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We have developed cross-linked polyrotaxane (cPR) that is composed of moveable cross-links and slide-ring components, in its backbone. The cPR is blended with oil well cement to improve elastic properties, and it has demonstrated improvement in elastic modulus with minimum effect on compressive strength. The optimization of curing time, fluid flow behavior, and dynamic strength development in the presence of cPR in cement are also evaluated. The Young’s modulus and compressive strength are measured at 20 MPa and 150°C to simulate downhole conditions. Remarkably, cement—cPR has, revealed a 33% increase in strain compared to neat cement.

The effect of a high-performance retarding additive in oil well cements was investigated under elevated temperature (165°C) and pressure (1000 psi) conditions via in situ synchrotron-based X-ray diffraction (XRD) and quasielastic neutron scattering (QENS) techniques. Under these temperature and pressure conditions, crystalline calcium silicate hydrates (C–S–H) are formed through the cement hydration process. From in situ XRD experiments, the retardation effect was observed by a change in the rate of the appearance of 11 Å tobermorites as well as a change in the rate of the α-C2SH generation and depletion. QENS analysis revealed that the retardation effect was related to the non-conversion of free water to chemical and constrained water components. A high presence of free water components was attributed to a decrease in 11 Å tobermorites along with slower consumption of the quartz and portlandite phases. Furthermore, QENS results infer that the water molecules experienced confinement in the restricted pore spaces. The retarder inhibited this initial water confinement by slowing the bulk diffusion of free water in the confined region.

Powerful synergies between phosphonate, zinc oxide, and acrylamido-tert-butyl-sulfonate (ATBS) copolymer chemical additives render superior performance in a high-temperature retarder system for oil well grade Portland cement. The phosphonate retarder and ATBS-based retarders establish a two-tiered strength development where amorphous C-S-H converts to crystalline dicalcium silicate hydrate (C2SH) in the first (low compressive strength) tier prior to the reaction of Portlandite with quartz. The three additive retarder system can be tuned with nanosilica to eliminate the two-tiered strength development effect leading to a smooth transition from the cement in the slurry form directly to its highest compressive strength.

Conjugates between proteins and small molecules enable access to a vast chemical space that is not achievable with either type of molecule alone; however, the paucity of specific reactions capable of functionalizing proteins and natural products presents a formidable challenge for preparing conjugates. Here we report a strategy for conjugating electron-rich (hetero)arenes to polypeptides and proteins. Our bioconjugation technique exploits the electrophilic reactivity of an oxidized selenocysteine residue in polypeptides and proteins, and the electron-rich character of certain small molecules to provide bioconjugates in excellent yields under mild conditions. This conjugation chemistry enabled the synthesis of peptide–vancomycin conjugates without the prefunctionalization of vancomycin. These conjugates have an enhanced in vitro potency for resistant Gram-positive and Gram-negative pathogens. Additionally, we show that a 6 kDa affibody protein and a 150 kDa immunoglobulin-G antibody could be modified without diminishing bioactivity. The preparation of conjugates between proteins and small molecules is often challenging and requires several synthetic steps to functionalize each component for conjugation. Now, a conjugation methodology that leverages an electrophilic Se–S bond of selenocysteine to create bioconjugates between polypeptides and complex small molecules has been described.

To combat antimicrobial infections, new active molecules are needed. Antimicrobial peptides, ever abundant in nature, are a fertile starting point to develop new antimicrobial agents but suffer from low stability, low specificity, and off-target toxicity. These drawbacks have limited their development. To overcome some of these limitations, we developed antibody-bactericidal macrocyclic peptide conjugates (ABCs), in which the antibody directs the bioactive macrocyclic peptide to the targeted Gram-negative bacteria. We used cysteine SN Ar chemistry to synthesize and systematically study a library of large (>30-mer) macrocyclic antimicrobial peptides (mAMPs) to discover variants with extended proteolytic stability in human serum and low hemolytic activity while maintaining bioactivity. We then conjugated, by using sortase A, these bioactive variants onto an Escherichia coli targeted monoclonal antibody. We found that these ABCs had minimized hemolytic activity and were able to kill E. coli at nanomolar concentrations. Our findings suggest macrocyclic peptides if fused to antibodies may facilitate the discovery of new agents to treat bacterial infections.

Objectives To determine the outcome of displaced talar neck fractures at long-term follow-up in terms of functional outcome and secondary reconstructive surgery. Design Retrospective cohort study. Setting Academic level 1 trauma center. Patients Seventy patients with displaced talar neck fractures. Intervention All patients were treated with open reduction and screw fixation. Main outcome measurements Functional outcome of patients who did not require secondary surgery was assessed using the Short Musculoskeletal Function Assessment, Ankle Osteoarthritis Scale score, and the American Orthopedic Foot and Ankle Society Ankle-Hindfoot Score. The incidence of secondary reconstructive hindfoot surgery, including arthrodesis or talectomy, was measured using life table analysis. Results Mean Short Musculoskeletal Function Assessment score was 20 +/- 18 out of 100, with a lower score indicative of better outcome; mean Ankle Osteoarthritis Scale score was 3.8 +/- 2.4 out of 10 (lower score better); and mean Ankle Society Ankle-Hindfoot Score was 71 +/- 19 out of 100 points (higher score better). The incidence of secondary reconstructive surgery increased from 24 +/- 5% at 1 year to 48 +/- 10% at 10 years postinjury. Conclusions Functional outcome varied and was most dependent upon the development of complications. The incidence of secondary reconstructive surgery following talar neck fractures increased over time and was most commonly performed to treat subtalar arthritis or misalignment.

