Reamed locked intramedullary nailing for studying femur fracture and its complications.

Morbidity associated with femur fractures in polytrauma patients is known to be high. The many unsolved clinical questions include the immunological effect of the fracture and its fixation, timing of fracture fixation, management of fracture non-union, effect of infection and critical size of bone defects. The aim of this study was to establish a clinically-relevant and reproducible animal model with regards to histological, biomechanical and radiological changes during bone healing. A custom-designed intramedullary nail with interlocking system (RabbitNail, RISystem AG, Davos Platz, Switzerland) was used for fixation, following femur fracture. New Zealand White rabbits were assigned to two groups: 1. closed fracture model (CF; non-survival model: n = 6, survival model: n = 3) with unilateral mid-shaft femur fracture created by blunt force; 2. osteotomy model (OT; survival model: n = 14) with unilateral transverse osteotomy creating femur fracture. There were no intraoperative complications and full-weight bearing was achieved in all survival rabbits. Significant periosteal reaction and callus formation were confirmed from 2 weeks postoperatively, with a significant volume formation (739.59 ± 62.14 mm3) at 8 weeks confirmed by micro-computed tomography (µ-CT). 2 months after fixation, there was no difference between the osteotomised and contralateral control femora in respect to the maximum torque (3.47 ± 0.35 N m vs. 3.26 ± 0.37 N m) and total energy (21.11 ± 3.09 N m × degree vs. 20.89 ± 2.63 N m × degree) required to break the femur. The data confirmed that a standardised internal fixation technique with an intramedullary nail for closed fracture or osteotomy produced satisfactory bone healing. It was concluded that important clinically-relevant studies can be conducted using this rabbit model.

Drift in susceptibility of Neisseria gonorrhoeae to ciprofloxacin and emergence of therapeutic failure.

Ciprofloxacin, 500 mg, was introduced as the first-line therapy for gonorrhea at St. Mary's Hospital, London, in 1989, when a surveillance program was initiated to detect the emergence of resistance. Isolates of Neisseria gonorrhoeae from consecutive patients attending the Jefferiss Wing, Genitourinary Medicine Clinic at St. Mary's Hospital, between 1989 and 1997 have been tested for susceptibility to ciprofloxacin by using an agar dilution breakpoint technique. Isolates considered potentially resistant (MIC, >0.12 microg/ml) were further characterized by determination of the MICs of ciprofloxacin, nalidixic acid, and penicillin, auxotyped and serotyped, and screened for mutations in the DNA gyrase gene, gyrA, and the topoisomerase IV gene, parC. A total of 4,875 isolates were tested. While the majority of isolates were highly susceptible (MIC, 0.12 microg/ml); all of these belonged to serogroup B, and NR/IB-1 was the most common auxotype/serovar class. The infections in 14 of the 18 patients were known to be acquired abroad, and 5 were known to result in therapeutic failure. The surveillance program has established that ciprofloxacin is still a highly effective antibiotic against N. gonorrhoeae in this population. However, it has identified a drift in susceptibility which may have resulted from increased usage of ciprofloxacin. High-level resistance has now emerged, although treatment failure is still uncommon.

Remote electronic blood release system.

BACKGROUND: The Hunter Area Pathology Service provides transfusion services to 4 metropolitan and 11 rural hospitals in Australia. To improve blood availability, conserve blood stocks, and reduce crossmatch-to-transfusion ratios, a networked electronic blood release system (EBRS) has been developed for computer cross-matching within the laboratory and at sites remote from the transfusion laboratory. It is innovative, in that non-laboratory staffs have been trained to release computer-matched blood at remote hospitals without transfusion laboratories. STUDY DESIGN AND METHODS: The EBRS software was tested and validated according to the Australian software standards AS 3563.1 and 3563.2 (1991). Over 7000 units were released by the EBRS in a laboratory trial conducted in conjunction with the conventional immediate-spin crossmatch. A further, 12-month study was conducted within the laboratory before the staged implementation of the EBRS at the remote hospitals. RESULTS: The EBRS has resulted in 1) a 25-percent reduction in the number of units requested by the medical staff, resulting from the reduction in time needed to provide compatible blood due to the elimination of the serologic crossmatch; 2) better blood stock management (reducing outdated red cell units by 30%); and 3) significant savings in laboratory workload (savings of approximately 100 hours/month). In addition, the rapid availability of computer-crossmatched red cells in emergency situations has enhanced patient safety. CONCLUSION: The EBRS is a safe and efficient means of providing red cells within the laboratory and at remote hospitals without laboratory services.

