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B A Green

Publications and source records attributed to B A Green.

At least 19 recordsLinked to original sources
PubMed2005

The electrochemical evaluation of a Zr-based bulk metallic glass in a phosphate-buffered saline electrolyte.

Bulk metallic glasses (BMGs) represent an emerging class of materials with an amorphous structure and a unique combination of properties. The objectives of this investigation were to define the electrochemical behavior of a specific Zr-based BMG alloy in a physiologically relevant environment and to compare these properties to standard, crystalline biomaterials as well as other Zr-based BMG compositions. Cyclic-anodic-polarization studies were conducted with a Zr52.5Cu17.9Ni14.6Al10.0Ti5.0 (at %) BMG in a phosphate-buffered saline electrolyte with a physiologically relevant oxygen content at 37 degrees C. The results were compared to three common, crystalline biomaterials: CoCrMo, 316L stainless steel, and Ti-6Al-4V. The BMG alloy was found to have a lower corrosion penetration rate (CPR), as compared to the 316L stainless steel, and an equivalent CPR, as compared to the CoCrMo and Ti-6Al-4V alloys. Furthermore, the BMG alloy demonstrated better localized corrosion resistance than the 316L stainless steel. However, the localized corrosion resistance of the BMG alloy was not as high as those of the CoCrMo and Ti-6Al-4V alloys in the tested environment. The excellent electrochemical properties demonstrated by the BMG alloy are combined with a low modulus and unparalleled strength. This unique combination of properties dramatically demonstrates the potential for amorphous alloys as a new generation of biomaterials.

Buffers↗
PubMed2001

Surgical treatment of post-traumatic myelopathy associated with syringomyelia.

STUDY DESIGN: Retrospective review. OBJECTIVE: Evaluate the clinical outcome of surgical intervention for post-traumatic syringomyelia. INTRODUCTION: Progressive post-traumatic cystic myelopathy (PPCM), or syringomyelia, can occur after spinal cord injury. The authors present their surgical treatment protocol and treatment outcome of a series of patients with post-traumatic syringomyelia. METHODS: The medical records of 53 patients with PPCM undergoing surgical treatment were reviewed. Laminectomies and intraoperative ultrasonography were performed. For patients with no focal tethering and only a confluent cyst on ultrasonography, a syringosubarachnoid shunt (stent) was inserted. For patients with both tethering and a confluent cord cyst, an untethering procedure was performed first. When a cyst showed significant size reduction (>50%) after untethering, no shunt was placed. When the cyst size persisted on ultrasonographic images, a short syringosubarachnoid shunt was used. The mean follow-up was 23.9 months for the 45 patients available for follow-up (range 12-102 months). RESULTS: The interval between the causative event and the operation was from 5 months to 37 years (mean 6.5 years). Pain was the most frequent manifestation, followed by motor deterioration and spasticity. Postoperative improvements in >50% of the patients were noted in those presenting with worsening motor function or spasticity. In 19 of 28 patients with associated tethered spinal cord, untethering alone caused significant collapse of the cyst. Postoperative MRI demonstrated cyst collapse in 95% of the patients with untethering alone and 93% of the patients with a syringosubarachnoid shunt. CONCLUSION: Post-traumatic syringomyelia can occur with or without cord tethering. Untethering alone for patients with cord tethering and cyst formation can reduce cyst size and alleviate the symptoms and signs of syringomyelia in the majority of these cases. Untethering with expansion of subarachnoid space with an expansile duraplasty may be a more physiologic way of treating a tethered cord with associated syringomyelia, i.e., treating the cause rather than the result.

Adult↗
PubMed2001

Contribution of the DDDD motif of H. influenzae e (P4) to phosphomonoesterase activity and heme transport.

