Structure-function relationships in tendons: a review

The purpose of the current review is to highlight the structure-function relationship of tendons and related structures to provide an overview for readers whose interest in tendons needs to be underpinned by anatomy. Because of the availability of several recent reviews on tendon development and entheses, the focus of the current work is primarily directed towards what can best be described as the 'tendon proper' or the 'mid-substance' of tendons. The review covers all levels of tendon structure from the molecular to the gross and deals both with the extracellular matrix and with tendon cells. The latter are often called 'tenocytes' and are increasingly recognized as a defined cell population that is functionally and phenotypically distinct from other fibroblast-like cells. This is illustrated by their response to different types of mechanical stress. However, it is not only tendon cells, but tendons as a whole that exhibit distinct structure-function relationships geared to the changing mechanical stresses to which they are subject. This aspect of tendon biology is considered in some detail. Attention is briefly directed to the blood and nerve supply of tendons, for this is an important issue that relates to the intrinsic healing capacity of tendons. Structures closely related to tendons (joint capsules, tendon sheaths, pulleys, retinacula, fat pads and bursae) are also covered and the concept of a 'supertendon' is introduced to describe a collection of tendons in which the function of the whole complex exceeds that of its individual members. Finally, attention is drawn to the important relationship between tendons and fascia, highlighted by Wood Jones in his concept of an 'ectoskeleton' over half a century ago - work that is often forgotten today.

Prospective randomized comparison of progressive dilational vs forceps dilational percutaneous tracheostomy

This trial prospectively compares two methods of percutaneous tracheostomy, both routinely used in ICU: the Ciaglia progressive dilational tracheostomy and the Griggs forceps dilational tracheostomy. One hundred patients were randomized using a single-blinded envelope method to receive progressive or forceps percutaneous tracheostomy performed at the bedside. Operative time, the occurrence of hypoxaemia or hypercapnia and complications were recorded. The progressive technique took longer than the forceps technique (median 7 (range 2-26) vs. 4 (1-16) minutes, P = 0.0005). Hypercapnia occurred in both groups but was more marked with the progressive technique (56 (16) vs. 49 (13) mmHg, P = 0.0082). Minor complications (minor bleeding, transient hypoxaemia, damage to posterior tracheal wall without emphysema) were also more frequent with the progressive technique (31 vs. 9 complications, P < 0.0001). Six major complications occurred with the progressive technique, none with the forceps technique (P = 0.0085): tension pneumothorax, posterior tracheal wall injury with subcutaneous emphysema, loss of airway with hypoxaemia, loss of stoma with impossible re-catheterization, and two conversions to another technique. In conclusion, progressive dilational tracheostomy took longer, caused more hypercapnia and more minor and major difficulties than forceps dilational tracheostomy.

Tétraplégie brutale C3-C4 révélant une fistule durale artérioveineuse intracrânienne à drainage veineux périmédullaire

We report a case of intracranial dural arteriovenous (DAVF) draining into the spinal medullary veins. A 49-year-old woman presented a rapidly progressive ascending myelopathy resulting in a C3-C4 tetraplegia associated with acute respiratory failure at the twelfth hour. MRI revealed swelling of the cervical spinal cord, hyperintensity on T2 and enhancement of enlarged veins on MR angiography. A conventional angiography showed the DAVF with venous drainage into the spinal vein extending to the conus medullaris. After embolization, neurological recovery occurred during the first week, allowing tracheal extubation on day 2. Clinical, radiological and therapeutic aspects of this uncommon pathology are presented.

[Isolated acquired factor VII deficiency in patient with severe head trauma: use of factor VII (factor VII-LFB]

We report a case of transient acquired and isolated factor VII deficiency associated with severe head trauma. A 16-year-old boy was involved in a motor vehicle accident. CT scan showed frontal brain contusion and a cerebral haematoma (5 cm). First prothrombine time (PT) was normal. Rapidly, a severe coagulopathy developed, unresponsiving to fresh frozen plasma and vitamin K. Haemostatic markers analysis showed an isolated deficiency of factor VII at 15%. No inhibitory activity against factor VII could be detected. We successfully treated the deficiency with intermittent intravenous human factor VII (factor VII-LFB) during 10 days. Factor VII return to normal at 84%. Physiopathological and therapeutic aspects of this rare pathology are presented.

