What is the best method for assessing lower limb force-velocity relationship?

This study determined the concurrent validity and reliability of force, velocity and power measurements provided by accelerometry, linear position transducer and Samozino's methods, during loaded squat jumps. 17 subjects performed squat jumps on 2 separate occasions in 7 loading conditions (0-60% of the maximal concentric load). Force, velocity and power patterns were averaged over the push-off phase using accelerometry, linear position transducer and a method based on key positions measurements during squat jump, and compared to force plate measurements. Concurrent validity analyses indicated very good agreement with the reference method (CV=6.4-14.5%). Force, velocity and power patterns comparison confirmed the agreement with slight differences for high-velocity movements. The validity of measurements was equivalent for all tested methods (r=0.87-0.98). Bland-Altman plots showed a lower agreement for velocity and power compared to force. Mean force, velocity and power were reliable for all methods (ICC=0.84-0.99), especially for Samozino's method (CV=2.7-8.6%). Our findings showed that present methods are valid and reliable in different loading conditions and permit between-session comparisons and characterization of training-induced effects. While linear position transducer and accelerometer allow for examining the whole time-course of kinetic patterns, Samozino's method benefits from a better reliability and ease of processing.

Effects of wearable resistance load placement on neuromuscular activity and stride kinematics: A preliminary study.

Background: Wearable resistance (WR) training is a modality that allows athletes to perform loaded sport-specific movements to develop force and power outputs. The acute responses by which WR works is still relatively unknown, and the effects of WR load and location of the load has not yet been examined. Objectives: To investigate the acute neuromuscular and stride characteristic responses to different wearable resistance (WR) loads and placements on the calf muscles during high-speed running. Methods: Ten well-trained subjects completed a workout of ten sets of three 10s runs at 18km.h-1 (20s of rest between runs and one min between sets). Five conditions were tested: (1) unloaded control, (2) bilateral 0.75 vs. 1.5% body mass (BM) loading on the distal posterior calf, (3) bilateral proximal vs. distal loading of 1.5% BM positioned posteriorly, (4) bilateral anterior vs. posterior loading of 1.5% BM positioned distally, (5) unilateral loading of 1.5% BM on the distal posterior calf. Data were collected using Electromyography (EMG) and back-mounted GPS-embedded accelerometers. Magnitude of differences of within athlete and between muscle comparisons were calculated using effect sizes (ES) ± 90% confidence limits (CL). Results: No substantial differences in accelerometry data were observed between any of the loaded conditions and the control. EMG activity was lower for proximal loading compared to the control for the gluteus maximus (ES±90%CL; -0.72±0.41), vastus lateralis (-0.89±0.47) and vastus medialis (VM) (-0.97±0.46). Anterior loading induced substantially lower EMG activity for the semitendinosus (-0.70±0.48) and VM (-0.64±0.39) muscles compared with the control. EMG activity of the VM (-0.73±0.46) muscle was also substantially lower for posterior loading compared to the control. Unilateral loading induced no substantial differences in EMG activity between the loaded and unloaded legs. Conclusion: This preliminary study has provided a rationale for the performance of further investigations into the effects of WR lower limb loading on stride characteristics and EMG activity from a chronic standpoint using a larger population.

Characterization of an Infectious Bronchitis Virus Isolated from Commercial Layers Suffering from False Layer Syndrome.

