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Biomedical subjects

B M Patterson

Publications and source records attributed to B M Patterson.

At least 19 recordsLinked to original sources
PubMed2004

Use of polymer mats in series for sequential reactive barrier remediation of ammonium-contaminated groundwater: field evaluation.

A pilot-scale field trial was undertaken to evaluate the potential of in situ polymer mats (installed in series) as permeable reactive barriers within a treatment wall remediation system to induce sequential bioremediation of ammonium-contaminated groundwater. The treatment wall consisted of 10 m wide impermeable wings on either side of a 0.75 m wide permeable reactive zone flow-through box. Two polymer mats were positioned in the flow-through box. The upgradient polymer mat within the flow-through box was used to deliver oxygen to induce bacterial nitrification of the ammonium to nitrite/nitrate as the groundwater moved past. The downgradient polymer mat delivered ethanol to induce bacterial denitrification of the nitrite/nitrate to produce nitrogen gas. The field trial was carried out at a near-shore location. Initially the flow-through box was left open; however, this resulted in substantial groundwater mixing, which inhibited sequential remediation. Once the flow-through box was in-filled with gravel, groundwater mixing was reduced, achieving a greater than 90% reduction in total N. Estimated first-order half-lives for nitrification and denitrification rates were 1.2 and 0.4 d, respectively. Field nitrification half-lives were approximately an order of magnitude greater than rates determined in large-scale columns using soil and groundwater from the site, while denitrification half-lives were similar. The results of this pilot-scale field trial indicate that sequential bioremediation of ammonium-contaminated groundwater at field scale is feasible using in situ polymer mats as permeable reactive barriers, although hydraulic conditions can be complex in such barrier systems.

Biodegradation, Environmental↗
PubMed2003

Measurement of atomic lifetimes with a mode-locked laser.

We present a new technique for measuring atomic lifetimes with a mode-locked laser. A single laser pulse excites the atoms and a subsequent frequency-doubled pulse ionizes the excited-state atoms. The ions are collected and counted. The measurement is repeated using excitation and detection pulses with different time separations, which determines the excited-state decay rate. We demonstrated this technique for the 6P(3/2) state of cesium. The measured lifetime was 30.5 ns and had a statistical uncertainty of 0.1 ns. Systematic effects limited the overall experimental uncertainty to approximately 0.6 ns in this initial experiment.

Journal Article↗
PubMed2002

Use of polymer mats in series for sequential reactive barrier remediation of ammonium-contaminated groundwater: laboratory column evaluation.

Large-scale column experiments were undertaken to evaluate the potential of in situ polymer mats (installed in series) to be used as permeable reactive barriers for delivery of oxidants and reductants to induce sequential bioremediation of ammonium-contaminated groundwater (approximately 120mg L(-1) NH4+-N), without bioaugmentation. The strategy was for the first group of polymer mats to deliver oxygen to induce bacterial nitrification of the ammonium to nitrite/ nitrate as the groundwater moved past and for the second group of polymer mats to deliver hydrogen or ethanol, to induce bacterial denitrification of the nitrite/nitrate to produce nitrogen gas. Once purging of the first polymer mat commenced, ammonium concentrations decreased downgradient from the polymer mats. Nitrification rates increased and stabilized over the 6-month experiment, with stable nitrification half-lives in the range 0.07-0.25 days. Nitrification most likely occurred in a biologically active zone at the polymer wall/aqueous interface. With hydrogen delivery via the polymer mats, a denitrification half-life (nitrate plus nitrite removal) of 3.5 days was induced. Denitrification rates were significantly enhanced when ethanol was delivered via a polymer mat, with denitrification half-lives in the range of 0.12-0.34 days. Nitrification/ denitrification rates were maintained for groundwater flow rates up to 300 m yr(-1), suggesting oxygen and ethanol delivery rates via the polymer mats were sufficient not to limit nitrification or denitrification. In soil columns, the polymer mat delivery system provided an effective and reliable technique for delivery of oxygen and hydrogen or ethanol for sequential nitrification/denitrification of ammonium-contaminated groundwater. Scale-up of this concept to a field pilot-scale is currently underway.

Biodegradation, Environmental↗
PubMed2002

Using polymer mats to biodegrade atrazine in groundwater: laboratory column experiments.

