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J C Pennington

Publications and source records attributed to J C Pennington.

At least 19 recordsLinked to original sources
PubMed2002

15N NMR investigation of the reduction and binding of TNT in an aerobic bench scale reactor simulating windrow composting.

T15NT was added to a soil of low organic carbon content and composted for 20 days in an aerobic bench scale reactor. The finished whole compost and fulvic acid, humic acid, humin, and lignocellulose fractions extracted from the compost were analyzed by solid-state CP/MAS and DP/MAS 15N NMR. 15N NMR spectra provided direct spectroscopic evidence for reduction of TNT followed by covalent binding of the reduced metabolites to organic matter of the composted soil, with the majority of metabolite found in the lignocellulose fraction, by mass also the major fraction of the compost. In general, the types of bonds formed between soil organic matter and reduced TNT amines in controlled laboratory reactions were observed in the spectra of the whole compost and fractions, confirming that during composting TNT is reduced to amines that form covalent bonds with organic matter through aminohydroquinone, aminoquinone, heterocyclic, and imine linkages, among others. Concentrations of imine nitrogens in the compost spectra suggest that covalent binding by the diamines 2,4DANT and 2,6DANT is a significant process in the transformation of TNT into bound residues. Liquid-phase 15N NMR spectra of the fulvic acid and humin fractions provided possible evidence for involvement of phenoloxidase enzymes in covalent bond formation.

Aerobiosis↗
PubMed2001

Effect of different location of atrial lead position on nearfield and farfield electrograms in dual chamber pacemaker-defibrillators.

The normal functioning of dual chamber pacemaker-cardioverter defibrillator (AV pacer/ICD) may be affected by oversensing of the farfield R wave (FFRW) by the atrial channel. This study aimed to investigate whether placement of the AV pacer/ICD's atrial lead at a lateral (LAT) wall location compared to a medial (MED) location i.e. the appendage of the right atrium, would reduce the amplitude of FFRWs but not the nearfield atrial electrograms (AEGMs) during sinus rhythm (SR) and ventricular fibrillation (VF). In 17 patients, real time electrograms were recorded during SR and induced VF through the atrial lead initially at the MED and subsequently at the LAT location. In 10 patients the electrograms in SR were also recorded on a computerized data acquisition and recording system at different band-pass filter settings. Although FFRWs were recorded both at MED and LAT locations, they were much smaller, 3.5+/-4.1mm during SR and 1.7+/-2.2mm during VF at the LAT location. At 30-500Hz band-pass filter, lower amplitudes of FFRWs 0.14+/-0.09 mV were recorded at the LAT location. The V/A ratios of the amplitudes of FFRWs and AEGMs were smaller at the LAT location during SR and VF. The nearfield AEGMs were of similar amplitudes at the MED and LAT locations. These data indicate that lower amplitudes of FFRWs are recorded by placement of the atrial lead at the lateral wall of the right atrium. Oversensing of FFRWs may be prevented to improve functioning of the AV pacer-ICD.

Aged↗
PubMed2000

Attenuation mechanisms of N-nitrosodimethylamine at an operating intercept and treat groundwater remediation system.

The North Boundary Containment System (NBCS), an intercept-and-treat system, was established at Rocky Mountain Arsenal (RMA), Commerce City, CO, to remove low-level organic contaminants from a groundwater plume exiting RMA to the north and northwest. N-nitrosodimethylamine (NDMA) was detected in groundwater collected from the dewatering and recharge zones of the NBCS system. Concern over the fate of NDMA, in terms of potentially exiting the boundaries of the arsenal, prompted an investigation to evaluate potential attenuation mechanisms for NDMA within the alluvial aquifer system and within the NBCS itself. Groundwater, soil, and granular activated carbon (GAC) samples were taken from key locations in the NBCS system. Soil and GAC samples were assayed for sorption kinetics and for adsorption and desorption properties using 14C-labeled NDMA. NDMA biodegradation experiments were conducted by following 14CO(2) evolution from 14C-labeled NDMA in soils and GAC samples under aerobic and anaerobic conditions. The sorptive capacity of the site soils for NDMA was insignificant. Furthermore, the adsorption of the NDMA by the soil was almost completely reversible. Evaluation of the degradation potential of the native microbial consortia indicated a high level of NDMA mineralization when measured using bench-scale microcosms. The native consortia had capability to mineralize the NDMA under both aerobic and anaerobic incubations, indicating facultative characteristics. Testing of the local groundwater chemistry revealed that the area of the aquifer of interest was microaerobic and neutral in pH. These conditions were optimal for NDMA removal. While sorption was insignificant, degradation was a significant attenuation mechanism, which may be the reason that no NDMA has migrated off-site. This gives rise to the potential of a long-term sink for attenuating NDMA within the recharge zone of the treatment system.

Adsorption↗
PubMed2000

Feasibility, safety, and determinants of extraction time of percutaneous extraction of endocardial implantable cardioverter defibrillator leads by intravascular countertraction method.