Haemophilus influenzae lipoprotein e (P4) is a member of the DDDD phosphohydrolase superfamily and mediates heme transport. Each of the aspartate residues of the signature motif is required for phosphomonoesterase activity, as none of the e (P4) single D mutants (D64A, D66A, D181N, and D185A) possessed detectable phosphomonoesterase activity. These results suggest that the signature motif is essential to the phosphomonoesterase activity of lipoprotein e (P4). When assessed for phosphomonoesterase-dependent heme transport activity in Escherichia coli hemA strains, plasmids containing D181N and D185A retained heme transport as indicated by aerobic growth while D64A and D66A did not. We conclude that phosphomonoesterase activity is not required for heme transport.

Aspartic Acid↗
PubMed2001

Recombinant PhpA protein, a unique histidine motif-containing protein from Streptococcus pneumoniae, protects mice against intranasal pneumococcal challenge.

The multivalent pneumococcal conjugate vaccine is effective against both systemic disease and otitis media caused by serotypes contained in the vaccine. However, serotypes not covered by the current conjugate vaccine may still cause pneumococcal disease. To address these serotypes and the remaining otitis media due to Streptococcus pneumoniae, we have been evaluating antigenically conserved proteins from S. pneumoniae as vaccine candidates. A previous report identified a 20-kDa protein with putative human complement C3-proteolytic activity. By utilizing the publicly released pneumococcal genomic sequences, we found the gene encoding the 20-kDa protein to be part of a putative open reading frame of approximately 2,400 bp. We recombinantly expressed a 79-kDa fragment (rPhpA-79) that contains a repeated HxxHxH motif and evaluated it for vaccine potential. The antibodies elicited by the purified rPhpA-79 protein were cross-reactive to proteins from multiple strains of S. pneumoniae and were against surface-exposed epitopes. Immunization with rPhpA-79 protein adjuvanted with monophosphoryl lipid A (for subcutaneous immunization) or a mutant cholera toxin, CT-E29H (for intranasal immunization), protected CBA/N mice against death and bacteremia, as well as reduced nasopharyngeal colonization, following intranasal challenge with a heterologous pneumococcal strain. In contrast, immunization with the 20-kDa portion of the PhpA protein did not protect mice. These results suggest that rPhpA-79 is a potential candidate for use as a vaccine against pneumococcal systemic disease and otitis media.

Administration, Intranasal↗
PubMed2001

NadN and e (P4) are essential for utilization of NAD and nicotinamide mononucleotide but not nicotinamide riboside in Haemophilus influenzae.

Haemophilus influenzae has an absolute requirement for NAD (factor V) because it lacks almost all the biosynthetic enzymes necessary for the de novo synthesis of that cofactor. Factor V can be provided as either nicotinamide adenosine dinucleotide (NAD), nicotinamide mononucleotide (NMN), or nicotinamide riboside (NR) in vitro, but little is known about the source or the mechanism of uptake of these substrates in vivo. As shown by us earlier, at least two gene products are involved in the uptake of NAD, the outer membrane lipoprotein e (P4), which has phosphatase activity and is encoded by hel, and a periplasmic NAD nucleotidase, encoded by nadN. It has also been observed that the latter gene product is essential for H. influenzae growth on media supplemented with NAD. In this report, we describe the functions and substrates of these two proteins as they act together in an NAD utilization pathway. Data are provided which indicate that NadN harbors not only NAD pyrophosphatase but also NMN 5'-nucleotidase activity. The e (P4) protein is also shown to have NMN 5'-nucleotidase activity, recognizing NMN as a substrate and releasing NR as its product. Insertion mutants of nadN or deletion and site-directed mutants of hel had attenuated growth and a reduced uptake phenotype when NMN served as substrate. A hel and nadN double mutant was only able to grow in the presence of NR, whereas no uptake of NMN was observed.

Bacterial Outer Membrane Proteins↗
PubMed2001

Threshold-level repetitive transcranial electrical stimulation for intraoperative monitoring of central motor conduction.