The respiratory syncytial virus (RSV) L protein is a viral RNA-dependent RNA polymerase that contains multiple enzyme activities required for RSV replication. The RSV L inhibitors described in literature are limited by their cytotoxicity or the lack of RSV B subtype coverage. Here, we characterize a new RSV L inhibitor with strong antiviral activity against both RSV A and B subtypes and no detectable cytotoxicity. This compound, AZ-27, was equally active against RSV live viruses and subgenomic replicons and demonstrated advantages over other classes of RSV inhibitors in time-of-addition and cell line dependency studies. Resistance studies identified a dominant mutation in the putative capping enzyme domain of L protein, which conferred strong resistance to the AZ-27 series but not other classes of RSV inhibitors, supporting RSV L protein as the direct target for AZ-27. This novel and broad-spectrum RSV L polymerase inhibitor may pave the way toward an efficacious RSV therapeutic and provide a new tool for interrogation of the L protein function.

A study was performed in dogs to evaluate the dose-response characteristics and effectiveness of recombinant human bone morphogenetic protein-2 with a collagen sponge carrier in a segmental defect model. Twenty-seven dogs underwent bilateral radial osteotomies with creation of a 2.5-cm diaphyseal defect. All received autogenous cancellous bone graft in one defect and a collagen implant in the other. These implants contained recombinant human bone morphogenetic protein-2 at the following doses: group 1 at 0 microg (three dogs, 0 microg/ml total implant volume), group 2 at 150 microg (three dogs, 50 microg/ml), group 3 at 600 ,g (three dogs, 200 microg/ml), group 4 at 2,400 microg (three dogs, 800 microg/ml), group 5 at 0 microg (five dogs, 0 microg/ml), group 6 at 150 microg (five dogs, 200 microg/ml), and group 7 at 600 microg (five dogs, 50 microg/ml). The defects were stabilized with external fixators. The dogs in groups 1-4 were killed at 12 weeks postoperatively, and those in groups 5-7 were killed at 24 weeks postoperatively except for one dog in group 7, which was killed at 48 weeks. Evaluation included monthly radiographs, biomechanical testing, and nondemineralized histology. All 27 radii with autogenous cancellous bone graft and all 19 implants treated with recombinant human bone morphogenetic protein-2 achieved radiographic and histologic union and gross stability. The eight radii treated with collagen carrier alone went on to radiographic and histologic nonunion and were grossly unstable at death. A dose-dependent occurrence of cyst-like bone voids was noted radiographically and histologically. Biomechanical performance tended to be better at the lowest dose studied at 12 weeks, and all three doses performed better than the placebo (p < 0.05) at 12 and 24 weeks. By 24 weeks, radiolucent areas corresponding to histologic bone voids persisted radiographically, although there was evidence of early bone remodeling. This remodeling progressed to 48 weeks in the single animal followed to this time point, although bone voids remained. These radiologic findings were confirmed histologically. Recombinant human bone morphogenetic protein-2 in a collagen sponge carrier has significant osteoinductive activity in this canine segmental defect model. A dose-response relationship is evident, with heterotopic bone and cyst-like void formation at higher doses and a minimum effective dose of 0-150 microg. At 12 and 24 weeks postoperatively, biomechanical parameters achieved by defects treated with recombinant human bone morphogenetic protein-2 were comparable with those of autograft controls and were significantly stronger than those of the placebo (p < 0.05).

Objectives/Hypothesis: At present, the optimal treatment for appropriately resuscitated, multiply injured patients includes fixation of long bone fractures within twenty-four hours of injury. This management approach has been shown to decrease the incidence of pulmonary complications, multiple organ failure, and death. Some investigators have hypothesized that acute reamed intramedullary nailing of the femur (RIMNF) may result in pulmonary dysfunction as a result of the pulmonary fat embolization generated during this procedure. Patients with concomitant thoracic trauma may be at particular risk for this potentially severe complication. In an attempt to determine whether RIMNF can be safely carried out regardless of the severity of a pulmonary injury, we monitored the pulmonary effects of RIMNF in sheep in which an acute respiratory disorder (ARDS)-like state had been induced. Our hypothesis was that, if the pulmonary fat embolization that occurs as a result of RIMNF has a clinically significant effect, it would be detectable in an animal model in which a severe lung injury had been induced prior to the start of RIMNF. Study Design: This was an acute experimental procedure performed on yearling sheep. Methods: Reamed intramedullary nailing of the femur was performed in two groups of instrumented sheep. The first group had no pulmonary injuries. The second group had an ARDS-like state induced by intravenous infusion of perilla ketone prior to RIMNF. Perilla ketone increases pulmonary microvascular permeability without changing filling pressures and is used to induce a model of human ARDS. Hemodynamic and oximetric parameters were measured or calculated, as was pulmonary dynamic compliance during the experiment. Results: Infusion of perilla ketone caused a significant pulmonary injury. RIMNF caused no additional significant effect on intrapulmonary shunt, mixed venous oxygen saturation, or dynamic compliance, which are clinically used to assess the severity of pulmonary dysfunction in injured patients. Conclusions: The fat embolization that occurs during RIMNF in an appropriately resuscitated sheep has no clinically significant effect on pulmonary function, even in the setting of a severe pulmonary dysfunction.

