects underwent simultaneous standardized nerve conduction studies. Results: The mean median nerve CSAs ± SD at the distal wrist crease was 7.2 ± 1 mm²; mid‐forearm 4.8 ± 0.9 mm²; mid‐arm 6.1 ± 1 mm²; axilla 5.9 ± 0.9 mm². The CSA at the wrist was the largest compared with other levels (P < 0.001), and it increased with advancing age (P < 0.002). Conclusions: These normative data show that median nerve CSA is not uniform along its length. There are differences between gender, and values increase with advancing age. Muscle Nerve 49 : 284–286, 2014     

Menopause is associated with decreased postprandial ghrelin,whereas a history of anorexia nervosa is associated with increased total ghrelin

Middle age has been linked with various dysfunctional eating patterns in women. The hormone ghrelin is related to food intake, with plasma levels rising before eating and decreasing immediately afterwards. Animal research has shown that oestradiol is an antagonist of ghrelin. Given that both menopause and anorexia nervosa (AN) are states characterised by reduced oestradiol, the present study aimed to investigate for the first time whether menopausal status and a history of AN are linked with altered ghrelin levels in middle‐aged women. Based on previous research, we hypothesised that (i) post‐menopausal women would demonstrate comparably increased ghrelin after food intake and (ii) women with a history of AN would exhibit increased total ghrelin levels. Healthy, middle‐aged women (n = 57) were recruited. Of the women, 31 were post‐menopausal and 27 had a history of AN. Plasma ghrelin was repeatedly collected before and after a meal standardised in terms of caloric content. Areas under the curves were calculated to indicate total (AUCg) and postprandial ghrelin (AUCi). Menopausal status was linked with postprandial ghrelin (AUCi ?1.6 ± 2.2 vs ?2.9 ± 2.6; P = 0.058), whereas a history of AN was linked with total ghrelin (AUCg 36.2 ± 5.6 vs 39.0 ± 3.7; P = 0.050). There were no interaction effects (both P > 0.466). A closer examination of the effects revealed that post‐menopausal women showed marginally greater decreases in ghrelin immediately after food intake (P = 0.064) and marginally greater re‐increases after 60 minutes (P = 0.084) compared to pre‐menopausal women. Women with a history of AN had significantly higher total ghrelin compared to women without a history of AN (P = 0.042). Post‐menopause was linked with higher sensitivity of ghrelin to food intake (trend), whereas a history of AN was related to greater total ghrelin. Future research should investigate to what extent the observed alterations in ghrelin may affect dysfunctional eating behaviour during middle age.     

Continuous low dose diclofenac sodium infusion to control fever in neurosurgical critical care

Introduction  Aim of this randomized prospective clinical trial is to compare two methods of antipyretics and evaluate their efficacy in controlling fever during the acute phase of brain damage. Methods  Twenty-two febrile comatose patients: 12 severe traumatic brain injury and 10 subarachnoid hemorrhage divided in 2 groups: Diclofenac low-dose infusion (10 patients) and extemporaneous boluses of NSAIDs (CTRL, 12 patients). The primary outcome measure was length of time with temperature >38°C. Secondary outcome measures were: 1) to assess the effects of each antipyretic strategy on intracranial pressure (ICP), cerebral perfusion pressure (CPP), mean arterial pressure (MAP) and heart rate; 2) to monitor adverse effects of each antipyretic strategy. The baseline characteristics in the two treatment groups were similar. Results  Primary findings: percentage of time per patient with temperature >38°C was significantly lower (P < 0.0001) in the DCF group, 4% (0–22%), vs. 34% (8–56%) in CTRL group. In addition, mean T°, max T° were lower in DCF than in CTRL (P < 0.05). Secondary findings: CPP and MAP were significantly higher in DCF group (P < 0.05) while ICP was not different (NS). However, if ICP pre randomization was < 25 mmHg, CTRL suffered a worst ICP (24 ± 11 vs. 16 ± 7 P = 0.01), MAP (89 ± 10 vs. 104 ± 10 P = 0.01) and CPP (75 ± 10 vs. 94 ± 17 P = 0.01) compared to DCF. No differences between the two treatment were recorded when ICP ≥ 25 mmHg before randomization. There was no gastrointestinal or intracranial bleeding. Conclusions  Low dose DCF infusion is a potential useful strategy for a successful control temperature better than intermittent NSAIDs dosing, minimizing potentially brain-damaging effects of fever.     

