Distal Shift Research Articles

Diagnostic Value of Measurements of Median Nerve Diameter at the Site of the Maximal Stenosis in Carpal Tunnel Syndrome.

Ultrasonography is increasingly used to diagnose the carpal tunnel syndrome (CTS). Most frequently, the enlargement of the nerve cross-sectional area (CSA) at the tunnel inlet serves to confirm the diagnosis. Recent research has shown that the nerve diameter is decreased within the tunnel, when measured at the level of pisiforme or capitatum. The stenosis index (SI), which uses the ratio of the diameter of median nerve at the tunnel inlet to the diameter within the tunnel (SI diameter), was proposed as the diagnostic marker of CTS. In this study, we compared the diameter of the median nerve measured at the site of maximal stenosis (DMS) between patients with CTS and controls. Additionally, we investigated the diagnostic utility of the modified SI, which uses the ratio of CSA at the inlet to the diameter within the tunnel (SI CSA). Forty-eight patients (72hands) with CTS and 18 asymptomatic controls (28hands) underwent electrodiagnostic testing and ultrasonography. CSA at the inlet was larger in patients, whereas DMS showed only trend towards being smaller in CTS. CTS was also associated with more distal localization of maximal stenosis. Both SI diameter and SI CSA were higher in patients, however the discriminative effect of SI CSA was stronger. SI diameter, SI CSA, CSA at the inlet and DMS correlated with the electrodiagnostic severity grade of CTS. The post-hoc analysis revealed that patients with moderate and severe electrodiagnostic grade of CTS have smaller DMS, whereas patients with mild CTS did not differ from controls. DMS seems to have only limited diagnostic potential in mild CTS, but it may be a marker of more advanced cases. CTS may be associated with the distal shift of DMS. SI CSA may have significant diagnostic potential in CTS.

Static magnetic stimulation induces structural plasticity at the axon initial segment of inhibitory cortical neurons

Static magnetic stimulation (SMS) is a form of non-invasive brain stimulation that alters neural activity and induces neural plasticity that outlasts the period of stimulation. This can modify corticospinal excitability or motor behaviours, suggesting that SMS may alter the intrinsic excitability of neurons. In mammalian neurons, the axon initial segment (AIS) is the site of action potential initiation and undergoes structural plasticity (changes in length and position from the soma) as a homeostatic mechanism to counteract chronic changes in neuronal activity. We investigated whether the chronic application of SMS (6 and 48 h, 0.5 T) induces structural AIS plasticity in postnatally derived primary cortical neurons. Following 6 h of SMS, we observed a shortening in mean AIS length compared to control, that persisted 24 h post stimulation. In contrast, 48 h of SMS induced an immediate distal shift that persisted 24 h post-stimulation. Pharmacological blockade of voltage gated L/T-type calcium channels during stimulation did not prevent SMS-induced AIS structural plasticity. Our findings provide the foundation to expand the use of chronic SMS as a non-invasive method to promote AIS plasticity.

Challenges Assessment in Endodontics Among Undergraduate Students.

Objective To explore perceptions of undergraduate dental students regarding difficulties faced during endodontic procedures. Methods An e-questionnaire was sent to 57 fourth-year and 45 fifth-year dental students. It comprised questions regarding demographic data and difficulties faced during different steps of the endodontic treatment. The responses were recorded on a 5-point Likert scale. During dichotomization, responses where one and two were chosen were considered yes whereas responses where three, four, and five were chosen were considered no. The sample size (SS) calculated using the Qualtrics SS calculator was 89. Data were analyzed using SPSS version 20. Frequencies and percentages were calculated. A p-value of less than 0.05 was considered significant. The chi-square test was applied for comparison based on the students' academic year and genders. Results Ninety students responded with an 88.2% response rate. Most students reported not facing any difficulty in differentiating healthy pulp and periapex from conditions of pulp pathosis (78.9%) and periapical pathosis (75.6%). Most males found access opening and de-roofing of the pulp chamber (35.6%) and working length determination (31.1%) difficult. Females reported having difficulty mostly in mesial and distal shift radiograph techniques (55.6%) and access openings (51.1%). No statistical difference was found based on an academic year or gender except in the use of mesial and distal shift techniques for radiograph acquisition Conclusion Assessing difficulties encountered by students during endodontic therapy can aid in the development of teaching strategies for preclinical and clinical instruction. Mesial and distal shift techniques, access cavity preparation, and working length determination are areas requiring more focus in the training process.

