Biomedical subjects

P Allard

Publications and source records attributed to P Allard.

At least 19 recordsLinked to original sources

PubMed2002

Main functional roles of knee flexors/extensors in able-bodied gait using principal component analysis (I).

This study was undertaken to demonstrate how principal component analysis (PCA) can be used to detect the main functional structure of actions taken by knee flexors/extensors during able-bodied gait. PCA was applied as a classification and curve structure detection method for knee sagittal muscle moment developed during walking of 20 young, healthy male subjects. Over 90% of the information provided by the first three principal components (PCs) was chosen for further biomechanical interpretation. PCA was able to identify the three main functional contributions of knee sagittal muscle moment during able-bodied gait, namely control balance, foot clearance/limb preparation and shock absorption.

Adolescent↗

PubMed2001

Proton- and sodium-coupled phosphate transport systems and energy status of Yarrowia lipolytica cells grown in acidic and alkaline conditions.

In this study we have used a newly isolated Yarrowia lipolytica yeast strain with a unique capacity to grow over a wide pH range (3.5-10.5), which makes it an excellent model system for studying H(+)- and Na(+)-coupled phosphate transport systems. Even at extreme growth conditions (low concentrations of extracellular phosphate, alkaline pH values) Y. lipolytica preserved tightly-coupled mitochondria with the fully competent respiratory chain containing three points of energy conservation. This was demonstrated for the first time for cells grown at pH 9.5-10.0. In cells grown at pH 4.5, inorganic phosphate (P(i)) was accumulated by two kinetically discrete H(+)/P(i)-cotransport systems. The low-affinity system is most likely constitutively expressed and operates at high P(i) concentrations. The high-affinity system, subjected to regulation by both extracellular P(i) availability and intracellular polyphosphate stores, is mobilized during P(i)-starvation. In cells grown at pH 9.5-10, P(i) uptake is mediated by several kinetically discrete Na(+)-dependent systems that are specifically activated by Na(+) ions and insensitive to the protonophore CCCP. One of these, a low-affinity transporter operative at high P(i) concentrations is kinetically characterized here for the first time. The other two, high-affinity, high-capacity systems, are derepressible and functional during P(i)-starvation and appear to be controlled by extracellular P(i). They represent the first examples of high-capacity, Na(+)-driven P(i) transport systems in an organism belonging to neither the animal nor bacterial kingdoms. The contribution of the H(+)- and Na(+)-coupled P(i) transport systems in Y. lipolytica cells grown at different pH values was quantified. In cells grown at pH values of 4.5 and 6.0, the H(+)-coupled P(i) transport systems are predominant. The contribution of the Na(+)/P(i) cotransport systems to the total cellular P(i) uptake activity is progressively increased with increasing pH, reaching its maximum at pH 9 and higher.

Acids↗

PubMed2001

A complete Hermitian operator basis set for any spin quantum number.

A new Hermitian operator basis set for spins of any quantum number is presented for use in simulations of NMR experiments. The advantage with a Hermitian operator basis is that the Liouville-von Neumann equation, including relaxation with dynamic frequency shifts, is real. Real algebra makes numerical calculations faster and simplifies physical interpretation of the equation system as compared to complex algebra. The unity operator is included in the Hermitian operator basis, which makes it easy to rewrite the inhomogeneous Liouville-von Neumann equation into a homogeneous form. The unity operator also simplifies physical interpretation of the equation system for coupled spin systems.

Journal Article↗

PubMed2001

Influence of postmenopausal hormone replacement therapy on platelet serotonin uptake site and serotonin 2A receptor binding.

