Pattern of primary tumors and tumor-like lesions of bone in children: retrospective survey of biopsy results

Background: Although primary bone tumors are relatively uncommon, they constitute the most important tumors in patients less than 20 years. We aimed to determine the frequencies of primary bone tumors and tumor-like lesions of bone and the anatomical sites of their occurrence. Methods: A retrospective review of histopathology reports of all bone specimens received in a private pathology laboratory in Istanbul between 2009 and 2015. Results: A total of 57 patients (aged 5 to 18 years) with a mean of 13.12 years were studied. Thirty five patients (61.4%) were males and 22 (38.6%) were females. Fifty five (94.4%) of the tumors were benign. Osteochondroma was the commonest tumor accounting for 31 cases (54.3%) followed by osteoid osteoma, 9 cases (15.7%). Chondrosarcoma observed in two patients and Ewing sarcoma in one patient as malignant tumors. Of the 57 bone tumors 13 (22.8%) occurred in the upper extremities, while 44 (77.2%) were in the lower extremities. Proximal humerus was the most commonly involved site in upper extremity tumors, with osteochondromas representing the most frequent type of tumor (4 patients; 7%). In the lower extremities again osteochondromas were the most common type of tumor (8 cases, 14%), with the femur being the most common site of involvement (18 patients, 31.5%). Of the patients with tumor-like lesions; four patients had fibrous dysplasia, 4 patients had non-ossified fibromas, 4 patients had simple bone cysts and 3 had aneurismal bone cyst. Conclusion: This study showed that primary bone tumors were mainly benign, settled predominantly in the lower extremities mostly in the femur with a male preponderance. Osteochondroma was the most common benign bone tumor. We didn’t observed osteosarcoma, which is the most frequent malignant bone tumor.     

Risk Factors of Germinal Matrix Intraventricular Hemorrhage in Premature Infants

Objective

To determine whether some clinical parameters can be used to predict the hemorrhage and whether the relationship between these clinical variables and the grades of hemorrhage is linear.

Methods

A total of 230 premature infants, born at a gestational age less than 34 weeks were retrospectively reviewed. Germinal matrix-intraventricular hemorrhage (GM-IVH), the grade of the hemorrhage, and clinical data were assessed with a checklist. Variables were analyzed by using Mann Whitney U and Fisher’s exact tests and then multiple logistic regression analysis was used to evaluate the independent risk factors.

Findings

Resuscitation, gestational age, hypotension, multiple birth, and birth weight were found to be independent risk factors. We determined non-linear relationship between the grades of hemorrhage and the clinical parameters. But when we classified hemorrhages as grade 1, grade 2-3 and grade 4, the relationships were found linear.

Conclusion

Premature infants who had resuscitation, low gestational age, hypotension, multiple birth, and low birth weight are more likely to have GM-IVH. The relationship between the clinical variables and the grades of GM-IVH does not seem to be linear.     

Atrial electromechanical coupling intervals in pregnant subjects

Atrial fibrillation (AF), which is the most common cardiac arrhythmia, may cause serious symptoms and impair quality of life.1 The development of AF is associated with many risk factors, including age, male gender, hypertension, heart failure, valvular disease, diabetes mellitus (DM) and left atrial (LA) enlargement.2-4 Electrical and/or mechanical remodelling of the atria is thought to be a pathophysiological characteristic of AF.5The pregnant state may be pro-dysrhythmic. This is related to the cardiovascular, hormonal, haemodynamic and autonomic changes during healthy pregnancy. Levels of oestrogen and β-human chorionic gonadotropin increase dramatically. Haemodynamic changes include an increase in circulating blood volume, which increases cardiac output. This results in myocardial stretch and an increase in cardiac end-diastolic volume. High plasma catecholamine concentrations and adrenergic receptor sensitivity increase sympathetic tone. All these changes in pregnant women may make them more prone to dysrhythmogenesis.6Most pregnant women complain of palpitations, dizziness and even syncope, but these symptoms are rarely associated with cardiac dysrhythmias. AF is the most common clinically significant cardiac arrhythmia in the general population but it is rarely seen in pregnant women. When it occurs, it can represent a benign, self-limited lone episode of AF or may be secondary to congenital or rheumatic valvular disease, hypertrophic cardiomyopathy, thyroid disease, or pre-excitation syndrome.Two simple electrocardiogram (ECG) markers, namely maximum P-wave duration (Pmax) and P-wave dispersion (PD), have been used to evaluate intra- and inter-atrial conduction times and the inhomogeneous propagation of sinus impulses, which are well-known electrophysiological characteristics of the atrium prone to fibrillation.7,8 Prolonged Pmax and PD have been reported to represent an increased risk for AF in patients with no underlying heart disease.7,8 Besides, evidence from laboratory and epidemiological research suggests that systemic inflammation may play a role in AF aetiology.9 It has also been demonstrated that atrial electromechanical coupling, measured by tissue Doppler imaging (TDI), as significantly longer in patients with paroxysmal AF than in control groups.10,11To our knowledge, no study evaluating PD and atrial electromechanical coupling has been investigated in pregnant subjects without additional systemic disease. Therefore, in this study we aimed to examine atrial electromechanical coupling and PD, reflecting inter-atrial conduction times in pregnant subjects.     