Previous studies of the removal of implantable cardioverter defibrillator (ICD) leads have been restricted to case reports or small series. In this report, we describe our experience in ICD lead extraction by intravascular countertraction method using Cook's extraction kit. A total of 47 high-voltage (HV) leads, 3 rate sensing (S) leads, and 2 subcutaneous arrays were removed from 42 patients (33 men, 9 women; mean age 59 years [range 14 to 81]). One HV superior vena cava (SVC) lead and 11 HV right ventricular (RV) leads were explanted by manual traction only and defined in the "lead removal" category. One S lead was removed using a femoral venous approach. The remaining 37 leads were explanted by SVC approach using extraction sheaths and defined in the "lead extraction" category. Twenty leads were extracted for "infectious" (group A) and 17 leads for "noninfectious" (group B) etiologies for which extraction times of 27.0+/-18.0 and 27.0+/-15.0 minutes (mean+/-SD), respectively, were not different. Although extraction time, 34.0+/-11.0 minutes, for leads implanted for >48 months was longer than 23.0+/-16.0, 28.0+/-18.0, and 24.0+/-14.0 minutes, for leads with implant durations of 12, 24, and 48 months, respectively, such differences were not statistically significant. The extraction time, however, was directly related to the degree of fibrosis around the lead, 39.0+/-15.0 minutes for leads with severe fibrosis compared with 13.0+/-6.0 minutes for the leads with mild fibrosis (p<0.001). Patient's age, sex, or history of coronary artery bypass graft surgery did not significantly affect extraction time. All except the initial 2 lead extractions were performed in the electrophysiology laboratory. No mortality or serious complications associated with the procedure using these methods were observed.

Defibrillators, Implantable↗
PubMed2000

Use of multisite electroanatomic mapping to facilitate ablation of intra-atrial reentry following the Mustard procedure.

Ablation of intra-atrial reentrant tachycardia following Mustard or Senning procedures has low success rates. The Biosense Carto system was used to map intra-atrial reentry in a 22-year-old woman who had undergone a Mustard procedure. A line of block was created connecting a Mustard baffle suture line to the tricuspid valve annulus, which terminated the arrhythmia and prevented its reinitiation. Multisite electroanatomic mapping was invaluable in defining atrial anatomy and the intra-atrial reentrant pathway, and in creating a contiguous line of block. This mapping may improve ablation success rates in patients following the Mustard or Senning repair.

Adult↗
PubMed1997

Heart protection: controlling risk factors for cardiovascular disease.

Cardiovascular disease is the leading cause of illness and death in the United States. Clinical data continue to support primary prevention through the aggressive treatment of well-defined cardiovascular risk factors. Three risk factors that can be modified to lower the risk of cardiovascular disease and death are hypercholesterolemia, hypertension, and cigarette smoking. Even patients with asymptomatic cardiovascular disease have been shown to benefit from aggressive cholesterol-lowering therapy. New JNC-VI guidelines for managing hypertensive disease recommend that treatment decisions be based on level of blood pressure plus presence or absence of target organ damage or other risk factors. The risk of myocardial infarction in former smokers approaches that of nonsmokers after 3 years.

Cardiovascular Diseases↗
PubMed1988

Public information.

Explore the source record for details and available documents.

Administrative Personnel↗
PubMed1977

Spinal epidural abscess in pregnancy.

A case of spontaneous epidural abscess occuring in a pregnant woman is reported. Some delay in diagnosis occurred. Decompression resulted in prompt recovery and improvement of a mild neurological deficit.

Abscess↗
PubMed1976

The anti-inflammatory and analgesic effects of norvedan a novel, non-steroidal agent.

Norvedan (2-phenyl-4-p-chlorophenyl-thiazole-5-ylacetic acid) has been investigated for anti-inflammatory activity using an 'adjuvant arthirits' in rats and for analgesic activity using a writhing test in mice and a pressure test in rats. At oral doses of 10, 30 and 100 mg/kg Norvedan caused a dose-related inhibition of the primary swelling of the paw injected with adjuvant and the development of secondary lesions was also inhibited. Writhing induced in mice by i.p. administered acetic acid was also reduced by Norvedan at oral doses of 30 mg/kg and above and the response was related to dose. Against pain induced in rats by application of pressure to an inflamed paw Norvedan alsp showed good activity which was present for at least 6 hr after dosing.

Acetates↗
PubMed1976

A safe method of amniocentesis for lecithin/sphingomyelin determination in late pregnancy using ultrasound.

Two hundred consecutive amniocenteses for lecithin/sphingomyelin (L/S) determination in late pregnancy are reviewed. These procedures were performed under ultrasonic control before induction of labor or elective cesarean section in a prospective study to determine a safe method for aminocentesis. Complications included 3 failures, 14 blood-stained samples, 2 cases of labor occuring within 24 hours after amniocentesis, and 1 maternal abdominal wall hematoma. There was no cases of perinatal morbidity or mortality. It is proposed that this is a safe method of abdominal amniocentesis for L/S determination in late pregnancy.

Amniocentesis↗