OBJECTIVE: To examine whether binding of [3H]paroxetine to the platelet serotonin transporter or binding of [3H]lysergic acid diethylamide (LSD) to the platelet 5-HT(2A) receptor are influenced by postmenopausal estrogen/progestogen treatment. METHODS: Twenty-three postmenopausal women with climacteric symptoms completed this double-blind, randomized, crossover study. The women received 2 mg of estradiol continuously during four 28-day cycles. In the last 14 days of each cycle, 10 mg of medroxyprogesterone acetate, 1 mg of norethindrone acetate, or placebo was given. Before treatment, as well as once during the last week of each treatment, blood samples were collected for analysis of [3H]LSD and [3H]paroxetine binding. The power of the study setup was 81%. The study had an effect size of 0.36, corresponding to the ability to detect a 15% difference in [3H]paroxetine and [3H]LSD binding between treatments with alpha =.05 and beta =.20, based on a previously reported standard deviation within cells of 20% of the mean binding values. RESULTS: The number of platelet receptors (B(max)), or the affinity of the radioligand to the receptor (K(d)), for [3H]paroxetine binding did not change during estrogen or estrogen-progestogen treatment, nor did B(max) or K(d) for [3H]LSD binding change during the different treatments. However, in a subgroup of depressed patients, the decrease in B(max) for [3H]LSD binding during treatment was significantly more pronounced than in the nondepressed subgroup (P <.05). CONCLUSION: Estrogen treatment with or without the addition of progestogen does not affect binding to the serotonin transporter or to the serotonergic 5-HT(2A) receptor in healthy postmenopausal women.

Blood Platelets↗

PubMed2001

Functional roles of ankle and hip sagittal muscle moments in able-bodied gait.

OBJECTIVE: The main objectives of this study on able-bodied gait were (a) to identify the main functions of the ankle and hip muscle moments and their contribution to support and propulsion tasks, and (b) to illustrate the interaction between the ankle and hip moment activities. DESIGN: Twenty young, able-bodied male subjects walked along a 13 m path at a freely chosen speed. BACKGROUND: Functional contributions of the ankle and hip muscles and their interactions in achieving support and propulsion tasks during gait are still subject to controversy. METHODS: Principal component analysis was applied as a curve structure detection method to identify the main functional characteristics of the ankle and hip muscle moments. The first two principal components which contained over 70% and 85%, respectively, of the information in the ankle and hip moment curves revealed their functional tasks. Ankle versus hip moment plots was used to illustrate the interactions between muscles acting at the hip and ankle in the sagittal plane. Correlation coefficient and covariance calculations quantified the interaction between the ankle and hip moments. RESULTS: The first principal component revealed that the main role of the ankle and hip is to keep the body from collapsing. The second principal component is associated with the functional contribution of both ankle plantarflexors and hip flexors during the propulsion phase (50-60% of the gait cycle). High coordination (r=0.82) between the ankle and hip moments was observed. CONCLUSION: Maintaining body support against gravity was identified as the first functional task of the ankle plantarflexors and hip extensors, while contribution to propulsion was recognised as the second major role for the ankle plantarflexors and hip flexors. RELEVANCE: Identifying the main roles of the muscles acting at the hip and ankle during able-bodied walking provides better insight into how pathological gait should be evaluated.

Adult↗

PubMed2001

Binding of [3H]paroxetine to serotonin uptake sites and of [3H]lysergic acid diethylamide to 5-HT2A receptors in platelets from women with premenstrual dysphoric disorder during gonadotropin releasing hormone treatment.

Changes in serotonergic parameters have been reported in psychiatric conditions such as depression but also in the premenstrual dysphoric disorder (PMDD). In addition, hormonal effects on serotonergic activity have been established. In the present study, binding of [3H]paroxetine to platelet serotonin uptake sites and binding of [3H]lysergic acid diethylamide ([3H]LSD) to platelet serotonin (5-HT)2A receptors were studied in patients with PMDD treated with a low dose of a gonadotropin releasing hormone (GnRH) agonist (buserelin) or placebo and compared to controls. The PMDD patients were relieved of premenstrual symptoms like depression and irritability during buserelin treatment. The number of [3H]paroxetine binding sites (Bmax) were significantly higher in the follicular phase in untreated PMDD patients compared to controls. When treated with buserelin the difference disappeared. No differences in [3H]LSD binding between the three groups were shown. The present study demonstrated altered platelet [3H]paroxetine binding characteristics in women with PMDD compared to controls. Furthermore, [3H]paroxetine binding was affected by PMDD treatment with a low dose of buserelin. The results are consistent with the hypothesis that changes in serotonergic transmission could be a trait in the premenstrual dysphoric disorder.

