The relationship between the aggrecan VNTR polymorphism and its content in lumbar intervertebral discs.

BACKGROUND: There is a specific polymorphism of the ACAN gene called the variable number of tandem repeats (VNTR), which is particularly interesting in the light of the development of intervertebral disc pathology and associated low back pain. MATERIALS AND METHODS: The nucleus pulposus specimens were harvested from the L5/S1 intervertebral discs. The aggrecan content was determined using enzyme- linked immunosorbent assay (ELISA). Moreover, the VNTR polymorphism in the ACAN gene was evaluated. RESULTS: The genotyping of VNTR polymorphism in ACAN gene was successful in 94 tissue samples (48 homozygotes and 46 heterozygotes). The alleles were divided into four groups, in accordance with the number of tandem repeats in the ACAN gene. No difference between groups in the mean aggrecan mass nor in the mean degree of tissue moisture was observed. CONCLUSIONS: No relationship between the ACAN gene VNTR polymorphism and the aggrecan content was observed in studied Caucasian cadavers. Such a relationship may be a more complex phenomenon and exists in other populations.

A three-headed piriformis muscle: an anatomical case study and narrative review of literature.

The piriformis muscle (PM) is found in the gluteal region, exiting the pelvis through the greater sciatic foramen and dividing it into the suprapiriform and infrapiriform foramina. The piriformis works as part of the hip external rotator muscle group, and is responsible for rotation of the femur upon hip extension and abduction of the femur during flexion of the hip joint. The aim of the present report is to describe a very rare case of the primary three-headed PM. To the best knowledge of the authors, the said variant has not yet been described in the existing literature. The 71-year-old male formalin-fixed cadaver was subjected to routine dissection. After careful removal of the connecting tissue, three separate, primary heads of the PM were identified. The lower head of the PM arose from the middle part of the sacral bone; 87.56 mm long and 9.73 mm wide. The medial head was attached to the internal part of the posterior inferior iliac spine; 121.6 mm long and 20.97 mm wide. The upper head was attached to the external part of the posterior inferior iliac spine; 78.89 mm long and 23.94 mm wide. All heads converged into a common tendon which inserted onto the greater trochanter. The clinical importance of this work comes down to the fact that the aberrant PM may be the reason behind the piriformis syndrome and its associated symptoms. Moreover, knowledge regarding the variant anatomy of the PM is of immense importance to, e.g. anaesthesiologists performing computed tomography- or ultrasound-guided sciatic nerve injection for local anaesthesia, radiologists interpreting imaging studies, and surgeons, especially during posterior approaches to the hip and pelvis.

Correlation of morphological and radiological characteristics of degenerative disc disease in lumbar spine: a cadaveric study.

BACKGROUND: Intervertebral disc (IVD) degeneration plays a crucial role in the pathophysiology of low back pain. Several grading systems have been developed for both morphological and radiological assessment. The aim of this study was to assess the morphological and radiological characteristics of IVD degeneration and validate popular radiological Pfirrmann scale against morphological Thompson grading system. MATERIALS AND METHODS: Full spinal columns (vertebrae L1-S1 and IVD between them) were harvested from cadavers through an anterior dissection. Magnetic resonance imaging scans of all samples were conducted. Then, all vertebral columns were cut in the midsagittal plane and assessed morphologically. RESULTS: A total of 100 lumbar spine columns (446 IVDs) were included in the analysis of the degeneration grade. Morphologic Thompson scale graded the majority of discs as grade 2 and 3 (44.2% and 32.1%, respectively), followed by grade 4 (16.8%), grade 1 (5.8%) and grade 5 (1.1%). The radiologic Pfirrmann grading system classified 44.2% of discs as grade 2, 32.1% as grade 3, 16.8% as grade 4, 5.8% as grade 1, and 1.1% as grade 5. The analysis on the effect of age on degeneration revealed significant, although moderate, positive correlation with both scales. Analysis of the agreement between scales showed weighted Cohen's kappa equal to 0.61 (p < 0.001). Most of the disagreement occurred due to a 1 grade difference (91.5%), whereas only 8.5% due to a 2 grade difference. CONCLUSIONS: With the increase of the prevalence of IVD disease in the population, reliable grading systems of IVD degeneration are crucial for spine surgeons in their clinical assessment. While overall there is agreement between both grading systems, clinicians should remain careful when using Pfirrmann scale as the grades tend to deviate from the morphological assessment.