Infectious bronchitis virus (IBV) is a gammacoronavirus that primarily induces an upper respiratory disease in chickens, also affecting the urogenital tract and occasionally leading to a condition called false layer syndrome (FLS), where sexually mature hens ovulate normally but are unable to lay eggs. Here, we describe an outbreak of FLS in Arizona from which an IBV variant that is nearly 90% homologous to DMV/1639 using the Spike subunit 1 gene, named AZ/FLS/17, was isolated and used in challenge experiments. Three-day-old specific-pathogen-free chicks were challenged with AZ/FLS/17 or M41 in high and low doses, and the disease outcomes were compared. Overall, no differences in microscopic lesions or viral loads in the reproductive tract were detected between AZ/FLS/17- and M41-infected birds. To minimize the losses linked to FLS in the problematic flocks, an updated live-attenuated IBV vaccine protocol including the use of the Ma5 strain at the hatchery was implemented, resulting in a drastic reduction of false layers in the subsequent flocks. To monitor the circulation of wild-type and vaccine strains in this population, a molecular surveillance study was performed. Samples were collected at 1, 7, 14, and 21 days of age, and from laying hens at 30 and 36 wk. In older birds, the IBV strains detected were more diverse than at 1 and 7 days of age. Nevertheless, live vaccine combinations are still widely used to decrease the losses caused by FLS in commercial egg laying flocks worldwide.

Caracterización de un virus de la bronquitis infecciosa aislado de aves de postura comerciales que padecían el síndrome de la falsa ponedora. El virus de la bronquitis infecciosa (IBV) es un gammacoronavirus que induce principalmente una enfermedad de las vías respiratorias superiores en los pollos, que también afecta el tracto urogenital y ocasionalmente conduce a una condición llamada síndrome de la falsa ponedora (FLS), donde las gallinas sexualmente maduras ovulan normalmente pero no pueden producir huevos. En este estudio se describe un brote del síndrome de la falsa ponedora en Arizona a partir del cual se aisló una variante del virus de bronquitis que es casi 90% similar a la variante DMV/1639 usando el gene S1, la cual se denominó AZ/FLS/17, y se usó en experimentos de desafío. Pollos de tres días de edad libres de patógenos específicos (SPF) fueron desafiados con el virus AZ/FLS/17 o con el virus M41 en dosis altas y bajas, y se compararon los resultados de la enfermedad. En general, no se detectaron diferencias en las lesiones microscópicas o en las cargas virales en el tracto reproductivo entre las aves infectadas con el virus AZ/FLS/17 y el virus M41. Para minimizar las pérdidas relacionadas con el síndrome de la falsa ponedora en las parvadas problemáticas, se implementó un protocolo actualizado con vacuna viva atenuada contra la bronquitis infecciosa que incluía el uso de la cepa Ma5 en la incubadora, lo que resultó en una reducción drástica de las gallinas falsas ponedoras en las parvadas subsecuentes. Para monitorear la circulación de cepas de tipo silvestre y vacunales en esta población, se realizó un estudio de vigilancia molecular. Se recolectaron muestras a los 1, 7, 14 y 21 días de edad y de gallinas de postura a las 30 y 36 semanas. En aves mayores, las cepas del virus de bronquitis detectadas fueron más diversas que a los días 1 y 7 de edad. Sin embargo, las combinaciones de vacunas vivas todavía se utilizan ampliamente para disminuir las pérdidas causadas por el síndrome de la falsa ponedora en las parvadas de postura de huevo comercial en todo el mundo.

Meiotic chromosome behavior in spread preparations of yeast.

Chromosome behavior in meiosis is well characterized from cytological and genetic descriptions but little is known of the underlying molecular mechanisms, largely because no one experimental system has been developed to support an integrated application of modern cytological, genetic, and molecular biological methods. To combine efficient analyses of meiotic chromosome structure and function in a single organism, we have extended to yeast methods for making spread preparations of nuclei. Features of yeast meiosis that parallel meiosis in large eukaryotes, such as bouquet formation and prophase chromosome condensation that occurs in concert with synaptonemal complex formation, are evident for the first time. The ability to analyze large numbers of nuclei at the light and electron microscopes in preparations amenable to a variety of cytological and immunocytological techniques will facilitate the description of meiosis at the molecular level in yeast.

"The VIHsibilite Project": HIV-positive people in the Quebec press and community responses.