Large-scale column experiments were undertaken to evaluate the potential of in situ polymer mats to deliver oxygen into groundwater to induce biodegradation of the pesticides atrazine, terbutryn and fenamiphos contaminating groundwater in Perth, Western Australia. The polymer mats, composed of woven silicone (dimethylsiloxane) tubes and purged with air, were installed in 2-m-long flow-through soil columns. The polymer mats proved efficient in delivering dissolved oxygen to anaerobic groundwater. Dissolved oxygen concentrations increased from <0.2 mg l(-1) to approximately 4 mg l(-1). Degradation rates of atrazine in oxygenated groundwater were relatively high with a zero-order rate of 240-380 microg l(-1) or a first-order half-life of 0.35 days. Amendment with an additional carbon source showed no significant improvement in biodegradation rates, suggesting that organic carbon was not limiting biodegradation. Atrazine degradation rates estimated in the column experiments were similar to rates determined in laboratory culture experiments, using pure cultures of atrazine-mineralising bacteria. No significant degradation of terbutryn or fenamiphos was observed under the experimental conditions within the time frames of the study. Results from these experiments indicate that remediation of atrazine in a contaminated aquifer may be achievable by delivery of oxygen using an in situ polymer mat system.

Atrazine↗
PubMed2001

A prospective evaluation of the clinical utility of the lower-extremity injury-severity scores.

BACKGROUND: High-energy trauma to the lower extremity presents challenges with regard to reconstruction and rehabilitation. Failed efforts at limb salvage are associated with increased patient mortality and high hospital costs. Lower-extremity injury-severity scoring systems were developed to assist the surgical team with the initial decision to amputate or salvage a limb. The purpose of the present study was to prospectively evaluate the clinical utility of five lower-extremity injury-severity scoring systems. METHODS: Five hundred and fifty-six high-energy lower-extremity injuries were prospectively evaluated with use of five injury-severity scoring systems for lower-extremity trauma designed to assist in the decision-making process for the care of patients with such injuries. Four hundred and seven limbs remained in the salvage pathway six months after the injury. The sensitivity, specificity, and area under the receiver operating characteristic curve were calculated for the Mangled Extremity Severity Score (MESS); the Limb Salvage Index (LSI); the Predictive Salvage Index (PSI); the Nerve Injury, Ischemia, Soft-Tissue Injury, Skeletal Injury, Shock, and Age of Patient Score (NISSSA); and the Hannover Fracture Scale-97 (HFS-97) for ischemic and nonischemic limbs. The scores were analyzed in two ways: including and excluding limbs that required immediate amputation. RESULTS: The analysis did not validate the clinical utility of any of the lower-extremity injury-severity scores. The high specificity of the scores in all of the patient subgroups did confirm that low scores could be used to predict limb-salvage potential. The converse, however, was not true. The low sensitivity of the indices failed to support the validity of the scores as predictors of amputation. CONCLUSIONS: Lower-extremity injury-severity scores at or above the amputation threshold should be cautiously used by a surgeon who must decide the fate of a lower extremity with a high-energy injury.

Adolescent↗
PubMed2000

Posterior locked lateral compression injury of the pelvis: report of three cases.

Lateral compression injuries to the pelvis typically result in a rotationally unstable and vertically stable condition including an impaction and compression fracture of the posterior pelvic ring. The operative and postoperative management, as well as the morbidity and mortality, of these fractures differs significantly from vertical shear injuries to the pelvis, which are characterized by vertical and rotational instability. We report on three unusual lateral compression injuries to the pelvis, resulting in a complete disruption of the pelvic ring with vertical and rotational instability, by definition. Nevertheless, in these patients, locking of the posterior pelvic ring with medial translation of the iliac wing anterior to the sacrum resulted in a pseudostable condition. Their high rate of fracture-related associated injuries and possible complications, as well as the malalignment of the pelvis, required surgical restoration of the pelvic ring. Fracture reduction was successfully performed through an anterior approach in one patient and a posterior approach in two patients; the posterior approach was preferred. Open reduction and internal fixation of these pelvic ring fractures can result in a satisfactory outcome if the associated injuries are successfully dealt with.

Adolescent↗
PubMed1998

Pathoanatomy of intra-articular fractures of the calcaneus.

