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Biomedical subjects

P Allard

Publications and source records attributed to P Allard.

At least 91 records · Page 5Linked to original sources
PubMed1995

Modelling and gait evaluation of asymmetrical-keel foot prosthesis.

The paper documents a new concept in prosthetic foot design. It is based on the capacity of a flexible keel to allow a greater medio-lateral function than previously available. The heel has a complex curvature consisting of a medially concave shape that joins the mid-foot. There a hump acting as a leaf-spring ends at the metatarsal break, with an inwardly curved toe extremity. These curvatures contribute to increased medio-lateral control at heel-strike and propulsion for weight transfer and push-off. Results from finite-element modelling indicate that the asymmetrically shaped keel is at least twice as active in storing energy compared with a completely symmetrical one. A preliminary gait study is carried out for a 24-year-old below-knee amputee fitted with the new design, the SPACE foot and a dynamic elastic response foot with a symmetrical keel. With the SPACE foot, there is a 14% increase in walking speed combined with a reduction in the phasic asymmetries. The absolute difference between the initial and terminal double support is 1.4% for the asymmetrical keel design compared with 4.4% for the symmetrical keel foot prosthesis. The peak ankle power generation burst indicates that the SPACE foot behaves as a dynamic elastic response foot.

Biomechanical Phenomena↗
PubMed1995

Bilateral gait patterns in subjects fitted with a total hip prosthesis.

OBJECTIVES: The purpose of this report was to determine whether the muscle powers and the mechanical energies developed during the push-off period of the gait cycle of patients having a total hip prosthesis were different from able-bodied subjects as well as the effect on the nonoperated limb. DESIGN: Case control study. SETTING: All patients where independent and functional. PATIENTS: Four patients participated in the study. The indication for surgery was degenerative arthritis of the hip. There was also an able-bodied group. INTERVENTION: A Harris-Galante total hip prosthesis was used to restore hip stability and function. The patients were all operated on by the same orthopedic surgeon and had the same type of total hip replacement. MAIN OUTCOME MEASURE: Gait analyses showed that not only the hips of the surgical group were affected but also the knees. RESULTS: Peak power did not show any significant difference except for a decrease in the frontal plane of the operated hip power absorption. The operated hip developed 35% and 48% less energy than that of the able-bodied group in the sagittal and frontal planes, respectively. The nonoperated hip was also affected and developed 35% more energy in the sagittal plane than the operated limb but 20% less than that of the able-bodied group. There was a reduction of 47% in the energies developed in the knees of the surgical patient group. CONCLUSION: These results confirmed the presence of some mechanical dysfunction in the nonoperated limb.

Aged↗
PubMed1995

Factors associated with length of survival among 1081 terminally ill cancer patients.

To improve their ability to estimate the survival of terminally ill cancer patients, palliative care physicians require accurate information on prognostic factors. The objective of this study was to assess the extent to which variables such as patient characteristics and primary tumor site affect the length of survival of terminally ill cancer patients. The study population consisted of 1081 cancer patients admitted for terminal care to a 15-bed palliative care unit from 1985 to 1991. Univariate Kaplan-Meier survival analysis and multivariate Cox regression analyses were used to examine the relationship between patient characteristics at admission and survival time. The factor most strongly associated with shorter survival was poor performance status; this strong relationship was not altered by taking into account sex and primary cancer site in the multivariate analysis. For patients who were bedridden at admission, the death rate was 5.5 times higher (95% confidence interval (Cl) 3.4-9.0) than that for ambulatory patients during the first four days of stay, and it was 2.8 times higher (95% Cl 2.0-3.9) subsequently (up to 19 days). The other prognostic factors significantly but slightly associated with poorer survival in the univariate analysis were primary lung cancer, male sex, and living with a spouse. These findings indicate that performance status is the main prognostic factor for accurately estimating the survival time of terminally ill cancer patients.

Aged↗
PubMed1995

Tumor-associated antigens as prognostic factors for recurrence in 382 patients with primary transitional cell carcinoma of the bladder.