OBJECTIVES To evaluate the efficacy of a bone graft substitute in healing of a segmental defect of a weight-bearing long bone. DESIGN An established canine model was used to perform a blinded, prospective, randomized study of the performance of bone graft substitute implants. This performance was compared with that of an accepted treatment modality (autograft) in a paired fashion. SETTING An accredited animal research facility. SUBJECTS AND INTERVENTION Twenty-eight dogs underwent bilateral radial osteotomies with creation of a 2.5-centimeter defect. On one side, the defect in every dog was filled with autogenous cancellous bone graft (ABG). Contralateral defects received, in a blinded, randomized fashion, cylindrical implants of demineralized bone matrix (DBM) allograft or DBM plus a constant dose (3.0 milligrams) of bovine-derived bone protein (DBM + BP). The defects were stabilized by external fixation. Subjects underwent monthly radiographs and were killed at six, twelve, or twenty-four weeks. Regenerate bone was studied by biomechanical testing and histology. Six animals were studied to determine the dose-response characteristics of the protein preparation. Three received implants containing 0.3 milligram of BP (group 1) and three received 1.0 milligram of BP (group 2). These animals were killed at twelve weeks of follow-up. RESULTS All twenty-eight ABG radii (100 percent) progressed to radiographic union, as did thirteen of thirteen (100 percent) DBM + BP radii compared with only four of fifteen (27 percent) of DBM radii. The difference between union rates was statistically significant (p < 0.05). Mean values for most biomechanical parameters of DBM + BP radii exceeded those of their contralateral ABG controls at twelve and twenty-four weeks, whereas those for DBM implants did not. Histology revealed microscopic evidence of normal bone healing in all ABG and DBM + BP radii, whereas most DBM radii demonstrated nonunions. In the dose-response arm of the study, six of six ABG radii (100 percent) achieved union; zero of three (0 percent) of group 1 and two of three (67 percent) of group 2 radii achieved grossly stable unions. Biomechanical testing was consistent with radiographic results, indicating that the 3.0-milligram dose was the most effective of those studied. CONCLUSIONS The DBM + BP composite implants were more effective at healing critical-sized segmental defects than DBM alone in this canine model when a 3.0-milligram per implant dose of BP was used. Biomechanical and histologic properties of the regenerated bone formed by DBM + BP implants was comparable to that of cancellous autograft.

Targeting viral polymerases has been a proven and attractive strategy for antiviral drug discovery. Herein we describe our effort in improving the antiviral activity and physical properties of a series of benzothienoazepine compounds as respiratory syncytial virus (RSV) RNA polymerase inhibitors. The antiviral activity and spectrum of this class was significantly improved by exploring the amino substitution of the pyridine ring, resulting in the discovery of the most potent RSV A polymerase inhibitors reported to date.

We performed a randomized, prospective study to compare the results of two methods for the operative fixation of fractures of the tibial plafond. Surgeons were assigned to a group on the basis of the operation that they preferred (randomized-surgeon design). In the first group, which consisted of eighteen patients, open reduction and internal fixation of both the tibia and the fibula was performed through two separate incisions. An additional patient, who had an intact fibula, had fixation of the tibia only through an anteromedial incision. The second group consisted of twenty patients who were managed with external fixation with or without limited internal fixation (a fibular plate or tibial interfragmentary screws). Ten (26 per cent) of the thirty-nine fractures were open, and seventeen (44 per cent) were type III according to the classification of Rüedi and Allgöwer. There were fifteen operative complications in seven patients who had been managed with open reduction and internal fixation and four complications in four patients who had been managed with external fixation. All but four of the complications were infection or dehiscence of the wound that had developed within four months after the initial operation. The complications after open reduction and internal fixation tended to be more severe, and amputation was eventually done in three patients in this group. At a minimum of two years postoperatively (average, thirty-nine months; range, twenty-five to fifty-one months), the average clinical score was lower for the patients who had had a type-II or III fracture, regardless of the type of treatment. With the numbers available, no significant difference was found between the average clinical scores for the two groups. All of the patients, in both groups, who had had a type-II or III fracture had some degree of osteoarthrosis on plain radiographs at the time of the latest follow-up. With the numbers available, there was no significant difference between the two groups with regard to the osteoarthrotic changes. We concluded that external fixation is a satisfactory method of treatment for fractures of the tibial plafond and is associated with fewer complications than internal fixation.