Radiographs of 220 calcaneal fractures (205 patients) were reviewed retrospectively. One hundred and sixty-three fractures were intra-articular; thirty (18 per cent) of the 163 fractures were a tongue-type injury, and 133 (82 per cent) were a joint-depression injury. Plain radiographs and computerized tomography scans in the coronal and axial planes were available for 116 intra-articular fractures (106 patients). These studies were reviewed, and the 116 fractures were grouped according to the Sanders classification of calcaneal fractures and the anterior extension of the primary fracture line was evaluated. Sixty-two primary fracture lines (53 per cent) extended into one articular surface; twenty-three (20 per cent), into two articular surfaces; twenty-three (20 per cent), into a periarticular location; and eight (7 per cent), into a medial or lateral location. Sixty-seven (58 per cent) involved the calcaneocuboid joint, thirty-one (27 per cent) involved the anterior facet of the talocalcaneal joint, and ten (9 per cent) involved the middle facet of the talocalcaneal joint. A distinct anterolateral fragment was identified in 108 fractures (93 per cent). Plain radiographs failed to demonstrate the anterior extension of fifty-one (47 per cent) of the primary fracture lines. The prevalence of involvement of the anterior facet was significantly greater in Sanders type-III fractures (sixteen of thirty-five; 46 per cent) than in the other types (p < 0.01). The prevalence of involvement of the calcaneocuboid joint and the middle facet was evenly distributed among the fracture types. The primary fracture line typically extends anterior to the angle of Gissane, creating a relatively consistent anterolateral fracture fragment. The primary fracture line cannot be reliably seen on plain radiographs and is better visualized on computerized tomographic scans.

Calcaneus↗
PubMed1997

Anterior sliding graft for tibiotalar arthrodesis.

The results using the anterior sliding graft technique with rigid internal fixation for tibiotalar arthrodesis were reviewed. The indications for anterior sliding graft technique included posttraumatic arthritis, rheumatoid arthritis, pseudarthrosis following prior attempt at arthrodesis, and postinfectious arthrosis. The arthrodesis rate was 95%. The overall prevalence of complications was 33%. The complications related to this method were minor and easily managed. The authors concluded that the anterior sliding graft technique is performed with readily available resources, has a high rate of union, and avoids the routine use of iliac bone graft.

Adult↗
PubMed1996

Functional lower limb salvage with an osteocutaneous filet flap of the foot.

An osteocutaneous foot filet flap based on the posterior tibial vessels was successfully used to provide tibial coverage in a patient requiring a below-knee amputation following a high-voltage electrical injury. Addition of the calcaneus to the standard foot filet flap provided a vascularized bone graft that served to both lengthen the tibia and secure the flap via a tibial-calcaneal synostosis. The synostosis provided firm anchoring of the flap and allowed for a partial end-bearing, below-knee prosthesis.

Aged↗
PubMed1996

Microbial biomass in a shallow, urban aquifer contaminated with aromatic hydrocarbons: analysis by phospholipid fatty acid content and composition.

The city of Perth contains a number of sites that have been contaminated with hydrocarbons due to leakage from petroleum underground storage tanks. Microbial biomass in groundwater and sediment cores from above and below the water table, and from within and outside a plume of hydrocarbon contamination, was examined using phospholipid fatty acid methyl ester analysis. Microbial numbers, calculated from the phospholipid content, ranged from 0.9 x 10(6) to 7.8 x 10(6) 'Escherichia coli equivalent cells' g-1 dry wt of sediment. Over 96% of the microbial biomass was attached to the sediment and the proportion of attached cells did not decrease within the plume of contaminants. The amount of biomass within aquifer samples seemed to be related more to the proximity of the rhizosphere to the shallow aquifer, and other unknown urban inputs, rather than to the effects of the plume of contaminants. Fatty acids common to many bacterial groups dominated within the plume, and as such the analyses gave limited insight into microbial community structure. For site assessment of intrinsic remediation of shallow aquifers in urban areas, estimates of microbial biomass may not provide information that is readily applicable to plume management.

Biomass↗
PubMed1995

Retrograde nailing of femoral shaft fractures.

OBJECTIVE: The purpose of the study was to define the outcome following retrograde nailing of the femoral shaft. DESIGN: Retrospective clinical study. MATERIALS AND METHODS: Seventeen retrograde intramedullary nailings of the femur were performed in 16 patients for management of complex orthopedic trauma. Thirteen patients were followed for an average of 22.8 months (range from 9 to 72 months). The indications for retrograde nailing were an ipsilateral femoral neck and shaft fracture in eight cases, knee disarticulation or long above knee amputation associated with a femoral shaft fracture in five cases, traumatic arthrotomy of the knee ipsilateral to a shaft fracture in two cases, one case of a shaft fracture ipsilateral to an acetabular fracture that required an extensile exposure, and one case of a femoral nonunion with a knee contracture. In fourteen of the seventeen cases the femur fracture was open including two grade III C injuries. MEASUREMENTS AND MAIN RESULTS: Two patients died in the early postoperative period due to the severity of the initial trauma and one patient was lost to follow-up. The results were generally poor and postoperative complications were common. There were five nonunions in the group, one which required revision to an above knee amputation for an infected nonunion following a grade III open femur fracture. The average range of motion of the knee was 3 degrees to 110 degrees, and two patients had an extensor lag of 5 degrees or more. Six patients underwent removal of hardware through a second arthrotomy with no significant loss of knee function related to the second procedure. CONCLUSIONS: The authors concluded that the high complication rate and poor results were related to the severity of the initial injury. An intercondylar starting can be used in properly selected cases with minimal effect on knee function.