An anatomical investigation of rare upper limb neuropathies due to the Struthers' ligament or arcade: a meta-analysis.

BACKGROUND: The Struthers' ligament (SL) is a fibrous band that originates fromthe supracondylar humeral process and inserts into the medial humeral epicondyle, potentially compressing both the median nerve and brachial artery. The controversial Struthers' arcade (SA) is a musculotendinous band found in the distal end of the arm that might compress the ulnar nerve. This study aimed to evaluate the pooled prevalence estimate of the SL and SA, and their anatomical features. MATERIALS AND METHODS: A meticulous search of major electronic medical databases was carried out regarding both structures. Applicable articles (and all relevant references) were analysed. Data from the eligible articles was extracted and evaluated. The quality and the potential risk of bias in the included studies were assessed using the AQUA tool. RESULTS: The arcade was reported in 13 studies (510 arms), whereas the ligament in 6 studies (513 arms). The overall pooled prevalence estimate of the ligament was 1.8%, and 52.6% for the arcade. Most frequently, the ulnar nerve was covered by a tendinous arcade (42.2%). In all cases, the ligament inserted into the medial humeral epicondyle, but had various origins. Only 1 study reported compression of the median nerve by the ligament, whilst another contradicted this view. CONCLUSIONS: Although the SL is rare, and the SA is a valid anatomical entity (though with a variable presentation), clinically meaningful neurovascular entrapments caused by these structures are infrequent. Nonetheless, a better understanding of each may be beneficial for the best patient outcomes.

The anatomical landmarks effective in the localisation of the median nerve during orthopaedic procedures.

BACKGROUND: The aim of this study was to create a safe zone for surgeons who perform procedures in the wrist to avoid iatrogenic damage to the median nerve (MN) by identifying anatomical landmarks using ultrasound (USG). MATERIALS AND METHODS: We measured the distances between the MN and two easily identifiable anatomical landmarks at the level of the proximal border of carpal ligament using USG. RESULTS: A total of 57 volunteers (n = 114 upper limbs) were included in this study. Our main findings revealed that the distance from the flexor carpi radialis tendon to MN (FCR-MN) was 7.87 mm (95% confidence interval 7.37-8.37) and the distance from flexor carpi ulnaris tendon to MN (FCU-MN) was 19.09 mm (95% confidence interval 18.51-19.67). CONCLUSIONS: The tendons of FCR and FCU are easily identifiable landmarks that can be distinguished using simple palpation. Based on our USG findings, the area around FCR should be carefully navigated to avoid iatrogenic injury to the MN during surgical procedures around the carpal tunnel.

Current concepts on the morphology of popliteus tendon and its clinical implications.

In this review we described the anatomy and biomechanics of popliteus muscle and its tendon. Furthermore, we combined the anatomy with clinics and discussed a wide spectrum of disorders regarding the popliteus and its musculotendinous complex. There are three main anatomical regions of the popliteus musculotendinous complex: the proximal origin, the mid-portion, the distal part on the tibia. The unique localisation and various origins of the tendon, connected with structures such as fibular head, Wrisberg, Humphrey and posterior cruciate ligament, lateral meniscus, medial collateral ligament, give an implication to diagnosis and treatment. Popliteus dysfunction is often overlooked, that is the reason why diagnosis and treatment of its injuries is mostly insufficient. Repetitive or acute direct varus forces, when the tibia is in external rotation, and knee hyperextension or flexion with forced external rotation of the tibia, are the main mechanisms of trauma. Popliteus injuries mainly affect the athletic population and lead to severe activity limitations. Chronic disorders of the popliteus tendon, less known, are often described as tendinopathy and are frequently seen in runners. Their symptoms can mimic the lateral meniscal tears. On the other hand, high-energy traumatic injuries of the popliteus tendon often accompany complex, multi ligamentous injuries seen in competitive sports. We also presented the implication of popliteus tendon in knee arthroplasty, due to its particular exposition to iatrogenic trauma during surgery. The issues such as proper tibial component location and well-designed cut systems are crucial to avoid the popliteus impingement and preserve its structure.

