Stair climbing test post-stroke: feasibility, convergent validity and metabolic, cardiac, and respiratory responses.

BACKGROUND: The 6-minute walk test (6MWT) and treadmill walk tests (TMW) are commonly used to assess post-stroke patients (PSP) aerobic capacity. However, these tests are not without their limitations (e.g. limited sensitivity to change and the use of external pacing). Therefore, there is a need for additional tools to assess PSP aerobic capacity. OBJECTIVE: To establish the feasibility, convergent validity, and metabolic, cardiac, and respiratory responses of a stair climbing test (SC), among chronic PSP. METHODS: Nineteen chronic PSP conducted SC, TMW, and 6 MWT. Metabolic (oxygen consumption - VO2), cardiac (heart rate), and respiratory (ventilation volume, breathing frequency, and tidal volume) measures were established. Adverse events were documented. Correlations established the convergent validity of the SC test. A repeated measures analysis of variance was performed to compare the participant's physiological responses at the end of the various tests. RESULTS: SC is feasible and safe, as all participants completed the test with no adverse events. The SC demonstrated convergent validity as numerous associations were found between SC and TMW, and 6 MWT. Metabolic, cardiac, and respiratory responses to the SC were significantly higher than these of the TMW and 6 MWT (e.g. VO2= 13.43 ± 2.19, 11.01 ± 2.0, and 11.26 ± 1.87 ml/kg/min, respectively) (P < 0.05). CONCLUSIONS: SC is a feasible and valid test within chronic PSP. SC is more metabolically demanding than TMW and 6 MW and therefore, may enable appropriate endurance capacity measurement, especially for high functioning PSP. Negotiating stairs is a common community ambulation requirement. Therefore, it is appropriate to incorporate SC test in PSP testing battery.

Mechanical efficiency and balance in adolescents and young adults with cerebral palsy.

Mechanical efficiency (ME) during stair-climbing measures ambulation ability. This study investigated the relationship between ME and age, anthropometric, functional walking, and balance parameters in 52 adolescents with cerebral palsy (CP), age 13.5-23.3 yrs, who participated in an intervention study to improve walking. Measurements included ME, 6-min and 10-m walk tests and the Berg balance scale (BBS). Walk test measures correlated significantly with ME, as expected, as did BBS (r=0.68) and age (r=0.51). The multiple correlation coefficient with both age and BBS increased to 0.80. The measurements were divided into two groups of low (<40, n=19) and high (>40, n=33) BBS scores. Repeating regression analyses, demonstrated that in the low BBS group ME was significantly related to BBS, but not age, in contrast to opposite results in the high BBS group. Regressions were calculated for each of the 14 items of the BBS with ME. For the whole group, 12 items correlated significantly, but only three in the high BBS group (one leg standing, reach while standing and tandem standing). In the low BBS group 10 of the items correlated significantly, with the former three ranking near the top. Balance is an important component of ambulation in children with CP. Mobility in those scoring>40 is related to age, but in those more deficient in balance (<40) mobility is more closely associated with balance than age. Effective therapy to improve walking in younger children might incorporate more balance-focused exercises, similar to those related to BBS items strongly associated with ME.

G protein coupled receptors -in silico drug discovery and design.

In silico drug discovery is a complex process requiring flexibility and ingenuity in method selection and a careful validation of work protocols. GPCR in silico drug discovery poses additional challenges due to the paucity of crystallographic data. This paper starts by reviewing selected GPCR in silico screening programs reported in the literature, including both structure-based and ligand-based approaches. Particular emphasis is given to library design, binding mode selection, process validation and compound selection for biological testing. Following literature review, we provide insights into in silico methodologies and process workflows used at EPIX to drive over 20 highly successful screening and lead optimization programs performed since 2001. Applications of the various methodologies discussed are demonstrated by examples from recent programs that have not yet been published.

Random perturbation: a potential aid in treatment of children with cerebral palsy.