Neurofilament accumulations in amyotrophic lateral sclerosis patients’ motor neurons impair axonal initial segment integrity

Amyotrophic lateral sclerosis (ALS) is the most common motor neuron (MN) disease in adults with no curative treatment. Neurofilament (NF) level in patient’ fluids have recently emerged as the prime biomarker of ALS disease progression, while NF accumulation in MNs of patients is the oldest and one of the best pathological hallmarks. However, the way NF accumulations could lead to MN degeneration remains unknown. To assess NF accumulations and study the impact on MNs, we compared MNs derived from induced pluripotent stem cells (iPSC) of patients carrying mutations in C9orf72, SOD1 and TARDBP genes, the three main ALS genetic causes. We show that in all mutant MNs, light NF (NF-L) chains rapidly accumulate in MN soma, while the phosphorylated heavy/medium NF (pNF-M/H) chains pile up in axonal proximal regions of only C9orf72 and SOD1 MNs. Excitability abnormalities were also only observed in these latter MNs. We demonstrate that the integrity of the MN axonal initial segment (AIS), the region of action potential initiation and responsible for maintaining axonal integrity, is impaired in the presence of pNF-M/H accumulations in C9orf72 and SOD1 MNs. We establish a strong correlation between these pNF-M/H accumulations, an AIS distal shift, increased axonal calibers and modified repartition of sodium channels. The results expand our understanding of how NF accumulation could dysregulate components of the axonal cytoskeleton and disrupt MN homeostasis. With recent cumulative evidence that AIS alterations are implicated in different brain diseases, preserving AIS integrity could have important therapeutic implications for ALS.

Gallstone Ileus—Lessons from a Missed Diagnosis

AbstractGallstone ileus is an uncommon presentation in patients with acute abdomen. Its diagnosis and treatment are often delayed due to its nonspecific clinical presentation. Presence of gallstone in ileum can be difficult to detect on computed tomography (CT) as mostly they are lucent. We report the case of a 66-year-old man with a 1-day history of vomiting and abdominal bloating. Initial CT could not identify the obstructing gall stone. On the follow-up CT, there was a distal shift of obstruction site in the intestine raising suspicion of a gallstone. We discuss the imaging findings on CT and the clues to diagnosing gallstone ileus.

Structural plasticity of axon initial segment in spinal cord neurons underlies inflammatory pain.

Physiological or pathology-mediated changes in neuronal activity trigger structural plasticity of the action potential generation site-the axon initial segment (AIS). These changes affect intrinsic neuronal excitability, thus tuning neuronal and overall network output. Using behavioral, immunohistochemical, electrophysiological, and computational approaches, we characterized inflammation-related AIS plasticity in rat's superficial (lamina II) spinal cord dorsal horn (SDH) neurons and established how AIS plasticity regulates the activity of SDH neurons, thus contributing to pain hypersensitivity. We show that in naive conditions, AIS in SDH inhibitory neurons is located closer to the soma than in excitatory neurons. Shortly after inducing inflammation, when the inflammatory hyperalgesia is at its peak, AIS in inhibitory neurons is shifted distally away from the soma. The shift in AIS location is accompanied by the decrease in excitability of SDH inhibitory neurons. These AIS location and excitability changes are selective for inhibitory neurons and reversible. We show that AIS shift back close to the soma, and SDH inhibitory neurons' excitability increases to baseline levels following recovery from inflammatory hyperalgesia. The computational model of SDH inhibitory neurons predicts that the distal shift of AIS is sufficient to decrease the intrinsic excitability of these neurons. Our results provide evidence of inflammatory pain-mediated AIS plasticity in the central nervous system, which differentially affects the excitability of inhibitory SDH neurons and contributes to inflammatory hyperalgesia.