Erratum: The Achilles tendon and the retrocalcaneal bursa: An anatomical and radiological study.

[This corrects the article DOI: 10.1302/2046-3758.67.BJR-2016-0340.R1.].

The Achilles tendon and the retrocalcaneal bursa: An anatomical and radiological study.

OBJECTIVES: Inflammation of the retrocalcaneal bursa (RB) is a common clinical problem, particularly in professional athletes. RB inflammation is often treated with corticosteroid injections however a number of reports suggest an increased risk of Achilles tendon (AT) rupture. The aim of this cadaveric study was to describe the anatomical connections of the RB and to investigate whether it is possible for fluid to move from the RB into AT tissue. METHODS: A total of 20 fresh-frozen AT specimens were used. In ten specimens, ink was injected into the RB. The remaining ten specimens were split into two groups to be injected with radiological contrast medium into the RB either with or without ultrasonography guidance (USG). RESULTS: In specimens injected with ink, diffusion outside the RB was observed with staining of the anterior portion of the AT. In eight contrast-injected specimens (five USG, three non-USG), a similar localised diffusion pattern was observed, with the contrast identified superiorly and anteriorly. In two contrast-injected specimens (non-USG), the diffusion pattern was more extensive. CONCLUSION: This study confirmed the existence of connections between the RB and the AT, especially rich in the anteroinferior portion of the tendon, which should be considered a weak zone for substances injected into the RB. We hypothesise that this part of the AT might be most vulnerable to rupture after corticosteroid injections.Cite this article: P. A. Pekala, B. M. Henry, J. R. Pekala, K. Piska, K. A. Tomaszewski. The Achilles tendon and the retrocalcaneal bursa: An anatomical and radiological study. Bone Joint Res 2017;6:446-451. DOI:10.1302/2046-3758.67.BJR-2016-0340.R1.

The twisted structure of the Achilles tendon unraveled: A detailed quantitative and qualitative anatomical investigation.

The Achilles tendon (AT) consists of fibers originating from the soleus muscle (SOL), which lies deep, and the medial (GM) and lateral (GL) heads of the gastrocnemius muscle, which lie superficial. As the fibers descend toward the insertion of the AT, the individual subtendons twist around each other. The aim of this study was to investigate the twisted structure of the AT and its individual subtendons. Specimens of the AT, with preserved calcaneal bone and a fragment of the triceps surae muscle, were obtained from 53 fresh-frozen, male cadavers (n=106 lower limbs). The angle of torsion of each of the AT's subtendons was measured using a specially designed and 3D-printed tool. The mean distance between the most distal fibers of the triceps surae muscle and the superior border of the calcaneal bone was 60.77±14.15 mm. The largest component of the AT at the level of its insertion into the calcaneal bone is the subtendon from the GL (44.43%), followed by the subtendon from SOL (27.89%), and the subtendon from GM (27.68%). The fibers originating from the GM rotate on average 28.17±15.15°, while the fibers originating from the GL and SOL twist 135.98±33.58° and 128.58±29.63°, respectively. The torsion of superficial fibers (GM) comprising the AT is significantly lower than that of deeper fibers (GL and SOL). The cross-sectional area of the AT is smaller at the level of the musculo-tendinous junction than at the level of its insertion. This study illustrates the three types of the AT with differently twisting subtendons, as well as a generalized model of the AT. Types of AT torsion may potentially alter the biomechanical properties of the tendon, thus possibly influencing the pathophysiologic mechanisms leading to the development of various tendinopathies.

The variable origin of the lateral circumflex femoral artery: a meta-analysis and proposal for a new classification system.