Thirty-seven patients with 37 proximal femoral fractures were treated with a reconstruction locked femoral nail. There were four ipsilateral intracapsular femoral neck and shaft fractures, two intertrochanteric fractures, 18 intertrochanteric fractures with diaphyseal extension, eight subtrochanteric fractures with involvement of the lesser trochanter, and five subtrochanteric fractures without involvement of the lesser trochanter. The overall union rate was 92%. Twenty-one complications developed in 13 patients (35%) which included three of the four femoral neck and shaft fractures, and six of 18 intertrochanteric fractures with diaphyseal extension. Of the five intertrochanteric fractures with diaphyseal extension in which anatomic reduction was not achieved, four developed a complication. Of the nine proximal screws in nine fractures, which were placed short (below the subchondral bone of the femoral head), six fractures developed a complication. The complications included three nonunions, one delayed union, two leg-length discrepancies of > 2.5 cm, two cases of varus deformity of > 10 degrees, two varus deformities < 10 degrees, four instances of revision surgery including one broken 13-mm nail, four proximal screws that backed out and required removal, two cases of pudendal nerve palsy, and one case of heterotopic ossification. Seven patients developed more than one complication. Eleven of the 13 patients with complications required a second surgery to treat the complication. We conclude that the reconstruction locked femoral nail is not a good choice for ipsilateral intracapsular neck and shaft fractures. Our recommendation is that anatomic reduction should be achieved for all cases using the reconstruction femoral nail, but it is absolutely required when treating the intertrochanteric fracture with diaphyseal extension. Reconstruction femoral nails have a high rate of complication due to the complex nature of the fractures as well as the device.

Eight-seven acetabular fractures in eighty-seven patients underwent open reduction and internal fixation at Vanderbilt University Hospital from 1984 to 1989. Fifty-six were treated by orthopaedic traumatologists. Fifty-six patients returned for long-term follow-up (range 24-80 months, average 43). Harris hip ratings were used to clinically grade the results. Poor results were found in 43%. Eighty-three percent of the patients with poor results had satisfactory surgical reductions with3 mm of residual displacement. Factors other than surgical reduction contributed significantly to the poor results. These included hip dislocation associated with the fracture, class III or IV heterotopic ossification, development of avascular necrosis, and age40 years. These factors in addition to adequacy of surgical reduction allow us to better counsel patients as to long-term prognosis.

Toward a complete LC-MS mapping system for peptides and proteins, we have coupled a precision-flow microbore HPLC system to an electrospray single quadrupole mass spectrometer. The HPLC system allows fast separation of protein digests with UV detection at the low pmol level. A 2 microliters/min portion (1:25) of the effluent is passed into a high-sensitivity electrospray MS system. The electrospray source allows for molecular mass associated ions (MH+, MH2(2+), MH3(3+), etc.) to be generated as well as collision induced dissociation of these ions before MS analysis. After LC-MS runs, with or without partial fragmentation, the data generated are largely interpreted by identification of predicted peptides, incompletely digested peptides, unusual peptide cleavages, and so on, using appropriate integrated software (PEPMAP, PEPMATCH). Examples of peptide mapping at the low pmol level using this integrated system will be shown (e.g., of the protein human growth hormone and of the glycoprotein, tissue plasminogen activator).

DNA ligases are indispensable enzymes playing a critical role in DNA replication, recombination, and repair in all living organisms. Bacterial NAD + -dependent DNA ligase (LigA) was evaluated for its potential as a broad-spectrum antibacterial target. A novel class of substituted adenosine analogs was discovered by target-based high-throughput screening (HTS), and these compounds were optimized to render them more effective and selective inhibitors of LigA. The adenosine analogs inhibited the LigA activities of Escherichia coli , Haemophilus influenzae , Mycoplasma pneumoniae , Streptococcus pneumoniae , and Staphylococcus aureus , with inhibitory activities in the nanomolar range. They were selective for bacterial NAD + -dependent DNA ligases, showing no inhibitory activity against ATP-dependent human DNA ligase 1 or bacteriophage T4 ligase. Enzyme kinetic measurements demonstrated that the compounds bind competitively with NAD + . X-ray crystallography demonstrated that the adenosine analogs bind in the AMP-binding pocket of the LigA adenylation domain. Antibacterial activity was observed against pathogenic Gram-positive and atypical bacteria, such as S. aureus , S. pneumoniae , Streptococcus pyogenes , and M. pneumoniae , as well as against Gram-negative pathogens, such as H. influenzae and Moraxella catarrhalis . The mode of action was verified using recombinant strains with altered LigA expression, an Okazaki fragment accumulation assay, and the isolation of resistant strains with ligA mutations. In vivo efficacy was demonstrated in a murine S. aureus thigh infection model and a murine S. pneumoniae lung infection model. Treatment with the adenosine analogs reduced the bacterial burden (expressed in CFU) in the corresponding infected organ tissue as much as 1,000-fold, thus validating LigA as a target for antibacterial therapy.