Efficacy of a newly designed angulation-adjustable film holder for reducing cone-cutting errors and saving time in horizontal tube-shift technique by dental students

ObjectivesTo compare the cone-cutting error frequency and the X-ray cone alignment time in the horizontal tube-shift technique between the newly designed angulation-adjustable and the extension cone paralleling (XCP) holders, by dental students. Materials and methodsTwo film holders were assigned for a random test. The mandibular left first molar position of a laboratory phantom head was used. Intraoral periapical radiography was performed horizontally at right-angle, 20° mesial-, and 20° distal projections by fifth-year dental students (n = 41). The cone-cutting error frequency and the X-ray cone alignment time were measured and analyzed statistically at a significant level of p < 0.05. ResultsUsing the two holders at right angle caused no significant difference (p > 0.05) in the cone-cutting error frequency or the X-ray cone alignment time. At the horizontal tube-shift angles, some significantly greater frequencies of cone-cutting errors at both 20° mesial (43.9%) and 20° distal (73.2%) shifts were detected in the XCP group, but none in the angulation-adjustable group. For X-ray cone alignment time at both 20° mesial and 20° distal shifts, the XCP group spent a significantly longer time (p < 0.05) than the angulation-adjustable group. ConclusionsThe usages of the angulation-adjustable holder in the horizontal tube-shift technique resulted in none of the cone-cutting error and a significant reduction of time for the X-ray cone alignment, when compared to those of the XCP instrument. Clinical significanceThe angulation-adjustable holder effectively reduced cone cutting error and treatment time, both of which were beneficial to the patients and the dental personnel.

Bendable osteochondral allografts for patellar resurfacing: A finite element analysis of congruence

Osteochondral allograft (OCA) transplantation provides a safe and effective treatment option for large cartilage defects, but its use is limited partly due to the difficulty of matching articular surface curvature between donor and recipient. We hypothesize that bendable OCAs may provide better curvature matching for patella transplants in the patellofemoral joint (PFJ). This finite element study investigates PFJ congruence for unbent and bendable OCAs, at various flexion angles. Finite element models were created for 12 femur-patella OCA pairings. Two grooves were cut in each OCA bony substrate, allowing the articular layer to bend. PFJs with either unbent (OCA) or permanently bent (BOCA) allografts were articulated from 40 to 70 degrees flexion and contact area was calculated. OCAs and BOCAs were then shifted 6 mm distally toward the tibia (S-OCA, S-BOCA) to investigate the influence of proximal–distal alignment on congruence. On average, no significant difference in contact area was found between native PFJs and either OCAs or BOCAs (p > 0.25), indicating that both types of allografts restored native congruence. This result provides biomechanical support in favor of an emerging surgical procedure. S-BOCAs resulted in a significant increase in contact area relative to the remaining groups (p < 0.02). The fact that BOCAs produced equally good results implies that bendable allografts may prove useful in future surgical procedures, with the possibility of transplanting them with a small distal shift. Surgeons who are reluctant to use OCAs for resurfacing patellae based on curvature matching capabilities may be more amenable to adopting BOCAs.

Influence of the Fluoroscopy Setting towards the Patient When Identifying the MPFL Insertion Point.

(1) The malposition of the femoral tunnel in medial patellofemoral ligament (MPFL) reconstruction can lead to length changes in the MPFL graft, and an increase in medial peak pressure in the patellofemoral joint. It is the cause of 36% of all MPFL revisions. According to Schöttle et al., the creation of the drill canal should be performed in a strictly lateral radiograph. In this study, it was hypothesized that positioning the image receptor to the knee during intraoperative fluoroscopy would lead to a relevant mispositioning of the femoral tunnel, despite an always adjusted true-lateral view. (2) A total of 10 distal femurs were created from 10 knee CT scans using a 3D printer. First, true-lateral fluoroscopies were taken from lateral to medial at a 25 cm (LM25) distance from the image receptor, then from medial to lateral at a 5 cm (ML5) distance. Using the method from Schöttle, the femoral origin of the MPFL was determined when the femur was positioned distally, proximally, superiorly, and inferiorly to the image receptor. (3) The comparison of the selected MPFL insertion points according to Schöttle et al. revealed that the initial determination of the point in the ML5 view resulted in a distal and posterior shift of the point by 5.3 mm ± 1.2 mm when the point was checked in the LM25 view. In the opposite case, when the MPFL insertion was initially determined in the LM25 view and then redetermined in the ML5 view, there was a shift of 4.8 mm ± 2.2 mm anteriorly and proximally. The further positioning of the femur (distal, proximal, superior, and inferior) showed no relevant influence. (4) For fluoroscopic identification of the femoral MPFL, according to Schöttle et al., attention should be paid to the position of the fluoroscopy in addition to a true-lateral view.

