Biomedical subjects

Mark Dolan

Publications and source records attributed to Mark Dolan.

4 recordsLinked to original sources

PubMed2006

Delayed epidural hematoma after spinal surgery: a report of 4 cases.

Symptomatic postoperative epidural hematoma is a rare and potentially devastating complication of spinal surgery. The overwhelming majority of reported cases have occurred in the immediate postoperative period. A recent publication defined the clinical entity of delayed postoperative epidural spinal hematoma as neurologic deterioration due to an epidural hematoma occurring at least 3 days after the index procedure. Only 2 such cases have been reported in the lumbar spine to date. Four cases of delayed postoperative spinal epidural hematoma were identified over a 6-year period among the spine surgeons at a single large academic institution. Each case involved the lumbar spine. The details of each patient's initial surgery, presentation, and hospital course were then gathered from a retrospective chart review. The 4 patients presented are unusual in their delayed symptomatic presentations of postoperative spinal epidural hematoma. Despite the longer time to onset, however, our patients exhibited many of the characteristics common to cases that presented in the acute postoperative period. The spine surgeon must remain vigilant for the possibility of postoperative spinal epidural hematoma in at-risk patients, even weeks after the original surgical procedure.

Aged↗

PubMed2005

Reductive dechlorination of the vinyl chloride surrogate chlorofluoroethene in TCE-contaminated groundwater.

At many trichloroethene (TCE)-contaminated field sites, microbial transformation of TCE results in the accumulation of vinyl chloride (VC), a known carcinogen and neurotoxin. Quantitative tools are needed to determine the in situ rates of VC transformation to ethene in contaminated groundwater. For this study, E-/Z-chlorofluoroethene (E-/Z-CFE) was evaluated as a surrogate for VC in laboratory microcosm and field push-pull tests. Single-well push-pull tests were conducted at a TCE-contaminated field site by injecting E-/Z-CFE and monitoring for the formation of fluoroethene (FE) over a period of up to 80 days. The rates for VC transformation to ethene and E-CFE transformation to FE were within a factor of 2.7 for laboratory microcosm systems and all preferentiallytransformed E-CFE over Z-CFE. In the field, the in situ rates of FE production from injected E-CFE ranged from 0.0018 to 1.15 microM/day, while the in situ rates of E-CFE disappearance ranged from 0.17 to 0.99 microM/day. No significant Z-CFE transformation was observed in field tests, which indicated preferential utilization of E-CFE over Z-CFE under in situ field conditions. The results of this study indicate E-CFE as a potential surrogate for estimating the in situ rates of VC transformation.

Chlorine↗

PubMed2005

Bacterial community composition determined by culture-independent and -dependent methods during propane-stimulated bioremediation in trichloroethene-contaminated groundwater.

An in situ co-metabolic air sparging (CAS) study was carried out at McClellan Air Force Base (MAFB), Sacramento, CA, USA, in a trichloroethene- (TCE) and cis-dichloroethene (cis-DCE)-contaminated aquifer where one test zone received 2% propane in air and the other served as a control and received only air. As part of that study, bacterial population shifts were evaluated by length heterogeneity polymerase chain reaction (LH-PCR). The results showed that an organism(s) that had a fragment size of 385 bp was positively correlated with propane removal rates. The 385 bp fragment consisted of up to 83% of the total fragments in the analysis when propane removal rates peaked. A 16S rRNA clone library made from the bacteria sampled from the propane-sparged groundwater included clones of a TM7 division bacterium that had a 385 bp LH-PCR fragment; no other bacterial species with this fragment size were detected. Both propane removal rates and the 385 bp LH-PCR fragment decreased as nitrate levels in the groundwater decreased. Extinction culturing in natural unamended groundwater medium was used to assess the bacterial diversity of the culturable fraction of microorganisms in both CAS and air-sparged groundwater and to bring novel species into culture for further study. The dominant cultures acquired from the CAS groundwater were from the Herbaspirillum/Oxalobacter clade. The dominant cultures from the air-sparged groundwater were from a novel beta-Proteobacterial clade, which we named after isolate HTCC333.

Bacteria↗

PubMedDate not supplied

AcroFlex design and results.

The AcroFlex prosthesis is unique when compared to other current devices, as it has an elastomeric core sandwiched between two titanium endplates. The purpose of this design was to optimize shock absorption qualities. This paper reviews the design of the AcroFlex Disc and relevant design and outcomes of two pilot studies carried out on 28 patients using the AcroFlex prosthesis. Although clinical outcomes of the pilot studies were successful, the pivotal randomized trial has not been carried out due to detection of mechanical failure of the elastomer on thin cut CT scans. The implications of this for the AcroFlex and other arthroplasties are discussed.

Adult↗