Estimates of persistent inward current in human motor neurons during postural sway

Persistent inward current (PIC) is a membrane property critical for increasing gain of motor neuron output. In humans, most estimates of PIC are made from plantarflexor or dorsiflexor motor units with the participant in a seated position with the knee flexed. This seated and static posture neglects the task-dependent nature of the monoaminergic drive that modulates PIC activation. Seated estimates may drastically underestimate the amount of PIC that occurs in human motor neurons during functional movement. The current study estimated PIC using the conventional paired motor unit technique which uses the difference between reference unit firing frequency at test unit recruitment and reference unit firing frequency at test unit de-recruitment (∆F) during triangular-shaped, isometric ramps in plantarflexion force as an estimate of PIC. Estimates of PIC were also made during standing anterior postural sway, a postural task that elicits a ramped increase and decrease in soleus motor unit activation similar to the conventional seated ramp contractions. For each motor unit pair, ∆F estimates of PIC made during conventional isometric ramps in the seated posture were compared to those made during standing postural sway. Baseline reciprocal inhibition (RI) was also measured in each posture using the post-stimulus time histogram (PSTH) technique. Hyperpolarizing input has been shown to have a reciprocal relationship with PIC in seated posture and RI was measured to examine if the same reciprocal relationship holds true during functional PIC estimation. It was hypothesized that an increase in ∆F would be seen during standing compared to sitting due to greater neuromodulatory input. We found that ∆F estimates during standing postural sway were equal (2.44 ± 1.17, p=0.44) to those in seated PIC estimates (2.73± 1.20) using the same motor unit pair. Reciprocal inhibition was significantly lower when measured in a standing posture (0.0031 ± 0.0251,

Task-dependent Modulation of Cortical Excitability and Balance Control in Individuals with Post-concussion Syndrome

In most cases, symptoms resolve between 7-10 days post-concussion. However, in 10-15% of the concussed population, symptoms can remain unresolved for months to years following the head injury. The purpose of this thesis was two-fold, and was broken up into two studies, where the same individuals participated in both studies. The purpose of the first study was to quantify the differences in balance control between individuals with PCS (i.e., had been experiencing symptoms for \u3c30 days) and non-concussed individuals during a lower-limb reaching task. Participants completed a static balance assessment before and after a lower-limb reaching task, which incorporated a Go/No-Go paradigm. Results from this study revealed no differences in the static stability assessments, however, individuals with PCS demonstrated increased medial-lateral COP displacement as well as greater trunk pitch during the reaching task. Overall, the findings reveal persistent balance impairments in individuals with PCS, which may put this population at an increased risk of further injury. The purpose of the second study was to assess task-dependent modulation of cortical excitability prior to planned index finger abduction contractions comparing a non-concussed population to a population with PCS. The protocol in this study consisted of both single and paired-pulse transcranial magnetic stimulation (TMS) which was applied prior to the beginning of 3 different tasks (i.e., a rest condition with no plan to contract, a precision contraction, and a powerful contraction). In addition to the three tasks, participants also had to respond to a Go/No-Go cue. The results of this study revealed an increase in excitability prior to a precision contraction in both non-concussed and PCS groups. No differences in task-dependent modulation were found between the two groups with respect to intracortical facilitation and inhibition, however a negative correlation between number of symptoms reported (SCAT3 symptom evaluation) and intracortical facilitation was revealed. The increase in corticospinal excitability prior to a precision contraction was not explained by the two cortical mechanisms we assessed and may therefore be due to spinal modulation or a different cortical mechanism. Overall, based on the results from this thesis, it appears that individuals with PCS have balance impairments, which may be a result of an inability to maximally activate their postural muscles. Furthermore, it appears that those individuals who reported a higher number of symptoms had greater reductions in intracortical facilitation, likely reflecting the heterogeneity of this clinical group

Down The Lane And Home Again

https://digitalcommons.library.umaine.edu/mmb-vp/5224/thumbnail.jp

Emerging Role of Nuclear Medicine in Oral and Maxillofacial Surgery

During the past several years, nuclear medicine has emerged as one of the most useful imaging studies in oral and maxillofacial surgery, not only in diagnosis and staging but also in the management plan and follow-up protocols of many cancer or inflammatory diseases. Nuclear medicine has in addition a special place in treating several benign and malignant diseases. The practicing maxillofacial surgeon’s knowledge of nuclear medicine capabilities and advantages and disadvantages of each modality is crucial in his or her daily work. The purpose of this chapter is to clarify the important role of nuclear medicine in diagnosis and treatment of oral and maxillofacial region pathologies as well as its indications and limitations in the daily practice of the oral and maxillofacial surgeon