OBJECT: The authors conducted a study to evaluate repetitive transcranial electrical stimulation (TES) to assess spinal cord motor tract function in individuals undergoing spine surgery, with emphasis on safety and efficacy. METHODS: Somatosensory evoked potentials (SSEPs) were elicited using standard technique. Muscle electromyographic values were measured in response to a three- or four-pulse train of stimulation delivered to the motor cortex via subdermal electrodes. They also evaluated whether changes in the minimum stimulus intensity (that is, threshold level) needed to elicit a response from a given muscle predict motor status immediately postoperatively, as well as whether changes in SSEP response amplitude and latency predict sensory status immediately postoperatively. Anesthesia was routinely induced with intravenous propofol and remifentanil, supplemented with inhaled nitrous oxide. Use of neuromuscular block was avoided after intubation. Satisfactory monitoring of muscle response to threshold-level repetitive TES was achieved in all but nine of the 194 patients studied. In contrast, cortical SSEP responses could not be elicited in 42 of 194 individuals. In cases in which responses were present, TES-based evoked responses proved to be extremely accurate for predicting postoperative motor status. Somatosensory evoked potential monitoring was nearly as accurate for predicting postoperative sensory status. There were frequent instances of postoperative motor or sensory deficit that were not predicted by SSEP- and TES-based monitoring, respectively. There were no adverse events attributable to TES-based monitoring, although since this study ended we have had a single adverse event attributable to threshold-level repetitive TES. CONCLUSIONS: Intraoperative threshold-level repetitive TES-based monitoring of central motor conduction has proven to be a simple, safe, and highly accurate technique for the prevention or minimization of inadvertent motor deficit during surgery involving the spine or spinal cord.

Adolescent↗
PubMed2000

Effective mucosal immunization against respiratory syncytial virus using purified F protein and a genetically detoxified cholera holotoxin, CT-E29H.

We exploited the powerful adjuvant properties of cholera holotoxin (CT) to create a mucosally administered subunit vaccine against respiratory syncytial virus (RSV). A genetically detoxified mutant CT with an E to H substitution at amino acid 29 of the CT-A1 subunit (CT-E29H) was compared to wild type CT for toxicity and potential use as an intranasal (IN) adjuvant for the natural fusion (F) protein of RSV. When compared to CT the results demonstrated that: (1) CT-E29H binding to GM1 ganglioside was equivalent, (2) ADP-ribosylation of agmatine was 11.7%, and (3) toxicity was attenuated in both Y-1 adrenal (1.2%) and patent mouse gut weight assays. IN vaccination with F protein formulated with CT-E29H induced serum anti-CT and anti-F protein antibodies that were comparable to those obtained after vaccination with equivalent doses of CT. Vaccinations containing CT-E29H at doses of 0.1 microg were statistically equivalent to 1.0 microg in enhancing responses to F protein. Antigen-specific mucosal IgA and anti-RSV neutralizing antibodies were detected in nasal washes and sera, respectively, of mice that had received F protein and 0.1 or 1.0 microg of CT-E29H. Anti-F protein IgA was not detected in the nasal washes from mice IN vaccinated with 0.01 microg CT-E29H or IM with F protein adsorbed to AlOH adjuvant. In addition, the formulation of purified F protein and CT-E29H (0.1 and 1.0 microg) facilitated protection of both mouse lung and nose from live RSV challenge. Collectively, the data have important implications for vaccine strategies that use genetically detoxified mutant cholera holotoxins for the mucosal delivery of highly purified RSV antigens.

Animals↗
PubMed2000

Comparisons of body image dimensions by race/ethnicity and gender in a university population.