Adult↗

PubMed2001

Pelvic and lower limb compensatory actions of subjects in an early stage of hip osteoarthritis.

OBJECTIVE: To determine if compensatory actions take place at the pelvis and other joints of the affected lower limb in subjects who were in an early stage of hip osteoarthritis (OA). DESIGN: Nonrandomized, case-control study. SETTING: A gait laboratory. PARTICIPANTS: Seventeen patients with OA of the hip (clinical group) matched with 17 healthy elderly subjects (nonclinical group). INTERVENTIONS: Video data obtained while subjects walked a 10-meter walkway twice and stepped across a forceplate. MAIN OUTCOME MEASURES: Four phasic and temporal gait parameters (walking speed, stance phase relative duration, stride length, cadence) 10 pelvic (pelvic tilt, obliquity, rotation at push-off maximum range of motion for all 3) and hip (3 hip angles at push-off, maximum hip flexion) kinematic parameters, 3 hip moments, and twenty-seven 3-dimensional peak muscle powers (labeled by joint, peak power, plane) developed in the lower limb joints during the gait cycle. RESULTS: Subjects in the clinical group were characterized by a 12.4% slower walking speed. The pelvis was more upwardly tilted (2.5 times) at push-off in the clinical group than in the nonclinical group. Obliquity, measured in the frontal plane, revealed that the pelvis dropped more (2.4 times) on the unsupported limb of the clinical group at push-off. In the sagittal plane, subjects in the clinical group absorbed less energy in their second hip peak power for decelerating the thigh extension and generated less hip pull (third hip peak power) than the nonclinical group by 34% and 29%, respectively. In the sagittal plane, the clinical group had 57% lower second knee peak power to straighten the joint shortly after heel strike, and 43% less knee absorption (third peak power) at push-off. During the push-off phase, the clinical group developed more than twice their third peak knee power in the frontal plane and 5 times more their third peak knee power in the transversal plane than the peak knee power of the nonclinical group in an attempt to control knee adduction and to facilitate body-weight transfer by an internal rotation. At the end of the swing phase, the fourth peak power in the sagittal plane showed the absorption power required to decelerate the leg; it was reduced by 35% in the clinical group, representing a strategy to increase walking speed by lengthening the stride length. CONCLUSIONS: Even at an early stage of hip OA, joint degeneration was compensated by an increase in pelvis motion and muscle power generation or absorption modifications in other lower limb joints.

Analysis of Variance↗

PubMed2001

Educational interventions to improve cancer pain control: a systematic review.

CONTEXT: Inadequate pain control is a dismaying reality in cancer patients. OBJECTIVES: To review studies on cancer pain control interventions, and describe their findings with respect to participants' attitudes and knowledge, pain management, and pain levels. DATA SOURCES: Computer searches were made in MEDLINE from January 1962, in PsychLIT from January 1974, and in CINAHL from January 1982 to August 1999, using a search strategy based on a combination of key words. STUDY SELECTION: Computerized listings from these sources contained 383, 26, and 85 articles, respectively. After exclusion of duplicates, abstracts, editorials, letters, and irrelevant articles, we retained for review 33 articles, of which 25 (76%) were interventions targeting health professionals, and 8 (24%) interventions targeting patients and family caregivers. DATA EXTRACTION: Study reports were reviewed using the following structured framework: Intervention Setting, Study Methods, Process Assessment, and Pain Outcome Assessment (Attitudes and Knowledge, Pain Management, and Pain Relief/Quality of Life). DATA SYNTHESIS AND CONCLUSION: Educational interventions can successfully improve cancer pain knowledge and attitudes of health care professionals, but without having much impact on patients' pain levels. The most promising avenue for improving cancer pain control in ambulatory settings may be brief, nursing interventions targeting patients in combination with a daily pain diary. This review suggests that further progress may occur through incorporating a systematic and valid method of documenting daily fluctuation in pain levels, and ensuring that documented uncontrolled pain is followed rapidly by clinical reassessment and dose adjustment.

Attitude of Health Personnel↗

PubMed2001

Muscle power compensatory mechanisms in below-knee amputee gait.

