Biomedical subjects

James E Anderson

Publications and source records attributed to James E Anderson.

6 recordsLinked to original sources

PubMed2005

NO signaling in the CNS: from the physiological to the pathological.

Nitric oxide (NO) is a free radical gas that has a Janus nature. As indicated by the literature and by our studies, in the cell, NO can either function as a beneficial physiological agent utilized for essential functions such as differentiation or neurotransmission, or as a pathological agent that causes or exacerbates central nervous system (CNS) disease and injury. Whether NO is helpful or harmful depends on a variety of factors, such as the cellular environment in which NO is released, the rate of NO flux, as determined by which NOS isozyme is activated, and what array of second messenger cascades are available for utilization by NO for beneficial or toxic cell signalling. Understanding the mechanisms by which NO is salutary in one set of circumstances and toxic in another is critical and will offer therapeutic targets for the mitigation of NO-mediated damage seen during CNS disease and injury. In fact, we have utilized the duality the NO to, in motor neurons, induce adaptive resistance (IAR) to toxic doses of NO. Understanding how the actions of NO are transduced in the cell will lead us to more targeted application of therapies such as IAR.

Animals↗

PubMed2005

Sternal nourishment in various conditions of vascularization.

BACKGROUND: Early changes in sternal perfusion were studied after midline sternotomy and different methods of mammary artery (MA) harvesting. METHODS: Our observations were made in the swine model after midline sternotomy. In group 1 (6 animals), after unilateral skeletonized MA harvesting, (99m)Tc particles were injected intravenously. In group 2 (7 animals), after unilateral mammary artery and vein harvesting (semiskeletonized technique), (99m)Tc particles were injected intravenously. In group 3 (5 animals), after skeletonized bilateral MA harvesting, 99mTc particles were injected into the intercostal musculature lateral to the sternal border. In groups 1 to 3, sternal samples were analyzed using gamma counting. In group 4 (6 animals), unilateral skeletonized MA harvesting was performed. In group 5 (5 animals), the MA was harvested unilaterally using the semiskeletonized technique. In groups 4 and 5, sternal blood flow was assessed using thermography. Data were collected in all groups for 5 hours postoperatively. RESULTS: Both radioactive and thermographic flow measurements showed a statistically significant decrease in sternal blood flow on the side of harvested mammary vessels, regardless of harvesting technique. Radioactivity of the devascularized hemisterni on the side of intramuscular particle injection was substantially higher than in the contralateral half, confirming the role of diffusion in sternal nourishment. The distal sternal segments were least perfused by the MA. CONCLUSIONS: There is an acute reduction of sternal perfusion during the early postoperative period, even if collaterals are preserved by skeletonized MA harvesting. Diffusion plays an important role in sternal nourishment, particularly of the xiphoid, and even more so after MA harvesting.

Animals↗

PubMed2005

Finite-difference time-domain simulation of a liquid-crystal optical phased array.

Accurate modeling of a high-resolution, liquid-crystal-based, optical phased array (OPA) is demonstrated. The modeling method is extendable to cases where the array element size is close to the wavelength of light. This is accomplished through calculating an equilibrium liquid-crystal (LC) director field that takes into account the fringing electric fields in LC OPAs with small array elements and by calculating the light transmission with a finite-difference time-domain method that has been extended for use in birefringent materials. The diffraction efficiency for a test device is calculated and compared with the simulation.

Journal Article↗

PubMed2003

Opposing selective forces for expression of the gonococcal lactoferrin receptor.

All isolates of Neisseria gonorrhoeae express receptors that bind human transferrin (Tf). Although lactoferrin (Lf) is abundant on mucosa and in purulent exudates, many gonococci do not express an Lf receptor. The naturally occurring Lf receptor deletion mutant FA1090 (LbpB-LbpA-) is infectious, but a Tf receptor mutant of FA1090 is unable to infect male volunteers [Cornelissen, C.N., Kelley, M., Hobbs, M.M., Anderson, J.E., Cannon, J.G., Cohen, M.S., and Sparling, P.F. (1998) Mol Microbiol 27: 611-616]. Here, we report that expression of an Lf receptor in the absence of the Tf receptor was sufficient for infection, and that expression of both Lf and Tf receptors resulted in a competitive advantage over a strain that made only the Tf receptor in mixed infection of male volunteers. We confirmed that nearly 50% of clinical isolates do not make an Lf receptor. Surprisingly, about half of geographically diverse Lf - isolates representing many different auxotypes and porin serovars carried an identical lbpB lbpA deletion. Among Lf+ strains, all produced the integral outer membrane protein LbpA, but 70% did not express the lipoprotein LbpB. Thus, there are apparently selective pressures for expression of the Lf receptor in the male urethra that are balanced by others against expression of the Lf receptor in niches other than the male urethra.

Bacterial Outer Membrane Proteins↗

PubMed2003

Renal colic: a prospective evaluation of non-enhanced spiral CT versus intravenous pyelography.

The aim of this study was to compare non-enhanced spiral CT (NECT) and intravenous pyelography (IVP) in patients with suspected acute renal colic. Two-hundred patients presenting to the Emergency Department with suspected acute renal colic were randomized into groups undergoing NECT or IVP. The main outcome measures were diagnostic utility, incidence of alternative diagnoses, requirement for further imaging, length of hospital stay, urological intervention rates, radiation dosage and costs. Non-enhanced spiral CT was better than IVP in making a definitive diagnosis of ureteric calculus or of recent calculus passage (65/102 or 66% vs 42/98 or 41%; P = 0.003). Calculi were missed in two patients in the IVP group. Two patients in each group had alternative diagnoses by initial imaging. There was no difference in the length of hospital stay or intervention rate. More plain X-rays during admission and more IVPs during follow up were performed in the NECT group. Effective radiation dosages were 2.97 mSv (IVP) and up to 5 mSv (NECT). Non-enhanced spiral CT provided greater diagnostic utility in this randomized comparison but no difference in measured outcomes. The incidence of alternative diagnoses was low, probably due to patient selection. Financial costs for each modality are comparable in a public tertiary hospital. Radiation dosages are higher for NECT and, for this reason, it might be appropriate to consider limiting NECT use to patients who have do not have classical symptoms of renal colic, to older patients and those with a contraindication to the administration of intravenous contrast media.

Acute Disease↗

PubMed2002

Point mutations in HpuB enable gonococcal HpuA deletion mutants to grow on hemoglobin.

Neisseria gonorrhoeae ordinarily requires both HpuA and HpuB to use hemoglobin (Hb) as a source of iron for growth. Deletion of HpuA resulted in reduced Hb binding and failure of growth on Hb. We identified rare Hb-utilizing colonies (Hb(+)) from an hpuA deletion mutant of FA1090, which fell into two phenotypic classes. One class of the Hb(+) revertants required expression of both TonB and HpuB for growth on Hb, while the other class required neither TonB nor HpuB. All TonB/HpuB-dependent mutants had single amino acid alterations in HpuB, which occurred in clusters, particularly near the C terminus. The point mutations in HpuB did not restore normal Hb binding. Human serum albumin inhibited Hb-dependent growth of HpuB point mutants lacking HpuA but did not inhibit growth when expression of HpuA was restored. Thus, HpuB point mutants internalized heme in the absence of HpuA despite reduced binding of Hb. HpuA facilitated Hb binding and was important in allowing use of heme from Hb for growth.

Bacterial Outer Membrane Proteins↗