OBJECTIVE: We examined affective and cognitive components of body image related to physical appearance, weight, and health among 120 university men and women of three racial/ethnic groups: African American, European American, and Latino/a American. METHOD: Participants completed a Background Information Sheet, the Multidimensional Body-Self Relations Questionnaire (MBSRQ), the Body-Esteem Scale (BES) with additional items, and the Balanced Inventory of Desirable Responding (BIDR). We tested for effects of race/ethnicity and gender on the body image measures while controlling for age, body size, social desirability, and socioeconomic status (SES). RESULTS: African Americans reported greatest body satisfaction and least overestimation of weight. Latino/a Americans were equal to or higher than European Americans on all indices. Gender differences occurred on global body image, weight concerns, fitness, and health. There were no Gender x Race/Ethnicity interactions. DISCUSSION: This pattern of racial/ethnic and gender differences shows a need for exploring a wider range of culturally relevant body image dimensions.

Adolescent↗
PubMed2000

Continuity and discontinuity models of bulimia nervosa: a taxometric investigation.

Past research evaluating the continuity and discontinuity models of bulimia has produced inconclusive results. In the current study, we performed a taxometric analysis of bulimia nervosa using means above minus below a sliding cut and maximum covariance analysis with a sample of women diagnosed with bulimia nervosa (n = 201) or women college students (n = 412). Indicators were derived from the Bulimia Test--Revised and the Eating Attitudes Test--26, and both a mixed sample and the nonclinical sample were analyzed. With both taxometric methods and both mixed and nonclinical samples, results were consistently suggestive of a latent taxon for bulimia. These results challenge a dimensional model of bulimia nervosa.

Adult↗
PubMed2000

The management of traumatic cervical bilateral facet fracture-dislocations with unicortical anterior plates.

The goal of this study was to evaluate single-level anterior cervical discectomy and stabilization for bilateral facet fracture dislocations using bone graft and anterior titanium plates with unicortical screw fixation in the clinical setting. We conducted a retrospective review during a consecutive 6-year period of patients treated in a single institution for traumatic single-level cervical bilateral facet fracture-dislocation. All fracture-dislocations that could be aligned with traction were subsequently stabilized using an anterior cervical discectomy with bone graft and titanium unicortical locking plates. All patients were examined after operation for radiographic evidence of healing and neurologic outcome. Twenty-two patients (M:F ratio, 16:6; average age, 47.7 years) underwent an anterior cervical discectomy and stabilization with either an allograft (n = 12) or an autograft (n = 10) and a titanium unicortical locking plate. Most patients had sustained a spinal cord injury (87%) or a radicular injury (9%). The average follow-up was 32 months, with a minimum follow-up of 1 year (range, 13 to 77 months). There was one instrumentation-related failure, but all 22 patients ultimately had evidence of stability at the instrumented level on the final follow-up examination. Anterior fixation with unicortical cervical locking plates as a single procedure offers an excellent surgical alternative in the management of many cervical bilateral facet fracture dislocations in patients who can be reduced preoperatively.

Adolescent↗
PubMed2000

Computer-assisted fluoroscopic targeting system for pedicle screw insertion.

OBJECTIVE: Biplanar fluoroscopic imaging linked to a computer-driven mechanical end-effector is under development as a targeting system for spinal surgery. This technology has the potential to enhance standard intraoperative fluoroscopic information for localization of the pedicle entry point and trajectory, and it may be an effective alternative to the computed tomography-based image-guided system (IGS) in pedicle screw placement. A preclinical study to assess the accuracy and time efficiency of this system versus a conventional IGS was conducted. METHODS: Pedicle screw placement was performed in six cadavers from T1 to S1 levels using the ViewPoint IGS (Picker International, Inc., Cleveland, OH) on one side versus the Fluorotactic guidance system (Z-Kat, Inc., Miami, FL) on the other side. Of 216 possible pedicles, 208 were instrumented; 8 pedicle diameters were too small or were not adequately imaged. Postinsertion, each pedicle was assessed for the presence and location of cortical perforation using computed tomographic scanning and direct visualization. RESULTS: The number of successful screw placements was 89 (87.3%) of 102 for IGS and 87 (82.1 %) of 106 for the Fluorotactic guidance system, respectively. The mean time to register and operate on one level using the Fluorotactic guidance system was 14:34 minutes (minutes:seconds), compared with 6:50 minutes using the IGS. The average fluoroscope time was 4.6 seconds per pedicle. CONCLUSION: Our data indicate that this first-generation fluoroscopy-based targeting system can significantly assist the surgeon in pedicle screw placement. The overall accuracy is comparable to an IGS, especially in the region of T9-L5. A second-generation system with a faster end-effector and user-friendly interface should significantly reduce the operating and fluoroscope time.