The lateral circumflex femoral artery (LCFA) is responsible for vascularisation of the head and neck of the femur, greater trochanter, vastus lateralis and the knee. The origin of the LCFA has been reported to vary significantly throughout the literature, with numerous branching patterns described and variable distances to the mid-inguinal point reported. The aim of this study was to determine the estimated population prevalence and pooled means of these anatomical characteristics, and review their associated clinical relevance. A search of the major electronic databases was performed to identify all articles reporting data on the origin of the lateral circumflex femoral artery and its distance to the mid-inguinal point. Additionally, an extensive search of the references of all relevant articles was performed. All data on origin, branching, and distance to mid-inguinal point was extracted and pooled into a meta-analysis. A total of 26 articles (n = 3731 lower limbs) were included in the meta-analysis. Lateral circumflex femoral artery most commonly originates from the deep femoral artery with a pooled prevalence of 76.1% (95% confidence interval 69.4-79.3). The deep femoral artery-derived lateral circumflex femoral artery was found to originate with a mean pooled distance of 51.06 mm (95% confidence interval 44.61-57.51 mm) from the mid-inguinal point. Subgroup analysis of both gender and limb side data were consistent with these findings. Due to variability in the lateral circumflex femoral artery's origin and distance to mid-inguinal point, anatomical knowledge is crucial for clinicians to avoid iatrogenic injuries when performing procedures in the femoral region, and thus radiographic assessment prior to surgery is recommended. Lastly, we propose a new classification system for origin of the lateral circumflex femoral artery.

Superficial fibular nerve variations of fascial piercing: A meta-analysis and clinical consideration.

The superficial fibular (peroneal) nerve (SFN) is one of the successive branches of the common fibular (peroneal) nerve and goes on to bifurcate into the medial dorsal cutaneous (MDN) and intermediate dorsal cutaneous (IDN) nerves. The SFN is a main contributor to sensory innervation of the foot and lower leg. It varies widely in its penetrance of the deep (crural) fascia, and differences in its subsequent course can result in iatrogenic injuries. Articles on the prevalence of this anatomical variation were identified by a comprehensive database search. The data collected were extracted and pooled into a meta-analysis. A total of 14 articles (n = 665 lower limbs) were included on the meta-analysis of SFN variations in fascial piercing. The normal Type 1 variation, where the SFN pierces the deep fascia as a single entity and later bifurcates into the MDN and IDN, had a pooled prevalence of 82.7% (95%CI: 74.0-89.4). The Type 2 variant, where the SFN bifurcates early and then pierces the fascial layer separately as the MDN and IDN, had a pooled prevalence of 15.6% (95%CI: 8.9-23.6). Type 3, when the SFN penetrates the deep fascia and courses similar to the MDN with absent IDN was noted in 1.8% (95%CI: 0.0-4.9) of cases. A substantial portion of the population has a pattern of SFN piercing that deviates from the normal Type 1 anatomy. It is recommended that possible SFN variants in patients should be addressed thoroughly to help prevent iatrogenic injuries and postoperative complications. Clin. Anat. 30:120-125, 2017. © 2016 Wiley Periodicals, Inc.

An assessment of the usefulness of a coconut as a model of the human skull for forensic identification of a homicide weapon.

The authors made an attempt to verify if a coconut can be used as a model of human skull to determine the homicide weapon. During our experiment 27 strike attempts were performed with the use of 9 different tools. Among them there were authentic murder weapons and instruments which had been used in similar experiments conducted on human skulls in 1955. Depending on the size of an area in contact with a coconut, weapons caused dents corresponding to the shape of a weapon, irregular fractures or long linear cracks. Our results have shown that coconut can be used as an inexpensive screening model of human skull, but only to determine fractures made by tools with small striking surface.

Tumor necrosis factor-alpha-induced insulin resistance in adipocytes.

