Development of an optimized and practical pharmacokinetics/pharmacodynamics analysis method for aztreonam/nacubactam against carbapenemase-producing K. pneumoniae.

BACKGROUND: Nacubactam, a new ß-lactamase inhibitor with antibacterial activity, is being developed as a single drug to be co-administered with cefepime or aztreonam. However, determining pharmacokinetics/pharmacodynamics (PK/PD) parameters in ß-lactam/ß-lactamase inhibitor combinations remains challenging. We aimed to establish a practical PK/PD analysis method for aztreonam/nacubactam that incorporates instantaneous MIC (MICi). METHODS: Based on chequerboard MIC measurements, MICi of aztreonam against carbapenemase-producing Klebsiella pneumoniae in the presence of nacubactam was simulated. RESULTS: The mean change in the bacterial count of thigh-infected mice in an in vivo PD study was plotted based on %fT>MICi and analysed using the inhibitory effect sigmoid Imax model. fT>MICi calculated from the PK experiments showed a high correlation with the in vivo bactericidal effect, suggesting that fT>MICi is the optimal PK/PD parameter for aztreonam/nacubactam. The target values of fT>MICi achieving growth inhibition, 1 log10 kill and 2 log10 kill, were 22, 38% and 75%, respectively. CONCLUSIONS: The PK/PD analysis method proposed in this study is promising for determining practical PK/PD parameters in combination therapy. In addition, this is the first report of aztreonam/nacubactam showing a potent in vivo therapeutic effect against NDM-producing K. pneumoniae.

Differences in Pharmacokinetic/Pharmacodynamic Parameters of Tedizolid Against VRE and MRSA.

PURPOSE: Vancomycin-resistant enterococci (VRE) have recently become a major cause of nosocomial infections and a global public health concern. Tedizolid exhibits powerful antibacterial activity against VRE in vitro, but its pharmacokinetic/pharmacodynamic (PK/PD) parameters remain unclear. Therefore, we aimed to determine the PK/PD indices of tedizolid action on VRE and the mechanisms underlying the PK/PD indices differences of tedizolid against VRE and methicillin-resistant Staphylococcus aureus (MRSA). METHODS: Optimal PK/PD target values of tedizolid were determined in vitro, based on time-kill curves and post-antibiotic effects (PAEs), and in vivo, using mouse models of thigh infection with VRE and MRSA strains. RESULTS: The tedizolid bactericidal activity on VRE and MRSA was time-dependent. Correlations were closest between fAUC24/MIC and the tedizolid PK/PD index against MRSA and VRE. To achieve 1 log10 kill tedizolid fAUC24/MIC in neutropenic mouse models of thigh infection with VRE and MRSA should be 14.2 and 138.5, respectively. The PAEs of tedizolid against VRE and MRSA were 2.39 and 0.99 h, respectively. CONCLUSION: Tedizolid showed bactericidal effects against VRE even in neutropenic mice unlike MRSA, which could be attributed to its longer PAE against VRE. Hence, we hypothesize that tedizolid treatment against VRE infections is promising for achieving therapeutic success in clinical.

In vivo Pharmacokinetics/Pharmacodynamics Profiles for Appropriate Doses of Cefditoren pivoxil against S. pneumoniae in Murine Lung-Infection Model.

PURPOSE: Cefditoren, the active form of cefditoren pivoxil, is an oral cephalosporin antimicrobial drug. Although cefditoren exhibits high antimicrobial activity against Streptococcus pneumoniae, its pharmacokinetics/pharmacodynamics (PK/PD) characteristics remain unknown. This study aimed to determine its PK/PD parameter with target values for cefditoren against S. pneumoniae in S. pneumoniae lung-infected mice and to simulate MIC range of S. pneumoniae that can be expected to be treated at approved cefditoren doses in human using population pharmacokinetic (PPK) data from patients. METHODS: Susceptibility testing and time-kill assays against S. pneumoniae ATCC® 49619 were performed for in vitro PD evaluation. Based on the results of a PK study in healthy mice and PD studies in S. pneumoniae lung-infected mice, optimal PK/PD parameters were determined using the correlation curve between the PK/PD parameters and lung bacterial count changes. The target value was calculated to achieve a 2 log10 reduction in the lung bacterial counts. RESULTS: In vitro PD evaluation showed that cefditoren had a potent antimicrobial effect against S. pneumoniae in a time-dependent manner at concentrations above the MIC. In PK/PD analyses, both fAUC24/MIC and fCmax/MIC were well correlated with bactericidal efficacy, achieving 2 log10-kill with fAUC24/MIC ≥ 63 and fCmax/MIC ≥ 16. CONCLUSIONS: Cefditoren pivoxil has good therapeutic efficacy against acute pneumonia caused by S. pneumoniae with a MIC ≤ 0.031-0.063 mg/L at approved doses in adults and children.