Adult↗
PubMed1995

Intraoperative complications during total hip arthroplasty.

Total hip replacement is one of the most common adult reconstructive procedures performed today. Even though training in total hip replacement has become fairly common in many orthopedic residency programs, complications can still occur during surgery. Preoperative planning and close attention to detail may prevent intraoperative problems. Awareness of the potential downfalls allows the surgeon to properly prepare for surgery, avoid intraoperative complications, and manage unavoidable problems when they do arise.

Acetabulum↗
PubMed1995

Pelvic ring injury and associated urologic trauma: an orthopaedic perspective.

Pelvic ring trauma is frequently associated with damage to many organ systems, including the vascular, genitourinary, nervous, reproductive, and intestinal systems. The orthopaedic treatment of these patients must incorporate the presence of these injured soft tissue structures and the physicians who are knowledgeable in the care of these anatomic regions in treatment decision making. Improvement in the treatment of these patients has been based on progress in areas of interventional radiology, general surgery, urology, and orthopaedics. The purposes of this report are to define the natural history and the survival rate after a pelvic fracture or dislocation, as well as to present classification schemes used by the orthopaedic surgeon, define current controversies, and recommend treatment based on the pattern of injury to the pelvic ring.

Fractures, Bone↗
PubMed1995

Tarsometatarsal (Lisfranc's) fracture-dislocation.

Tarsometatarsal (Lisfranc's) fracture-dislocations account for 0.2% of all fractures. As many as 20% of these injuries are misdiagnosed or overlooked, especially in the polytrauma patient with other distracting injuries. The mechanism of injury, clinical diagnosis, treatment, and prognosis are reviewed. Results of arthrodesis of the tarsometatarsal joint for patients with symptomatic posttraumatic arthritis of the tarsometatarsal joint are discussed. A thorough understanding of this often misdiagnosed injury should facilitate the physician's prompt diagnosis and management of this potentially debilitating lesion, resulting in improved functional recovery for the patient.

Arthrodesis↗
PubMed1992

Surgical management of gonarthrosis in patients with poliomyelitis.

The authors reviewed nine cases of degenerative disease of the knee in patients with a history of poliomyelitis. All patients were treated with a cemented total knee arthroplasty. The average follow-up period was 6.8 years (range, 6 months to 13 years), and the average follow-up knee score using the Hospital for Special Surgery rating scale was 70. Three of the patients required revision total knee arthroplasty to a more constrained implant. Pain relief was predictably very good and knee stability was initially improved. However, many of the patients suffered a decline in ambulatory ability with time.

Aged↗
PubMed1992

Protein depletion and metabolic stress in elderly patients who have a fracture of the hip.

A prospective study was performed to determine the effect of protein depletion and postoperative nutritional status on the outcome in sixty-three elderly patients who had been admitted to the hospital because of a fracture of the hip. The parameters that were used to determine the degree of protein depletion included levels of albumin, of prealbumin, and of transferrin; total lymphocyte count; and nitrogen-balance studies. The outcomes that were examined were the development of complications, the length of the stay in the hospital, the ability to return to the pre-fracture level of function, and over-all survivorship. The hypothesis was that the acute fracture and the subsequent operation are severe stresses in these elderly, often compromised patients. The results supported the hypothesis. Thirty-seven patients (58 per cent) in the study group were in a protein-depleted state during the period of hospitalization. The patients who were protein-depleted had a higher prevalence of complications, were less likely to return to their pre-fracture environment, and tended to stay in the hospital longer, as compared with the nonprotein-depleted patients. Survivorship analysis showed that protein-depleted patients had a significantly lower probability of survival one year after the fracture of the hip (p = 0.02). Elderly patients who sustain the trauma of a fracture of the hip should be managed appropriately with regard to intake of nutrients in the postoperative period.

Aged↗