This prospective study was designed to assess the prognostic value of tumor-associated antigens, designated 19A211, M344, T138, and T43, with respect to recurrence of primary superficial bladder cancer. Between September 1990 and April 1992, all patients with primary superficial bladder tumors treated by endoscopic resection in 15 participating hospitals were enrolled. Immunostaining for 19A211 and M344 was performed on paraffin-embedded material, and for T43 and T138 on frozen tissue. Antigenic expression was evaluated blindly by a single pathologist. Patients were followed up with the standard schedule of control cystoscopies. Cox regression was used to estimate hazard ratios (HRs) for first recurrence, and Poisson regression was used to estimate recurrence rate ratios and tumor rate ratios adjusted for primary tumor characteristics. By March 1994, 2254 follow-up cystoscopies had been performed on 368 of the 382 study patients, and tumor recurrence was detected in 55.7% of patients. Positivity to 19A211 was detected in 90% of primary tumors, its expression being associated with a decrease in first recurrence hazard ]HR, 0.65; 95% confidence interval (CI), 0.42-1.03] and in recurrence rate (recurrence rate ratio, 0.70; 95% CI, 0.53-0.92). Positivity to T138 was detected in 15% of tumors, and its expression was associated with an increase in first recurrence hazard (HR, 1.43; 95% CI, 0.92-2.22) and in recurrence rate (recurrence rate ratio, 1.31; 95% CI, 1.00-1.72). Positivity to M344 was detected in 71% of tumors, and its expression was associated with an increase in tumor rate (tumor rate ratio, 1.77; 95% CI, 1.41-1.97). T43 expression was not associated with recurrence end points. In conclusion, recurrence of superficial bladder cancer was associated with antigenic expression of 19A211, T138, and M344, independently of primary tumor characteristics.

Adult↗
PubMed1994

Conformation of dCDP bound to protein R1 of Escherichia coli ribonucleotide reductase.

Deoxycytidine 5'-diphosphate (dCDP) is a product and competitive inhibitor of ribonucleoside-diphosphate reductase (EC 1.17.4.1) from Escherichia coli. Its conformation in the enzyme-bound state is of importance for understanding the reaction mechanism. Free and bound dCDP are in fast exchange and the transferred nuclear Overhauser effect in two-dimensional 1H NMR was used to obtain information about interproton distances within bound dCDP. The results are consistent with a model of dCDP with the base in anti conformation and the sugar in S-type puckering, when bound either to the complete enzyme complex or to the large protein subunit alone.

Deoxycytosine Nucleotides↗
PubMed1994

Solution structure by 1H and dynamics by natural abundance 13C NMR of a receptor recognising peptide derived from a C-terminal fragment of neuropeptide Y.

A peptide consisting of 20 amino acid residues, derived from a C-terminal fragment of neuropeptide Y (NPY) and showing high affinity to NPY receptors, was synthesised. Its sequence is PAADLARYRHYINLITRQRY-NH2, and the solution structure was calculated from NMR-derived distance and torsion angle restraints, obtained at 15 degrees C in a solvent mixture of water and 30% (v/v) 1,1,1,3,3,3-hexafluoro-2-propanol, by using DIANA and restrained energy minimisation. The structure was found to consist of a well-defined alpha-helix in the centre, with a few residues at the termini having less well defined conformations. The spin-lattice and spin-spin relaxation rates of alpha-carbons have been determined on 13C at natural abundance. From 1D experiments the global rotational correlation time was determined and from 2D experiments the dynamics of each individual residue was obtained. The results demonstrate that the C alpha-H alpha vectors in the alpha-helix essentially follow the global motion. Towards the termini, contributions from local dynamics increase. This tendency is correlated to the increasing uncertainty of the structure towards the peptide ends. An effective molecular volume was calculated from the temperature dependence of the global rotational correlation time. This is well compatible with a monomeric peptide, solvated by water and 1,1,1,3,3,3-hexafluoro-2-propanol. The presence of peptide dimers was ruled out as being inconsistent with the relaxation data.

