Maximal isometric force and neural activity during bilateral and unilateral elbow flexion in humans

We investigated maximal isometric force and electromyographic (EMG) activity of the biceps brachii muscle during rapid bilateral (BL) and unilateral (UL) elbow flexion in 11 right-handed subjects. The BL exhibited a deficit in force for both arms and more so for the right than the left arm during the rising phase of force generation. The EMG of the left biceps brachii muscle was similar during UL and BL, but for the right arm EMG was lower during BL than during UL for the rising phase of force generation. The BL to UL ratio of mean power frequency of the EMG was lower for the right than for the left arm. The data would suggest that the relatively small BL strength was associated with a equally small EMG and a shift to a lower mean power frequency especially for the fast motor units of the dominant muscle.     

Further insight into the task-dependent excitability of motor evoked potentials in first dorsal interosseous muscle in humans

We have reexamined the contradictory evidence in which task-dependent excitation of motor evoked potentials (MEPs) in the first dorsal interosseous (FDI) muscle was stronger with increasingly more complex finger tasks than with individual finger movement tasks. In the first step of the experiment, based on previous findings, we investigated remarkable functional differences between intrinsic and extrinsic hand muscles during complex finger tasks (precision and power grip). During the performance of the tasks, the optimal stimulus intensity of the transcranial magnetic stimulation (TMS) was applied to the contralateral motor cortex. MEPs of the FDI, extensor carpi radialis (ECR), and flexor carpi radialis (FCR) muscles were recorded simultaneously with increased background EMG activity step by step in both tasks. The intensity threshold of TMS was lower in the precision grip. Furthermore, the MEP amplitudes of FDI muscle dependent on the background EMG activity were different between these two tasks, i.e., MEP amplitudes and regression coefficients in a precision grip were larger than those in a power grip. Although our results for MEP amplitude and threshold in the FDI muscle were similar to previous reported evidence, the different contributions of a synergistic muscle (in particular, the ECR muscle) during performance in these tasks was new evidence. Since there were no differences in cutaneous afferent effects on both tasks, corticomotoneuronal (CM) cells connected to FDI motoneurons seemed generally to be more active during precision than power gripping, and there were different contributions from synergistic muscles during the performance of these tasks. In the second part of the experiment, the results obtained from the complex tasks were compared with those from a simple task (isolated index finger flexion). MEP amplitudes, dependent on the background EMG activity during isolated index finger flexion, varied among subjects, i.e., the relationship between the MEP amplitude and the background EMG of the FDI muscle showed individual, strategy-dependent modulation. There were several kinds of individual motor strategies for performing the isolated finger movement. The present results may explain the previous contradictory evidence related to the contribution of the CM system during coordinated finger movement.     

Retrograde labeling of mouse spinal descending tracts by a recombinant adenovirus

The present study tested whether a gene-transfer based upon the retrograde axonal transport of the lacZ adenovirus is effective in the spinal descending tracts of the adult mouse. A small volume of a replication-defective recombinant adenovirus encoding E. coli beta-galactosidase was injected into the upper lumbar cord, and, seven days later, the mice were transcardially perfused by a fixative solution. X-gal staining of coronal or sagittal sections of the spinal cord and the brain revealed that many sites of origin for rubrospinal, vestibulospinal, and reticulospinal tracts were retrogradely labeled, whereas few of the corticospinal tract neurons were retrogradely labeled. Ependymal cells surrounding the central canal of the spinal cord, which were located far from the injection site, showed a high expression of beta-galactosidase activity. Motoneurons around the injection site were strongly stained by X-gal staining, and their axons in the ventral root were anterogradely labeled. Afferent fibers in the dorsal root were labeled by the transganglionic transport of beta-galactosidase. To examine the efficacy of the uptake and retrograde transport of HRP and adenovirus, we injected a mixed solution of 10% HRP and recombinant adenovirus. The number of HRP-labeled corticospinal neurons overwhelmed the number of X-gal stained ones, while the numbers of HRP-labeled rubrospinal and subcoeruleus-spinal neurons were smaller in comparison with the numbers of beta-galactosidase-positive counterparts. The present study revealed that the origins for the spinal descending tracts except for corticospinal neurons could be efficiently gene-transferred by the retrograde infection of a recombinant adenovirus. Such a difference in efficacy of retrograde infection among the spinal descending tracts is practically important when an adenovirus-mediated gene transfer is designed to treat certain neurological diseases affecting the spinal descending tracts.     