Intramedullary nails were placed prospectively in 25 acute femoral shaft fractures in 25 patients without the use of a fracture table. A femoral distractor was used in 21 of the 25 patients to aid in obtaining and holding a reduction. Our goals were to determine if the technique was safe and effective for insertion of intramedullary nails in a wide spectrum of femoral fractures--with no increase in morbidity when compared to the use of the more familiar fracture table--and to determine the potential complications and pitfalls of using this technique. A retrospective evaluation of the most recent 25 patients with 27 femoral fractures that underwent intramedullary nailing on a fracture table was done to compare operative time, estimated blood loss, complications, and postoperative fracture alignment. In addition to the clinical evaluation, cadaveric dissections were undertaken to determine the exact location of the proximal distractor screw in relation to the contents of the femoral triangle. The femoral nerve was a minimum of 2.5 cm, and the femoral artery a minimum of 3.0 cm from the proximal screw. In comparing the two studies, no significant difference was noted in the age of the patients, fracture types or locations, associated injuries, operative time, estimated blood loss, final fracture reduction, or nail position. No complications were encountered in the placement of the proximal femoral distraction screw. Although the distraction method is technically difficult because the reduction is obtained entirely during the procedure, there are certain situations when this technique could be employed with the benefit of decreasing intraoperative patient manipulation, thereby shortening operative time.(ABSTRACT TRUNCATED AT 250 WORDS)

Let G G be a complex, simply connected semisimple analytic group with K K a closed connected reductive subgroup. Suppose V V is an irreducible holomorphic G G -module and W W an irreducible holomorphic K K -module. We prove that Hom K ( W , V ) _{K}(W,V) possesses the structure of an irreducible U ( g ) K U(\mathfrak {g})^{K} -module whenever Hom K ( W , V ) \text {Hom}_{K}(W,V) is ≠ ( 0 ) \neq (0) . Moreover, dim ⁡ Hom K ( W , V ) ≤ 1 \dim \text {Hom}_{K} (W,V)\le 1 for all W W and V V if and only if U ( g ) K U{(\mathfrak {g})}^{K} is commutative.

Femoral shaft fractures are common injuries to most hospital emergency rooms. Treatment of the fractures has undergone major changes throughout the decade of the 1980s. Intramedullary nailing with locked nails is now the most accepted treatment worldwide. The techniques used for intrameduallary nailing of the more unstable fractures requires distinct attention to detail as described in this article.

Six integral membrane proteins of bacterial, animal, and plant origin, which are believed to function in solute transport, share sequence identity and are grouped together as members of the MIP family. These include the Escherichia coli glycerol facilitator, the major intrinsic protein from bovine lens fibre junction membranes, a plant tonoplast membrane protein, a soybean protein from the peribacteroid membrane, and a Drosophila neurogenic protein. These proteins, each of which appears to consist of six transmembrane helical segments per subunit, apparently arose by internal duplication of a three-transmembrane segment. Phylogenetic 'trees' interrelating these proteins and segments are presented.

Naphthyridones that were recently described as a class of translation inhibitors in gram-positive bacteria mediate their mode of action via GyrA in Haemophilus influenzae and Escherichia coli . These are the first examples of compounds in which modes of action in different bacterial pathogens are mediated through widely different targets.

A model was established in 39 dogs to investigate the growth factor modulation of regenerate bone in distraction osteogenesis. A segment of the diaphysis of the radius was resected unilaterally. An osteotomy was made proximal to the segmental defect to create a transport segment. A monolateral external fixator was applied. After a latency period, the segment was transported across the defect. One week after the transport assembly contacted the distal pin clamp, an ipsilateral osteotomy of the proximal ulna was performed. In 20 dogs, transforming growth factor-beta was injected into the regenerate bone halfway through the transport period. Four dogs were sacrificed before docking, when the regenerate bone was still immature. In specimens harvested halfway through the transport period, evidence was found of intramembranous ossification during distraction. In specimens harvested after the transport assembly contacted the distal pin clamp, evidence was found that the mature regenerate formed by endochondral ossification. Therefore, a combined mechanism of ossification is proposed for this segmental defect model that includes mechanical stimulus for bone differentiation. The one-time administration of transforming growth factor-beta retarded the formation of a stable, united regenerate. It is concluded that transforming growth factor-beta caused an effect opposite to that which was desired.

Background: This study evaluated the effect of immediate weightbearing on fractures of the humeral shaft treated with dynamic compression plates. Methods: Eighty-three fractures met the inclusion criteria. The weightbearing status of the humerus was based on associated injuries and not the fracture pattern. There were no differences between the weightbearing and nonweightbearing groups in patient or fracture demographics. Results: Ninety-four percent of the fractures healed after the initial operation. Two in the nonweightbearing group and three in the weightbearing group required a second operation to achieve union. Alignment did not differ between the two groups. Immediate full weightbearing had no effect on the union or malunion rate. Conclusion: When indicated, open reduction and internal fixation of the diaphysis of the humerus, followed by immediate weightbearing through the involved humerus, is a safe and efficacious procedure.

This retrospective review of surgically treated distal tibia fractures was undertaken to determine whether treatment with open reduction and internal fixation (ORIF) was more efficacious in achieving fracture union than one of two external fixation methods.Of the 60 study patients with pilon fractures, 21 patients were treated with an ankle-spanning half-pin external fixator, 15 patients with a single-ring hybrid external fixator, and 24 patients with ORIF. The severity of injuries was similar across groups.There was no significant difference in complication rates between groups, although two below-knee amputations were required in the ORIF group. A greater (p = 0.03) number of malunions occurred in the fractures treated with external fixation when compared with those treated with ORIF. Fractures in the external fixator groups showed this significant tendency to lose their initial adequate reduction, independent of bone grafting or fibula fixation. There was no significant difference between groups in the need for bone grafting. There was a trend for patients treated with a single ring hybrid frame to require late bone grafting for metaphyseal-diaphyseal nonunion.External fixation offers advantages in the treatment of the soft-tissue injury associated with pilon fractures, but malunion continues to be a problem with this method of fixation.