The VIHsibilite Project is a community-based action-research initiative that examines newspaper coverage of HIV/AIDS issues in Quebec from 1988 to 2004. Using standard qualitative research methods, and in consultation with an advisory committee of people directly impacted by HIV/AIDS news coverage, the project discerns trends in reporting on HIV/AIDS and undertakes discursive content analysis of these, aiming to better understand in what normative ways seropositive people are represented in print media, and, ultimately, to reduce the stigma attendant upon HIV infection. Preliminary findings include indications that seropositive women tend to be represented markedly differently from men in the news.

DNA sequence analysis of spontaneous mutations in the SUP4-o gene of Saccharomyces cerevisiae.

A collection of 196 spontaneous mutations in the SUP4-o gene of the yeast Saccharomyces cerevisiae was analyzed by DNA sequencing. The classes of mutation identified included all possible types of base-pair substitution, deletions of various lengths, complex alterations involving multiple changes, and insertions of transposable elements. Our findings demonstrate that at least several different mechanisms are responsible for spontaneous mutagenesis in S. cerevisiae.

Quantification of cellular adhesion molecules on malignant B cells from non-Hodgkin's lymphoma.

The expression of five cellular adhesion molecules (CAMs), CD54, CD58, CD11a, CD29 and CD49d, was studied in 113 B cell non-Hodgkin's lymphomas (NHL) and in normal B cells from 12 control lymph nodes. Rather than reporting the percentage of positive cells, which does not discriminate between NHL subtypes, we quantified the intensity of CAM expression using flow cytometry. Apart from CD49d the expression of all these CAMs was statistically different among the NHL subtypes as defined by the REAL classification. Low grade NHL-small lymphocytic, follicular and mantle cell lymphoma--which are derived from quiescent cells and show an indolent disease course, expressed low levels of CAMs. Conversely, high grade NHL-diffuse large cell lymphoma--which are derived from proliferating cells and are clinically aggressive, expressed high levels of CAMs. These results indicate that in malignant NHL B cell tumour growth and clinical aggressiveness may be related to the adhesive capacities of the tumour cells.

High-resolution allelotype analysis of childhood B-lineage acute lymphoblastic leukemia.

Knowledge of the patterns of allelic loss has been useful in identifying tumor suppressor genes in many solid tumors. Although the loss of genetic material in acute lymphoblastic leukemias has been documented by cytogenetic studies and microsatellite typing, a global overview of losses of heterozygosity occurring throughout the genome was not yet available. We have performed a high resolution allelotype analysis in 63 childhood B-lineage acute lymphoblastic leukemia. A total of 247 microsatellite markers, evenly distributed along the autosomes were typed in blast and in remission samples from every patient. An average of 41 patients were informative for each marker. LOH at one or several loci was observed in 41 of the 63 patients (64%). The mean values for the fractional allelic loss (FAL) and the hemizygosity index, calculated for each patient, were 0.03 (range 0 to 0.23) and 0.024 (range 0 to 0.18), respectively. The most frequently involved chromosomal arms were 9p (36%), 12p (31%), 20q (15%), 6q (12%), 5p (10%) and 10p (10%). Three regions on chromosomal arms 9p, 12p and 6q were previously identified as the targets of recurring deletions, the target genes being identified for two of them (9p and 12p). The three new regions defined by this allelotype may contain tumor-suppressor genes implicated in the initiation or progression of childhood B-ALLs.

Relationships between susceptibility to LAK cell-mediated lysis, conjugate formation and expression of adhesion molecules in B-cell derived non-Hodgkin's lymphomas.

Adoptive immunotherapy with LAK cells has been investigated for the treatment of B-cell-derived lymphomas, but only a few significant tumor regressions were obtained. In order to explain this refractory state, the sensitivity to normal LAK-mediated lysis of 30 non-Hodgkin's lymphoma (NHL) malignant B-cells was determined using flow cytofluorimetry. A large heterogeneity was found, and we report a close correlation (p < 0.001) between the extent of lysis of malignant B-cells and their ability to form conjugates with LAK cells; which is the first step in LAK-mediated cytolysis. The levels of expression of HLA class I molecules, LFA-1 (CD11a/CD18), CD54 and CD58 were also studied and found to be expressed very heterogeneously. CD54 expression on malignant B-cells plays a major role in the initial conjugate formation with LAK cells (p < 0.001), and this was confirmed by inhibition experiments. Our results suggest that a weak expression of CD54 could constitute one mechanism by which NHL tumor B-cells escape natural immune surveillance and resist LAK cells immunotherapies.