Requirement of IL-5 for induction of autoimmune hemolytic anemia in anti-red blood cell autoantibody transgenic mice

IL-5, IL-10 and lipopolysaccharide (LPS) are known to activateB-1 cells in vivo in normal mice and anti-red blood cell autoantibodytransgenic mice (HL mice). To assess the exact role of IL-5in proliferation and activation of peritoneal B-1 cells, weanalyzed IL-5 receptor chain-deficient HL (IL-5R^–/–x HL) mice generated by the cross between IL-5R^–/–and HL mice. In IL-5R^–/– x HL mice, Ig-producingB-1 cells in the peritoneal cavity were negligible, althoughthe total number of B-1 cells in the peritoneal cavity wereas many as 30% of that in HL mice. Moreover, LPS- or IL-10-induceddifferentiation of B-1 cells into antibody-producing cells wasseverely impaired in IL-5R^–/– x HL mice. We alsoused in vivo 5-bromo-2'-deoxyuridine labeling to estimate theproliferation of B-1 cells in IL-5R^–/– mice. Theabsence of IL-5R did not affect spontaneous proliferation ofperitoneal B-1 cells. However, induced proliferation of peritorealB-1 cells by oral administration of LPS was markedly impairedin IL-5R^–/– mice. These results suggest that IL-5is required for activation-associated proliferation of B-1 cellsbut not for their spontaneous proliferation and support theidea that IL-5 plays an important role on the induction of autoantibodyproduction from B-1 cells.     

The role of γδ T cells in priming macrophages to produce tumor necrosis factor-α

The secretion of tumor necrosis factor (TNF)-α from macrophages is regulated by both priming and triggering signals. We found that macrophages from mice lacking γδ T cells [T cell receptor (TCR) δ^?/- mice], which lack the gene encoding the δ chain, produced only small amounts of TNF-α in response to lipopolysaccharide (LPS) and showed a reduced level of expression of CD14. Pre-incubation of macrophages from TCR δ-/- mice with γδ T cells from their TCR δ^+/- littermates restored their capacity to produce TNF-α in response to LPS. The priming activity of γδ T cells was in part inhibited by neutralizing anti-interferon (IFN)-γ monoclonal antibodies. Collectively, these results suggest that γδ T cells play a role in priming macrophages to a steady state of activation via IFN-γ secretion, which allows them to produce TNF-α when exposed to LPS.     

Positron CT imaging using a high resolution PCT device (Positologica-I),11CO,13NH3, and18FDG in clinical evaluation of cerebrovascular diseases

Positron computed tomography (PCT) was performed in 3 normal volunteers and 21 patients with cerebrovascular diseases using a high resolution PCT device Positologica-I and three tracers¹¹CO,¹³NH₃, and¹⁸FDG. Relatively early lesions showed various accumulation patterns, and metabolism and perfusion mismatches were clearly shown by this measurement. One type of mismatch is luxury perfusion which had a slight increase of blood volume. Another type of uncoupling is misery perfusion. Remote effects of ischemic lesions also appeared on PCT with¹⁸FDG and¹³NH₃. From our clinical results, the PCT method with a high resolution device and radiopharmaceuticals such as¹¹CO,¹³NH₃, and¹⁸FDG is very useful in the assessment of cerebrovascular diseases and in defining circulatory dysfunction in man.     

Potential predictors of the onset of focal intestinal perforation in extremely low birth weight infants based on an analysis of coagulation and fibrinolysis markers at birth: A case-control study based on ten years of experience at a single institution

Purpose: We aimed to investigate potential predictors of focal intestinal perforation (FIP) in extremely low birth weight infants (ELBWIs) among coagulation and fibrinolysis markers at birth.Methods: We reviewed the medical records of FIP patients and their coagulation and fibrinolysis markers at birth between 2010 and 2019, and matched patients according to gestational age. FIP was diagnosed based on macroscopic intestinal perforation with a punched-out lesion without necrosis. Patient characteristics and blood test results, including coagulation and fibrinolysis marker levels, were compared between the groups.Results: Two hundred forty ELBWIs were enrolled in this study (FIP, n = 18; controls, n = 222). In the FIP group, the gestational age at birth was significantly younger (p = 0.023) and the birth weight was significantly lower (p = 0.007) in comparison to the control group. Furthermore, the FIP group showed significantly lower levels of fibrinogen (p = 0.027) and factor XIII (F-XIII) (p = 0.007). The receiver operating characteristics curves for fibrinogen and F-XIII revealed that the 95% confidence intervals of fibrinogen and F-XIII were 0.530–0.783 (p = 0.027), and 0.574–0.822 (p = 0.007), respectively.Conclusions: This is the first report focusing on coagulation and fibrinolysis markers in FIP patients at birth. The fibrinogen and F-XIII values at birth are potential predictors of FIP in ELBWIs.Type of Study: Study of Diagnostic Test (Case Control Study)Level of Evidence: Level IV     

Safety and efficacy of Tolvaptan in real-world patients with autosomal dominant polycystic kidney disease- interim results of SLOW-PKD surveillance

Clinical and Experimental Nephrology - Tolvaptan is a vasopressin type 2 receptor antagonist and has been used to treat autosomal dominant polycystic kidney disease (ADPKD) since 2014. There has...