Group B Streptococcus (GBS) types VI and VIII are prevalent among serotypes isolated from pregnant women in Japan. Maternal vaccination with a safe and effective GBS vaccine has been proposed as a rational approach to prevent neonatal GBS disease. Because antibody specific for the capsular polysaccharide (CPS) antigens of GBS is protective, vaccines were developed with purified type VI and VIII CPS coupled to tetanus toxoid. In rabbits the newly synthesized conjugate vaccines elicited high-titered, type-specific antibody that was opsonically active in vitro. Moreover, litters born to mice actively vaccinated with the conjugate vaccines, in contrast to uncoupled CPS or saline, were protected against an ordinarily lethal challenge of GBS of homologous serotype. GBS types VI and VIII conjugate vaccines of the design presented may be important components of a multivalent GBS vaccine for use in regions where these serotypes predominate.

The care of the patient with the fractured femur entails a multiple surgical team approach. Healing of the fracture and expediency in the operating room are both important. We sought to determine the results of the treatment of fractures of the femoral shaft with interlocking femoral nails inserted with closed techniques, and to compare the outcomes of fractures nailed by using a fracture table with those stabilized with the leg draped free on a radiolucent table.Eight hundred eighty-two consecutive patients with fractures of the femoral shaft treated with a first-generation intramedullary nail at the authors' institution during the years 1986 to 1996 were identified. Five hundred fifty-one fractures in 515 patients met the inclusion criteria.Treatment with an intramedullary nail led to a union rate of 98.9%. There were six infections, all occurring in closed fractures. Thirty-eight percent of the fractures had hardware removed, most commonly because of pain. One nail and 13 locking bolts broke. Four hundred eighteen fractures had adequate radiographs available to assess fracture alignment. No fracture healed with more than 10 degrees of angulation in either plane. Forty-four fractures healed with more than 5 degrees of angulation. A distal third fracture was found to be associated with an increased incidence of malalignment. There were no differences in outcomes between fractures stabilized with or without a fracture table.Reamed intramedullary nailing of femoral shaft fractures results in a low rate of nonunion, malunion, infection, and hardware failure. There is no difference in the outcomes of fractures treated with and without the use of a fracture table. This is particularly useful in the patient with multiple injuries for whom transfer to a fracture table may not be time effective.

Nonpregnant adults with group B streptococcus bacteremia were identified by active surveillance in three hospitals. Serum samples collected within 2 days of the time of blood culture were assayed for IgG antibodies to the capsular polysaccharide of the infecting strain: serotype Ia (3 isolates), III (5 isolates), or V (4 isolates). In 7 of 12 bacteremia episodes, the serum level of IgG to the infecting isolate was > or = 3.5 microg/mL, higher than the 1-2 microg/mL level thought to be protective in neonates. Among selected acute-phase sera, 4 of 5 that contained > or = 3.5 microg/mL specific IgG mediated efficient opsonophagocytic killing of the corresponding group B streptococcus isolate in vitro. High levels of specific antibodies during the acute phase of invasive group B streptococcus infection in nonpregnant adults may reflect a rapid antibody response to infection or, in some cases, may indicate that susceptibility is due to defects in other immune effectors.

The efficacy of a bone-graft substitute (bovine-derived bone protein in a carrier of natural coral) in the healing of a segmental defect of a weight-bearing long bone was evaluated. Twenty dogs, divided into two groups, underwent bilateral radial osteotomies with creation of a 2.5 cm defect. On one side of each dog, the defect was filled with autogenous cancellous bone graft. Contralateral defects received, in a blinded randomized fashion, cylindrical implants consisting of natural coral (calcium carbonate) or calcium carbonate enhanced with a standard dose of bovine-derived bone protein (3.0 mg/implant; 0.68 mg bone protein/cm3). The limbs were stabilized with external fixators, and all animals underwent monthly radiographs. They were killed at 12 (group 1) or 24 (group 2) weeks, and regenerated bone was studied by biomechanical testing and histology. Radiographic union developed in all 20 radii with autogenous cancellous bone grafts and in all 10 of the radii with the composite implants. None of the radii with implants of calcium carbonate alone showed radiographic evidence of union. This represented a statistically significant difference between implant types. In addition, calcium carbonate implants both with and without bone protein demonstrated radiographic evidence of near total resorption of the radiodense carrier by 12 weeks. This resorption facilitated radiographic evaluation of healing. Mean values for biomechanical parameters of radii with the composite implants exceeded those for the contralateral controls at 12 and 24 weeks; the difference was statistically significant at 12 weeks. Histology revealed scant residual calcium carbonate carrier at either time in the defects with calcium carbonate implants; however, a moderate amount was present in defects with the composite implants. In these specimens, the residual carrier was completely surrounded by newly formed bone that may have insulated the calcium carbonate from further degradation. The present study used a carrier of granular calcium carbonate reconstituted with bovine type-I collagen to deliver an osteoinductive protein to the defect site. This carrier is of nonhuman origin (eliminating the risk of disease transmission or antigenicity) and resorbs rapidly. In this model, bovine-derived bone protein in a natural coral carrier performed consistently better than the gold standard autogenous cancellous bone graft in terms of the amount of bone formation and strength of the healed defect. This may have implications for removal of hardware or resumption of weight-bearing in certain clinical situations. These data also indicate that coralline calcium carbonate alone represents a poor option as a bone-graft substitute in this critical-sized segmental defect model.

