External iliac artery occlusion due to pelvic fracture: management with a cross-femoral bypass graft

Vascular injury is not uncommon in cases of major pelvic trauma. Venous injury is by far the most common associated problem and may lead to exsanguinating hemorrhage. Arterial injury is less common, but certainly not without associated morbidity and mortality. It can lead to persistent bleeding after fixation and stabilization of the pelvic girdle, and occlusion of major pelvic arteries can cause limb ischemia and limb loss. The potential problems with revascularizing the ischemic extremity are (1) other life-threatening injuries that may be present and (2) a retroperitoneal hematoma that can interfere with an anatomic approach. Our solution to the latter problem, as presented here, is placement of a cross-femoral bypass graft, which rapidly and safely restores blood flow in the presence of pelvic fracture and an occluded external iliac artery. The pelvic hematoma is avoided, thereby restoring circulation more quickly, with less blood loss and greater ease.     

Vertebral artery injury associated with a Jefferson fracture

BACKGROUND: The evaluation and treatment of Jefferson fractures, a burst fracture of the ring of Cl, has been well documented in the medical literature. Vertebral artery injury associated with a Jefferson fracture is very rare. METHODS: The case study technique was used to summarize the case. Review of the literature was performed to discuss the case. Retrospective chart review of the 174 patients with cervical fractures admitted to St. Michael's Hospital from 1989-1994 was also performed. RESULTS: The case of a patient with a Jefferson fracture, with bilateral lateral displacement of the lateral masses causing bilateral vertebral artery occlusions resulting in a lateral medullary and cerebellar infarction is reported. A review of the literature is provided. CONCLUSION: A high index of suspicion for this injury is paramount, especially in patients with multiple trauma, where the diagnosis of Jefferson fractures can be delayed.     

The tragus as a donor area of cartilage grafts: anatomic study

The American Dental Association (ADA) has developed many resources to address growing concerns regarding HIV (human immunodeficiency virus) issues in dental practice, including continuing education courses, workshops, journal articles, and monographs. In addition, the ADA Council on Dental Practice has established a network for dentists with HIV/AIDS (acquired immune deficiency syndrome). The network has been named PEERS, which stands for Prevention, Education, Ethics, Resources, and Support. This paper provides guidelines for developing programs in each state to address the needs of dentists with HIV/AIDS.     

The relation of passage of gas an abdominal bloating to colonic gas production

OBJECTIVE: To determine the relation of gas passage and abdominal bloating to the production of gas in the colon. DESIGN: Randomized, double-blind, crossover study of gaseous symptoms during a 1-week period. SETTING: A Veterans Affairs medical center. PARTICIPANTS: 25 healthy medical center employees. INTERVENTION: Participants' diets were supplemented with either a placebo (10 g of lactulose, a nonabsorbable sugar), psyllium (a fermentable fiber), or methylcellulose (a nonfermentable fiber). MEASUREMENTS: All participants were polled for gaseous symptoms (including number of gas passages, impression of increased rectal gas, and abdominal bloating), and five were examined for breath hydrogen excretion. RESULTS: Participants passed gas 10 +/- 5.0 times per day (mean +/- SD) during the placebo period. A significant increase in gas passages (to 19 +/- 12 times per day) and a subjective impression of increased rectal gas were reported with lactulose but not with either of the two fiber preparations. Breath hydrogen excretion, an indicator of hydrogen production in the colon, did not increase after ingestion of either of the fibers. However, a statistically significant (P < 0.05) increase in feelings of abdominal bloating (which the participants perceived as excessive gas in the bowel) was reported with both fiber preparations and with lactulose. CONCLUSIONS: The physician should distinguish between excessive gas (which indicates excessive gas production) and feelings of bloating (which are usually unrelated to excessive gas production). Treatment of the former consists of limiting the supply of fermentable material to the colonic bacteria. Symptoms of bloating usually indicate the irritable bowel syndrome, and therapy should be directed accordingly.     

