Alterations of the CxxC domain preclude oncogenic activation of mixed-lineage leukemia 2

The mixed-lineage leukemia (MLL) family of histone methyltransferases has become notorious for the participation of the founding member, MLL, in fusion proteins that cause acute leukemia. Despite structural conservation, no other MLL homolog has so far been found in a similar arrangement. Here, we show that fusion proteins based on Mll2, the closest relative of MLL, are incapable of transforming hematopoietic cells. Elaborate swap experiments identified the small CxxC zinc-binding region of Mll2 and an adjacent 'post-CxxC' stretch of basic amino acids as the essential determinants for the observed difference. Gel shift experiments indicated that the combined CxxC and post-CxxC domains of MLL and Mll2 possess almost indistinguishable DNA-binding properties in vitro. Within the cellular environment, however, these motifs guided MLL and Mll2 to a largely nonoverlapping target gene repertoire, as evidenced by nuclear localization, reporter assays, and measurements of homeobox gene levels in primary cells expressing MLL and Mll2 fusion proteins. Therefore, the CxxC domain appears to be a promising target for therapies aimed at MLL fusion proteins without affecting the general function of other MLL family members.

Benefits of active motion for joint position sense

Anterior cruciate ligament (ACL) ruptures lead to a proprioceptive deficit and therefore joint position sense. This study examined whether active motion is better suited than passive motion to address this deficit. Sixty patients with ACL rupture were prospectively randomised into two groups [continuous active motion (CAM)/continuous passive motion (CPM)]. All patients had an ACL reconstruction. An angle reproduction test was used to assess the proprioceptive deficit. The relevant examinations were performed before surgery (pre-op evaluation) and after the seventh postoperative day. No preoperative difference was found between the two groups. After postoperative treatment, the deficit was reduced in both groups. Significantly better results were, however, obtained in the CAM group (CPM, 4.2+/-1.6 degrees; CAM, 1.9+/-1.2 degrees; P<0.001). During the first postoperative week, a CAM device produced a significantly greater reduction in the proprioceptive deficit and should be the first choice in immediately postoperative rehabilitation after ACL replacement.

The effect of fixation and location on the stability of the markers in navigated total hip arthroplasty

In navigated total hip arthroplasty, the pelvis and the femur are tracked by means of rigid bodies fixed directly to the bones. Exact tracking throughout the procedure requires that the connection between the marker and bone remains stable in terms of translation and rotation. We carried out a cadaver study to compare the intra-operative stability of markers consisting of an anchoring screw with a rotational stabiliser and of pairs of pins and wires of different diameters connected with clamps. These devices were tested at different locations in the femur. Three human cadavers were placed supine on an operating table, with a reference marker positioned in the area of the greater trochanter. K-wires (3.2 mm), Steinman pins (3 and 4 mm), Apex pins (3 and 4 mm), and a standard screw were used as fixation devices. They were positioned medially in the proximal third of the femur, ventrally in the middle third and laterally in the distal portion. In six different positions of the leg, the spatial positions were recorded with a navigation system.

Compared with the standard single screw, with the exception of the 3 mm Apex pins, the two-pin systems were associated with less movement of the marker and could be inserted less invasively. With the knee flexed to 90° and the dislocated hip rotated externally until the lower leg was parallel to the table (figure-four position), all the anchoring devices showed substantial deflection of 1.5° to 2.5°. The most secure area for anchoring markers was the lateral aspect of the femur.

Dynamic 13C NMR studies of ligand exchange in linear (d10) silver(I) and gold(I) and square-planar (d8) rhodium(I) homoleptic metal carbonyl cations in superacidic media

The dynamic CO exchange of the monovalent metal carbonyl cations [Ag(13CO)]+, [Au(13CO)2]+-Au(13CO) SO3F and [Rh(12CO)4-x(13CO)x]+ (x < or = 1) in superacidic solutions was studied by variable-temperature 13C NMR methods. The exchange rates are strongly dependent on the acidity of the solvent, the concentration of metal carbonyl cations and temperature. Whereas a suitable exchange rate of the Ag(I) system is only accessible in magic acid (HSO3F-SbF5), the more stable Au(I) and Rh(I) systems were studied in the less acidic fluorosulfuric acid. Selected solutions of Ag(I), Rh(I) and Au(I) yielded activation barriers deltaG* of 42.7, 43.5, and 56.2 kJ mol(-1) respectively.