In seven cases of Lisfranc joint injury after trauma, bunion deformity developed. This "traumatic bunion" occurs over a prolonged period of time after injury. A high index of suspicion is needed to identify the deformity as being traumatic in origin. Injury about the first metatarsophalangeal joint complex may also contribute to this deformity. When recognized, it may need to be treated with a first metatarsal-cuneiform fusion and distal soft tissue realignment.

Three porous ceramic bone graft materials were compared with regard to their ability to heal a 2.5 cm defect created surgically in a bilateral canine radius model. The ceramic materials were analyzed at 12 and 24 weeks after surgery and included tricalcium phosphate, hydroxyapatite, and collagen hydroxyapatite, which contained a mixture of 35% tricalcium phosphate and 65% hydroxyapatite with added collagen. Each material was evaluated alone and with added bone marrow aspirate. All the implants were compared with a graft of autogenous cancellous bone in the contralateral radius. Biomechanical testing and radiographic evaluation revealed that the addition of bone marrow aspirate was essential for tricalcium phosphate and hydroxyapatite to achieve results comparable with those of cancellous bone. Collagen hydroxyapatite performed well without the addition of bone marrow, although the addition of marrow did have a positive effect. Further qualitative radiographic and histological analysis demonstrated that tricalcium phosphate was the only ceramic that showed any sign of degradation at 24 weeks. This observed degradation proved to be an important factor in evaluating radiographs because the radiodensity of collagen hydroxyapatite and hydroxyapatite interfered with the determination of radiographic union. At 24 weeks, tricalcium phosphate with bone marrow was the material that performed most like cancellous bone. In this study, the biomechanical and radiographic parameters of tricalcium phosphate with bone marrow were roughly comparable with those of cancellous bone at 12 and 24 weeks. Tricalcium phosphate was the only implant that showed significant evidence of degradation at 24 weeks by both histological and radiographic evaluations, and this degradation took place only after a degree of mechanical competence necessary for weight-bearing was achieved.

The capsular polysaccharide (CPS) of group B streptococci (GBS) is an important virulence factor that also serves to protect cells from nonspecific host defense mechanisms. Expression of CPS by GBS, as with other encapsulated bacterial pathogens, is not constitutive but varies during growth in vitro and in primary cultures isolated from different sites of infection. Despite this understanding, little is known about regulation of this surface-expressed carbohydrate antigen in GBS. Here we report that expression of type III CPS by GBS strain M781 grown in continuous culture with a modified chemically defined medium is regulated by growth rate. Cells in steady state at mass doubling times (tds) of 0.8, 1.4, and 1.6 h expressed an average of sixfold more cell-associated CPS than did cells held at tds of 2.3 and 11 h. Strain M781 grown at a td of 1.4 h repeatedly produced more type III CPS than those held at a td of 11.0 h, even when limited for glucose, pyridoxamine, or thiamine. In our studies, > or = 93% of the total CPS expressed by strain M781 was cell associated. Strain M781 grown at a td of 11.0 h (i.e., lowered CPS expression) was susceptible to in vitro complement-mediated opsonophagocytosis and killing by human peripheral blood leukocytes, whereas cells grown at a td of 1.4 h (i.e., higher CPS expression) were not killed unless type III CPS-specific antibody was present. Factors that allow GBS to asymptomatically colonize women yet cause invasive infection to both mother and infant are poorly understood. Our results shed new light on parameters that regulate the pathogenic potential of GBS and may also serve as a way to discern more fully the genetics and biochemistry of GBS capsule synthesis.

We have recently developed an open-chest sheep model to monitor and study the effects of major orthopedic procedures on pulmonary physiology. In this pilot study, we focused on reamed intramedullary femoral nailing in animals without pulmonary injury. Details of the model are described herein. The control group consisted of sheep that underwent thoracotomy and invasive monitoring only, while the study group also underwent femoral osteotomy, reaming, and intramedullary nailing. Baseline, postthoracotomy, and post-reaming/nailing values were recorded for mean pulmonary arterial pressure, central venous pressure, left arterial pressure, dynamic compliance, arterial blood gas, mixed venous O 2 , cardiac index, and mean arterial pressure so that hemodynamic and oxygen transport data could be calculated. Postprocedure values were recorded at hourly intervals for 4 h. A physiologically stable, reproducible model was created. No statistically significant differences were found between the control and experimental groups, indicating no adverse effect of femoral reaming/nailing. In one animal, using echocardiography, pulmonary embolization was documented while reaming and inserting the intramedullary nail. Reamed femoral intramedullary nailing is not detrimental to sheep with otherwise normal lungs. This finding suggests that femoral reaming and nailing in trauma patients without associated pulmonary injuries and otherwise normal lungs may be carried out without risk of inducing significant respiratory complications.

