Stab or throw? Biomechanical studies on the injuring potential of glass fragments

During a Christmas party, two male guests started fighting. The perpetrator was allegedly pushed onto a glass table by the victim or fell into the table together with that man so that the glass top broke and caused a cut wound on the perpetrator's back. According to his statement he then threw a fragment of the broken glass table in the direction of the other man hitting him accidentally in a way so that the subclavian artery was severed and he died from exsanguination. Tests on the breaking characteristics of the glass table, the flying behaviour and the kinetics of thrown glass fragments conducted on various models supported the conclusion that the fatal injury on the victim's neck could not have been caused by a thrown glass fragment. It was much more likely that a stab with a blade-shaped glass fragment was the cause of the fatal injuries.

Endoscopic resection of laryngeal and tracheal lesions using the microdebrider

CONCLUSION: Endoscopic resection of laryngeal and tracheal lesions using the microdebrider is a safe, accurate and reliable method. OBJECTIVE: The microdebrider is an important tool for endoscopic nasal and sinus surgery and over the last few years a powered blade with a long shaft has been developed for endoscopic laryngeal and tracheal surgery. The aim of this non-randomized prospective study was to determine the advantages and disadvantages of the microdebrider for treating patients with different laryngeal and tracheal pathologies. MATERIAL AND METHODS: The laryngeal microdebrider was used under endoscopic control in 37 patients. In 29 cases a benign laryngeal lesion was removed endoscopically. In four patients debulking of a malignant obstructive endolaryngeal tumor was performed in order to avoid a tracheotomy. In four cases a bulky obstructing endotracheal lesion was removed. RESULTS: All laryngotracheal lesions could be removed, and this was facilitated by the use of angled rigid telescopes and the laryngeal blade. No traumatic lesions to normal laryngeal tissue occurred as a result of use of the microdebrider and no postoperative endolaryngeal bleeding was observed. The histological diagnosis of the biopsies taken with the microdebrider was accurate in every case. In three of the four cases with obstructive laryngeal malignancies, a tracheotomy was avoided until definitive therapy was undertaken. Normal breathing was restored in all patients with endotracheal lesions.

The transpedicular approach as an alternative route for intervertebral disc regeneration

STUDY DESIGN Descriptive anatomical study on ovine and human cadaveric lumbar spinal segments. OBJECTIVE To describe the alternative transpedicular approach to deliver therapeutic agents into intervertebral disc (IVD). SUMMARY OF BACKGROUND DATA The present delivery approach of therapeutic agents (growth factors/cells/hydrogels) within the IVD is through injection, via the annulus fibrosus (AF). However, it has recently been demonstrated that small needle puncture of the AF leads to further degeneration and disc herniation. In addition, the injected material has a high chance to be extruded through the AF injury. METHODS Lumbar ovine and human spinal segments were used. Under fluoroscopy, a 2-mm Kirschner wire was introduced in the caudal vertebra through the pedicle and the inferior endplate to the nucleus pulposus. Gross anatomy analysis and high-resolution peripheral quantitative computed tomography (HR-pQCT) were performed to assess the right position of the wire in pedicles. Discography and nucleotomy were performed using a 14G cannula insertion or a 2-mm arthroscopic shaver blade, respectively. Nucleoplasty was also performed with agarose gel/contrast agent and imaged with HR-pQCT. RESULTS Gross anatomy, fluoroscopy, and HR-pQCT images showed that the nucleus pulposus could be approached through the endplate via the pedicle without affecting the spinal canal and the neural foramina. The contrast agent was delivered into the IVD and nucleus pulposus was removed from the disc and filled with agarose gel. CONCLUSION This study describes how a transpedicular approach can be used as an alternative route to deliver therapeutic agents to the disc without disruption of the AF showing the potential use of this technique in preclinical research and highlighting its clinical relevance for IVD regeneration.

Bacterial meningitis causes two distinct forms of cellular damage in the hippocampal dentate gyrus in infant rats.

Bacterial meningitis causes neurological sequelae in up to 50% of survivors. Two pathogens known for their propensity to cause severe neurological damage are Streptococcus pneumoniae and group B streptococci. Some forms of neuronal sequelae, such as learning and memory deficits, have been associated with neuronal injury in the hippocampus. To learn more about hippocampal injury in meningitis, we performed a comparative study in bacterial meningitis due to S. pneumoniae and group B streptococcus, in which 11-day-old infant rats were infected intracisternally with either of the two pathogens. Histopathological examination of the neuronal injury in the dentate gyrus of the hippocampus showed that S. pneumoniae caused predominantly classical apoptotic cell death. Cells undergoing apoptosis were located only in the subgranular zone and stained positive for activated caspase-3 and TUNEL. Furthermore, dividing progenitor cells seemed particularly sensitive to this form of cell death. Group B streptococcus was mainly responsible for a caspase-3-independent (and TUNEL-negative) form of cell death. Compared with the morphological features found in apoptosis (e.g., apoptotic bodies), this form of neuronal death was characterized by clusters of uniformly shrunken cells. It affected the dentate gyrus throughout the blade, showing no preferences for immature or mature neurons. Thus, depending on the infecting agent, bacterial meningitis causes two distinct forms of cell injury in the dentate gyrus.