In vivo Pharmacokinetic/Pharmacodynamic Analysis of the Efficacy of the Cefepime/Nacubactam Combination Against ß-Lactamase-Producing Enterobacterales based on the Instantaneous MIC Concept.

PURPOSE: Nacubactam (NAC) is a novel diazabicyclooctane ß-lactamase inhibitor used in combination with cefepime (CFPM). In this study, we aimed to determine the target pharmacokinetics (PK) and pharmacodynamics (PD) values of CFPM/NAC in mice infected with ß-lactamase-producing Enterobacterales, such as the carbapenemase-producing Enterobacterales. METHODS: Three strains of ß-lactamase-producing Enterobacterales, Klebsiella pneumoniae MSC 21444, Escherichia coli MSC 20662, and K. pneumoniae ATCC BAA-1898, were used for checkerboard assays and fractionation studies and dose-range studies. A PK study was performed in neutropenic mice. Additionally, PK/PD analysis was performed based on the instantaneous minimum inhibitory concentration (MICi) concept. RESULTS: Checkerboard measurements revealed that higher NAC concentrations decreased the CFPM MIC in a concentration-dependent manner. In all tested strains, fT > MICi calculated from the PK experiments showed a high correlation with the mean change in the bacterial count of thigh-infected mice in the in vivo PD study, suggesting that fT > MICi is an optimal PK/PD parameter for monitoring the CFPM/NAC combination. The target fT > MICi values for CFPM/NAC to achieve a bacteriostatic effect, 1-log10-kill, and 2-log10-kill values were 30, 49, and 94%, respectively. CONCLUSIONS: Our results indicate that fT > MICi is a PK/PD parameter is suitable for monitoring the CFPM/NAC combination. The minimum target value for achieving a static effect against ß-lactamase-producing Enterobacterales is 30%.

Subjective and objective evaluation of swallowing in lateral decubitus positions examined in healthy volunteers.

BACKGROUND: Dysphagia can result from shock, trauma, aging, head and neck neoplasms, and some cerebrovascular diseases or neuromotor degenerative disorders. Swallowing rehabilitation therapy combined with postural control of the neck, head, and body can be effective for patients with dysphagia. Though the lateral decubitus posture has been a favorable option for swallowing rehabilitation therapy, available clinical data pertaining to it are scarce. METHODS: Twenty-seven healthy volunteers were enrolled in this study. The subjects underwent a repetitive saliva swallowing test, food swallowing test, and water swallowing test. The trials were performed in four different positions: upright sitting position, lateral decubitus position with the head raised to 60°, lateral decubitus position with the head raised to 30°, and complete lateral decubitus position. After each trial, the subjects were asked to declare the swallowing difficulty utilizing a visual analogue scale. Swallowing time and swallowing sound level were recorded simultaneously, as objective evaluation in each trial. We analyzed the visual analogue scale scores, swallowing time, and swallowing sound levels for all the four positions. RESULTS: The results of the visual analogue scale of the water swallowing test in the sitting position were significantly lower than those of the complete lateral decubitus position (p < 0.01). However, statistical significance was not detected in swallowing time or the swallowing sound level among the four different positions. Although subjective discomfort in swallowing was identified, difficulty of swallowing was not objectively evident in the trials, irrespective of the position. CONCLUSIONS: A complete lateral decubitus position can be an effective and safe position in swallowing.

Cefmetazole as an Alternative to Carbapenems Against Extended-Spectrum Beta-Lactamase-Producing Escherichia coli Infections Based on In Vitro and In Vivo Pharmacokinetics/Pharmacodynamics Experiments.

