Characterisation of bone following ultrasonic cutting

Objectives

Ultrasonic surgery is an increasingly popular technique for cutting bone, but little research has investigated how the ultrasonic tip oscillations may affect the cuts they produce in bone. The aim of this investigation was to evaluate the oscillation and cutting characteristics of an ultrasonic surgical device.

Materials and methods

A Piezosurgery 3 (Mectron, Carasco, Italy) ultrasonic cutting system was utilised with an OP3 style tip. The system was operated with the tip in contact with porcine bone samples (loads of 50 to 200 g) mounted at 45° to the vertical insert tip and with a water flow of 57 ml/min. Tip oscillation amplitude was determined using scanning laser vibrometry. Bone surfaces defects were characterised using laser profilometry and scanning electron microscopy.

Results

A positive relationship was observed between the magnitude of tip oscillations and the dimensions of defects cut into the bone surface. Overloading the tip led to a reduction in oscillation and hence in the defect produced. A contact load of 150 g provided the greatest depth of cut. Defects produced in the bone came from two clear phases of cutting.

Conclusions

The structure of the bone was found to be an important factor in the cut characteristics following piezosurgery.

Clinical relevance

Cutting of bone with ultrasonics is influenced by the load applied and the setting used. Care must be used to prevent the tip from sliding over the bone at low loadings.     

The surgical management of pancreatic cancer

There have been significant advances made over the years in the areas of critical care, anesthesia, and surgical technique, which have led to improved mortality rates and survival after resection for pancreatic cancer. The standard of care is currently PD or PPPD for pancreatic cancers of the head, uncinate process, or neck and DP for pancreatic cancers of the body or tail. Resections are performed with the goals of negative margins and minimal blood loss, and referral to high-volume centers and surgeons is encouraged. However, 5-year survival rate after curative resection still remains at less than 20%. In an effort to improve survival and extend the limits of resectability, many centers have attempted extended lymphadenectomy and portal venous and even arterial resection and reconstruction. Extended lymphadenectomy has not led to improved survival for these patients. Portal vein resection has increased the number of patients amenable to resection, with equivalent survival rates compared with those of standard resections. Portal vein invasion is thus no longer considered a contraindication to resection at many large centers. Resection and reconstruction of involved arteries have been rarely performed and are currently not considerations for most patients. It is likely that future improvements in survival lie in the realm of adjuvant therapy. As chemotherapeutic and other tumor-directed agents continue to evolve and advance, this will hopefully lead to improved survival for patients undergoing surgical resection for pancreatic cancer.     

Argyrophilic grain disease differs from other tauopathies by lacking tau acetylation

Post-translational modifications play a key role in tau protein aggregation and related neurodegeneration. Because hyperphosphorylation alone does not necessarily cause tau aggregation, other post-translational modifications have been recently explored. Tau acetylation promotes aggregation and inhibits tau’s ability to stabilize microtubules. Recent studies have shown co-localization of acetylated and phosphorylated tau in AD and some 4R tauopathies. We developed a novel monoclonal antibody against acetylated tau at lysine residue 274, which recognizes both 3R and 4R tau, and used immunohistochemistry and immunofluorescence to probe 22 cases, including AD and another eight familial or sporadic tauopathies. Acetylated tau was identified in all tauopathies except argyrophilic grain disease (AGD). AGD is an age-associated, common but atypical 4R tauopathy, not always associated with clinical progression. Pathologically, AGD is characterized by neuropil grains, pre-neurofibrillary tangles, and oligodendroglial coiled bodies, all recognized by phospho-tau antibodies. The lack of acetylated tau in these inclusions suggests that AGD represents a distinctive tauopathy. Our data converge with previous findings to raise the hypothesis that AGD could play a protective role against the spread of AD-related tau pathology. Tau acetylation as a key modification for the propagation tau toxicity deserves further investigation.     

Predoctoral interns’ nondisclosure in supervision

Abstract

In interviews with 14 counseling center predoctoral interns regarding a significant nondisclosure in supervision, eight interns reported good supervisory relationships and six indicated that they experienced problematic supervisory relationships. Nondisclosures for the interns in good supervisory relationships related to personal reactions to clients, whereas nondisclosures for interns in problematic supervisory relationships related to global dissatisfaction with the supervisory relationship. In both groups, interns mentioned concerns about evaluation and negative feelings as typical reasons for nondisclosure. Additional reasons for nondisclosure for interns in problematic supervision were power dynamics, inhibiting demographic or cultural variables, and the supervisor's theoretical orientation. Both groups described negative effects of nondisclosure on themselves and their relationships with clients. Interns in problematic supervision also reported that nondisclosures had negative effects on the supervisory relationship.     

Stabbing energy and force required for pocket-knives to pierce ribs

Purpose

In addition to reconstructing the course of events, the medical examiner will often have to answer questions regarding the force necessary to inflict a certain injury in stabbing incidents. Several groups have examined the force needed to penetrate soft-tissue and clothing; however, no studies addressing the energy needed for penetrating ribs exist. Therefore, we decided to investigate this force on an animal model.

Method

Ribs from healthy, 8 to 10-month-old pigs were used as a substitute for human ribs. These ribs were then stabbed either transversely or longitudinally with two different pocket-knife blades, namely a Swiss Army pocket knife and a sturdier pocket knife (Classic Schnitzmesser, Herbertz Solingen) dropped from a drop-tower at defined heights and therefore defined energies.

Results

Longitudinally orientated stabs showed complete piercing of the ribs at approximately 11 Joules (J) or with a stabbing force in excess of 906 Newton (N) for both blade types. Transversely orientated stabs, however, displayed complete piercing between 11 and 16 J, or in excess of 1198 N, with the sturdy pocket knife tending to require a little more energy than the Swiss army pocket knife.

Conclusions

Young adult porcine ribs are completely pierced by pocket knife blades at energies between 11 and 16 J. Assuming the porcine ribs are comparable to those ribs of young adult humans, our results indicate that a complete penetration of the chest wall through the ribs by stabbing with a pocket knife is rather easily achieved.

     

An overview of the potential strategies for NK cell‐based immunotherapy for acute myeloid leukemia

Patients with acute myeloid leukemia (AML) have relatively low survival rates compared to patients with other pediatric cancers. Relapse is frequent with conventional treatment and is a major cause of morbidity and mortality. Natural killer (NK) cells offer an alternative approach to chemotherapy that combats relapse by substantially eradicating AML blasts. New methods for enhancing NK cell activation and expression of the activating ligand on target malignant cells will increase the likelihood of success with this approach. We review these latest discoveries in NK cell‐based therapy for AML and delineate recent advances in sensitizing AML cells to NK cell‐mediated immunosurveillance.