ОПРЕДЕЛЕНИЕ ПОГРЕШНОСТЕЙ В ТЕХНОЛОГИИ ИЗГОТОВЛЕНИЯ ОККЛЮЗИОННЫХ ШИН ДЛЯ ЛЕЧЕНИЯ ЗАБОЛЕВАНИЙ ВНЧС

Currently, occlusive splints are widely used for the treatment of TMJ diseases. However, the manufacturing errors of occlusive splints for the treatment of TMJ diseases still remain not fully understood, which determined the purpose of this study.&#x0D; The purpose of the study is to identify and study errors in the technological manufacture of occlusive mouthguards (tires) for the rehabilitation of patients with musculoskeletal dysfunction of the TMJ and other diseases of the TMJ.&#x0D; Materials and methods&#x0D; For this study, an examination was conducted in 30 patients with a distal shift of the TMJ condyles within 1-1.5 mm. 3 occlusal splints were made for 30 patients according to technologies (Fig. 3-4):&#x0D; 1. Cold polymerization of plastic&#x0D; 2. 3-D printing techniques, Fig. 2.&#x0D; 3. CAD-CAM-manufacturing-milling, Fig. 1.&#x0D; Revealed a discrepancy in the size of the occlusal bus and the control model when comparing them by zones (points) that were previously accepted for analysis by us.&#x0D; Research results:&#x0D; We consider it important to note that a comparison of CAD-CAM bus scans with a scan of a virtual control model in stl format revealed no errors, the images were superimposed along their boundaries in the hamulus pterygoideus and incisive papilla sections.&#x0D; Conclusions&#x0D; 1. The 3D printing technique makes it possible to technologically create occlusal splints adjacent to the dentition with high accuracy.&#x0D; 2. Milled occlusal tires have a bending strength of 115 MPa, which gives an advantage in this parameter in comparison with 3D printing technology – 80-90 MPa. Occlusal tires made on a 3D printer are superior to milled tires in elasticity.&#x0D; 3. Occlusal splints made according to the traditional method of plastic polymerization, when compared with two other materials, have lower rates of adhesion to the dentition.

Differences in action potential propagation speed and axon initial segment plasticity between neurons from Sprague-Dawley rats and C57BL/6 mice.

Action potentials (APs) in neurons are generated at the axon initial segment (AIS). AP dynamics, including initiation and propagation, are intimately associated with neuronal excitability and neurotransmitter release kinetics. Most learning and memory studies at the single-neuron level have relied on the use of animal models, most notably rodents. Here, we studied AP initiation and propagation in cultured hippocampal neurons from Sprague-Dawley (SD) rats and C57BL/6 (C57) mice with genetically encoded voltage indicator (GEVI)-based voltage imaging. Our data showed that APs traveled bidirectionally in neurons from both species; forward-propagating APs (fpAPs) had a different speed than backpropagating APs (bpAPs). Additionally, we observed distinct AP propagation characteristics in AISs emerging from the somatic envelope compared to those originating from dendrites. Compared with rat neurons, mouse neurons exhibited higher bpAP speed and lower fpAP speed, more distally located ankyrin G (AnkG) in AISs, and longer Nav1.2 lengths in AISs. Moreover, during AIS plasticity, AnkG and Nav1.2 showed distal shifts in location and shorter lengths of labeled AISs in rat neurons; in mouse neurons, however, they showed a longer AnkG-labeled length and more distal Nav1.2 location. Our findings suggest that hippocampal neurons in SD rats and C57 mice may have different AP propagation speeds, different AnkG and Nav1.2 patterns in the AIS, and different AIS plasticity properties, indicating that comparisons between these species must be carefully considered.