The SM protein Sly1 accelerates assembly of the ER–Golgi SNARE complex

Soluble N-ethylmaleimide–sensitive factor attachment protein receptor (SNARE) and Sec1/Munc18 (SM) proteins constitute the core of an ancient vesicle fusion machine that diversified into distinct sets that now function in different trafficking steps in eukaryotic cells. Deciphering their precise mode of action has proved challenging. SM proteins are thought to act primarily through one type of SNARE protein, the syntaxins. Despite high structural similarity, however, contrasting binding modes have been found for different SM proteins and syntaxins. Whereas the secretory SM protein Munc18 binds to the ‟closed conformation” of syntaxin 1, the ER–Golgi SM protein Sly1 interacts only with the N-peptide of Sed5. Recent findings, however, indicate that SM proteins might interact simultaneously with both syntaxin regions. In search for a common mechanism, we now reinvestigated the Sly1/Sed5 interaction. We found that individual Sed5 adopts a tight closed conformation. Sly1 binds to both the closed conformation and the N-peptide of Sed5, suggesting that this is the original binding mode of SM proteins and syntaxins. In contrast to Munc18, however, Sly1 facilitates SNARE complex formation by loosening the closed conformation of Sed5.In eukaryotic cells, material is transported in vesicles that pinch off of one set of membranes and move along microtubule tracks to the next compartment, where they specifically fuse. Key players in the fusion of a vesicle with its acceptor membrane are the soluble N-ethylmaleimide–sensitive factor attachment protein receptor (SNARE) proteins. Heterologous sets of SNARE proteins drive the fusion of two membranes by zippering into a tight four-helix bundle structure. Distinct sets of SNARE proteins carry out different vesicle fusion steps in the cell. An essential SNARE protein for transport into and across the Golgi is Sed5/syntaxin 5 (1). Besides SNARE complexes, Sed5 exists also in a 1:1 complex with the Sec1/Munc18 (SM) protein Sly1 that is essential for ER–Golgi and intra-Golgi trafficking (2). Distinct types of SM proteins are thought to function together with the respective SNARE complex, specifically its syntaxin (reviewed in refs. 3–8).The very N-terminal region, the so-called N-peptide, of Sed5 binds with nanomolar affinity to the outer surface of Sly1 (9–12). This mode of interaction is consistent with the notion that Sly1 can stay bound during SNARE complex formation and that it might even be actively involved in this reaction (13). This idea was strengthened by the observation that Sec1, the SM protein essential for secretion in yeast, interacts with the assembled SNARE complex but not with its isolated syntaxin (14). Unfortunately, for the interaction of Sec1 with its SNARE unit, no definitive structural foundation exists so far, and it remains uncertain whether Sec1 can be considered as a model for SM protein function. Fortunately, the animal counterpart of Sec1, Munc18-1, has been studied in more detail. However, the results of numerous biochemical studies on Munc18-1 appear not to fit into the concept of SM proteins being factors that promote SNARE assembly. On the contrary, initial studies found that Munc18-1 strongly interferes with the ability of its cognate syntaxin 1 to form a SNARE complex (15, 16). This inhibition is difficult to reconcile with an essential role of Munc18-1 during neurotransmitter release (17). The structure of the Munc18-1/syntaxin 1a complex revealed that the central cavity of Munc18-1 wraps around syntaxin in the so-called “closed conformation” (18). In this conformation, the three-helix bundle formed by syntaxin’s N-terminal Habc domain folds back onto its SNARE motif (19), restricting the availability of syntaxin for its SNARE partners. Thus, although they share a similar structure, Munc18-1 and Sly1 appear to bind to their cognate syntaxins in different modes.New light on this discrepancy was shed when it was discovered that Munc18-1 is able to bind simultaneously to a second, spatially separated binding site on syntaxin 1 (15). This second site involves the N-peptide region of syntaxin 1 that, similar to the Sed5 N-peptide (12), binds to the outer surface of Munc18-1. Interestingly, both binding sites are also present in the Munc18/syxtaxin 1 complex of the choanoflagellate Monosiga brevicollis (20). This suggests that the binding mode involving two different sites is evolutionarily conserved. A comparable binding mode was also described for the SM protein Vps45, which regulates trans-Golgi network trafficking. Vps45 binds tightly to the N-peptide of its cognate syntaxin Tlg2/syntaxin 16 (21). It was shown later that Vps45 is also able to interact with the remainder of its Qa-SNARE, possibly in a closed conformation (15, 22).Not all SM proteins are known to bind to the N-peptide of their cognate syntaxin. For example, in the SM protein Vps33, which plays an essential role in the degradation pathway, the N-peptide binding pocket is blocked (23, 24). Vps33 is part of a multisubunit tethering complex known as the homotypic fusion and protein sorting complex (25). Nevertheless, the structure of Vps33 is very similar to other SM protein types despite having low sequence similarity (23, 24). It would be surprising if such structures were not preserved to maintain similar molecular functions. This raises the question of whether there are missing pieces to our understanding of the molecular role of SM proteins.With the idea of a conserved molecular role of SM proteins in mind, we aimed here at a more thorough comparison of Sly1 and Munc18, which are still thought to represent two examples of SM proteins with contrasting syntaxin binding modes. So far nothing is known about a second binding site in the Sly1/Sed5 complex, but the presence of a homologous N-peptide binding site in Munc18 and Sly1 reveals a certain similarity of the two SM protein types. It is debated whether binding of Sly1 to the N-peptide of Sed5 is essential for Golgi trafficking while biochemically less is known (11, 26–28). Neither the effect of Sly1 on SNARE complex assembly has been determined rigorously, nor is it clear whether Sed5 can adopt a closed conformation that interferes with its ability to form a SNARE complex. We therefore sought to determine whether Sly1, in addition to its tight interaction with the N-peptide of Sed5, interacts with the remaining part of Sed5 and, if so, whether this interaction would have an impact on the ability of Sed5 to form a SNARE complex. We found that Sed5 adopts a closed conformation. Comparable to Munc18-1, Sly1 binds simultaneously to both the closed conformation and the N-peptide region of Sed5, although the latter is the major contributor to its affinity to the complex. Remarkably, in contrast to Munc18-1, which blocks SNARE complex assembly, Sly1 was found to assist Sed5 in forming a SNARE complex.     