PURPOSE: Cefmetazole (CMZ) has received attention as a pharmaceutical intervention for extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-EC) infections. This study aimed to investigate the pharmacokinetics/pharmacodynamics (PK/PD) characteristics of CMZ against ESBL-EC. METHODS: The susceptibility and time-killing activity of CMZ against clinically isolated ESBL-EC (EC9 and EC19) were determined in vitro. The optimal PK/PD index and its target value were calculated based on the results of a PK study in healthy mice and PD study in neutropenic murine thigh infection model mice. RESULTS: The minimum inhibitory concentrations (MICs) of CMZ against EC9 and EC19 were 2.0 and 1.0 µg/mL, respectively. Time-kill studies showed that colony-forming units decreased in a time-dependent manner at CMZ concentrations in the range of 4-64 × MIC. In in vivo PK/PD studies, the antibacterial effect of CMZ showed the better correlation with the time that the free drug concentration remaining above the MIC (fT>MIC), with the target values for a static effect and 1 log10 kill reduction calculated as 57.6% and 69.6%, respectively. CONCLUSION: CMZ possesses time-dependent bactericidal activities against ESBL-EC and is required to achieve "fT>MIC" ≥ 69.6% for the treatment of ESBL-EC infections.

Comparison of a Bayesian estimation algorithm and singular value decomposition algorithms for 80-detector row CT perfusion in patients with acute ischemic stroke.

PURPOSE: A variety of postprocessing algorithms for CT perfusion are available, with substantial differences in terms of quantitative maps. Although potential advantages of a Bayesian estimation algorithm are suggested, direct comparison with other algorithms in clinical settings remains scarce. We aimed to compare performance of a Bayesian estimation algorithm and singular value decomposition (SVD) algorithms for the assessment of acute ischemic stroke using an 80-detector row CT perfusion. METHODS: CT perfusion data of 36 patients with acute ischemic stroke were analyzed using the Vitrea implemented a standard SVD algorithm, a reformulated SVD algorithm and a Bayesian estimation algorithm. Correlations and statistical differences between affected and contralateral sides of quantitative parameters (cerebral blood volume [CBV], cerebral blood flow [CBF], mean transit time [MTT], time to peak [TTP] and delay) were analyzed. Agreement of the CT perfusion-estimated and the follow-up diffusion-weighted imaging-derived infarct volume were evaluated by nonparametric Passing-Bablok regression analysis. RESULTS: CBF and MTT of the Bayesian estimation algorithm were substantially different and showed a better correlation with the standard SVD algorithm (ρ = 0.78 and 0.80, p < 0.001) than with the reformulated SVD algorithm (ρ = 0.59 and 0.39, p < 0.001). There is no significant difference in MTT only when using the reformulated SVD algorithm (p = 0.217). Regarding the regression lines, the slope and intercept were nearly ideal with the Bayesian estimation algorithm (y = 2.42 x-6.51; ρ = 0.60, p < 0.001) in comparison with the SVD algorithms. CONCLUSIONS: The Bayesian estimation algorithm can lead to a better performance compared with the SVD algorithms in the assessment of acute ischemic stroke because of better delineation of abnormal perfusion areas and accurate estimation of infarct volume.

The Use of the Carotid Sheath as a Rotation Anchor to Detect an Anomalous Ascending Pharyngeal Artery in Carotid Endarterectomy.

Carotid endarterectomy (CEA) requires complete control of the blood backflow. An anomalous ascending pharyngeal artery (AphA) has been reported to result in incomplete control of the blood flow during CEA. Here, we present a case of symptomatic right internal carotid stenosis for which CEA was performed. An anomalous AphA was confirmed based on its origin from the distal internal carotid artery (ICA) on 3-dimensional rotational angiography (3DRA). The anomalous AphA arose near the distal end of the plaque, and the origin of the AphA was located in the dorsal wall of the ICA, hidden from the surgical view. The origin of the AphA was detected with rotation of the ICA within the carotid sheath (CS). Intraoperatively, the blood flow from the AphA was completely controlled with clamping of the origin of the AphA. We emphasize the importance of the 3DRA to detect an anomalous AphA and propose the use of the CS as an anchor to rotate the ICA for optimizing the surgical view behind the ICA. This simple surgical technique facilitates to detect and clamp an anomalous AphA arising from the ICA.

Histochemical study of rabbit medial pterygoid muscle during postnatal development.

