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Biomedical subjects

J P Blanchard

Publications and source records attributed to J P Blanchard.

At least 19 recordsLinked to original sources
PubMed2000

Ultrasound investigation of the rotator cuff after computed arthrotomography coupled to bursography.

OBJECTIVES: To evaluate the diagnostic performance of ultrasound rotator cuff imaging after injection of contrast medium into the glenohumeral joint and subacromial bursa. PATIENTS AND METHODS: Twenty-eight patients underwent ultrasonography before and after injection into the glenohumeral joint and subacromial bursa of a mixture of iodinated contrast medium and lidocaine solution. Findings were compared with those from computed tomography of the joint and bursa. RESULTS: Sixteen 16 (16/28, 57%) post-contrast ultrasound scans revealed or confirmed rotator cuff lesions. For supraspinatus and infraspinatus lesions, there were three false-negatives and no false-positives. Three false-negatives were recorded for subscapularis lesions. All false-negatives occurred both before and after the contrast medium injections. CONCLUSION: Injecting contrast medium into the glenohumeral joint and subacromial bursa improves the diagnostic yield of rotator cuff ultrasonography. We suggest that ultrasonography be performed after injections of drugs into the shoulder structures, particularly the subacromial bursa.

Acromioclavicular Joint↗
PubMed1999

Experimental determination of hydrogen bandwidth for the ion parametric resonance model.

The ion parametric resonance (IPR) model predicts that distinct patterns of field-induced biological responses will occur at particular magnetic field combinations which establish ion resonances. An important characteristic of resonance is the bandwidth response of the system, in part because it determines the required tolerances of the test system. Initial development of the IPR model used literature data to estimate the bandwidth for any ion resonance to be -/+10% of its exact resonance. Because the charge-to-mass ratio of hydrogen is much larger than any other biologically significant ion, hydrogen resonance provides a unique test case by which a single ionic bandwidth can be clearly measured. Of particular relevance is work by Trillo et al. that demonstrated a hydrogen-only, resonance-based IPR response of neurite outgrowth in PC-12 cells. The work reported here considers the response of nerve-growth-factor-stimulated PC-12 cells exposed to magnetic fields tuned at or near hydrogen resonance. This work was designed to test directly the IPR model hypothesis of a -/+10% ionic bandwidth. Consistent with the work of Trillo et al., resonance conditions were established using a 2.97 microT static magnetic field, and the AC frequency and field strength were varied to prove different aspects of the resonance. With this static field 45 Hz was the resonance frequency identified for hydrogen, 42.5 and 47.5 Hz were near-resonance frequencies, and 40 and 50 Hz bounded the assumed -/+10% hydrogen resonance bandwidth. We repeated each test three times. The cell responses at 45 Hz exposures agreed with the IPR model predictions and replicated results obtained by Trillo et al. Cells exposed to 42.5 and 47.5 Hz (near resonance) magnetic fields responded in the same general pattern as those exposed to 45 Hz fields, but neurite outgrowth was less than that observed at resonance. Measured results for cells exposed to either 40 Hz or 50 Hz fields were indistinguishable from off-resonance responses, consistent with the hypothesized bandwidth. These results confirm that the response bandwidth for the hydrogen ion is no greater than -/+10%, and give further support to the resonance-based predictions of the IPR model.

Animals↗
PubMed1999

Rotator cuff imaging using bursography coupled to helical computed arthrotomography.

OBJECTIVE: To describe a rotator cuff imaging method with high sensitivity for the detection of partial tears of the superficial surface of the rotator cuff. PATIENTS AND METHODS: 33 patients with shoulder pain and no conventional arthrography evidence of a full-thickness rotator cuff tear were investigated by bursography coupled with helical computed arthrotomography. Nine subsequently underwent surgery or bursoscopy. RESULTS: Helical computed arthrotomography disclosed an abnormality of the superficial surface of the rotator cuff in 15 patients (45.5%). In the nine patients who had surgery or bursoscopy, findings from this investigation were consistent with those from bursography plus helical computed tomography. CONCLUSION: Bursography coupled with helical computed tomography may be of assistance for the diagnosis of lesions of the superficial cuff surface, which often escape detection by ultrasonography and magnetic resonance imaging.

Bursa, Synovial↗
PubMed1998

Double blind test of magnetic field effects on neurite outgrowth.