Pyélonéphrite emphysémateuse : diagnostic et traitement

Emphysematous pyelonephritis is a necrotizing kidney infection characterized by the presence of gas in renal parenchyma, collecting system or perinephric tissue. This rare affection occurs almost exclusively in patients with diabetes mellitus and is due to non-anaerobic gas-producing bacteria. This life-threatening condition leads to septic shock and multiple organ failure. Diagnosis is suspected when a pyelonephritis does not respond to correct treatment, especially with altered vital signs or a diabetic patient. Computed tomography scan permits visualization of the gas and a radiologic classification with a prognostic value. Current treatment modalities are based upon repeated clinical and scanographic evaluations. In addition to systematic antibiotic therapy, percutaneous drainage is probably the first therapeutic stage in the majority of cases, but should not delay emergent rescue nephrectomy if necessary.

Nitric oxide inhalation is useful in the management of right ventricular failure caused by myocardial contusion

We report a severe head injury and blunt chest trauma with sternal and multiple rib fractures with high-energy impact in a 22-year-old man. Twelve hours after the accident, haemodynamic status of the patient rapidly worsened because of right ventricular (RV) failure due to myocardial contusion, requiring increasing doses of catecholamine. Nitric oxide inhalation was used to decrease RV afterload, and produced an immediate improvement in haemodynamic status, permitting a decrease in catecholamine administration. From days 2 through 8, cardiac function continued to improve, and was normal on day 9. Nitric oxide inhalation was stopped on day 4.

First inventory of resorption lacunae on rods and plates of trabecular bone as observed by scanning electron microscopy

In the present study a novel systematic distribution scheme of resorption lacunae (RL) was applied using scanning electron microscopy. RL, classified as either reticulate patch resorption lacunae (RPR) or as longitudinally extended resorption lacunae (LER) [11, were analyzed and quantified according to their localizations on rods (middle, nodes or both) and plates (central or peripheral) in standardized segments from the femoral head of 24 Caucasian subjects without bone disease. Age and gender variations were explored. No clear gender-related distribution pattern could be detected on plates. On rods of males, however, the distribution of RL tended to be higher at the nodes, but seemed to be more prevalent in the middle or extended from the middle to the nodes of rods in females. Certain other non-conclusive tendencies in relation to age, gender, type of RL and localization were observed.

Differential gene expression in stromal cells of human giant cell tumor of bone

Giant cell tumor (GCT) offers a unique model for the hematopoietic-stromal cell interaction in human bone marrow. Evidence has been presented that GCT stromal cells (GCTSCs) promote accumulation, size and activity of the giant cells. Although GCTSCs are considered the neoplastic component of GCT, little is known about their genetic basis and, to date, a tumor-specific gene expression pattern has not been characterized. Mesenchymal stem cells (MSCs) have been identified as the origin of the GCT neoplastic stromal cell. Using state of the art array technology, expression profiling was applied to enriched stromal cell populations from five different GCTs and two primary MSCs as controls. Of the 29 differentially expressed genes found, 25 showed an increased expression. Differential mRNA expression was verified by real-time polymerase chain reaction analysis of 10 selected genes, supporting the validity of cDNA arrays as a tool to identify tumor-related genes in GCTSCs. Increased expression of two oncogenes, JUN and NME2, was substantiated at the protein level, utilizing immunohistochemical evaluation of GCT sections and Western-blot analysis. Increased phosphorylation of JUN Ser-63 was also found.

Microstructural classification of resorption lacunae and perforations in human proximal femora

Resorption lacunae and perforation types mirror resorptional activity of osteoclasts and are important for the integrity of bone architecture. In the present study, distinctive microstructural features of cancellous bone dissected from femoral heads of 28 autopsy subjects (14 females and 14 males) were defined and evaluated by light microscopic (LM) histology and scanning electron microscopy (SEM). The work differentiates two types of resorption lacunae in trabecular bone: the longitudinally extended resorption lacunae (LER) and the reticulate patch resorption lacunae (RPR). Further, two types of perforations are distinguished: the lacunar perforation (LP) and the tunneling perforation (TP), which are differentiated from potential blood vessel canals (BC). Evidence is presented that the spatial distribution on rods or plates is highly correlated with the resorption type. The RPR type was more frequently seen and was primarily localized at the nodes of rods, in the middle regions of rods, and in the center region of plates as compared to the LER type. The presented evaluation scheme of resorption and perforation types could prove useful in future studies for systematically investigating potential microstructural changes associated with disturbed bone turnover.

[cDNA array approach to cytokine expression profile of aseptic loosened hip arthroplasty]

FACTS

Aseptic loosening of hip arthroplasties are the main reason for revision operations. Basic research indicates a significant relevance of the interface membrane formed between the implant an the surrounding bone. Their cellular composition and the influence of various factors on the process of aseptic loosening has attracted scientific interest. Cytokines are essential for intracellular communication.

QUESTION

Is it possible to reveal differences in the expression profile of cytokines between well-fixed and failed hip arthroplasties using the cDNA array approach? AIM. Generation of a cytokine expression profile characteristic for failed hip arthroplasty.