OBJECTIVE: This three-dimensional and bilateral gait study on five below-knee amputees was undertaken to demonstrate the following: (1) how hip muscle powers can compensate for the lack of ankle function on the amputated side; and (2) how these compensatory mechanisms can influence muscle power activities in the sound limb. DESIGN: Gait data were assessed by an eight-camera high-speed video system synchronized to two force plates. The three-dimensional mechanical muscle powers were calculated at the joints of the lower limbs. Significant differences between each limb were determined using the Student's t test for paired data with P < 0.05. RESULTS: In the absence of ankle plantar flexor power, hip extensors and flexors as well as hip external rotators became the major power generators, whereas hip abductors and adductors and knee extensors muscle powers became the main source of absorption. For the sound limb, increased hip extensor activity was observed, accompanied by less hip abduction-adduction activity. CONCLUSIONS: Perturbations in below-knee amputee gait affected the hip muscle powers on the amputated side in all three planes, although the hip frontal plane balance was modified in the sound limb.

Adult↗

PubMed2001

Lower limb muscle power relationships in bilateral able-bodied gait.

OBJECTIVE: The purpose of this study was to test the hypothesis that limb propulsion is mainly associated with the interaction of a number of muscle power bursts developed throughout the stance phase and that the control actions are mainly achieved by the contralateral limb through different power-burst interactions. We also hypothesized that the power activities of the propulsion limb would be related to those of the control limb. DESIGN: Sixty gait trials of 20 subjects with dominant right hands and right legs were chosen for analysis. Each trial represents a performance of an able-bodied gait. Data were assessed using an eight-camera, high-speed, video-based system synchronized to two force plates. The muscle powers and their related mechanical energies were calculated at each joint and in each plane of the lower limbs by use of an inverse dynamic technique. The Pearson correlation method was used to determine the relationships within each limb by use of the data identified by principal component analysis, whereas a canonical correlation analysis was performed to illustrate the interaction between the limbs. RESULTS: Gait propulsion was an activity initiated by the hip shortly after heel-strike and maintained throughout the stance phase. Control was the main task of the left limb as evidenced by the power absorption bursts at the hip and knee. The left limb power generations were generally secondary to control activities and were possibly involved in adjustments to correct the other limb's propulsion. Interlimb interaction further emphasized the functional relationship between forward progression and control tasks developed by each limb and highlighted the importance of the frontal and transverse plane actions during gait. CONCLUSION: These results do not support the hypothesis that the ankle was a major contributor to forward progression.

Adult↗

PubMed2001

Caudate nucleus dopamine D(2) receptors in depressed suicide victims.

Several lines of evidence indicate the involvement of the dopamine system in depressive states. In this post-mortem study, the binding of [(3)H]raclopride to dopamine D(2) receptors in the caudate nucleus was investigated in 13 depressed suicide victims and 19 controls. There were no differences in B(max) or K(d) between the two groups. A subgroup consisting of individuals with major depression, however, had significantly higher K(d) values than controls. Previous findings regarding changes in dopamine metabolism in depression and antidepressant effects of dopamine agonists seem, according to the present study, not to be reflected by alterations in density or affinity of dopamine D(2) receptors in depressed suicide victims.

Adult↗

PubMed2001

[Palliative care: profile of medical practice in the Quebec city region].

OBJECTIVE: To describe the palliative care provided by physicians in the Quebec city region and to identify factors that affect its delivery. DESIGN: Mailed survey. SETTING: Quebec city region. PARTICIPANTS: General practitioners in active clinical practice. MAIN OUTCOME MEASURES: Physicians' personal and professional characteristics and their palliative care practice (volume of work, source of requests for follow-up care, place of delivery of care, resources used, difficulties, encountered). RESULTS: Of the 476 physicians (67%) who responded to our survey, 295 (62%) provided palliative care. Of these, 70% saw no more than two patients requiring palliative care per month, and 55% devoted no more than 2 hours per week to this aspect of patient care. Most (76%) provided palliative care in a variety of settings (private office, home, institution). Home care teams working out of local community health centres are the resource physicians drew upon most frequently (69%). The main difficulties encountered were a lack of clinical expertise, scheduling home care, and providing patients and families with emotional support. CONCLUSION: Most physicians in the Quebec city region provided palliative care occasionally. This care could be improved by removing various logistical and professional barriers.