Factors involved in cardiac autonomic neuropathy in diabetic patients.

The role cardiac autonomic neuropathy (CAN) plays in diabetes is not well known. The aim of this study was to identify the factors involved in CAN in diabetic patients. One hundred patients, 44 insulin-dependent (IDDM) and 56 non-insulin-dependent (NIDDM), were investigated, using five standard tests. Three of these tests were for parasympathetic control (cardiac response to the lying-to-standing, deep breathing, and Valsalva tests), and the other two measured sympathetic control (testing for orthostatic hypotension and evaluating heart and blood pressure response to the handgrip test). Results were compared to those found in a series of 40 healthy volunteers. An age-adjusted comparison with the controls, showed that 34 patients had one abnormal parasympathetic test, 23 had two, and 6 patients had three. Cardiac parasympathetic neuropathy was thus present in 63% of the patients. The handgrip test was completed by 84 diabetic patients. There was evidence of orthostatic hypotension and/or an abnormal cardiac response to the handgrip in 15 of these patients, who all had a parasympathetic abnormality as well. There was no significant association between the type of diabetes and the presence of CAN. The duration of diabetes was significantly longer in patients with CAN (9.3 +/- 0.9 years) (p < 0.01) than in those with all three parasympathetic tests normal (5.8 +/- 0.9 years) (p < 0.01). The HbA1c level was also higher in patients with CAN than in those with three normal parasympathetic tests (9.95 +/- 0.35% versus 8.17 +/- 0.42%, p < 0.005). There was a significant association between the presence of retinopathy, observed by angiofluorography, and the presence of peripheral neuropathy confirmed by the electrophysiological investigation and the presence of CAN (p < 0.001). However, more than half the patients without retinopathy or nephropathy had CAN, and 11 of the 31 patients with a normal electrophysiological investigation also had CAN. Eighteen patients (6 IDDM) without retinopathy and nephropathy, who had been diabetic for less than 2 years, also had CAN. This study shows that CAN occurs early and is frequently found in a population of unselected diabetic patients. Metabolic factors may play an important role in its occurrence. CAN is significantly associated with the presence of retinopathy, which suggests that an impairment of autonomic peripheral blood flow control might be a contributing factor in the formation of microvascular lesions.

Diabetic peripheral neuropathy: effects of age, duration of diabetes, glycemic control, and vascular factors.

The aim of this study was to determine the factors associated with diabetic peripheral neuropathy and more particularly its relation to precisely assessed microangiopathy. Peripheral neuropathy was assessed in 135 diabetic patients: 28 insulin-dependent diabetes mellitus (IDDM), 85 non-insulin-dependent diabetes mellitus (NIDDM), and 22 insulin-treated NIDDM patients, on the basis of both clinical findings and extensive electrophysiological testing (four motor nerves and four sensory nerves, and right and left Hoffmann's reflex), using a total of 20 parameters. The percentage of women with severe clinical neuropathy was significantly higher than that of men, and the clinical neurological stage correlated significantly with age and duration of diabetes. According to multivariate analysis the clinical stage correlated only with gender and duration of diabetes. Several electrophysiological parameters were significantly more abnormal in women and correlated with age, type and duration of diabetes, and recent glycemic control. The multivariate analysis showed that 17 electrophysiological parameters correlated with duration of diabetes, nine correlated with age, seven with glycemic control, and only one with gender. The presence of clinical neuropathy also correlated with presence of retinopathy, arterial hypertension, macroangiopathy, and biological signs of nephropathy. All the electrophysiological parameters were significantly more abnormal in patients with retinopathy or macroangiopathy than in patients without these complications. Separate parameter analysis showed that at least one abnormal electrophysiological parameter was almost always found in patients with retinopathy, macroangiopathy, or incipient nephropathy, but abnormalities were also found to a slightly lesser extent in patients without these complications. Multivariate analysis showed that when duration of diabetes, retinopathy, macroangiopathy, and biological signs of nephropathy were introduced into the model, 11 electrophysiological parameters correlated with duration of diabetes, 11 with retinopathy, seven with macroangiopathy, and five with a sign of nephropathy. This study demonstrates that age and glycemic control have an effect, and diabetes duration a major effect on peripheral nerve function. It suggests that vascular factors may participate in the development of nerve lesions.