The medial pterygoid muscle is a layered structure like the masseter muscle. This study aimed at investigating the regional differences in fiber type composition and fiber diameter of the medial pterygoid muscle in the rabbit from birth until 33 weeks of age. Histochemical analysis of the medial pterygoid muscle was performed during five developmental stages (4, 9, 12, 18, and 33 weeks after birth) in 30 male Japanese white rabbits. Six fiber types (I, IC, IIC, IIA, IIAB, and IIB) were identified by mATPase staining. An increase in diameter was observed in fiber types I and IC until 9 weeks of age, and in fiber types IIC, IIA, IIAB, and IIB until 33 weeks of age. No significant differences in fiber diameter were noted in the different regions of the pterygoid muscle. Moderate fast to slow fiber type shifts occurred from weeks 4-12; thereafter, a rapid slow to fast fiber type shift was observed. Significant differences in fiber type composition based on regional differences were noted at 4 weeks of age. However, there was no difference in fiber type composition between regions at 33 weeks. In conclusion, it was clear that the diameter and proportion of fast fibers had increased even after reaching sexual maturity in rabbits. In addition, the medial pterygoid muscle tissues appeared to be homogenous at 33 weeks of age with very few differences between regions.

Endovascular Treatment May Be Effective in Preventing Recurrence of Ischemic Stroke in Vertebral Artery Stump Syndrome: A Case Series.

Vertebral artery stump syndrome (VASS) is a rare condition that can cause posterior circulation ischemic stroke due to occlusion of the ipsilateral vertebral artery (VA) orifice, resulting in blood flow stagnation and embolus formation. Although there is no established treatment for this condition, we observed 3 cases of VASS out of 326 acute ischemic stroke cases at a single institution from April 2021 to October 2022. Despite the best possible antithrombotic treatment, all 3 patients had recurrent ischemic strokes. One patient underwent drug-eluting stenting of the VA orifice to relieve occlusive flow. The other 2 patients received coil embolization, which resulted in the disappearance of their culprit collateral flow. None of the patients had recurrent ischemic strokes after endovascular intervention. Based on our observations, stenting and coil embolization are effective methods for preventing future recurrences of VASS.

Dilation of proximal internal carotid artery collapse due to severe distal stenosis after angioplasty for distal stenosis: A case report.

Background: We report a case of proximal internal carotid artery (ICA) collapse due to severe distal stenosis that dilated after angioplasty for distal stenosis. Case Description: A 69-year-old woman underwent thrombectomy for the left ICA occlusion due to stenosis of C3 portion and was discharged home with a modified Rankin Scale score of 0. One year later, she developed cerebral infarction due to progressive stenosis of the C3 portion of the left ICA with proximal ICA collapse and underwent emergency percutaneous transluminal angioplasty (PTA) for distal stenosis. Device guidance to the stenosis was difficult due to proximal ICA collapse. After PTA, blood flow in the left ICA increased, and proximal ICA collapse dilated over time. Due to severe residual stenosis, she underwent more aggressive PTA followed by Wingspan stenting. Device guidance to the residual stenosis was facilitated because proximal ICA collapse had already dilated. Six months later, proximal ICA collapse further dilated. Conclusion: PTA for severe distal stenosis with proximal ICA collapse may result in dilation of proximal ICA collapse over time.

Correlation of Scoring Systems with the Requirement of an External Ventricular Drain in Intraventricular Hemorrhage.

BACKGROUND: External ventricular drainage (EVD) is required to resolve acute hydrocephalus associated with intraventricular hemorrhage (IVH). The correlation of scoring systems of IVH with indications for EVD for acute hydrocephalus related to IVH is currently unknown. METHODS: We identified 213 hypertensive patients with IVH and divided them into 2 groups according to treatment method: 187 patients receiving blood pressure control alone and 26 patients undergoing EVD. The following patients were excluded: pediatric patients, patients undergoing intracranial hematoma removal, patients with fetal status, and patients without sufficient clinical data. We compared the Glasgow Coma Scale score, Graeb score, LeRoux score, Evans index, and bicaudate index values between the 2 groups and determined the prognostication accuracy of each scoring system. RESULTS: There were significant differences in all 4 scoring systems between the 2 groups (P < 0.001). The cutoff values (sensitivity and specificity) of each scoring system were as follows: Glasgow Coma Scale, 8 (65.4%, 87.7%); Graeb score, 6 (80.8%, 75.4%); LeRoux score, 9 (80.8%, 76.5%); Evans index, 0.245 (80.8%, 67.9%); and bicaudate index, 0.186 (76.9%, 76.5%). The value of the area under the curve of each scoring system (95% confidence interval) was as follows: Glasgow Coma Scale, 0.806 (0.705-0.907); Graeb score, 0.852 (0.779-0.925); LeRoux score, 0.875 (0.812-0.937); Evans index, 0.788 (0.702-0.875); and bicaudate index, 0.778 (0.673-0.883). CONCLUSIONS: The LeRoux score is better for identifying patients with IVH who are more likely to have EVD.