Prevalence of Chlamydia abortus in Belgian ruminants

Chlamydia (C.) abortus enzootic abortion still remains the most common cause of reproductive failure in sheep-breeding countries all over the world. Chlamydia abortus in cattle is predominantly associated with genital tract disease and mastitis. In this study, Belgian sheep (n=958), goats (n=48) and cattle (n=1849) were examined, using the ID Screen (TM) Chlamydia abortus indirect multi-species antibody ELISA. In the sheep, the highest prevalence rate was found in Limburg (4.05%). The animals of Antwerp, Brabant and Liege tested negative. The prevalence in the remaining five regions was low (0.24% to 2.74%). Of the nine goat herds, only one herd in Luxembourg was seropositive. In cattle, the highest prevalence rate was found in Walloon Brabant (4.23%). The animals of Limburg and Namur tested negative. The prevalence rate in the remaining seven regions ranged between 0.39% and 4.02%

Sectioning and Counting of Motor Neurons in the L3 to L6 Region of the Adult Mouse Spinal Cord

Histology is the study of the microscopic structure of tissues. This protocol permits the generation of frozen transverse sections of lumbar spinal cord regions L3 to L6. It enables counting of murine ventral horn lumbar motor neurons in a reproducible manner. Methods include spinal column dissection, hydraulic extrusion, and histological processing. The preparation for cryo-sectioning includes embedding lumbar spinal cord in optimal cutting temperature (OCT) medium. The correct orientation of the tissue is critical as calculating the amount of tissue to discard saved time overall. Specific details regarding section thickness and mounting are described. These requirements not only allow optimum coverage of specific regions but also ensure that no individual motor neuron was counted twice. The Nissl bodies of the motor neurons were stained using gallocyanin. The sections obtained are all of a comparable area and quality assurance is consistent. The specificity of the staining enables the scientist to identify and reliably quantify lumbar motor neurons. © 2022 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Euthanasia of mouse and isolation of spinal cord. Basic Protocol 2: Hydraulic extrusion of the spinal cord. Basic Protocol 3: Identification of the lumbar region. Basic Protocol 4: Embedding cord in OCT. Basic Protocol 5: Collection of frozen sections onto slides. Basic Protocol 6: Gallocyanin staining. Basic Protocol 7: Motor neuron counting

Improved haemodynamic stability and cerebral tissue oxygenation after induction of anaesthesia with sufentanil compared to remifentanil : a randomised controlled trial

Background: Balanced anaesthesia with propofol and remifentanil, compared to sufentanil, often decreases mean arterial pressure (MAP), heart rate (HR) and cardiac index (CI), raising concerns on tissue-oxygenation. This distinct haemodynamic suppression might be attenuated by atropine. This double blinded RCT, investigates if induction with propofol-sufentanil results in higher CI and tissue-oxygenation than with propofol-remifentanil and if atropine has more pronounced beneficial effects on CI and tissue-oxygenation in a remifentanil-based anaesthesia. Methods: In seventy patients scheduled for coronary bypass grafting (CABG), anaesthesia was induced and maintained with propofol target controlled infusion (TCI) with a target effect-site concentration (Cet) of 2.0 mu g ml(- 1)and either sufentanil (TCI Cet 0.48 ng ml(- 1)) or remifentanil (TCI Cet 8 ng ml(- 1)). If HR dropped below 60 bpm, methylatropine (1 mg) was administered intravenously. Relative changes (increment ) in MAP, HR, stroke volume (SV), CI and cerebral (SctO(2)) and peripheral (SptO(2)) tissue-oxygenation during induction of anaesthesia and after atropine administration were analysed. Results: The sufentanil group compared to the remifentanil group showed significantly less decrease in MAP (increment = - 23 +/- 13 vs. -36 +/- 13 mmHg), HR (increment = - 5 +/- 7 vs. -10 +/- 10 bpm), SV (increment = - 23 +/- 18 vs. -35 +/- 19 ml) and CI (increment = - 0.8 (- 1.5 to - 0.5) vs. -1.5 (- 2.0 to - 1.1) l min(- 1) m(- 2)), while SctO(2) (increment = 9 +/- 5 vs. 6 +/- 4%) showed more increase with no difference in increment SptO(2) (increment = 8 +/- 7 vs. 8 +/- 8%). Atropine caused higher increment HR (13 (9 to 19) vs. 10 +/- 6 bpm) and increment CI (0.4 +/- 0.4 vs. 0.2 +/- 0.3 l min(- 1) m(- 2)) in sufentanil vs. remifentanil-based anaesthesia, with no difference in increment MAP, increment SV and increment SctO(2) and increment SptO(2). Conclusion: Induction of anaesthesia with propofol and sufentanil results in improved haemodynamic stability and higher SctO(2) compared to propofol and remifentanil in patients having CABG. Administration of atropine might be useful to counteract or prevent the haemodynamic suppression associated with these opioids