Adult↗

PubMed2000

Maternal germ-line transmission of mutant mtDNAs from embryonic stem cell-derived chimeric mice.

We report a method for introducing mtDNA mutations into the mouse female germ line by means of embryonic stem (ES) cell cybrids. Mitochondria were recovered from the brain of a NZB mouse by fusion of synaptosomes to a mtDNA-deficient (rho degrees ) cell line. These cybrids were enucleated and the cytoplasts were electrofused to rhodamine-6G (R-6G)-treated female ES cells. The resulting ES cell cybrids permitted transmission of the NZB mtDNAs through the mouse maternal lineage for three generations. Similarly, mtDNAs from a partially respiratory-deficient chloramphenicol-resistant (CAP(R)) cell line also were introduced into female chimeric mice and were transmitted to the progeny. CAP(R) chimeric mice developed a variety of ocular abnormalities, including congenital cataracts, decreased retinal function, and hamaratomas of the optic nerve. The germ-line transmission of the CAP(R) mutation resulted in animals with growth retardation, myopathy, dilated cardiomyopathy, and perinatal or in utero lethality. Skeletal and heart muscle mitochondria of the CAP(R) mice were enlarged and atypical with inclusions. This mouse ES cell-cybrid approach now provides the means to generate a wide variety of mouse models of mitochondrial disease.

Animals↗

PubMed2000

Another piece of the ribosome: solution structure of S16 and its location in the 30S subunit.

BACKGROUND: X-ray crystallography has recently yielded much-improved electron-density maps of the bacterial ribosome and its two subunits and many structural details of bacterial ribosome subunits are now being resolved. One approach to complement the structures and elucidate the details of rRNA and protein packing is to determine structures of individual protein components and model these into existing intermediate resolution electron density. RESULTS: We have determined the solution structure of the ribosomal protein S16 from Thermus thermophilus. S16 is a mixed alpha/beta protein with a novel folding scaffold based on a five-stranded antiparallel/parallel beta sheet. Three large loops, which are partially disordered, extend from the sheet and two alpha helices are packed against its concave surface. Calculations of surface electrostatic potentials show a large continuous area of positive electrostatic potential and smaller areas of negative potential. S16 was modeled into a 5.5 A electron-density map of the T. thermophilus 30S ribosomal subunit. CONCLUSIONS: The location and orientation of S16 in a narrow crevice formed by helix 21 and several other unassigned rRNA helices is consistent with electron density corresponding to the shape of S16, hydroxyl radical protection data, and the electrostatic surface potential of S16. Two protein neighbors to S16 are S4 and S20, which facilitate binding of S16 to the 30S subunit. Overall, this work exemplifies the benefits of combining high-resolution nuclear magnetic resonance (NMR) structures of individual components with low-resolution X-ray maps to elucidate structures of large complexes.

Amino Acid Sequence↗

PubMed2000

[Inventory of geriatric psychiatry in Sweden. In short supply where demand does not determine resource allocation].

In 1999 The Swedish Society for Old Age Psychiatry conducted an investigation in all Swedish counties in order to survey existing organizations and resources for medical services intended for elderly people with psychiatric complaints. In some counties there were no out-patient units specifically aimed at elderly people with psychiatric diseases, while more than half had no out-patient units for the large group of elderly with psychiatric ailments other than dementia. The total number of beds was far less than international recommendations. Less than 5 per cent of the total number of Swedish psychiatrists and geriatricians hold positions exclusively for geriatric psychiatry. Access to geriatric psychiatry resources appears to be unevenly distributed, and may be found mainly in or near university cities.

Aged↗

PubMed2000

A brief pain diary for ambulatory patients with advanced cancer: acceptability and validity.

