Natural selection for 2,4,5-trichlorophenoxyacetic acid mineralizing bacteria in agent orange contaminated soil.

Agent Orange contaminated soils were utilized in direct enrichment culture studies to isolate 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) and 2,4-dichlorophenoxyacetic acid (2,4-D) mineralizing bacteria. Two bacterial cultures able to grow at the expense of 2,4,5-T and/or 2,4-D were isolated. The 2,4,5-T degrading culture was a mixed culture containing two bacteria, Burkholderia species strain JR7B2 and Burkholderia species strain JR7B3. JR7B3 was able to metabolize 2,4,5-T as the sole source of carbon and energy, and demonstrated the ability to affect metabolism of 2,4-D to a lesser degree. Strain JR7B3 was able to mineralize 2,4,5-T in pure culture and utilized 2,4,5-T in the presence of 0.01% yeast extract. Subsequent characterization of the 2,4-D degrading culture showed that one bacterium, Burkholderia species strain JRB1, was able to utilize 2,4-D as a sole carbon and energy source in pure culture. Polymerase chain reaction (PCR) experiments utilizing known genetic sequences from other 2,4-D and 2,4,5-T degrading bacteria demonstrated that these organisms contain gene sequences similar to tfdA, B, C, E, and R (Strain JRB1) and the tftA, C, and E genes (Strain JR7B3). Expression analysis confirmed that tftA, C, and E and tfdA, B, and C were transcribed during 2,4,5-T and 2,4-D dependent growth, respectively. The results indicate a strong selective pressure for 2,4,5-T utilizing strains under field condition.

A bioluminescent whole-cell reporter for detection of 2, 4-dichlorophenoxyacetic acid and 2,4-dichlorophenol in soil.

A bioreporter was made containing a tfdRP(DII)-luxCDABE fusion in a modified mini-Tn5 construct. When it was introduced into the chromosome of Ralstonia eutropha JMP134, the resulting strain, JMP134-32, produced a sensitive bioluminescent response to 2, 4-dichlorophenoxyacetic acid (2,4-D) at concentrations of 2.0 microM to 5.0 mM. This response was linear (R(2) = 0.9825) in the range of 2.0 microM to 1.1 x 10(2) microM. Saturation occurred at higher concentrations, with maximal bioluminescence occurring in the presence of approximately 1.2 mM 2,4-D. A sensitive response was also recorded in the presence of 2,4-dichlorophenol at concentrations below 1.1 x 10(2) microM; however, only a limited bioluminescent response was recorded in the presence of 3-chlorobenzoic acid at concentrations below 1.0 mM. A significant bioluminescent response was also recorded when strain JMP134-32 was incubated with soils containing aged 2,4-D residues.

Biofilm ecology: On-line methods bring new insights into mic and microbial biofouling.

Microbial biofilms were formed on coupons with defined coatings in once-through laminar flow fields of controlled bulk-phase composition and shear. Dilute media were utilized to select for biofilm growth. The formation, succession, and stability of the biofilms were monitored with non-destructive on-line methods (fluorescence, bioluminescence, attenuated total reflectance Fourier transform infrared spectrometry [ATR-FTIR] and electrochemical impedance spectroscopy) and by high resolution destructive analysts (viable and direct counts and phospholipid fatty acid signature methods) at the termination of the experiments. Biofilms of reproducible composition can be formed and the order of inoculation of multi-component biofilms affects their composition at harvest. The corrosion rates of mild steel depended on the biofilm composition but not the attached biomass. Examination of biofilms with the scanning vibrating electrode in a microscope field showed effects of heterogeneity in biofilm structure which promoted localized anodic activity. Pseudomonas stains were engineered to contain the lux gene cassette as a "reporter"; and the formation of the exopolymer alginate was shown not to promote attachment of the strain or secondary colonization by Vibrio. Examination of mutants forming different alginate structures showed differential attachment and biofilm structure. Studies of mutants of lipopolysaccharide structure showed differential attachment to substrata. Specific antifouling and fouling-release coatings showed a wide range of attachment and release properties as well as sublethal toxicity.

Distribution of alginate genes in bacterial isolates from corroded metal surfaces.

The distribution of alginate genes encoding biosynthesis of alginate was examined for bacterial isolates associated with corrosive biofilms recovered from source water, cooling lines, and reactor surfaces of a nuclear power plant. A total of 120 diverse Gram-positive and -negative isolates were obtained. Using DNA:DNA hybridization, 11 isolates were shown to contain sequences homologous to structural (algD, algG, alg-76) and/or regulatory (albB) alginate biosynthetic genes derived from an alginate-producing cystic fibrosis isolate of Pseudomonas aeruginosa (FRD1). Identification of isolates was accomplished by fatty acids methyl esters (FAME) analysis and the Biolog identification system. Nine of the twelve isolates were identified as various Pseudomonas spp., and two additional Gram-negative isolates were tentatively identified as Aeromonas veronii and Stenotrophomonas maltophilia. The remaining isolate was identified as a Gram-positive Bacillus pumilus. The results of the investigation extend current knowledge on the distribution of alginate biosynthetic genes in environmental isolates and permits the development of a more environmentally realistic model system to investigate the role of exopolymer production in biofilm formation and biocorrosion processes.

Development of a written investment policy.

Like many medical groups, J. Frederick Rice's had no formal method of evaluating the performance of the investment manager employed to manage the benefits plan. Rice, FACMGA, in his case study, describes how his group set formal, written goals as a means of measuring performance.