Maternal soluble tumour necrosis factor receptor type 2 (sTNFR2) and adiponectin are both related to blood pressure during gestation and infant's birthweight

OBJECTIVE

Tumour necrosis factor alpha (TNF-alpha) and adiponectin are strongly related to insulin sensitivity; insulin resistance of pregnancy is a major determinant of infant's birthweight. We aimed to study the contributions of maternal serum concentrations of soluble TNF-alpha receptors (sTNFR1 and sTNFR2) and adiponectin to infant's birthweight.

DESIGN

Cross-sectional, hospital-based study of insulin sensitivity during gestation.

PATIENTS

Fifty-one healthy women with uncomplicated pregnancy and delivery (except for elective Caesarian section) and their healthy newborn infants. measurements Maternal blood levels of glucose, insulin, glycosylated haemaglobin (HbA1c), sTNFR1, sTNFR2 and adiponectin at delivery; cord-blood levels of sTNFR1, sTNFR2 and adiponectin.

RESULTS

At delivery, maternal sTNFR2 correlated with systolic blood pressure (SBP; r = 0.38, P = 0.005). In multiple regression analyses, SBP and HbA1c were independent predictors of sTNFR2, explaining 18 and 7% of its variance, respectively; insulin resistance index (HOMA-IR), body mass index at delivery and SBP were independent predictors of adiponectin, explaining 15, 8 and 7% of its variance, respectively. Both maternal sTNFR2 and SBP were negatively correlated with infant's birthweight (r = -0.28, P = 0.04 and r = -0.36, P = 0.01 respectively, adjusted for sex and gestational age). In multivariate regression analyses, infant's sex and either maternal sTNFR2 or adiponectin were independent predictors of infant's birthweight, each explaining between 6 and 9% of birthweight variance. Further addition of maternal SBP to these models revealed that this variable was the main predictor of infant's birthweight, explaining 13% of its variance.

CONCLUSIONS

Maternal sTNFR2 and adiponectin are independently related to both maternal blood pressure and infant's birthweight in uncomplicated pregnancy. The contributions of the TNF-alpha system and adiponectin to hypertensive disorders of pregnancy and fetal growth merit further studies.

Contamination during removal of cement in revision hip arthroplasty. A cadaver study using ultrasound and high-speed cutters

Instruments used in surgery which rotate or vibrate at a high frequency can produce potentially contaminated aerosols. Such tools are in use in cemented hip revision arthroplasties. We aimed to measure the extent of the environmental and body contamination caused by an ultrasound device and a high-speed cutter. On a human cadaver we carried out a complete surgical procedure including draping and simulated blood flow contaminated with Staphylococcus aureus (ATCC 12600). After cemented total hip arthroplasty, we undertook repeated extractions of cement using either an ultrasound device or a high-speed cutter. Surveillance cultures detected any environmental and body contamination of the surgical team. Environmental contamination was present in an area of 6 x 8 m for both devices. The concentration of contamination was lower for the ultrasound device. Both the ultrasound and the high-speed cutter contaminated all members of the surgical team. The devices tested produced aerosols which covered the whole operating theatre and all personnel present during the procedure. In contaminated and infected patients, infectious agents may be present in these aerosols. We therefore recommend the introduction of effective measures to control infection and thorough disinfection of the operating theatre after such procedures.

Retrograde injection of a nutrient vein with cement in cemented total hip arthroplasty

An 80-year-old woman received a cemented total hip arthroplasty. The surgery was performed without intraoperative complications. Postoperative radiographs and a computed tomography scan revealed a nutrient vein perforating the femur, which was retrogradely filled with cement. An abdominal and thoracic computed tomography scan showed no further dissemination of cement.

Excessive heat generation during cutting of cement in the Robodoc hip-revision procedure

The ROBODOC system is a promising new method for removing cement with high-speed milling. Heat is generated during the milling process. This study was designed to measure temperatures in the cutting area, and to assess the risk of heat injury and the effectiveness of irrigation. We measured temperatures at the bone-cement cutting area in three experimental settings, two involving the proximal area comprising a cement mantle, and one the distal cement plug beneath the prosthesis. Without cooling facilities, a mean temperature of 94 degrees C was measured in proximal areas. However, this could effectively be reduced below 70 degrees C with irrigation. In the area of the distal cement plug, we measured a mean temperature of 172 degrees C without irrigation. In this area, the integrated irrigation system with an additional high-flow irrigation system could not guarantee cooling to an acceptable temperature of below 70 degrees C since the irrigation stream was impeded by the cutter in the narrow cavity. We need an integrated irrigation device that guarantees continuous cooling at the cutting interface in front of the cutter.

Multiple previous surgeries, infection, and preoperative radiation: a cause for arterial rupture in closed reduction?