METHODS AND RESULTS

Radioactively labeled cDNA probes were synthesised from mRNA isolated from the interface membrane of six patients with aseptic loosened hip arthroplasty. Using a phosphorimager the analysis of the cDNA arrays revealed nine cytokines which were overexpressed compared with the reference tissue (Calgranulin A, Calgranulin B, IL-10, MCP-1, RANTES, TFDG1, TNFR2, RAI, THYB10).

CONCLUSION

In this study four out of these nine cytokines were found to be connected with the process of aseptic loosening for the first time.

[Scanning electron microscopic characterization of resorption lacunae and perforations in the cancellous bone of the human femoral head]

STAND: Light microscopic investigation of histologic and grinding sections indicates structural differences by resorption lacunae and perforations

QUESTION

Is it possible to characterize different types of resorption lacunae and perforations on the basis of ultrastructural differences within them? AIM. Morphological characterization of resorption lacunae and perforations in cancellous bone of the human femoral head

METHODS

Samples from the femoral head of 28 patients without skeletal diseases were macerated, dried, gold sputtered and analysed by scanning electron microscopy. RESULTS. We were able to distinguish two types of resorptions lacunae as well as two types of perforation: The longitudinal extended resorption (LER), the reticulate patched resorption (RPR), the lacunar perforation (LP), the tunneling perforation (TP). Moreover we demarcate perforations from blood vessel canals.

CONCLUSION

The differentiated types of resorption lacunae and perforations suggest the influence of local factors which regulates osteoclastic activity or indicate different subspecies of osteoclasts.

[Histogenesis of giant cell tumors]

The giant cell tumor of bone (GCT) is a local osteolytic tumor with variable degrees of aggressiveness. In rare cases pulmonary metastases can be observed. The lesion most frequently occurs in the epiphysis of long tubular bones of the knee region, predominantly affecting young adults after closure of the growth plate. The characteristic histological appearance of GCT displays a high number of osteoclast-like multinucleated giant cells, which resulted in the classification "osteoclastoma" or "giant cell tumor". Apart from the multinucleated giant cells, there are two mononuclear cell types in the GCT. The first one has a round morphology and resembles a monocyte. The second cell type is the spindle-shaped, fibroblast-like stromal cell. Cell culture experiments with GCT cells revealed the stromal cell to be the proliferating component of the GCT. The other two cell types, the monocyte and the multinucleated giant cell, were lost after a few cell culture passages. Furthermore, latest results from GCT reveal that the stromal cells secrete a variety of cytokines and differentiation factors, including MCP1, ODF and M-CSF. These molecules are monocyte chemoattractants and are essential for osteoclast differentiation, suggesting that the stromal cell stimulates blood monocyte immigration into tumor tissue and enhances their fusion into osteoclast-like, multinucleated giant cells. The multinucleated giant cell itself demonstrates properties of a normal osteoclast that is able to resorb bone leading to extended osteolysis. This new model of GCT genesis supports the hypothesis that the stromal cell is the neoplastic component whilst the monocytes and the multinucleated giant cells are just a reactive component of this tumor. Taking this into consideration, the nomenclature of the "giant cell tumor" needs to be reconsidered.

What can we learn from explanted endovascular devices?

OBJECTIVE

To examine the durability of the Stentor and Vanguard endovascular devices in human implants.

METHODS

The textile covering, the polypropylene ligatures and the stent metal of 34 devices (25 Stentor, 9 Vanguard) with a mean duration of implantation of 28.8 +/- 16 months was examined by means of stereomicroscopy and scanning electron microscopy.

RESULTS

The polyester textile covering showed gaps along the sutured seam and isolated holes in the fabric. All of the examined polypropylene ligatures were worn, some ruptured. Four different types of stent corrosion were classified--pits (100%), bizarre craters (68%), large deficiencies (14%) and fractures (32%).

CONCLUSION

Holes in the polyester fabric and frame dislocations are specific for the design of Stentor and Vanguard grafts. The early corrosion of the stent metal Nitinol in these devices is surprising. Until more experience is gained with other devices, we have to be reminded, that the "gold standard" for the long-term durability of artificial vascular grafts is still "today's" conventional graft.