Microsurgical and laser ablation analysis of leaf positioning and dorsoventral patterning in tomato

Leaves are arranged according to regular patterns, a phenomenon referred to as phyllotaxis. Important determinants of phyllotaxis are the divergence angle between successive leaves, and the size of the leaves relative to the shoot axis. Young leaf primordia are thought to provide positional information to the meristem, thereby influencing the positioning of new primordia and hence the divergence angle. On the contrary, the meristem signals to the primordia to establish their dorsoventral polarity, which is a prerequisite for the formation of a leaf blade. These concepts originate from classical microsurgical studies carried out between the 1920s and the 1970s. Even though these techniques have been abandoned in favor of genetic analysis, the resulting insights remain a cornerstone of plant developmental biology. Here, we employ new microsurgical techniques to reassess and extend the classical studies on phyllotaxis and leaf polarity. Previous experiments have indicated that the isolation of an incipient primordium by a tangential incision caused a change of divergence angle between the two subsequent primordia, indicating that pre-existing primordia influence further phyllotaxis. Here.. we repeat these experiments and compare them with the results of laser ablation of incipient primordia. Furthermore. we explore to what extent the different pre-existing primordia influence the size and position of new organs. and hence phyllotaxis. We propose that the two youngest primordia (P-1 and P-2) are sufficient for the approximate positioning of the incipient primordium (I-1), and therefore for the perpetuation of the generative spiral, whereas the direct contact neighbours of I-1 (P-2 and P-3) control its delimitation and hence its exact size and position. Finally. we report L I specific cell ablation experiments suggesting that the meristem L-1 layer is essential for the dorsoventral patterning of leaf primordia.

The shape of a bone scraper: an in vitro pilot study using porcine bone chips.

Bone scrapers are commonly used to harvest autologous bone in oral and implant surgery. The angle of the cutting blade is a variable that distinguishes bone scrapers. In the present study, the impact of the angle of the cutting blade on the in vitro characteristics of harvested bone was determined. Bone scrapers with blade angles of 15°, 25°, 35°, 45°, and 55° were used to harvest porcine cortical mandibular bone. The number and characteristics of the cells that grew out from the bone chips were examined. The data showed that, independent of the angle of the cutting blade, viable cells were barely detectable in fresh bone grafts. However, cells with a fibroblastic morphology appeared within 1 week in the culture dishes. After 21 days, the number of cells did not differ significantly between the five preparations. Moreover, cells responded to incubation with bone morphogenetic protein 7 (BMP-7) with an increased alkaline phosphatase activity, irrespective of the preparation. The data suggest that bone scrapers with different cutting angles produce bone chips with comparable in vitro characteristics.

Qualitative Distinction of Autotrophic and Heterotrophic Processes at the Leaf Level by Means of Triple Stable Isotope (C–O–H) Patterns

Foliar samples were harvested from two oaks, a beech, and a yew at the same site in order to trace the development of the leaves over an entire vegetation season. Cellulose yield and stable isotopic compositions (δ13C, δ18O, and δD) were analyzed on leaf cellulose. All parameters unequivocally define a juvenile and a mature period in the foliar expansion of each species. The accompanying shifts of the δ13C-values are in agreement with the transition from remobilized carbohydrates (juvenile period), to current photosynthates (mature phase). While the opponent seasonal trends of δ18O of blade and vein cellulose are in perfect agreement with the state-of-art mechanistic understanding, the lack of this discrepancy for δD, documented for the first time, is unexpected. For example, the offset range of 18 permil (oak veins) to 57 permil (oak blades) in δD may represent a process driven shift from autotrophic to heterotrophic processes. The shared pattern between blade and vein found for both oak and beech suggests an overwhelming metabolic isotope effect on δD that might be accompanied by proton transfer linked to the Calvin-cycle. These results provide strong evidence that hydrogen and oxygen are under different biochemical controls even at the leaf level.

Prevention of cement leakage into the hip joint by a standard cement plug during PFN-A cement augmentation: a technical note.

Medial penetration of the helical blade into the hip joint after fixation of trochanteric fractures using the proximal femur nail antirotation (PFN-A) is a potential failure mode. In low demand patients a blade exchange with cement augmentation may be an option if conversion to total hip arthroplasty is unfeasible to salvage the cut-through. This article describes a technique to avoid intraarticular cement leakage using a cement plug to close the defect in the femoral head caused by the cut-through.