We report a patient who underwent revision hip arthroplasty with preoperative radiation after a septic loosening of the primary hip prosthesis. Subsequently the patient presented with a dislocation of the hip. During the closed reduction with general anesthesia, a rupture of the arteria profunda femoris occurred. The patient was treated by angiographic obliteration of the arteria profunda femoris followed by an open reduction and augmentation of the acetabular component.

Environmental and body contamination through aerosols produced by high-speed cutters in lumbar spine surgery

STUDY DESIGN

A cadaver study to evaluate contamination in the operating room through the use of a high-speed bone cutter.

OBJECTIVES

To determine the grade of contamination of animate and inanimate objects through an aerosol intraoperatively, produced by a high-speed cutter during lumbar laminectomy.

SUMMARY OF BACKGROUND

In spinal surgery, high-speed cutters are used that produce an aerosol consisting of a mixture of irrigation solution, blood, and tissue debris. Such aerosols can be contaminated with potential pathogens. The surgical personnel and the environment are therefore exposed to a contamination risk.

METHODS

Laminectomies at three points (L2-L4) were performed on a human cadaver using a high-speed cutting device. The aerosol produced by the irrigation solution was contaminated with Staphylococcus aureus ATCC 12600. To detect the contamination of the environment and of the surgical team, surveillance cultures were used.

RESULTS

By air sampling, staphylococci were detected in the operating room at an extension of 5 by 7 m. The surgical team showed extensive face and body contamination with S. aureus. Despite protection by a barrier drape, similar contamination was observed on both the cadaver's head and the anesthesiologist.

CONCLUSIONS

The use of high-speed cutters in spinal surgery produces an aerosol that can be contaminated with blood-borne pathogens from infected patients. This aerosol is spread over the whole surgical room and contaminates the room and all personnel present. It is therefore critical to ensure that effective infection control measures are performed, not only by the surgeons but by everyone present in the operating room. The room itself must be sufficiently disinfected after such procedures.

Knee pain caused by a fiducial marker in the medial femoral condyle: a clinical and anatomic study of 20 cases

After 2-pin-based ROBODOC hip arthroplasty procedures, 10 of 18 patients reported persistent severe pain at the site of pin implantation in the medial femoral condyle. In a cadaver study, we found that the infrapatellar branch of the saphenous nerve, the saphenous nerve and the anterior cutaneous branches of the femoral nerve had been injured by the pins. At least one of these nerves was injured in 11 of the 20 specimens examined. Our findings indicate that the knee-pain may be partly caused by injuries to these nerves.

Aerosols produced by high-speed cutters in cervical spine surgery: extent of environmental contamination

High-speed cutters are used in the surgery of the cervical spine. Such high-speed devices can produce an aerosol cloud. As a patient can be a reservoir for pathogens, with aerosol-borne paths of transmission, such an aerosol has to be seen as a potential risk of infection for health care professionals present during the surgery and for patients if micro-organisms are transferred through the medical personnel. The study was performed in order to measure the extension of environmental and body contamination through contaminated aerosols produced by a high-speed cutter. Three laminectomies (C4-C6) were performed on an intact human cadaver with a high-speed 0.6-mm ball cutter. A complete surgical setup was arranged, including surgical draping and a barrier drape to the anesthesiologist's workplace. Body and environmental contamination was detected by the use of surveillance cultures. The irrigation solution was artificially contaminated with Staphylococcus aureus ATCC 12600. Following the surgery, staphylococci were detected in the operating room at an extension of 5x7 m. Everybody showed extensive face and body contamination with Staphylococcus aureus. The study showed that the use of high-speed cutters in surgery of the cervical spine produces an aerosol cloud that is spread over the whole surgical room and contaminates the theater and all personnel present. Such aerosols can be contaminated with pathogens if the patient was infected or colonized. Therefore, sufficient protective measures have to be recommended for everyone present in the operating room during such surgeries. In addition, efficient disinfection of the room and all mobile equipment is necessary after each surgery involving high-speed cutting devices.

Semiclassical treatment of reactions at surfaces with electronic transitions

The semiclassical treatment of reactions at surfaces with electronic transitions based on the fewest-switches algorithm is compared with full quantum mechanical results. As a model system the ionization probability in I2 scattering from a diamond surface is chosen. In the calculations we treat the molecular distance from the surface and one surface oscillator coordinate explicitly. Furthermore, we also consider molecular rotation in the semiclassical calculations. The semiclassical results agree with the quantum results although some discrepancies remain, as far as the phase coherence is concerned. We identify energy transfer to molecular and surface degrees of freedom as a possible mechanism that could explain the experimental dependence of the ionization probability on the incident kinetic energy of the molecule.