Assessment of symptoms during gastric emptying scintigraphy to correlate symptoms to delayed gastric emptying

Background Symptoms of gastroparesis based on patient recall correlate poorly with gastric emptying. The aim of this study is to determine if symptoms recorded during gastric emptying scintigraphy (GES) correlate with gastric emptying and with symptoms based on patient recall. Methods Patients undergoing GES completed the Patient Assessment of GI Symptoms (PAGI‐SYM) assessing symptoms over the prior 2 weeks and a questionnaire for which patients graded six symptoms during GES. A Symptom Severity Index (SSI) represented the mean of six symptoms at each time point. Key Results A total of 560 patients underwent GES for clinical evaluation of symptoms. Of 388 patients included in the study: 232 patients had normal GES (NGES), 156 delayed GES (DGES), and 11 rapid GES (RGES). Symptom severity index increased pre to postprandial for each group: NGES: 0.51 ± 0.07 to 0.92 ± 0.03, DGES: 0.60 ± 0.09 to 1.13 ± 0.05, and RGES: 0.56 ± 0.12 to 0.79 ± 0.13. Delayed gastric emptying scintigraphy patients had a higher postprandial SSI than NGES patients (1.13 ± 0.05 vs 0.92 ± 0.03, P < 0.05). Postprandial symptoms of stomach fullness (1.9 ± 0.12 vs 1.5 ± 0.09; P = 0.011), bloating (1.4 ± 0.11 vs 1.1 ± 0.09; P = 0.033), and abdominal pain (1.1 ± 0.08 vs 0.7 ± 0.12; P = 0.012) were higher in DGES than NGES. Symptom severity based on PAGI‐SYM for 2 weeks prior to GES correlated with symptoms during the test for nausea (NGES, r = 0.61; DGES, r = 0.70), stomach fullness (NGES, r = 0.47; DGES, r = 0.60), and bloating (NGES, r = 0.62, DGES, r = 0.66). Conclusions & Inferences Stomach fullness, bloating, and abdominal pain recorded during GES were higher in patients with delayed gastric emptying than in patients with normal gastric emptying. Symptoms recorded during GES correlated with those during daily life by patient recall.     

Brain sonography insight into the midbrain in myotonic dystrophy type 2

Introduction: The aim of this study was to analyze transcranial sonography (TCS) findings in genetically confirmed myotonic dystrophy type 2 (DM2) patients. Methods: Forty DM2 patients and 38 gender‐ and age‐matched healthy controls (HCs) underwent TCS through the pre‐auricular acoustic bone window. Results: Substantia nigra hyperechogenicity was found in 20% of DM2 patients compared with 3% of HCs. Brainstem raphe (BR) hypoechogenicity was more common in DM2 patients compared with HCs (56% vs. 10%, P < 0.01), and it was more common in patients with fatigue and excessive daytime sleepiness (P < 0.05). Diameter of the third ventricle was increased in DM2 patients compared with HCs (5.8 ± 1.7 vs. 5.1 ± 1.0 mm, P < 0.05). Conclusions: Finding BR hypoechogenicity might have clinical implication because of the potential response to serotonin‐reuptake inhibitors. TCS revealed alterations in brain structures previously not seen in MRI studies. Muscle Nerve 53 : 700–704, 2016     

Anger in Parkinson's disease: A case‐control study

Cognitive‐psychiatric features of Parkinson's disease (PD) are common and they may be as disabling as the motor features of the disease. PD has been associated with stoic and inflexible personality traits. While many features of personality have been studied in PD, a systematic study of anger trait and anger expression in PD has not been performed. We used the Spanish adapted version of the state–trait anger Expression Inventory‐2 (STAXI‐2), comprised of six scales and an anger expression index, to measure anger trait and anger expression. There were 126 PD patients with depressive symptoms and 126 age‐ and gender‐matched controls. PD patients had lower levels of state anger (15.8 ± 3.1 vs. 17.9 ± 5.3, P < 0.001), trait anger (19.2 ± 5.3 vs. 20.7 ± 6.0, P < 0.05), anger expression‐out (9.0 ± 2.5 vs. 10.5 ± 3.0, P < 0.001), and anger expression index (26.1 ± 8.8 vs. 29.6 ± 9.4, P = 0.002); and higher levels in anger expression‐in (14.0 ± 3.4 vs. 12.2 ± 3.2, P < 0.001), anger control‐out (18.6 ± 5.0 vs. 16.1 ± 5.0, P < 0.001), and anger control‐in (14.3 ± 4.7 vs. 13.0 ± 4.5, P < 0.05) than controls. These differences persisted in analyses adjusting for age, gender, and depressive symptoms. Conclusions: PD patients showed lower levels of external expression of anger and higher levels of control of anger. Our results demonstrate another dimension to the stoic personality trait seen in PD. © 2007 Movement Disorder Society     