Efficacy of surgical skin preparation with chlorhexidine in alcohol according to the concentration required to prevent surgical site infection: meta-analysis.

BACKGROUND: A combination of chlorhexidine gluconate and alcohol (CHG-alcohol) is recommended for surgical skin preparation to prevent surgical site infection (SSI). Although more than 1 per cent CHG-alcohol is recommended to prevent catheter-related bloodstream infections, there is no consensus regarding the concentration of the CHG compound for the prevention of SSI. METHODS: A systematic review and meta-analysis was performed. Four electronic databases were searched on 5 November 2020. SSI rates were compared between CHG-alcohol and povidone-iodine (PVP-I) according to the concentration of CHG (0.5 per cent, 2.0 per cent, 2.5 per cent, and 4.0 per cent). RESULTS: In total, 106 of 2716 screened articles were retrieved for full-text review. The risk ratios (RRs) of SSI for 0.5 per cent (6 studies) and 2.0 per cent (4 studies) CHG-alcohol were significantly lower than those for PVP-I (RR = 0.71, 95 per cent confidence interval (c.i.) 0.52 to 0.97; RR = 0.52, 95 per cent c.i 0.31 to 0.86 respectively); however, no significant difference was observed in the compounds with a CHG concentration of more than 2.0 per cent. CONCLUSIONS: This meta-analysis is the first study that clarifies the usefulness of an alcohol-based CHG solution with a 0.5 per cent or higher CHG concentration for surgical skin preparation to prevent SSI.

Population genomics and haplotype analysis in spelt and bread wheat identifies a gene regulating glume color.

The cloning of agriculturally important genes is often complicated by haplotype variation across crop cultivars. Access to pan-genome information greatly facilitates the assessment of structural variations and rapid candidate gene identification. Here, we identified the red glume 1 (Rg-B1) gene using association genetics and haplotype analyses in ten reference grade wheat genomes. Glume color is an important trait to characterize wheat cultivars. Red glumes are frequent among Central European spelt, a dominant wheat subspecies in Europe before the 20th century. We used genotyping-by-sequencing to characterize a global diversity panel of 267 spelt accessions, which provided evidence for two independent introductions of spelt into Europe. A single region at the Rg-B1 locus on chromosome 1BS was associated with glume color in the diversity panel. Haplotype comparisons across ten high-quality wheat genomes revealed a MYB transcription factor as candidate gene. We found extensive haplotype variation across the ten cultivars, with a particular group of MYB alleles that was conserved in red glume wheat cultivars. Genetic mapping and transient infiltration experiments allowed us to validate this particular MYB transcription factor variants. Our study demonstrates the value of multiple high-quality genomes to rapidly resolve copy number and haplotype variations in regions controlling agriculturally important traits.

Two neuronal groups for NaCl with differential taste response properties and topographical distributions in the rat parabrachial nucleus.

It is crucial for animals to discriminate between palatable (safe) and aversive (toxic) tastants. The mechanisms underlying neuronal discrimination of taste stimuli remain unclear. We examined relations between taste response properties (spike counts, response duration, and coefficient of variation [CV]) and location of taste-sensitive neurons in the pontine parabrachial nucleus (PBN). Extracellular single units' activity in the PBN of Wistar rats was recorded using multibarrel glass micropipettes under urethane anesthesia. Forty taste-sensitive neurons were classified as NaCl (N)-best (n = 15), NaCl/HCl (NH)-best (n = 14), HCl (H)-best (n = 8), and sucrose (S)-best (n = 3) neurons. The net response to NaCl (15.2 ± 2.3 spikes/s) among the N-best neurons was significantly larger than that among the NH-best (4.5 ± 0.8 spikes/s) neurons. The response duration (4.5 ± 0.2 s) of the N-best neurons to NaCl was significantly longer than that of the NH-best (2.2 ± 0.3 s) neurons. These differences in the spike counts and the response durations between the two neuronal types in the PBN were similar to that previously reported in the rostral nucleus of the solitary tract (rNST). The CVs in the N-best and the NH-best neurons were significantly smaller in the PBN than those in the rNST. Histologically, most N-best neurons (12/13, 92%) were localized to the medial region, while NH-best neurons (11/13, 85%) were primarily found within the brachium conjunctivum. These results suggest that NaCl-specific taste information is transmitted by two distinct neuronal groups (N-best and NH-best), with different taste properties and locations within rNST to PBN tractography. Future studies on the higher order nuclei for taste could reveal more palatable and aversive taste pathways.