The recent orthopaedic literature reflects a growing number of bone graft substitutes and osteogenic growth factors under investigation in a number of animal models. We attempted to establish a well-controlled, large animal model of a segmental defect in a weight-bearing long bone by developing a bilateral diaphyseal radial defect model in the canine. We also evaluated the effectiveness of ground cortical autograft as a graft material. Twenty-three adult mongrel dogs underwent bilateral radial osteotomies with creation of a 2.0-2.5-cm diaphyseal defect on each side. All dogs received cancellous autograft (CAN) on one side, nine received no graft material (DEF) on the opposite side, and 14 received morselized cortical autograft (CORT) on the opposite side. Radii were stabilized by external fixation. Animals were followed radiographically at 6-week intervals to evaluate the healing process. Thirteen dogs were sacrificed at short-term follow-up (8-12 weeks postsurgery) and 10 at long-term (16-24 weeks). Biomechanical torsion testing to failure and histological evaluation were performed on each defect. All CAN radii achieved union (100%) while only one of nine DEF radii (11%) and none of 14 (0%) of CORT radii achieved union. Statistically significant differences in biomechanical parameters between both test groups and their corresponding autograft control radii were found. Histology revealed fibrous nonunions in the DEF and CORT radii. These results demonstrate that the bilateral canine radial defect model represents a consistent and reproducible model for bone healing of segmental defects in weight-bearing long bones and that ground cortical autograft is an ineffective graft material.

Many bacterial capsular polysaccharides are regularly repeating units of oligosaccharides. Bacterial oligosaccharides have been used in neoglycoconjugate vaccines and as reagents in the study of specific antibody binding. Unfortunately, separation methods have not been adequate for the purification of preparative quantities of bacterial oligosaccharides. Here we describe a size-exclusion procedure that resulted in the resolution of group B Streptococcus type III oligosaccharides composed of 4-25 sugars.

Intramedullary (IM) nails were prospectively placed in 32 consecutive femoral shaft fractures without the use of a fracture table. All fractures were reduced using manual traction. Pathologic and nonacute fractures and those requiring a reconstruction nail were excluded. The results are compared with results of two prior study groups from this institution that underwent IM nailing with or without a fracture table using a femoral distractor. Ten patients had unstable spine or pelvis fractures. Four nailings followed exploratory laparotomy. Twelve patients underwent two or more procedures on the lower extremities under the same preparation and drape. Six fractures were open. Sixty-seven percent of results were anatomic, 27% had5 mm lengthening/shortening or5 degree varus/valgus, and 7% had5 mm lengthening/shortening or5 degree varus/valgus. Average operative time was 95 min. No complications occurred that were attributable to the technique. Compared with the prior study groups, no statistical difference in the fracture types or results was found. However, operative time was significantly less in the manual traction group (p.05). We feel that this technique is a safe, simple, and effective alternative to using a fracture table. The technique is especially useful in the polytrauma patient, significantly decreasing anesthetic time.

The functional characterization of numerous transport systems across the vacuolar membrane (tonoplast) has provided a better understanding of the versatile role played by the vacuole in plant cells. The tonoplast H+-ATPase and the H+-pyrophosphatase pump protons into the vacuole making this organelle inside positive and acidic (Hedrich et al., 1989; Taiz, 1992). Maintaining an electrochemical gradient of protons, in addition to its role in cytoplasmic pH regulation, energizes various transport processes across the tonoplast. Several types of ions channels have been identified by the patch clamp technique, but the selectivity of most of them and hence their physiological role remain elusive (Hedrich and Schroeder, 1989). They probably represent major transport pathways for ions such as K+ and Cl-, the main determinants of cell turgor, and NO3- which can be stored in and mobilized from the vacuole. Calcium-permeable channels as well as a Ca++/H+ antiporter occur in plant vacuoles (Alexandre et al., 1990; Blackfordet al., 1990). They reflect the role that the vacuole as a major calcium store plays in signal transduction in plants. The tonoplast also carries Na+/H+ exchangers and Cd+ transporters that can account for the detoxifying role of the vacuole during saline and heavy metal stress, respectively (Taiz, 1992).

Tonoplast intrinsic protein (TIP) is a member of a family of putative membrane channels found in bacteria, animals, and plants. Plants have seed-specific, vegetative/reproductive organ-specific, and water-stress-induced forms of TIP. Here, we report that the seed-specific TIP is a phosphoprotein whose phosphorylation can be monitored in vivo by allowing bean cotyledons to take up [(32)P]orthophosphate and in vitro by incubating purified tonoplasts with gamma-labeled [(32)P]ATP. Characterization of the in vitro phosphorylation of TIP indicates that a membrane-bound protein kinase phosphorylates TIP in a Ca(2+)-dependent manner. The capacity of the isolated tonoplast membranes to phosphorylate TIP declined markedly during seed germination, and this decline occurred well before the development-mediated decrease in TIP occurs. Phosphoamino acid analysis of purified, radiolabeled TIP showed that serine is the major, if not only, phosphorylated residue, and cyanogen bromide cleavage yielded a single radioactive peptide peak on a reverse-phase high-performance liquid chromatogram. Estimation of the molecular mass of the cyanogen bromide phosphopeptide by laser desorption mass spectroscopy led to its identification as the hydrophilic N-terminal domain of TIP. The putative phosphate-accepting serine residue occurs in a consensus phosphorylation site for serine/threonine protein kinases.