Recent studies examining the link between insulin resistance and the development of obesity and noninsulin-dependent diabetes mellitus are consistent with the involvement of tumor necrosis factor-alpha (TNF-alpha) as a central mediator. In insulin resistant obese mouse models, neutralization of TNF-alpha in circulation has been demonstrated to restore insulin-mediated glucose uptake. Adipose tissue has been shown to be a site for synthesis of TNF-alpha, with the degree of adiposity directly correlated with the level of synthesis. Studies conducted on obese human patients have demonstrated a correlation between levels of TNF-alpha, the extent of obesity, as well as the level of hyperinsulinemia observed. Mechanistic studies in cell culture have suggested that TNF-alpha functions to render cells insulin resistant through regulation of the synthesis of the insulin responsive glucose transporter as well as through interference with insulin signaling. This review will address these issues and additionally introduce the reader to the molecular aspects of TNF-alpha, its receptors as well as TNF-alpha-initiated signaling cascades, that are necessary to understand the function of this cytokine in the regulation of adipose tissue metabolism.

The influence of mRNA stability on glucose transporter (GLUT1) gene expression.

One mechanism for modification of glucose transport activity occurs through regulation of the cellular content of transporter protein by alteration of transcript stability. Regulated mRNA decay has been shown to play an important role in control of posttranscriptional gene expression. Implicated, as a pivotal element in this regulation is the 3'-untranslated region (UTR) of the message. Recent work from several labs has focused on sequence motifs within the 3'-UTR of glucose transporter (GLUT1) mRNA that serve as destabilizing or stabilizing elements and recognition of these elements by specific proteins. In this review, we address several critical studies each of which has identified elements in the GLUT1 3'-UTR that are involved in the control of transcript stability and demonstrated that these sequence motifs are recognized by specific binding proteins.

Tumour necrosis factor-alpha regulates expression of the CCAAT-enhancer-binding proteins (C/EBPs) alpha and beta and determines the occupation of the C/EBP site in the promoter of the insulin-responsive glucose-transporter gene in 3T3-L1 adipocytes.

We have demonstrated previously that treatment of 3T3-L1 adipocytes with tumour necrosis factor-alpha (TNF) results in a rapid (4 h) and significant (75-80%) reduction in the rate of transcription of the GLUT4 gene. Control of GLUT4 gene transcription has been suggested at least in part to reside with the CCAAT-enhancer-binding protein (C/EBP) family (alpha, beta and delta isoforms) of transcription factors. Using electrophoretic mobility shift assays, we have examined the ability of TNF to alter the occupation of the C/EBP site in the GLUT4 promoter. The data suggest that in fully differentiated adipocytes the C/EBP site is a ligand for predominantly alpha/alpha homodimers; however, after exposure to TNF, a shift in occupancy of the site occurs and the ligands become alpha/beta heterodimers and beta/beta homodimers. Partner selection in dimer formation appears to be controlled by selective translocation of the beta-isoform from the cytosol to the nucleus after exposure of the cells to TNF.

Tumor necrosis factor-alpha initiated signal transduction in 3T3-L1 adipocytes.

Examination of the ability of tumor necrosis factor-alpha (TNF) to activate both the p44/42 and p38 MAP kinase cascades in fully differentiated 3T3-L1 adipocytes indicated a rapid MEK1/2-dependent activation of p44/42 MAP kinase. Use of the MEK1/2 inhibitor PD98059 indicated that this pathway at least in part was responsible for nuclear localization of the transcription factor NF-kappaB. The stress/cytokine-activated p38 MAP kinase was observed to be constitutively active, and its phosphorylation (activation) status was not altered with TNF treatment. However, TNF treatment did result in activation of the transcription factor, ATF-2, a primary downstream target of p38 MAP kinase. Use of the p38 MAP kinase inhibitors SB202190 and SB203580 did not interfere with the ability of TNF to activate ATF-2, suggesting that either the gamma isoform of p38 MAP kinase or a p38-independent pathway was utilized by TNF to increase the phosphorylated fraction of ATF-2. In previous studies we had demonstrated the ability of TNF to suppress the transcription of the GLUT4 gene. Prevention of activation of either the p44/42 MAP kinase pathway (PD98059) or the p38 MAP kinase pathway (SB202190 and SB202580) indicated that these pathways did not control GLUT4 transcription.

Tumor necrosis factor-alpha mediated activation of signal transduction cascades and transcription factors in 3T3-L1 adipocytes.