Amino Acid Sequence↗
PubMed1994

[3H]GBR-12935 binding to human cerebral cortex is not to dopamine uptake sites.

The binding of the dopamine uptake inhibitor [3H]GBR-12935 to 16 regions of the human brain was investigated in competition experiments with increasing concentrations of GBR-12909, mazindol, and dopamine. The methodology used included a relatively high tissue concentration (8 mg/ml) and addition of 5 mM KCl in the assay buffer. GBR-12909 inhibited 80-90% of the binding in most regions, whereas dopamine only inhibited the binding in the striatum. Mazindol inhibited only part of the cortical binding at concentrations of > 1 microM, whereas the inhibition in the caudate and the putamen also contained a high-affinity component representing the dopamine uptake site. It is concluded that the [3H]GBR-12935 binding sensitive to GBR-12909 cannot be regarded as specific binding to the dopamine uptake site because the displaceable binding most likely is not related to the dopamine uptake site.

Aged↗
PubMed1994

[3H]GBR-12935 binding to cytochrome P450 in the human brain.

The presence of multiple [3H]GBR-12935 binding sites in the human brain has been revealed in several recent studies. One site represents the dopamine uptake site. In rat brain it was demonstrated that [3H]GBR-12935 also binds to nondopaminergic "piperazine acceptor sites." One of these sites has been identified as cytochrome P450IID1 in canine brain. [3H]GBR-12935 binding to the piperazine acceptor sites in the human brain was investigated in the present study. A pharmacological definition of the piperazine acceptor sites is presented: the [3H]GBR-12935 binding fraction that could be discriminated by 10 microM GBR-12909 in the presence of 0.3 microM mazindol. This binding fraction was saturable, with binding affinity in the range of 3-8 nM. It was also demonstrated that the piperazine acceptor or cytochrome P450-sensitive drugs cis-flupentixol and proadifen (SKF 525 A) compete for the same binding sites, suggesting the cytochrome P450 nature of the binding. The findings presented support the proposal that at least part of this fraction represents cytochrome P450IID6, the human form of P450IID1. The distribution of [3H]GBR-12935 binding to the suggested P450IID6-site in 12 brain regions was examined, without significant differences in binding densities between the regions. The significance of the present findings on the cytochrome P450 system in brain is discussed.

Aged↗
PubMed1994

[Current epidemiology of tuberculosis].

A major health threat in developing countries, the incidence of tuberculosis has decreased steadily in Western countries over the last century. However, since 1986, first in the United States, then more recently in several European countries, the number of declared cases has increased. The current epidemiology of tuberculosis is presented with special emphasis on French data. The possible causes of this revival have been carefully analyzed: better registration, role of immunodepression and particularly the HIV epidemic, geographical origin, drug abuse, poor living conditions.... Based on the description of resistant forms and the observations of hospital epidemics, particularly in the United States and in patients with HIV infection, curative and preventive measures may and must be undertaken whenever a case of tuberculosis is observed.

Disease Notification↗
PubMed1994

[Scanner and mechanical lumbar diseases in private practice. Apropos of 106 patients covered by the Caisse Maladie Régionale du Nord].

The aim of this study was to prospectively evaluate use of computed tomography (CT) of the lumbar spine in office practice. The "Caisse Maladie Régionale du Nord" provides health insurance to self-employed retailers and craft persons (92,500 people at the end of 1991). The authors prospectively studied 106 patients insured by this organisation (60 males, 46 females, mean age: 51.27 years) who underwent CT of the lumbar spine between August 2, 1991 and January 23, 1993. They examined all insurance claims (physician visits, surgery, drugs, physiotherapy, laboratory tests, imaging studies, and hospitalizations) filed by each study patient during the 4 months before and the 4 months after the index CT. Reason for the CT, specified on 65 of the 106 radiologist reports, were isolated low back pain and nerve root pain in 26.2% and 56.9% of the patients respectively. CT findings were discal prolapse in 27 patients (25.5%), facet joint osteoarthritis in 33 patients (31.3%), discal protrusion in 29 patients (27.4%) and were considered as normal in 19 patients (18%). CT was preceded by plain radiographs in 50% of patients, by a rheumatologist visit in 31%, by a visit to the sole general practitioner in 51%, by local steroid injection in 15%. During the 4 months subsequent to the index CT, 14 (13.2%) patients had surgery and one underwent chemonucleolysis. These findings suggest that consensus conference recommendations concerning lumbar spine CT are not currently being followed in France.