Metabolomics of Aerobic Exercise in Chronic Stroke Survivors: A Pilot Study

BackgroundUnderstanding the metabolic response to exercise may aid in optimizing stroke management. Therefore, the purpose of this pilot study was to evaluate plasma metabolomic profiles in chronic stroke survivors following aerobic exercise training.MethodsParticipants (age: 62 ± 1 years, body mass index: 31 ± 1 kg/m², mean ± standard error of the mean) were randomized to 6 months of treadmill exercise (N = 17) or whole-body stretching (N = 8) with preintervention and postintervention measurement of aerobic capacity (VO₂peak). Linear models for microarray data expression analysis was performed to determine metabolic changes over time, and Mummichog was used for pathway enrichment analysis following analysis of plasma samples by high-performance liquid chromatography coupled to ultrahigh resolution mass spectrometry.ResultsVO₂peak change was greater following exercise than stretching (18.9% versus −.2%; P < .01). Pathway enrichment analysis of differentially expressed metabolites results showed significant enrichment in 4 pathways following treadmill exercise, 3 of which (heparan-, chondroitin-, keratan-sulfate degradation) involved connective tissue metabolism and the fourth involve lipid signaling (linoleate metabolism). More pathways were altered in pre and post comparisons of stretching, including branched-chain amino acid, tryptophan, tyrosine, and urea cycle, which could indicate loss of lean body mass.ConclusionsThese preliminary data show different metabolic changes due to treadmill training and stretching in chronic stroke survivors and suggest that in addition to improved aerobic capacity, weight-bearing activity, like walking, could protect against loss of lean body mass. Future studies are needed to examine the relationship between changes in metabolomic profiles to reductions in cardiometabolic risk after treadmill rehabilitation.     

Twitch potentiation induced by two different modalities of neuromuscular electrical stimulation: Implications for motor unit recruitment

Introduction: We tested the hypothesis that twitch potentiation would be greater following conventional (CONV) neuromuscular electrical stimulation (50‐µs pulse width and 25‐Hz frequency) compared with wide‐pulse high‐frequency (WPHF) neuromuscular electrical stimulation (1‐ms, 100‐Hz ) and voluntary (VOL) contractions, because of specificities in motor unit recruitment (random in CONV vs. random and orderly in WPHF vs. orderly in VOL). Methods: A single twitch was evoked by means of tibial nerve stimulation before and 2 s after CONV, WPHF, and VOL conditioning contractions of the plantar flexors (intensity: 10% maximal voluntary contraction; duration: 10 s) in 13 young healthy subjects. Results: Peak twitch increased (P < 0.05) after CONV (+4.5 ± 4.0%) and WPHF (+3.3 ± 5.9%), with no difference between the 2 modalities, whereas no changes were observed after VOL (+0.8 ± 2.6%). Conclusions: Our results demonstrate that presumed differences in motor unit recruitment between WPHF and CONV do not seem to influence twitch potentiation results. Muscle Nerve 51: 412–418, 2015     

The effect of gastric secretion on gastric physiology and emptying in the fasted and fed state assessed by magnetic resonance imaging

Abstract Conventional measurement of gastric secretion is invasive and cannot assess the intra‐gastric distribution of gastric contents or the effects of secretion on gastric function. This study assessed the effect of gastric secretion on gastric volume responses and emptying (GE) using a validated fast T₁ mapping magnetic resonance imaging (MRI) technique. Twelve healthy participants were studied in the fasted state and after 200 kcal Gadolinium‐DOTA labelled glucose meal during intravenous infusion of pentagastrin or placebo in double‐blind, randomized order. Total gastric volume (TGV) and gastric content volume (GCV) was assessed by MRI volume scans and secretion by fast T₁ mapping. Data was described by the κ‐coefficient (volume change after meal ingestion), by GE half time (T₅₀) and maximal GE rate (GER_max) derived all from a GE model. Pentagastrin increased GCV and TGV compared to placebo [κ(GCV):1.6 ± 0.1 vs 0.6 ± 0.1; κ(TGV): 1.6 ± 0.1 vs 0.7 ± 0.1; P < 0.001]. T₁ maps revealed a secretion layer above the meal, the volume of which was associated with κ (R² = 83%, P < 0.001). TGV and GCV change were similar in both conditions (κ; P = ns). T₅₀ was higher for pentagastrin than for placebo (84 ± 7 vs 56 ± 4min, P < 0.001); however, GER_max was similar (5.9 ± 0.6 vs 4.9 ± 0.4 mL min^?1, P = ns). This study shows volume and distribution of gastric secretion can be quantified in‐vivo by non‐invasive MRI T₁ mapping. Increased GCV drove TGV accommodation without evidence of a direct effect of pentagastrin or excess acid on gastric function. Secretion increases GCV thus prolongs GE as assessed by T₅₀; however, GE rate is unchanged.     