Mutagenicity and cytotoxicity of the carcinogen-mutagen aflatoxin B1 in Streptococcus pneumoniae (Pneumococcus) and Salmonella typhimurium: dependence on DNA repair functions.

Strains R6, R6x and R6uvr-1 of Streptococcus pneumoniae (Pneumococcus) are sensitive to the cytotoxic effects of the mutagen/carcinogen aflatoxin B1 (AFB1). R6uvr-1 is more prone to the cytotoxic effects of AFB1 than the repair-proficient parental strain, R6. The same differential susceptibility of strains R6, R6x and R6uvr-1 was observed when UV light replaced metabolically activated AFB1. All pneumococcal strains were immutable by AFB1. AFB1 mutagenesis in Salmonella typhimurium strains was dependent on a functional RecA gene product. The enhancing effects of delta uvrB and plasmid pKM101 were found to be additive. Data presented are consistent with the following: (i) AFB1 toxic effects are due mainly to DNA binding of AFB1; (ii) AFB1 mutagenesis is dependent on error-prone DNA repair; (iii) Pneumococcus lacks an active error-prone (SOS) DNA-repair system.

Development of a yeast system to assay mutational specificity.

We have developed a system wherein DNA alterations occurring in a target gene in the yeast Saccharomyces cerevisiae can be determined by DNA sequencing. The target gene, SUP4-o, an ochre suppressor allele of a yeast tyrosine tRNA gene, has been inserted into a shuttle vector (YCpMP2) which is maintained in yeast at a copy number of one per cell Mutations in SUP4-o are selected by virtue of their inactivation of suppressor activity. Rapid DNA preparations from these mutants are used to transform an appropriate bacterial strain. Since YCpMP2 also carries the M13 phage replication origin, superinfection of bacterial cells containing the plasmid with wild-type M13 phage yields single stranded YCpMP2 DNA suitable for dideoxynucleotide chain termination sequencing. We have used this system to examine mutations arising spontaneously in the SUP4-o gene. The spontaneous mutants occurred at a frequency of 3.2 X 10(-6)/viable cell, corresponding to a rate of 2.7 X 10(-7) events/cell division. Following bacterial transformation, 16% of the recovered plasmids tested displayed altered gel mobility consistent with loss of significant portions of the plasmid. Hybridization analysis of total yeast DNA and use of purified YCpMP2 revealed that these very large deletions were not generated in yeast but were associated with bacterial transformation. Among the SUP4-o mutants analyzed by DNA sequencing, we identified each type of single base pair substitution (transitions and transversions), small deletions of varying length (1-32 base pairs) and more extensive deletions of undetermined size. These results demonstrate that the SUP4-o system can be used to detect various types of mutation at numerous sites in a single eukaryotic gene and to characterize the DNA sequence changes responsible for the mutations selected.

Analysis of the spectrum of mutations induced by the rad3-102 mutator allele of yeast.