Ligand-stimulated beta 2-adrenergic receptor internalization via the constitutive endocytic pathway into rab5-containing endosomes.

The small GTPase rab5 appears to be rate-limiting for the constitutive internalization of transferrin receptor and for fluid-phase endocytosis. However, it is unknown whether rab5 regulates receptors whose internalization is stimulated by the binding of ligand, and whether such receptors change the underlying rate of the endocytic pathways they utilize. As a model for ligand-stimulated endocytosis, we used transfected HEK293 cells expressing high levels of an epitope-tagged human beta 2-adrenergic receptor. Nearly all receptors were on the cell surface in the absence of agonist, but within ten minutes of agonist addition > 50% of receptors internalized and colocalized extensively with rab5. Hypertonic sucrose blocked beta 2-adrenergic receptor internalization, as well as that of transferrin receptor, suggesting a clathrin-mediated process. In contrast, an inhibitor of potocytosis had little effect upon beta 2-adrenergic receptor internalization, suggesting that this process did not require active caveolae. Consistent with this finding, caveolin was not detectable in the 12 beta 6 line, as assessed by western blotting with a polyclonal anti-caveolin antibody. Stimulated receptor internalization did not affect the rate or capacity of the constitutive endocytic pathway since there was no detectable increase in fluid-phase endocytosis after addition of beta-agonist, nor was there a significant change in the amount of surface transferrin receptor. Altogether, these data suggest that beta 2-adrenergic receptors internalize by a clathrin-mediated and rab5-regulated constitutive endocytic pathway. Further, agonist-stimulated receptor internalization has no detectable effect upon the function of this pathway.

Symbolic substitution modified signed-digit optical adder.

A high-accuracy fixed-point optical adder that operates in parallel on many long words and that uses a pipelined correlator architecture is described. A symbolic substitution algorithm with the modified signed-digit number representation is used to perform fixed-point additions with limited carries. A new set of substitution rules and encodings is developed to combine the recognition and substitution steps into one correlation operation. This reduces hardware requirements, improves throughput by reducing the space-bandwidth product needed, and reduces latency (the delay between when data enter the processor and when the final output is available) by a factor of 2. This algorithm and our new modified signed-digit encodings and substitution rules improve the performance of other correlator and noncorrelator optical numeric computing architectures.

Characterization of a virus isolated from a case of human infectious hepatitis.

A new viral agent, isolated from the serum of an infectious hepatitis patient and designated as Agent II-B, was extensively studied in in vitro and in vivo systems. Agent II-B multiplied well in primary and serial animal cell cultures and in embryonated hen's eggs. Quantal and quantitative infectivity assays were performed in monolayers of African green monkey kidney cells. Effective concentrations of 5-iodo-2-deoxyuridine and guanidine hydrochloride did not inhibit the multiplication of Agent II-B, although 2-hydroxybenzyl-benzimidazole was an effective inhibitor. Essential lipids were not detected. The diameter of the agent is 16-25 nm and its buoyant density in CsCl equilibrium density gradients was 1.35 gm/ml. Neutralization test results did not reveal antigenic relatedness between Agent II-B and known human picornaviruses. Apparently, this new viral agent is a picornavirus which possesses the capacity to multiply in unexpectedly diverse cell types.