Orexin‐A increases the firing activity of hippocampal CA1 neurons through orexin‐1 receptors

Orexins including two peptides, orexin‐A and orexin‐B, are produced in the posterior lateral hypothalamus. Much evidence has indicated that central orexinergic systems play numerous functions including energy metabolism, feeding behavior, sleep/wakefulness, and neuroendocrine and sympathetic activation. Morphological studies have shown that the hippocampal CA1 regions receive orexinergic innervation originating from the hypothalamus. Positive orexin‐1 (OX₁) receptors are detected in the CA1 regions. Previous behavioral studies have shown that microinjection of OX₁ receptor antagonist into the hippocampus impairs acquisition and consolidation of spatial memory. However, up to now, little has been known about the direct electrophysiological effects of orexin‐A on hippocampal CA1 neurons. Employing multibarrel single‐unit extracellular recordings, the present study showed that micropressure administration of orexin‐A significantly increased the spontaneous firing rate from 2.96 ± 0.85 to 8.45 ± 1.86 Hz (P < 0.001) in 15 out of the 23 hippocampal CA1 neurons in male rats. Furthermore, application of the specific OX₁ receptor antagonist SB‐334867 alone significantly decreased the firing rate from 4.02 ± 1.08 to 2.11 ± 0.58 Hz in 7 out of the 17 neurons (P < 0.05), suggesting that endogenous orexinergic systems modulate the firing activity of CA1 neurons. Coapplication of SB‐334867 completely blocked orexin‐A–induced excitation of hippocampal CA1 neurons. The PLC pathway may be involved in activation of OX₁ receptor–induced excitation of CA1 neurons. Taken together, the present study's results suggest that orexin‐A produces excitatory effects on hippocampal neurons via OX₁ receptors. © 2016 Wiley Periodicals, Inc.     

Coordination of fingertip forces during precision grip in premanifest Huntington's disease

Precision grip control is important for accurate object manipulation and requires coordination between horizontal (grip) and vertical (load) fingertip forces. Manifest Huntington's disease (HD) subjects demonstrate excessive and highly variable grip force and delayed coordination between grip and load forces. Because the onset of these impairments is unknown, we examined precision grip control in premanifest HD (pre‐HD) subjects. Fifteen pre‐HD and 15 age‐ and sex‐matched controls performed the precision grip task in a seated position. Subjects grasped and lifted an object instrumented with a force transducer that measured horizontal grip and vertical load forces. Outcomes were preload time, loading time, maximum grip force, mean static grip force, and variability for all measures. We compared outcomes across groups and correlated grip measures with the Unified Huntington's Disease Rating Scale and predicted age of onset. Variability of maximum grip force (P < .0001) and variability of static grip force (P < .00001) were higher for pre‐HD subjects. Preload time (P < .007) and variability of preload time (P < .006) were higher in pre‐HD subjects. No differences were seen in loading time across groups. Variability of static grip force (r² = 0.23) and variability of preload time (r² = 0.59) increased with predicted onset and were correlated with tests of cognitive function. Our results indicate that pre‐HD patients have poor regulation of the transition between reach and grasp and higher variability in force application and temporal coordination during the precision grip task. Force and temporal variability may be good markers of disease severity because they were correlated with predicted onset of disease. © 2011 Movement Disorder Society     

Effects of Thalamic Reticular Nucleus Electrical Stimulation in Rats in a T‐maze Perseverative Behavior Model Induced by 8‐OH‐DPAT

Objective. Evaluate the possible decrease of chemically induced perseverative behavior in rats after electrical stimulation at different frequencies in the thalamic reticular nucleus. Material and Methods. A total of 28 male rats were divided in four groups: control, sham, OFF stimulation, and ON stimulation (450 µsec, 1 V, 6 and 120 Hz) that underwent the administration of saline solution and 8‐OH‐DPAT. The animals were evaluated in a T‐maze model in which three choices or more in the same branch are considered as perseverative. Intragroup analysis was done through paired T‐student and intergroup analysis through an ANOVA test. Results. The numbers of perseverations mean for the control group were 1.3 before and 1.4 post saline solution injections. Sham group mean of 1.3 pre and 3.4 post 8‐OH‐DPAT administration; OFF stimulation group 1.1 pre and 3.3 post 8‐OH‐DPAT administration; and for ON stimulation 1.1 pre and 1.9 post 8‐OH‐DPAT administration for stimulation at low frequency (6 Hz) and 3.4 at high frequency (120 Hz). Evident intergroup statistical differences were shown (p < 0.01). Conclusions. Electrical stimulation with the low‐frequency group was the only group that after manipulation with 8‐OH‐DPAT showed a decrease in perseverative behavior, even close to baseline.