Previous work reported that nerve growth factor-stimulated neurite outgrowth in PC-12 cells could be altered by exposure to parallel alternating current (AC) and direct current (DC) magnetic fields under a variety of exposure conditions, producing results that are consistent with the predictions of the ion parametric resonance (IPR) model. The credibility of these results, considered extraordinary by some scientists, could be strengthened if the cell response were found to persist under alternate assay conditions. We replaced part of our standard assay procedure with a double blind procedure. This new procedure obscured 1) whether a particular set of dishes of cells was exposed or not, and 2) which individual dish was in which exposure system. The goal was to determine whether the previously observed responses of PC-12 cells to magnetic fields would be sufficiently robust to decode the imposed blinding, thereby removing any question of experimenter bias in reported results. We placed three coded dishes of cells in each of two otherwise identical exposure systems, one not energized and one energized to produce exposure conditions predicted to maximally suppress neurite outgrowth (Bdc of 36.6 microT, parallel 45 Hz AC of 23.8 microT rms). Each of the six dishes were recoded before assay to further obscure the exposure identity of any individual dish. The combined results of four distinct runs of these double blind experiments unequivocally demonstrated that 1) there was a clear, distinctive, repeatable consistency with the actual energization of the exposure systems and location of each dish, and with the predictions of the IPR model; 2) only the explicitly stated experimental variables influenced the experiment; and 3) the reported response of the cells was very improbably due to chance (P = .000024).

Animals↗
PubMed1996

Effect of ac and dc magnetic field orientation on nerve cells.

Recent tests of the influence of parallel ac and dc magnetic fields on neurite outgrowth in PC-12 cells showed good agreement with the predictions of an ion parametric resonance model. However, experimental results from earlier work involving both a perpendicular (160 mG) and a parallel (366 mG) dc magnetic field were not as consistent with the ion parametric resonance model predictions. Test results reported here show that the cell response to perpendicular ac and de magnetic fields is distinct and predictably different from that found for parallel ac and dc magnetic fields, and that the response to perpendicular fields is dominant in an intensity-dependent nonlinear manner.

Analysis of Variance↗
PubMed1996

Magnetic fields at resonant conditions for the hydrogen ion affect neurite outgrowth in PC-12 cells: a test of the ion parametric resonance model.

PC-12 cells primed with nerve growth factor (NGF) were exposed to sinusoidal extremely-low-frequency (ELF) magnetic fields (MFs) selected to test the predictions of the ion parametric resonance (IPR) model under resonance conditions for a single ion (hydrogen). We examined the field effects on the neurite outgrowth (NO) induced by NGF using three different combinations of flux densities of the parallel components of the AC MF (Bac) and the static MF (Bdc). The first test examined the NO response in cells exposed to 45 Hz at a Bdc of 2.96 microT with resonant conditions for H+ according to the model. The Bac values ranged from 0.29 to 4.11 microT root-mean-square (rms). In the second test, the MF effects at off-resonance conditions (i.e., no biologically significant ion at resonance) were examined using the frequency of 45 Hz with a Bdc of 1.97 microT and covering a Bac range between 0.79 and 2.05 microT rms. In the third test, the AC frequency was changed to 30 Hz with the subsequent change in Bdc to 1.97 microT to tune for H+ as in the first test. The Bac values ranged from 0.79 to 2.05 microT rms. After a 23 h incubation and exposure to the MF in the presence of NGF (5 ng/ml), the NO was analyzed using a stereoscopic microscope. The results showed that the NGF stimulation of neurite outgrowth (NSNO) was affected by MF combinations over most of the Bac exposure range generally consistent with the predictions of the IPR model. However, for a distinct range of Bac where the IPR model predicted maximal ionic influence, the observed pattern of NSNO contrasted sharply with those predictions. The symmetry of this response suggests that values of Bac within this distinct range may trigger alternate or additional cellular mechanisms that lead to an apparent lack of response to the MF stimulus.

Animals↗
PubMed1996

Nonbinomial distribution of relative neurite outgrowth in PC-12 cells.

Previously we reported the results of a series of experimental tests using PC-12 cells to examine the biological effect of prescribed combinations of both nerve growth factor and magnetic fields. Because our assay of the PC-12 cells is based on binary classification of the cells following treatment, our data might be expected to have a binomial distribution. However, our data consistently show a smaller variability than that predicted by the binomial distribution model. In this paper, we examine some possible reasons for this reduction in variability in our results.

Algorithms↗
PubMed1995

Evaluation of whole-animal data using the ion parametric resonance model.