Aged↗
PubMed2000

Identification of a Haemophilus influenzae 5'-nucleotidase protein: cloning of the nucA gene and immunogenicity and characterization of the NucA protein.

We report on the identification of a surface-exposed, highly conserved, immunogenic nontypeable Haemophilus influenzae (NTHi) protein, which elicits cross-reactive bactericidal antibodies against NTHi. The protein was extracted from NTHi strain P860295 with KSCN and purified; it migrated as a single band on a sodium dodecyl sulfate-polyacrylamide gel with an apparent molecular mass of 63 kDa. Mouse antiserum generated against the purified protein was reactive on whole-cell enzyme-linked immunosorbent assay (ELISA) with seven NTHi strains and type b Eagan and Whittier strains and exhibited bactericidal activity to homologous and heterologous NTHi strains. However, the protein is made in small amounts in NTHi as corroborated by immunoelectron microscopy. To further study this protein, we cloned, sequenced, and expressed it recombinantly in Escherichia coli. The recombinant protein is localized in the periplasm of E. coli and has been purified to homogeneity. Both the recombinant and native proteins possess 5'-nucleotidase activity; hence, the protein has been called NucA. Mouse antiserum directed against the recombinant NucA protein was reactive on Western immunoblots and whole-cell ELISA with all H. influenzae strains tested including Eagan and was bactericidal for two heterologous strains tested. The antiserum also resulted in a log reduction in bacteremia, in an infant-rat protection study with H. influenzae type b as the challenge strain. These features suggest that NucA is a potential subunit vaccine candidate against NTHi disease.

5'-Nucleotidase↗
PubMed2000

Outcome after surgical treatment of progressive posttraumatic cystic myelopathy.

OBJECT: Progressive posttraumatic cystic myelopathy (PPCM) can occur after an injury to the spinal cord. Traditional treatment of PPCM consists of inserting a shunt into the cyst. However, some authors have advocated a more pathophysiological approach to this problem. The authors of the present study describe their surgical treatment protocol and outcome in a series of patients with syringomyelia. METHODS: Medical records of 34 patients undergoing surgical treatment for PPCM were reviewed. Laminectomies and intraoperative ultrasonography were performed. In patients without focal tethering of the spinal cord and in whom only a confluent cyst had been revealed on ultrasonography, a syringosubarachnoid shunt was inserted; in those with both tethering and a confluent cord cyst, an untethering procedure was performed first. When a significant reduction (>50%) in the size of the cyst was shown after the untethering procedure, no shunt was inserted. When no changes in cyst size were demonstrated on ultrasonography, a short syringosubarachnoid shunt was used. The mean follow-up period was 28.7 months (range 12-102 months). The interval between the mechanism of injury and the operation ranged from 5 months to 37 years (mean 11 years). Pain was the most frequent symptom, which was followed by motor deterioration and spasticity. Postoperative improvement was noted in 55% of patients who experienced motor function deterioration and in 53% of those who demonstrated worsening spasticity. In 14 of 18 patients with an associated tethered spinal cord, tethering alone caused significant collapse of the cyst. Postoperative magnetic resonance imaging demonstrated cyst collapse in 92% of patients who had undergone untethering alone and in 93% of those who underwent syringosubarachnoid shunt placement. Treatment failure was observed in 7% of the former group and in 13% of the latter. CONCLUSIONS: Posttraumatic cystic myelopathy can occur with or without the presence of tethered cord syndrome. Intraoperative ultrasonography can readily demonstrate this distinction to aid in surgical decision making. Untethering alone in patients with tethered cord syndrome and cyst formation can reduce the cyst size and alleviate symptoms and signs of posttraumatic cystic myelopathy in the majority of these cases. Untethering procedures in which duraplasty is performed to expand the subarachnoid space may be a more physiologically effective way of treating tethered cord with associated syringomyelia.