BACKGROUND: Undertreatment of pain is common among ambulatory patients with advanced cancer. Available pain assessment tools are complex and not easy to use in ambulatory care settings. METHODS: The authors developed and assessed the acceptability and psychometric properties of a simple, brief 4-week pain diary for ambulatory care assessing 3 indicators: current pain intensity on rising and retiring, number of daily rescue doses, and weekly impact of pain on quality of life. Selected European Organization for Research and Treatment (EORTC) Quality of Life Questionnaire subscales were administered once concurrently for validation purposes. Subjects were 98 adult French-speaking ambulatory patients with advanced cancers who were on opioids, free of apparent cognitive impairment, and recruited through 2 oncology clinics in Quebec City, Quebec, Canada. RESULTS: In the first 3 weeks, > or =80% of patients completed all requested diary data. Internal consistencies of the 5-item scale assessing pain impact on quality of life were 0.87-0.92 over the study period. Pain intensity predicted both increased use of rescue doses and negative pain impact on quality of life. This latter scale was also responsive to decreases in pain intensity over 1-week intervals. As hypothesized, pain intensity, rescue doses, and pain impact on quality of life correlated with EORTC scale scores. Pain intensity correlated most strongly with the EORTC pain and global quality of life scales (r = 0.65 and -0.55, respectively). CONCLUSIONS: This diary is simple, very brief, acceptable to patients, and appears to be valid. It can thus likely be used to monitor pain management for advanced cancer patients.

Adolescent↗

PubMed2000

The solution structure of ribosomal protein L36 from Thermus thermophilus reveals a zinc-ribbon-like fold.

We have determined the solution NMR structure of the ribosomal protein L36 from Thermus thermophilus. L36 is the smallest protein in the large subunit of the prokaryotic ribosome. The sequence contains three completely conserved cysteine residues and one conserved histidine residue in a C-X(2)-C-X(12)-C-X(4)-H motif. Extended X-ray absorption fine structure spectroscopy was used to confirm that a purified L36 sample contains an equimolar amount of zinc. The structure of L36 was determined using simulated annealing based on NOE distance restraints, dihedral angle restraints and hydrogen bond distance restraints derived from NMR spectra of (15)N-labeled and non-labeled L36 samples at pH 7 and 12 degrees C, and by imposing tetrahedral zinc ion coordination geometry. The L36 fold is characterized by a triple-stranded antiparallel beta-sheet with the zinc-binding site at one end. The structure of the zinc site is well-determined and shows that the three cysteine sulphur atoms are supported by hydrogen bonds to backbone amide protons. The conserved histidine residue is located in a short 3(10)-helix and coordinates zinc by the N(delta1) atom. The electrostatic surface potential and location of conserved Arg, Lys and His side-chains suggest a large continuous L36-rRNA interaction interface. The folding topology as well as position and conformation of many conserved side-chains in L36 are very similar to those of zinc-ribbon domains found in the archaeal transcription factor TFIIB N terminus and the eukaryal transcription elongation factor hTFIIS C terminus. Given the relative antiquity of the ribosome it is possible that L36 reflects the parent of transcription-related zinc ribbons.

Amino Acid Motifs↗

PubMed2000

Links between Fer tyrosine kinase expression levels and prostate cell proliferation.

In our cloning strategy to identify tyrosine kinases implicated in the regulation of prostate growth, the dog fer cDNA was obtained and shown to be highly homologous to known fer cDNAs. Using a polyclonal Fer antibody directed against a C-terminal peptide, we studied its associations with cortactin, beta-catenin and p120Cas in human prostate carcinoma PC-3 cells. In contrast to previous reports, no interactions were observed. To assess its functional role, fer cDNA constructs were transfected in PC-3 cells. Antisense clones exhibiting a marked diminution of Fer expression had a reduced growth rate (doubling time of 29 vs. 42 h) and were unable to form colonies in soft agar. In agreement with these results, Fer protein expression was linked to human prostatic proliferative diseases, with enhanced levels in extracts from cancer tissues as compared to those from normal and hyperplastic ones, and was also expressed in the human prostate carcinoma cell lines DU145 and LNCaP. In the dog model, Fer expression was up-regulated in dividing versus resting prostate epithelial cells in vitro, and also in vivo when basal cell hyperplasia and metaplasia was induced by estrogen after castration. Minimal effects were observed when renewing the luminal epithelium with androgens. Taken together, these results show that Fer expression is associated with prostate cell proliferation and enhanced in prostate cancer.

Amino Acid Sequence↗