Neural excitability increases with axonal resistance between soma and axon initial segment

The position of the axon initial segment (AIS) is thought to play a critical role in neuronal excitability. Previous experimental studies have found that a distal shift in AIS position correlates with a reduction in excitability. Yet theoretical work has suggested the opposite, because of increased electrical isolation. A distal shift in AIS position corresponds to an elevation of axial resistance R a We therefore examined how changes in R a at the axon hillock impact the voltage threshold (Vth) of the somatic action potential in L5 pyramidal neurons. Increasing R a by mechanically pinching the axon between the soma and the AIS was found to lower Vth by ∼6 mV. Conversely, decreasing R a by substituting internal ions with higher mobility elevated Vth All R a -dependent changes in Vth could be reproduced in a Hodgkin-Huxley compartmental model. We conclude that in L5 pyramidal neurons, excitability increases with axial resistance and therefore with a distal shift of the AIS.

The role of scapholunate interosseous, dorsal intercarpal, and radiolunate ligaments in wrist biomechanics

Rupture to wrist ligaments predisposes the joint to degenerative changes. Scapholunate interosseous ligament (SLIL) rupture, especially when compounded by dorsal intercarpal ligament (DIC) and long radiolunate ligament (LRL) disruption, can cause carpal bone kinematic abnormalities. It is essential to delineate the role of these ligaments and their constraints on wrist range-of-motion (ROM) and center of rotation (COR). Wrist ROM and COR location were determined in 9 specimens using a six degree-of-freedom robotic musculoskeletal simulator in 24 directions of wrist motion for four experimental conditions: intact, and after sequential sectioning of the SLIL, DIC, and LRL. Sectioning the SLIL alone did not change wrist ROM in any direction (p > 0.10), while sectioning the SLIL and both the DIC and LRL caused significant increases in radial deviation, radial-extension, and ulnar-flexion ROM (p < 0.05). The COR of the intact wrist was located between the proximal third and middle third of the capitate, depending on the direction of wrist motion. While SLIL sectioning alone did not affect the COR, subsequent DIC sectioning led to a distal shift of COR in motions involving ulnar-extension relative to the intact condition. Additional sectioning of the LRL caused a proximal shift of COR in motions involving radial-flexion. A proximal shift implies a more dominant role of the radiocarpal joint, while a distal shift of the COR implies an increased role for the midcarpal joint. Understanding the role of ligaments on overall wrist mechanics is critical to devising new treatment strategies to restore wrist function.

Retinal vessel shift and its association with axial length elongation in a prospective observation in Japanese junior high school students.

PurposeTo investigate retinal vessel shift (RVS) and its association with axial length (AL) elongation in junior high school students.MethodsTotal 161 eyes of 161 healthy junior high school students were prospectively studied. Optical AL and anterior chamber depth (ACD) measurements, and fundus photography were performed in the first and third grades. Eyes of subjects in the first and third grade that had perfect matching among all the retinal vessels were allocated to the RVS(−) group, otherwise allocated to the RVS(+) group. In the RVS(+) group, the peripapillary retinal arteries angle (PRAA) was measured for quantitative analysis of RVS; the angle between the major retinal arteries. The variables related to PRAA were identified using model selection with the corrected Akaike information criterion.ResultsForty-two eyes (26.1%) were allocated to the RVS(+) group. There were seven patterns in the RVS of those in the RVS(+) group, including clockwise shift in the supra temporal area (5 eyes), infra temporal area (7 eyes), and nasal area (9 eyes); anticlockwise shift in the supra temporal area (7 eyes), infra temporal area (5 eyes), and nasal area (2 eyes); and distal shift in the temporal area (7 eyes). The optimal model for the PRAA narrowing included larger AL and body weight in the first grade, and greater AL elongation.ConclusionVarious (seven) RVS patterns were observed in about 25% of the junior high school students within two years. RVS was associated with AL elongation, and useful to reveal the mechanism of myopic retinal stretch.