Subarachnoid Hemorrhage From a Distal Middle Cerebral Artery Aneurysm Possibly Related to Segmental Arterial Mediolysis.

BACKGROUND: Distal middle cerebral artery aneurysm (DMCAAn) is rare, and the clinical features and the etiology are not well understood. Segmental artery mediolysis (SAM) is a pathologic entity that affects the media of the muscular artery and can cause arterial dissection and a hemorrhagic event. Subarachnoid hemorrhage (SAH) due to SAM in the vertebral artery has been documented. However, SAH from a ruptured DMCAAn due to SAM has not yet been described. CASE DESCRIPTION: A 49-year-old woman presented with a headache and vomiting. Computed tomography (CT) revealed SAH, and CT angiography showed a DMCAAn, which was treated by trapping and resection. Histopathologic studies showed loss of the media and reparative changes in the arterial wall including intimal hyperplasia and increased vasa vasorum in the adventitia. These findings were indicative of SAM in the reparative phase. She did not show any other possible etiologies of DMCAAn including infectious endocarditis and vasculitis, and CT angiography of the trunk did not show any other vascular lesions. She was discharged from the hospital approximately 3 weeks after the surgery without any apparent neurological deficits. CONCLUSIONS: Our case suggests that SAM can also occur in the middle cerebral artery and result in DMCAAn.

Changes in masseter muscle fibers by liquid diet rearing in rabbits and recovery by chewing of solid diet.

OBJECTIVE: To investigate the effects of liquid diet on the development of masseter muscle fibers and whether the changes in the masseter muscle can be recovered by chewing of solid diet. DESIGN: Masseter muscles from 40 rabbits (solid- and liquid-diet groups, n = 30; unweaned group, n = 5; recovery group, n = 5) were histochemically examined at 4, 12, 18, and 33 weeks after birth. Six fiber types (I, IC, IIC, IIA, IIAB, and IIB) were distinguished via mATPase staining. Muscle fiber diameter and fiber type composition were measured and compared between groups. RESULTS: In the liquid diet group, the diameter of types IIAB (solid group: 81.7 µm, liquid group: 60.9 µm) and IIB (solid group: 89.3 µm, liquid group: 68.8 µm) and the fiber type composition of type I (solid group: 18.4%, liquid group: 9.6%) decreased significantly at 33 weeks of age. In the recovery group, the fiber type composition of type I fibers recovered to 16.5%, while no recovery of type IIAB (56.6 µm) and IIB (64.6 µm) fiber diameter was observed. CONCLUSIONS: Liquid diet caused atrophy of muscle fibers and an increase in the proportion of fast-twitch fibers. Although the diameter and ratio of slow-twitch fibers were recovered by chewing of solid diet, recovery was not observed for fast-twitch fibers. Our findings are relevant for dental medicine as it explored the possibility of masticatory muscle function recovery by hard food.

Movement of the mandibular condyle and activity of the masseter and lateral pterygoid muscles during masticatory-like jaw movements induced by electrical stimulation of the cortical masticatory area of rabbits.

We examined the functional role of the lateral pterygoid muscle (LP) and the masseter muscle (MS) in the movement of the mandibular condyle in masticatory-like jaw movements induced by electrical stimulation of the cortical masticatory area of urethane-anaesthetised rabbits. EMGs of the LP and MS were recorded along with video images of the mandibular condyle movement filmed with a high-speed CCD camera at a time resolution of 8 ms. The time required for the contractile force of the MS and LP to emerge as bite force or jaw movement was determined by direct electrical stimulation to respective muscles: 32.8+/-1.5 ms for the MS and 34.3+/-2.9 ms for the LP. The LP on the working side showed biphasic activity not only in the jaw-opening phase but also in the middle occlusal phase. It is assumed that the MS on the working side begins to exert actually the maximum mechanical influence on the bite force 32.8 ms after its EMG peak in the early occlusal phase. Such development of the mechanical effect of the MS during middle occlusal phase is appeared to be involved in stabilization of the condyle in the middle occlusal phase. Approximately 25 ms (25.1+/-2.5 ms) after the peak of mechanical influence of the MS, the mechanical influence of the working-side LP activity reached maximum in the late stage of the occlusal phase. This LP mechanical influence seems to be functionally associated with an antero-inferior movement of the working side condyle in the late stage of the occlusal phase that is coincident with a movement of the incisal point towards the balancing side across the midline.