Adult↗
PubMed1999

Neuroprotective effects of basic fibroblast growth factor following spinal cord contusion injury in the rat.

Cytokines and neurotrophic factors have been implicated in the pathophysiology of injury to the central nervous system. While some cytokines are considered pro-inflammatory, other factors promote neuronal growth and survival. The present study investigated the neuroprotective effects of interleukins 1 (IL-1), 4 (IL-4), and 6 (IL-6), nerve growth factor (NGF), ciliary neurotrophic factor (CNTF), and basic fibroblast growth factor (bFGF) in a contusion model of spinal cord injury. Female Sprague-Dawley rats (n = 55) sustained a 10-g weight-drop injury to the lower thoracic spinal cord (T10) from a height of 12.5 mm using the NYU impactor. A micro-infusion system (Alzet minipump) was used to continuously deliver drugs or vehicle directly into the epicenter of the contused spinal cord starting 1 or three h postinjury. At the end of 7 days, animals were perfused and the cords removed for histopathological analysis. Longitudinal serial sections were cut on a freezing microtome and stained with cresyl violet. Areas of central necrosis, partial preservation, and total zone of tissue injury were identified and traced by an independent reviewer using a computer based imaging system. The mean total zone of injury in five animals receiving vehicle infusion was 18.04+/-4.20 mm3. The mean zone of partial preservation in these animals was 16.46+/-3.32 mm. Basic fibroblast growth factor reduced the total zone of injury by 33% [p<0.01, least significant difference (LSD) of Fisher] in five animals and the zone of partial preservation by 32% (p<0.01, LSD of Fisher) when compared to controls. There were trends toward reduction in total zone of injury and zone of partial preservation in rats treated with IL-4, CNTF, and NGF versus vehicle; however, none of these reached statistical significance. No significant differences were observed between animals receiving vehicle versus bFGF treatment commencing 3 h after injury. These data demonstrate that the continuous intramedullary infusion of bFGF initiated one hour after moderate contusion injury of the spinal cord significantly reduces the total zone of injury and the zone of partial preservation. These results support the further investigation and possible future clinical application of bFGF in the treatment of acute spinal cord contusion injury.

Animals↗
PubMed1999

Reproductive potential after methotrexate treatment of ectopic gestation in a community hospital.

OBJECTIVE: To compare the rates of ipsilateral tubal patency after methotrexate treatment versus conservative surgical treatment in a small community hospital lacking personnel dedicated to methotrexate management. STUDY DESIGN: From hospital and clinic records, cases of ectopic gestation within a six-year interval were identified. Method of treatment and location of the ectopic gestation were documented by review of records and confirmed by patient interviews. Women desiring fertility were offered hysterosalpingography (HSG) to evaluate tubal patency. HSG was performed under fluoroscopy with water-soluble contrast medium. RESULTS: HSG was completed in 11 cases of linear salpingostomy and 11 cases of ectopic gestations treated by methotrexate. Ipsilateral patency was documented in 8 of 11 (72%) tubes treated by linear salpingostomy and 9 of 11 (81%) methotrexate-treated tubes. One methotrexate case had a prior ipsilateral ectopic treated by salpingostomy, and two additional cases had a prior contralateral ectopic removed by salpingectomy. Each of these three cases had ipsilateral tubal patency after methotrexate for the most recent ectopic gestation. CONCLUSION: Data from this study suggest comparable tubal patency rates after methotrexate and conservative surgery. Comparable tubal patency outcomes were obtained in our community hospital despite a less-rigorous-than normal follow-up protocol.

Abortifacient Agents, Nonsteroidal↗