An efficacious horizontal angulation separated radiographically superimposed canals in upper premolars with different root morphologies

ObjectivesTo determine the effect of various horizontal beam angulations on radiographically separating superimposed canals in upper premolars with different external root morphologies. Materials and methodsThe independent variables were 1) three different external root morphologies of upper premolars (n = 30); one-root (A), fused-root (B) and two-root (C), 2) thirteen angulations (0° and mesial (Ms) and distal (Ds) shifts of 15, 20, 25, 30, 35, and 40°), and 3) the superimposed canal at the apex (apx) and 5-mm from the apex (5apx). The dependent variables were the percentage of radiographs demonstrating canal separation. The separated canal distances were analysed using analysis of variance (ANOVA) and Tukey HSD. ResultsSeparation distances at apx and 5apx on one-root, fused-root and two-root premolar radiographs increased as the angulation increased. Ms angulations generated a higher separation distance (SepDist) in mm compared with the Ds angulations. Significantly different separation distances were observed from various horizontal shift angulations (p < 0.05). Percentage of canal separation from 0o was achieved differently in different morphology of upper premolars (14–80%) at apx and 10–40% at 5apx. The 20–40Ms/Ds and 25Ds/30‒40Ms/Ds resulted in 100% of radiographs with canal separation for two-root and fused-root premolars, respectively, at apx and 5apx. Only the 35/40Ms resulted in 100% of radiographs with separation at apx in one-root teeth. ConclusionThe ideal horizontal angulation which revealed the superimposed canal at the apx/5apx for one-root, fused-root, and two-root teeth are 35M/35M, 20D/20M, and 15M/20M, respectively. SignificanceThe 25Ms was the optimal angulation which strongly recommended with the highest probability of separation and acceptable image quality in endodontic and prosthodontic treatment for unknown morphologies evaluated.

Theoretical relation between axon initial segment geometry and excitability.

In most vertebrate neurons, action potentials are triggered at the distal end of the axon initial segment (AIS). Both position and length of the AIS vary across and within neuron types, with activity, development and pathology. What is the impact of AIS geometry on excitability? Direct empirical assessment has proven difficult because of the many potential confounding factors. Here, we carried a principled theoretical analysis to answer this question. We provide a simple formula relating AIS geometry and sodium conductance density to the somatic voltage threshold. A distal shift of the AIS normally produces a (modest) increase in excitability, but we explain how this pattern can reverse if a hyperpolarizing current is present at the AIS, due to resistive coupling with the soma. This work provides a theoretical tool to assess the significance of structural AIS plasticity for electrical function.

Risk factors of preoperative Hirschsprung-associated enterocolitis

BackgroundHirschsprung-associated enterocolitis (HAEC) is a life-threatening complication of Hirschsprung disease (HSCR), that might occur preoperatively. We investigated the risk factors of preoperative HAEC.MethodWe retrospectively reviewed all medical records of HSCR patients admitted at Dr. Sardjito Hospital, Indonesia from March 2012 until March 2015. Diagnosis of HAEC was determined using the Delphi scoring system.ResultsSixty-one HSCR patients were involved in this study, of whom 48 were males and 13 females. Eighteen percent (11/61) patients had a preoperative HAEC. The most common findings of the HAEC score found in our patients were distended abdomen (100%) and dilated loops of bowel (100%), followed by lethargy (72.7%), cut-off sign in rectosigmoid with absence of distal air (72.7%), leukocytosis (72.7%), and shift to left (63.6%). There was no association between gender, age of HSCR diagnosis, early/late diagnosis during neonatal period, aganglionosis type, albumin level nor body mass index with preoperative HAEC (p = 0.69, 0.76, 0.33, 1.0, 0.86, and 0.50, respectively). In addition, the maternal age, gestational age, and maternal education level also did not correlate with the development of preoperative HAEC (p = 0.71, 0.59, and 0.32, respectively).ConclusionThe incidence of preoperative HAEC in our hospital is considered relatively moderate, with the most common findings of distended abdomen and dilated loops of bowel. None of the identified risk factors have an association with the development of HAEC in our patients.

Hysteresis and Synergy of the Central Commands to Muscles Participating in Parafrontal Upper Limb Movements.