Velocity-dependent EMG activity of masseter and sternocleidomastoideus muscles during a ballistic arm thrusting movement.

Two experiments were conducted to investigate the functional relationship between the general somatic motor function and the oral motor function. In Experiment 1, we analyzed the relationship between the amount of masseter muscle (MSS) activity and the velocity of a ballistic, 'karate-do' arm thrusting movement (ThrMov). ThrMov velocity was measured from video images taken with a high-speed CCD camera at a frequency of 500Hz. EMGs of MSS and sternocleidomastoideus (SCM) muscles as well as other related muscles were recorded simultaneously with video images in 6 varsity 'karate-do' athletes. Pearson's correlation coefficients were calculated between EMG amplitude and movement velocity. EMG activity of MSS as well as the other muscles increased as a function of ThrMov velocity in all participants, as evidenced by highly significant (p<.01) correlation coefficients, ranging from .64 to .87 (mean: .75). MSS EMG activity attained during ThrMovs performed at maximum velocity ranged between 14.6% and 113.8% of this muscle's MVC (45.7+/-39.3% MVC, mean+/-SD). SCM was also strongly active and closely associated with MSS. Besides changes in amount of EMG activity, it was further found that R-MSS EMG onset progressively shifted to the earlier phase of the ThrMov as ThrMov velocity increased. EMG onset time of R-MSS as well as R- and L-SCMs was negatively correlated with ThrMov velocity; when performed at maximum velocity MSS activation preceded the start of ThrMov by more than 100ms, whereas MSS was recruited last at approximately 150ms after the start of ThrMov when performed at moderate speed ( approximately 50% of maximum). In Experiment 2, the effects of head movement relative to the trunk on R-MSS and SCMs EMG activity were tested in both gazing and sidelong glancing conditions. A much smaller head rotation relative to the trunk was necessary during the ThrMov in the sidelong glancing condition compared to the gazing condition. R-MSS EMG activity was affected significantly by the difference between these conditions and decreased by 5.2% MVC in the sidelong glancing condition compared to the gazing condition. In association with the change in requirement for head movement between those conditions, EMG balance between the bilateral SCMs changed substantially. Finally, marked muscle activity during ThrMov was found in the MSS that was not directly involved in performing this movement, indicating a form of 'remote facilitation'.

External Ventricular Drainage Preceding the Removal of a Nail from the Intracranial Space as a Safe Management Strategy for Predicted Secondary Intraventricular Hemorrhage.

BACKGROUND: Intracranial nail gun injury is a rare traumatic event and can result from a suicide attempt. Cerebral angiography is essential in the evaluation of damage to the intracranial vessels, and surgical removal of nails is generally the optimal treatment. Intraventricular hemorrhage can happen after removal of intracranial nails. Endovascular surgery or intraoperative computed tomography has been reported to be useful for detection and treatment of intraventricular hemorrhage. After the surgical removal of nails, attention should be paid for complications such as pseudoaneurysm and infection. CASE DESCRIPTION: A 63-year-old man with a history of depression was transferred to our hospital in an unconscious state. Physical examination showed 2 nails puncturing his left thorax, and computed tomography revealed a nail puncturing the intracranial space. No damage to these intracranial vessels was observed on computed tomography angiography and venography. After drainage for potential intraventricular hemorrhage, the nails were removed. Postoperatively, prophylactic antibiotic therapy was administrated for secondary infection. Computed tomography angiography did not detect any postoperative pseudoaneurysms. The patient also underwent therapy from a psychiatrist and was transferred to another hospital. CONCLUSIONS: As for treatment of a case of intracranial nail gun injury, our case shows that preoperative cerebral angiography is not always needed in intracranial nail gun injury when there is no apparent damage to the intracranial vessels and emergent removal of nails is required. External ventricular drainage preceding the removal of a puncture object can be an effective management strategy for secondary intraventricular hemorrhage.