Adult↗
PubMed1993

Comparison of gait between young adults fitted with the space foot and nondisabled persons.

Prosthetic feet having new keel configurations were specially designed to store deformation energy during early and midstance and release it at push-off. These prosthetic components display longitudinal symmetry favoring good energy storage/release capability in the sagittal plane. The need for inverters/everters either as independent components or within the foot structure has long been recognized. This article documents the walking and slow jogging performances of six young adults wearing below-knee prostheses fitted with the Space Foot, a flexible foot prosthesis that provides medio-lateral control at heel-strike and lateral and forward propulsion at push-off. Results indicate that the Space Foot behaves as a flexible keel foot prosthesis. Its gait performances are also good for fast walking; however, the Space Foot's actual design should be modified if used in sporting activities involving running.

Adult↗
PubMed1993

A computerized system for morphometric analysis of digitized images of histologically prepared arterial cross sections.

A method is described for computerized, operator-assisted, morphometric measurement of histologically prepared arterial cross sections. The system is composed of an image cytometer equipped with a one power lens and a digitizing camera interfaced with an imaging board residing in a PC computer. Algorithms were developed for automated segmentation of the areas of interest. The method is rapid, objective, accurate and requires minimum operator intervention. It gives reliable and reproducible results in the measurement of all elements of the cross section including circumference, area of the media, circumference of the internal elastic lamina, area of the lumen and percent occlusion of the lumen by the intimal thickening. While manual measurements using computerized planimetric methods give similar results, this method is an order of magnitude faster (1-2 min vs. 10-20 min per cross section) thus facilitating the study of large numbers of specimens. A blinded re-measurement of 284 sections of artery for reproducibility yielded r values of 0.86-0.97.

Adult↗
PubMed1993

[Lymphomatoid granulomatosis].

Lymphomatoid granulomatosis, reported in 450 cases in the literature, is a pathological and clinical entity frequently associated with systemic manifestations. The nodular lymphoproliferative formations lead to vessel destruction which immunohistochemistry and molecular biology has linked to T-lymphocyte proliferation. The major pulmonary and extra-pulmonary manifestations are described here together with diagnostic criteria. The prognosis has been greatly improved with the use of corticosteroids and cyclophosphamide-corticoid combinations.

Adult↗
PubMed1993

[Duckett's+ simple surface or double surface? Comparison of 2 urethroplasty procedures. Report of 91 hypospadias].

The results and complications of the treatment of hypospadias were studied in relation to the two pedicle foreskin mucosal flap techniques described successively by Duckett, "single surface" and "double surface". 91 urethroplasties were performed: 58 "single surface" and 33 "double surface" Duckett urethroplasties. The children were operated between the ages of 18 months and 16 years with a mean age of 4 years. 75% of children had a good result on long-term follow-up. In the case of major complications, essentially fistula, distal necrosis àf the urethra or stricture, a single reoperation increased the percentage of good results to almost 98% for the entire series. However, when the two procedures were compared, a good result was obtained immediately in 81% of cases for the "single surface" operation versus 66% for the "double surface" operation. The fistula rate was 27.2% with the "double surface" flap versus 13.7% with the "single surface" flap and the distal stricture rate was 15.1% with the "double surface" flap versus 3.4% with the "single surface" flap. In the light of these results, Duckett's "double surface" procedure has been abandoned in favour of the "single surface" flap.

Adolescent↗