The effect of HER-2/neu overexpression on chemotherapeutic drug sensitivity in human breast and ovarian cancer cells

INTRODUCTION: Determination of the optimal electrode configuration during implantable cardioverter defibrillator (ICD) implantation remains largely an empirical process. This study investigated the feasibility of using a finite element model of the thorax to predict clinical defibrillation metrics for internal defibrillation in humans. Computed defibrillation metrics from simulations of three common electrode configurations with a monophasic waveform were compared to pooled metrics for similar electrode and waveform configurations reported in humans. METHODS AND RESULTS: A three-dimensional finite element model was constructed from CT cross-sections of a human thorax. Myocardial current density distributions for three electrode configurations (epicardial patches, right ventricular [RV] coil/superior vena cava [SVC] coil, RV coil/SVC coil/subcutaneous patch) and a truncated monophasic pulse with a 65% tilt were simulated. Assuming an inexcitability threshold of 25 mA/cm2 (10 V/cm) and a 75% critical mass criterion for successful defibrillation, defibrillation metrics (interelectrode impedance, defibrillation threshold current, voltage, and energy) were calculated for each electrode simulation. Values of these metrics were within 1 SD of sample-size weighted means for the corresponding metrics determined for similar electrode configurations and waveforms reported in human clinical studies. Simulated myocardial current density distributions suggest that variations in current distribution and uniformity partially explain differences in defibrillation energy requirements between electrode configurations. CONCLUSION: Anatomically realistic three-dimensional finite element modeling can closely simulate internal defibrillation in humans. This may prove useful for characterizing patient-specific factors that influence clinically relevant properties of current density distributions and defibrillation energy requirements of various ICD electrode configurations.     

Stretching DNA with optical tweezers

Force-extension (F-x) relationships were measured for single molecules of DNA under a variety of buffer conditions, using an optical trapping interferometer modified to incorporate feedback control. One end of a single DNA molecule was fixed to a coverglass surface by means of a stalled RNA polymerase complex. The other end was linked to a microscopic bead, which was captured and held in an optical trap. The DNA was subsequently stretched by moving the coverglass with respect to the trap using a piezo-driven stage, while the position of the bead was recorded at nanometer-scale resolution. An electronic feedback circuit was activated to prevent bead movement beyond a preset clamping point by modulating the light intensity, altering the trap stiffness dynamically. This arrangement permits rapid determination of the F-x relationship for individual DNA molecules as short as -1 micron with unprecedented accuracy, subjected to both low (approximately 0.1 pN) and high (approximately 50 pN) loads: complete data sets are acquired in under a minute. Experimental F-x relationships were fit over much of their range by entropic elasticity theories based on worm-like chain models. Fits yielded a persistence length, Lp, of approximately 47 nm in a buffer containing 10 mM Na1. Multivalent cations, such as Mg2+ or spermidine 3+, reduced Lp to approximately 40 nm. Although multivalent ions shield most of the negative charges on the DNA backbone, they did not further reduce Lp significantly, suggesting that the intrinsic persistence length remains close to 40 nm. An elasticity theory incorporating both enthalpic and entropic contributions to stiffness fit the experimental results extremely well throughout the full range of extensions and returned an elastic modulus of approximately 1100 pN.     

T-strand integration in maize protoplasts after codelivery of a T-DNA substrate and virulence genes

We describe a plant protoplast transformation method that provides transformants with a simple pattern of integration of a foreign gene. The approach is to deliver into plant protoplasts by direct gene transfer the Agrobacterium virulence genes virD1 and virD2 with or without virE2, together with a target plasmid containing a gene of interest flanked by Agrobacterium T-DNA border repeat sequences of 25 bp. We present evidence of T-DNA formation in maize protoplasts and its integration into the maize genome. The frequency of VirD1-VirD2-mediated integration events was about 20-35% of the total number of transformants. The addition of virE2 doubled the transformation efficiency. The method described here is of sufficient efficiency and simplicity to be useful for the production of transgenic plants with single-copy well-defined transgenic inserts.     

Electroconvulsive therapy for treatment of intractable seizures. Initial findings in two children

We treated two children with intractable epilepsy with electroconvulsive therapy (ECT) for seizure control. One child showed a change in seizure pattern with treatment, which at greater intensity was also effective in stopping nonconvulsive status epilepticus. The other child showed a decrease in spontaneous seizure frequency during short-term treatment. These findings suggest a possible role for ECT in the management of intractable epilepsy in children who are not candidates for epileptic surgery.