The product of the RAD3 gene of Saccharomyces cerevisiae is required for mitotic cell viability and excision repair of UV-induced pyrimidine dimers. Certain rad3 mutant alleles (originally called rem1) increase the rates of both spontaneous mitotic recombination and mutation. The increase in mutation rates is not dependent upon the presence of the RAD6 error-prone pathway. The mutator phenotype suggests that the wild-type RAD3 gene product may be involved in the maintenance of fidelity of DNA replication in addition to its known role in excision repair. To investigate the role that RAD3 might play in mutation avoidance, we have utilized a well-characterized shuttle vector system to study the mutational spectrum occurring in rad3-102 strains and compare it to that seen in RAD3 strains. The results put constraints on the role that the rad-102 mutant gene product must play if the RAD3 protein is a component of the replication complex. Alternatively, the mutational spectrum is consistent with the hypothesis that the rad3-102 mutant protein interferes with postreplication mismatch repair.

Surface EMG and motor unit activity of partially denervated human muscle during fatiguing submaximal isometric contraction.

The extent to which the normal fatigue compensatory mechanisms are disturbed in partially denervated muscles was investigated in human patients. Surface EMG, as well as motor unit electrical and mechanical activity, were analyzed from the partially denervated first interosseous muscle, during fatiguing isometric submaximal contraction. The EMG power and frequency changes which reveal the local fatigue process of healthy muscle have not been systematically found. Motor unit firing rate changes were rather normal and twitch contraction time did not increase during the fatiguing exercise. Differences between normal and partially denervated muscles could be explain by the occurrence of a central fatigue process more or less important in neurogenic lesions.

[Sensory neuropathy of the trigeminal nerve and scleroderma]. / Neuropathie sensitive du nerf trijumeau et sclérodermie.

Sensory neuropathy of trigeminal nerve is one of the neurological complications of systemic diseases, particularly scleroderma. Three cases are reported in which onset occurred at different stages of the disease, the main symptom being painful dysesthesias. All three branches of the trigeminal nerve may be affected but a preference is apparent for V2 and V3. Signs are usually limited to hypoesthesia and the chronic course is influenced little by treatment.

[Diagnostic contribution of 2 electrophysiological methods in a case of central pontine myelinolysis. Early auditory evoked potentials and blink reflex]. / Apport diagnostic de deux méthodes électrophysiologiques dans un cas de myélinolyse centro-pontine. Potentiels évoqués auditifs précoces et réflexe de clignement.

A case of central point myelinolysis is described in a heavy beer drinker who was found to have severe water and electrolyte disturbances on admission. The patient subsequently developed quadriparesis with pseudobulbar symptoms. The authors stress the diagnostic value of brain stem auditory-evoked responses and of blink-reflex, which were restored to normal as the patient recovered.

An intragenic ERG deletion is a marker of an oncogenic subtype of B-cell precursor acute lymphoblastic leukemia with a favorable outcome despite frequent IKZF1 deletions.

Oncogenic subtypes in childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL) are used for risk stratification. However, a significant number of BCP-ALL patients are still genetically unassigned. Using array-comparative genomic hybridization in a selected BCP-ALL cohort, we characterized a recurrent V(D)J-mediated intragenic deletion of the ERG gene (ERG(del)). A breakpoint-specific PCR assay was designed and used to screen an independent non-selected cohort of 897 children aged 1-17 years treated for BCP-ALL in the EORTC-CLG 58951 trial. ERG(del) was found in 29/897 patients (3.2%) and was mutually exclusive of known classifying genetic lesions, suggesting that it characterized a distinct leukemia entity. ERG(del) was associated with higher age (median 7.0 vs. 4.0 years, P=0.004), aberrant CD2 expression (43.5% vs. 3.7%, P<0.001) and frequent IKZF1 Δ4-7 deletions (37.9% vs. 5.3%, P<0.001). However, ERG(del) patients had a very good outcome, with an 8-year event-free survival (8-y EFS) and an 8-year overall survival of 86.4% and 95.6%, respectively, suggesting that the IKZF1 deletion had no impact on prognosis in this genetic subtype. Accordingly, within patients with an IKZF1 Δ4-7 deletion, those with ERG(del) had a better outcome (8-y EFS: 85.7% vs. 51.3%; hazard ratio: 0.16; 95% confidence interval: 0.02-1.20; P=0.04). These findings have implications for further stratification including IKZF1 status.