We have previously demonstrated that exposure of fully differentiated 3T3-L1 adipocytes to TNF results in an activation of at least two separate signal transduction pathways: 1. the sphingomyelinase leading to generation of ceramide and 2. the proliferative and cell growth regulating p44/42 MAP kinase cascade. In the current study we extend those observations and examine the ability of both TNF and ceramide to activate the stress/cytokine activated p38 MAPK, the JNK and JAK-STAT pathways. Interestingly, the p38 MAP kinase was observed to be constitutively active and its phosphorylation status (activation) was not altered with either TNF or ceramide treatment. Analysis of the JNK and JAK-STAT pathways also demonstrated an absence of TNF-induced activation. Similar results were obtained when the adipocytes were treated with a cell permeable analog of ceramide. However, the adipocytes were observed to respond to TNF with a rapid alteration in the GSH-GSSG equilibrium in a manner consistent with a cellular response to an oxidative stress. This response may mediate the TNF-induced metabolic disturbances observed in the adipose cell.

Acute and chronic regulation of Na+/K+-ATPase transport activity in the RN22 Schwann cell line in response to stimulation of cyclic AMP production.

Na+/K+-ATPase-dependent Rb+ uptake of RN22 Schwann cells was stimulated by cholera toxin (0.25 microg/ml), forskolin (2 mM), or 8-bromo cAMP (1 mM). At 2 h Rb+ uptake was increased by 162+/-6% (cholera toxin), 151+/-14% (forskolin), and 207+/-15% (8-bromo cAMP). Cholera toxin or 8-bromo cAMP treatment for 12-24 h resulted in a second peak of Na+/K+-ATPase-dependent Rb+ transport activity of 186+/-12 and 265+/-9% of control, respectively. Cholera toxin also transiently stimulated the activity of the Na+, K+, 2Cl- -cotransporter with a peak at 2 h (179+/-9%), returning to basal levels by 24 h. Inhibition of the Na+,K+,2Cl- -cotransporter by bumetanide (0.1 mM) or by reduction of the Na+ gradient (10 mM veratridine treatment) prevented the early peak in ATPase activity but not the second peak. These results indicated that the early transient stimulation of Na+/K+ ATPase activity by cholera toxin was due to an increase in cellular Na+, secondary to stimulation of Na+,K+,2Cl -cotransport activity. Western blot analysis of cellular homogenates and purified membrane fractions showed that the second peak of Rb+ uptake activity was a result of translocation of transport protein from an intracellular microsomal pool to the plasma membrane. Rb+ uptake by dominant negative protein kinase A mutants of the RN22 cell was not stimulated by cholera toxin treatment (acute or chronic) confirming the cAMP/protein kinase A dependency of both acute and long-term regulation of transport activity. In the absence of a change in Michaelis constants or of an increase in total transport protein of cellular homogenates, neither a change in enzyme kinetics nor an increase in de novo synthesis of transport protein could account for the increase in transport activity.

Ectopic expression of Hel-N1, an RNA-binding protein, increases glucose transporter (GLUT1) expression in 3T3-L1 adipocytes.

3T3-L1 preadipocytes ectopically expressing the mammalian RNA-binding protein Hel-N1 expressed up to 10-fold more glucose transporter (GLUT1) protein and exhibited elevated rates of basal glucose uptake. Hel-N1 is a member of the ELAV-like family of proteins associated with the induction and maintenance of differentiation in various species. ELAV proteins are known to bind in vitro to short stretches of uridylates in the 3' untranslated regions (3'UTRs) of unstable mRNAs encoding growth-regulatory proteins involved in transcription and signal transduction. GLUT1 mRNA also contains a large 3'UTR with a U-rich region that binds specifically to Hel-N1 in vitro. Analysis of the altered GLUT1 expression at the translational and posttranscriptional levels suggested a mechanism involving both mRNA stabilization and accelerated formation of translation initiation complexes. These findings are consistent with the hypothesis that the Hel-N1 family of proteins modulate gene expression at the level of mRNA in the cytoplasm.