The averaged electromyograms (EMGs) were registered from the arm muscles of ten subjects in movements of the right hand performed under visual guidance on the horizontal plane along linear trajectories going parallel to the frontal plane at various distances from the trunk. The tests consisted of the steady movements (speed 4 cm/s) between two points symmetrical about the shoulder axis; the hand moved firstly from left to right, then in the opposite direction. The tests repeated ten times for each of two equal loads (10.2 N) applied to the hand along movement trajectory in the right- (Fr) or leftward (Fl) directions. The elbow and shoulder flexors reacted predominantly on Fr loads; the extensors were mostly activated by Fl loads. Positional changes of the averaged EMGs in both flexor and extensor muscles belonging to different joints demonstrated hysteresis properties; the respective hysteresis loops had counterclockwise direction in flexors and clockwise in extensors. The muscles predominantly opposing the loading forces of a given direction participate in a cocontraction mode as antagonists when the direction of load is changed; in this case, together with a decrease in the amplitude of the hysteresis loops, their direction is also reversed. The multiplication index of synergy (MIS), which is based on multiplication of the respective normalized averaged EMG records, has been proposed to evaluate quantitatively changes in the synergy effects between various muscle groups. For distal shifts of the movement traces, the synergy effects are shown to be changed in different directions, increasing in flexors and decreasing in extensors. The obtained results demonstrate that the muscle hysteresis leads to strong modification of the central commands during movements.

Are the male reproductive units of Juniperus drupacea Labill. (Cupressaceae s.str.) a compound, polyaxial inflorescence or a dense cluster of simple, uniaxial pollen cones?

The Juniperus Section Caryocedrus (Cupressaceae) is one of the three putatively monophyletic sections of the genus. It is monotypic, presented only by J. drupacea. Male reproductive units of this species show several distinct features distinguishing it distinctly from all other Juniperus species, including an inflorescence‐like arrangement of pollen cones, an increased number of microsporangia per microsporangiophore, and microsporangia attached to the stalk in up to three subsequent rows. The male reproductive units in J. drupacea have been investigated with paraffin technique and SEM. They are hypothesized to represent a distal cluster of densely arranged, simple pollen cones, which are interpreted as being derived from an ancestral condition that is still presented in species of the Section Juniperus. This is assumed to have occurred by a profound reduction of internodes of the fertile shoot axis carrying the pollen cone and a distal shift. The increased number of microsporangia per microsporangiophore may be a response to the decreasing number of pollen cones per tree compensating for the loss of pollen, that occurred during the evolution of inflorescence‐like male reproductive units.

Wide-Field In Vivo Confocal Microscopy of Meibomian Gland Acini and Rete Ridges in the Eyelid Margin.

PurposeIn vivo confocal microscopy (IVCM) has been widely used to evaluate changes in the meibomian glands (MGs) in response to age and disease. This study examined the structures described as MGs using wide-field IVCM and laser scanning confocal microscopy (LSCM) in situ and characterized their spatial distribution and localization relevant to the eyelid margin.MethodsIVCM was performed on 30 subjects aged 18 to 38 to visualize structures in the eyelid margin. Size, shape, and distribution characteristics were measured, and individual frames were montaged into wide-field images. Structures observed on IVCM were then visualized using LSCM of whole-mount and cryosectioned cadaver eyelids stained with Nile red, mucin-1 (MUC1), laminin-5, and 4′,6-diamidine-2′-phenylindole dihydrochloride.ResultsThe size, distribution, and staining patterns of the reflective structures seen on IVCM did not correspond to the MGs in cadaver eyelids. Instead, staining profiles indicated that these structures corresponded to the rete ridges present at the dermal–epidermal junction. Wide-field imaging showed a densely populated field of rete ridges with distinct size and shape characteristics depending on their location relative to the meibomian orifices. A distal shift of the mucocutaneous junction (MCJ) was evident in some eyelids.ConclusionsIVCM is unable to visualize MGs in the human eyelid margin due to light attenuation at that tissue depth. LSCM confirms that these structures are rete ridges located at the dermal–epidermal junction. Alterations in the structure of the dermal–epidermal junction within the eyelid margin indicate a shifting of the MCJ and may impact tear film dynamics.