Changes observed in the behavioral response of land snails from exposure to parallel ac and dc magnetic fields demonstrate limited agreement with the predictions of an interaction model proposed by Lednev and the predictions of a recently proposed ion parametric resonance (IPR) model. However, the inadequate number of reported data points, particularly in a critical exposure range, prevents unambiguous application of either the Lednev or the IPR model.

Animals↗
PubMed1995

The ion parametric resonance model predicts magnetic field parameters that affect nerve cells.

An ion parametric resonance (IPR) model recently developed by Blanchard and Blackman predicts distinct magnetic field interactions with biological systems based on a selective relation among four factors: the flux density of the static magnetic field, the frequency and flux density (Bac) of the parallel ac magnetic field, and the charge-to-mass ratio of ions of biological relevance. To test this model, PC-12 cells stimulated by nerve growth factor to produce neurites were exposed for 23 h in a 5% CO2 incubator using a multiple-coil exposure system to produce 45 Hz ac and dc (366 mG parallel to ac; less than 2 mG perpendicular to ac) magnetic fields. Our earlier work showed a cycle of inhibition/no inhibition of neurite outgrowth consistent with the IPR model predictions for Bac exposures between 0 and 468 mG rms. The work described here tests neurite outgrowth over a broader range of Bac (233-1416 mG rms). The experimental results remain consistent with earlier results, and with IPR model predictions of a second cycle of inhibition, return to control values, followed by a third cycle of inhibition of neurite outgrowth. These responses support the fundamental relationships predicted by the IPR model. The results have broad significance for biology.

Animals↗
PubMed1994

Clarification and application of an ion parametric resonance model for magnetic field interactions with biological systems.

Theoretical models proposed to date have been unable to clearly predict biological results from exposure to low-intensity electric and magnetic fields (EMF). Recently a predictive ionic resonance model was proposed by Lednev, based on an earlier atomic spectroscopy theory described by Podgoretskii and Podgoretskii and Khrustalev. The ion parametric resonance (IPR) model developed in this paper corrects mathematical errors in the earlier Lednev model and extends that model to give explicit predictions of biological responses to parallel AC and DC magnetic fields caused by field-induced changes in combinations of ions within the biological system. Distinct response forms predicted by the IPR model depend explicitly on the experimentally controlled variables: magnetic flux densities of the AC and DC magnetic fields (Bac and Bdc, respectively); AC frequency (fac); and, implicitly, charge to mass ratio of target-ions. After clarifying the IPR model and extending it to combinations of different resonant ions, this paper proposes a basic set of experiments to test the IPR model directly which do not rely on the choice of a particular specimen or endpoint. While the fundamental bases of the model are supported by a variety of other studies, the IPR model is necessarily heuristic when applied to biological systems, because it is based on the premise that the magnitude and form of magnetic field interactions with unhydrated resonant ions in critical biological structures alter ion-associated biological activities that may in turn be correlated with observable effects in living systems.

Algorithms↗
PubMed1994

Empirical test of an ion parametric resonance model for magnetic field interactions with PC-12 cells.

A companion paper describes a predictive ion parametric resonance (IPR) model of magnetic field interactions with biological systems based on a selective relation between the ratio of the flux density of the static magnetic field to the AC magnetic field and the charge-to-mass ratio of ions of biological relevance. Previous studies demonstrated that nerve growth factor (NGF)-stimulated neurite outgrowth (NO) in PC-12 cells can be inhibited by exposure to magnetic fields as a function of either magnetic field flux density or AC magnetic field frequency. The present work examines whether the PC-12 cell response to magnetic fields is consistent with the quasi-periodic, resonance-based predictions of the IPR model. We tested changes in each of the experimentally controllable variables [flux densities of the parallel components of the AC magnetic field (Bac) and the static magnetic field (Bdc) and the frequency of the AC magnetic field] over a range of exposure conditions sufficient to determine whether the IPR model is applicable. A multiple-coil exposure system independently controlled each of these critical quantities. The perpendicular static magnetic field was controlled to less than 2 mG for all tests. The first set of tests examined the NO response in cells exposed to 45 Hz Bac from 77 to 468 mG(rms) at a Bdc of 366 mG. Next, we examined an off-resonance condition using 20 mG Bdc with a 45 Hz AC field across a range of Bac between 7.9 and 21 mG(rms). Finally, we changed the AC frequency to 25 Hz, with a corresponding change in Bdc to 203 mG (to tune for the same set of ions as in the first test) and a Bac range from 78 to 181 mG(rms). In all cases the observed responses were consistent with predictions of the IPR model. These experimental results are the first to support in detail the validity of the fundamental relationships embodied in the IPR model.