Parathyroid hormone (1-34) regulates integrin expression in vivo in rat osteoblasts

Intermittent administration of parathyroid hormone (PTH) activates new sites of bone formation by stimulating osteoblast differentiation and function resulting in an increase in bone mass. Because integrins have been shown to play a crucial role in osteoblast differentiation and bone formation, in the present study, we evaluated whether human PTH (1-34) upon administration to rats, influenced integrin expression in osteoblastic cells isolated from the metaphysis and the diaphysis of rat long bones. Initial immunohistochemical evaluation of bone sections demonstrated that the osteoblasts expressed at least alphav, alpha2, alpha3, and alpha5beta1 integrins. Immunocolocalization studies for integrins and vinculin established that alphav, alpha2, and alpha5beta1, but not alpha3 integrins were present in the focal adhesion sites of osteoblasts attached to FN coated surfaces. Osteoprogenitor cells isolated from metaphyseal (but not diaphyseal) marrow of rats injected with intermittent PTH (1-34) exhibited greater alphav and reduced alpha2 levels, with no apparent changes in alpha3, and alpha5beta1 integrin levels, as assessed by immunohistochemistry, Northern, and Western blot analyses. However, these changes were not observed on the same cells treated with PTH in vitro. These observations suggest that integrin modulation by PTH is likely to be indirect and that selective phenotypic expression of integrin subtypes is part of the cascade of events that lead to PTH (1-34) mediated osteoblast differentiation.

Gsalpha gene mutations in monostotic fibrous dysplasia of bone and fibrous dysplasia-like low-grade central osteosarcoma

A series of nine cases with monostotic fibrous dysplasia (FD) and five cases of fibrous dysplasia-like low-grade central osteosarcoma (fd-like lgcOSA) were applied in a mutational analysis. Restriction digestion analysis, single-stranded conformational polymorphism (SSCP) analysis, and repeated sequencing demonstrated a R201H mutation in six cases and a R201C mutation in three cases of patients with monostotic FD. These results demonstrate that the presence of Gsalpha gene mutations is a constant finding in monostotic FD. To our knowledge, this is the first report in the literature investigating Gsalpha gene mutations in lgcOSA, which is one of the most important differential diagnoses of FD because of its low-grade malignant behavior. In four of five cases of fd-like lgcOSA, no mutation has been detected. In one case of this tumor, a R201C mutation could be demonstrated. Because our results demonstrate a low prevalence of Gsalpha gene mutations in this tumor in contrast to monostotic FD, mutational analysis may be an additional helpful parameter in individual cases for the differential diagnosis of FD and fd-like lgcOSA.

The nature of giant cell tumor of bone

Giant cell tumor of bone (GCT) is a locally osteolytic tumor with variable aggressiveness. In rare cases, pulmonary metastasis can be observed. The lesion most frequently occurs in the epiphysis of long tubular bones of the knee region, predominantly affecting young adults after closure of the growth plate. The characteristic histological appearance of GCT displays a high number of osteoclast-like multinucleated giant cells, which resulted in the classification "osteoclastoma" or "giant cell tumor". Apart from the multinucleated giant cells, there are two mononuclear cell types in GCT. The first one has a round morphology and resembles monocytes. The second cell type is the spindle-shaped, fibroblast-like stromal cell. Cell culture experiments with GCT cells revealed the stromal cell to be the proliferating component of the GCT. The other two cell types, the monocyte and the multinucleated giant cell, were lost after a few cell culture passages. Furthermore, latest results from GCT reveal that the stromal cells secrete a variety of cytokines and differentiation factors, including MCP1, ODF, and M-CSF. These molecules are monocyte chemoattractants and are essential for osteoclast differentiation, suggesting that the stromal cell stimulates blood monocyte immigration into tumor tissue and enhances their fusion into osteoclast-like, multinucleated giant cells. The multinucleated giant cell itself resembles a normal osteoclast that is able to resorb bone leading to extended osteolysis. This new model of GCT genesis supports the hypothesis that the stromal cell is the neoplastic component whilst the monocytes and the multinucleated giant cells are just reactive components of this tumor. Taking this into consideration, the nomenclature of the "giant cell tumor" needs to be reconsidered.

Determination of trace anions in high-nitrate matrices by ion chromatography

An ion chromatography method was developed to determine trace anionic contamination in matrices that have a high concentration of nitrate ion. Contaminant anions of interest were separated on an IonPac AS15 high-capacity anion-exchange column and detected by suppressed conductivity detection. An EG40 eluent generator was used to prepare high-purity and carbonate-free potassium hydroxide. Using the EG40, performance at trace levels was enhanced because background conductivity decreased and retention time reproducibility improved. Trace anionic contamination from the mobile phase was minimized when using the eluent generator compared to using conventionally prepared sodium hydroxide eluents. The signal-to-noise ratio was also improved with the use of a temperature controlled conductivity cell and chromatography hardware in the microbore (2-mm) format. The eluent concentration was optimized to separate the contaminant anions from the excess of the nitrate matrix ions. The procedure was demonstrated for a solution of reagent-grade sodium nitrate and high-purity 0.7% nitric acid. Method detection limits for chloride, sulfate and phosphate of 150 microg/l and lower were achieved.