A stretcher that facilitates the radiographic evaluation and closed reduction of spinal fractures.

A rigid and exceptionally radiolucent stretcher with an attachment for cervical traction has been constructed. A patient is able to remain on this stretcher in the same position during the entire radiographic examination of a spinal fracture, including plain x-ray and computed tomographic and myelographic studies. Two advantages are obtained if this stretcher is used: 1) A patient's spine is well supported and does not need to be moved at any time during these radiographic studies, and 2) the application of traction during the myelography or closed reduction of a cervical fracture is facilitated.

The radiographic description of thoracolumbar fractures.

The X-ray films of 40 patients with thoracolumbar fractures were studied in order to classify the fractures, to investigate the causes of neural compression, and to define which fractures were unstable. Each fracture could be classified as a wedge fracture, a burst fracture, or a fracture-dislocation. The fragment of bone that produced neural compression in wedge and burst fractures almost always arose from the upper half of the vertebral body and had a characteristic triangular shape, as viewed on lateral x-ray films of the spine. Based on radiographic evidence, fracture-dislocations, severe burst fractures, and wedge fractures associated with marked subluxation, traumatic spondylolisthesis, or horizontal fractures of a pedicle were considered to be unstable. Mild burst fractures and most wedge fractures were considered to be stable.

Solvent abuse associated cortical atrophy.

Eleven of 42 toluene inhalers were evaluated with computed tomography scans because of neurologic abnormalities. Six of the 11 were found to have cerebral cortical atrophy. In addition, two of the six had cerebellar atrophy. All six had been exposed to toluene for at least 10 years. This study suggests that atrophy of the central nervous system may occur in chronic toluene abusers.

The demonstration and significance of neural compression after spinal injury.

Standard metrizamide myeLography and CT myelography can accurately and safely define neural compression after a spinal injury. A lateral C1-C2 spinal puncture and a radiolucent fracture board reduce movement of the spine, and by injecting metrizamide in an isotonic concentration and by limiting the amount of contrast above a block, the risk of seizure is minimized. This capability for directly determining neural compression has important implications for the treatment of spinal fractures, and the significance of persisting posttraumatic neural compression is discussed. We believe neural compression should be the primary indication for surgical decompression after spinal injury and that evaluation for it should now be a standard part of the examination of patients with spinal fractures with potential for neurological recovery.

Electrocardiographic changes in cerebrovascular hemorrhage.

The electrocardiographic abnormalities found in localized cerebrovascular hemorrhage which have been documented by computerized tomography (CT) scans are described. Frontal lobe hemorrhages are associated especially with the electrocardiographic abnormalities of QT prolongation and neurogenic T waves. Brain stem hemorrhage seems to be associated with noncardiogenic pulmonary edema, and sudden development of atrial fibrillation. It is proposed that the cause of ECG abnormalities in association with lesions in the vicinity of area 13 on the orbital surface of the frontal lobe, or around the circle of Willis, results from alterations in sympathetic and parasympathetic tone mediated by fibers from the orbito-frontal area to the heart via the stellate ganglia.

Lateral C1-2 puncture for myelography: posterior approach.

The lateral C1-2 puncture approach for myelography is a modification of the technique for percutaneous radiofrequency cervical cordotomy. Positioning of the needle in the posterior, rather than anterior, one third of the canal avoids injury to anomalous vertebral artery branches which lie in the anterior half of the neural canal at this level.

Normal and high accuracy computed tomography of the brain: dose and imaging considerations.

The high accuracy scanning mode of the EMI CT1010 scanner generates scans with imaging characteristics superior to those produced in the normal accuracy mode. The comparative dosimetry of normal and high accuracy scans is presented, along with an analysis of the image quality of the two scanning modes. High accuracy scanning is an effective adjunct in patients with difficult lesions in the cerebral hemispheres.

The superficial recurrent ophthalmic artery: meningeal supply to petrous ridge meningiomas.

The superficial recurrent ophthalmic artery arising from the second portion of the ophthalmic artery is rarely visible angiographically. Described herein is a patient having a recurrent ophthalmic artery which had hypertrophied to a degree sufficient to supply a highly vascularized meningioma of the petrous ridge. Coexistence of marginal tentorial branches, namely the superficial recurrent ophthalmic artery and the meningohypophyseal trunk, is an embryological dilemma. Furthermore, this case demonstrates the capacity of the ophthalmic artery to supply posteriorly situated neoplasms.

Scintiscans and computer assisted tomographic findings of herpesencephalitis.

The radionuclide, CAT and angiographic features of a case of herpes simplex encephalitis are present. A dramatic change in the abnormal perfusion and static concentration of tracer activity resulted following chemotherapy with Adenine arabinoside. The improvement seen on the dynamic and static scintiscans correlates closely with the patient's clinical course and CAT findings. The radionuclide perfusion study is of particular importance in documenting the diminished activity of the inflammatory process following therapy.

Spinal subarachnoid hemorrhage during myelography. Case report.

Neoplasms of the conus medullaris and cauda equina have been shown to cause subarachnoid hemorrhage (SAH). In such instances, the hemorrhage has been the presenting symptom. A patient with a neurofibrom at T12-L1 experienced spinal SAH during myelography for suspected lumbar disc disease. The roentgenograms showing the lesion itself first and the subarachnoid clot subsequently may be unique. The cause of hemorrhage in this patient may have been the shearing of bridging capsular veins because of diminished cerebrospinal fluid pressure below the almost obstructing lesion.