Animals↗
PubMed1993

Electromagnetic pulse (EMP), Part I: Effects on field medical equipment.

The electromagnetic pulse (EMP) from a high-altitude nuclear detonation has the potential to cover an area as large as the continental United States with damaging levels of EMP radiation. In this study, two of seven items of medical equipment were damaged by an EMP simulator. Computer circuit analysis of 17 different items showed that 11 of the 17 items would be damaged by current surges on the power cords, while two would be damaged by current surges on external leads. This research showed that a field commander can expect approximately 65% of his electronic medical equipment to be damaged by a single nuclear detonation as far as 2,200 km away.

Altitude↗
PubMed1993

Electromagnetic pulse (EMP), Part II: Field-expedient ways to minimize its effects on field medical treatment facilities.

Part I of this paper showed that a field commander can expect approximately 65% of his unprotected electronic medical equipment to be damaged by the electromagnetic pulse (EMP) from a single nuclear detonation as far as 2200 km away. Using computer modeling, field-expedient ways to minimize the effects of EMP were studied. The results were: (1) keep wiring near the ground, (2) keep wiring short, (3) unplug unused equipment, (4) run power cabling and tents in a magnetic north-south direction (avoid running power cabling in the east-west direction), and (5) place sensitive equipment in International Organization for Standardization shelters.

Computer Simulation↗
PubMed1989

[Gingival hyperpigmentation caused by dental restorations: the mechanism of detoxification using selenium].

X-ray microanalysis and electron diffraction made on granular metallic deposits of the gingival lamina propria, inducing partial periodontal tattoos, demonstrated that these deposits consisted of crystalline particles combining silver, sulphur and selenium. The role of selenium precipitating of silver and other metals as well as its role in detoxication are discussed.

Chemical Precipitation↗
PubMed1988

[Madreporic, polarized total arthroplasties of the hip. Apropos of 2688 cases].

This paper reports an experience over ten years with cementless total hip arthroplasty in a series of 2688 personal cases commencing in 1975. Stress is laid on the results over a period greater than 5 years and up to 10 years as much on the long-term effects on the host bone as on the implant itself. The causes of failure of biological anchorage by endosteal osteogenesis are analysed. Various phenomena, particularly the reaction of the cortices to stress, several cases of bony resorption with debris due to wear and fatigue fractures of the stem of the prosthesis have been seen. These and the problems posed by the occasional need for extraction have led to the progressive development of the prosthesis, resulting in 1983 in a new type of anchorage with a polarised surface and a better-balanced prosthesis in relation to stress and extractability.

Adult↗
PubMed1988

Cementless revisions of failed aseptic cemented and cementless total hip arthroplasties. 284 cases.

Over the past 13 years, 284 revisions of aseptic total hip arthroplasty failures have been performed with cementless implants. There were 213 cases involving cemented implant failures and 71 involving cementless ones. Considered as salvage procedures, these revisions provided a satisfactory result in about 70% of the reviewed patients after five years. A biologic fixation by bony ingrowth can be expected under certain conditions from decorticated living bone, a tight mechanical fitting, and a retentive corrugated surface of the implant. A prosthetic reimplantation, safely done without cement, appears more economical for the bone stock and prevents the long-term complications related with cement. Bone grafts are often required but cannot ensure the incoming osteogenic fixation of the implant. Long-term results and complications mandate harmless extractability of the revisional implant, a forged stem, an easy exchange of the plastic liner (in a two-part acetabular component), and an updated low-friction system (high-density polyethylene wear being a potential long-term problem).

Asepsis↗
PubMed1987

Infection rate in total hip arthroplasty as a function of air cleanliness and antibiotic prophylaxis. 10-year experience with 2,384 cementless Lord madreporic prostheses.

To separate the respective effects of sterile air and antibiotic prophylaxis in orthopedic surgery, the authors reviewed 2,384 cementless total hip replacements performed from 1975 to 1984 for incidence of deep sepsis. During this period, a conventionally ventilated room (100 particle-forming units (pfu)/m3) and a laminar vertical flow (1 pfu/m3) were alternately used, without significant difference in the sepsis rate. Beginning in 1979, a prophylactic antibiotic regimen was added, which from 1979 to 1984 reduced the incidence of deep sepsis from 2.78% to 0.52%. There was also a change in common infecting organisms, from sensitive to resistant strains, which is not an insignificant consequence.

Air Microbiology↗