An outpatient clinical study of dissociative disorder not otherwise specified

The relatively high prevalence of the diagnosis of dissociative disorder not otherwise specified is frequently considered to be disproportionate. The disproportionate rate of this diagnosis is thought to be related to nosologic and/or diagnostic issues in dissociative identity disorder. We sought to investigate and compare the symptom patterns of these two clinical entities. We conducted a cross-sectional study involving 1314 participants who were screened with the Dissociative Experience Scale (DES) and the Somatoform Dissociation Questionnaire (SDQ). Of the participants, 272 who scored above the cut-off points for the screening questionnaires (DES score > 30 and/or SDQ score > 40 points) were invited to complete a structured interview using the Dissociative Disorders Interview Schedule (DDIS); of this subsample, only 190 participants agreed to participate in the second phase of the study. The mean score for the DES was 18.55 ± 17.23, and the mean score for the SDQ was 30.19 ± 13.32. Of the 190 participants, 167 patients were diagnosed as having a dissociative disorder (87.8%). We found that DD-NOS was the most prevalent category of dissociative disorder.     

Dynamic changes in cervical glycosaminoglycan composition during normal pregnancy and preterm birth

Glycosaminoglycans (GAG) have diverse functions that regulate macromolecular assembly in the extracellular matrix. During pregnancy, the rigid cervix transforms to a pliable structure to allow birth. Quantitative assessment of cervical GAG is a prerequisite to identify GAG functions in term and preterm birth. In the current study, total GAG levels increased at term, yet the abundance, chain length, and sulfation levels of sulfated GAG remained constant. The increase in total GAG resulted exclusively from an increase in hyaluronan (HA). HA can form large structures that promote increased viscosity, hydration, and matrix disorganization as well as small structures that have roles in inflammation. HA levels increased from 19% of total GAG in early pregnancy to 71% at term. Activity of the HA-metabolizing enzyme, hyaluronidase, increased in labor, resulting in metabolism of large to small HA. Similar to mice, HA transitions from high to low molecular weight in term human cervix. Mouse preterm models were also characterized by an increase in HA resulting from differential expression of the HA synthase (Has) genes, with increased Has1 in preterm in contrast to Has2 induction at term. The Has2 gene but not Has1 is regulated in part by estrogen. These studies identify a shift in sulfated GAG dominance in the early pregnant cervix to HA dominance in term and preterm ripening. Increased HA synthesis along with hyaluronidase-induced changes in HA size in mice and women suggest diverse contributions of HA to macromolecular changes in the extracellular matrix, resulting in loss of tensile strength during parturition.