BACKGROUND AND PURPOSE: The motor behaviour of children with cerebral palsy (CP) can be viewed in terms of a stable mode with very little flexibility that prevents adaptation to tasks. We hypothesized that the use of random perturbations (RP) would weaken excessive stability, introduce flexibility and enhance the effects of physical treatment. The objective was to evaluate the contribution of RP to gross motor function and mechanical efficiency (MEg) during intensive physiotherapy in children with CP. METHODS: A convenience sample of 20 children with CP (mean age 8.2, range: 5.9-12.9 yrs) were matched by age and GMFCS level, and randomly assigned to structured intensive treatment (SIT) or to SIT + RP groups. Groups received one month of daily treatment. RP was applied by engine-induced random passive cycling for upper and lower limbs for up to 10 min in a 90-min treatment session. Gross Motor Function Measure (GMFM)-66 and gross mechanical efficiency (MEg) during stair climbing (MEg) were measured before and after treatment. RESULTS: GMFM-66 scores increased by about 1.0 in both groups. However, external work and MEg increased significantly more in SIT + RP than SIT. The increase in MEg in SIT + RP was independent of the level of motor function at baseline. CONCLUSION: The addition of RP in treatment of children with CP may have weakened previously established stereotypical motor patterns and introduced flexibility, thereby improving mechanical efficiency of a complex motor task. RP may enhance the effects of intensive treatment.

Method of analysing the performance of self-paced and engine induced cycling in children with cerebral palsy.

PURPOSE: To develop a method of quantifying the features of cycling in children with CP by comparing them to typically developed children, and to demonstrate the applications of this tool for evaluating treatment effects in children with CP. METHODS: Twenty-seven typically developed children and 51 with CP, classified by their gross motor function levels, were studied. Angular velocities were measured during self-paced active cycling and during passive cycling imposed by an electrically powered stationary cycle. Angular velocities were compared with the gross motor function levels, Modified Ashworth Scale and the Adductor Tone Rating. RESULTS: Significant differences between children with CP and those typically developed demonstrated in passive mode that the cycling task is sensitive to differences in resistance offered by the subjects. Active and passive cycling velocities differ significantly between groups classified by their functional levels (p < 0.01). Children with CP in the mild group showed no differences from typically developed children. The correlations between passive cycling and clinical tests were significant and higher at higher speeds (r = 0.62). Correlations with anthropometric measurements for the typically developed group associated the cycling task with growth and development, and for children with CP with motor control adjustments and impairments. CONCLUSIONS: Measuring of these two cycling modes could be applicable in assessing lower extremity function in children with CP and changes following interventions.

Modeling the 3D structure of GPCRs from sequence.

G-protein-coupled receptors (GPCRs) are a large and functionally diverse protein superfamily, which form a seven transmembrane (TM) helices bundle with alternating extra-cellular and intracellular loops. GPCRs are considered to be one of the most important groups of drug targets because they are involved in a broad range of body functions and processes and are related to major diseases. In this paper we present a new technology, named PREDICT, for modeling the 3D structure of any GPCR from its amino acid sequence. This approach takes into account both internal protein properties (i.e., the amino acid sequence) and the properties of the membrane environment. Unlike competing approaches, the new technology does not rely on the single known structure of rhodopsin, and is thus capable of predicting novel GPCR conformations. We demonstrate the capabilities of PREDICT in reproducing the known experimental structure of rhodopsin. In principle, PREDICT-generated models offer new opportunities for structure-based drug discovery towards GPCR targets.

Reorganization of nuclear factors during myeloid differentiation.

Differentiation in several stem cell systems is associated with major morphological changes in global nuclear shape. We studied the fate of inner-nuclear structures, splicing factor-rich foci and Cajal (coiled) bodies in differentiating hemopoietic, testis and skin tissues. Using antibodies to the splicing factors PSF, U2AF(65) and snRNPs we find that these proteins localize in foci throughout the nuclei of immature bone marrow cells. Yet, when granulocytic cells differentiate and their nuclei condense and become segmented, the staining localizes in a unique compact and thread-like structure. The splicing factor-rich foci concentrate in the interior of these nuclei while the nuclear periphery and areas of highly compact chromatin remain devoid of these molecules. Differentiated myeloid cells do not stain for p80 coilin, the marker for Cajal bodies. Immature myeloid cells contain Cajal bodies although these usually do not coloclaize with PSF-rich foci. Following complete inhibition of transcription in myeloid cells, the threaded PSF pattern becomes localized in several foci in the different lobes of mature granulocytes while in human HL-60 immature myeloid leukemia cells PSF is found in the perinucleolar compartment. Studies of other differentiating stem cell systems show that PSF staining disappears completely in differentiated, transcriptionally inactive sperm cells, is scarce as cells migrate from the inner skin layers outward and is lost as cells of the hair follicle mature. We conclude that the formation and distribution of splicing factor-rich foci in the nucleus during differentiation of various cell lineages is dependent on the levels of chromatin condensation and the differentiation status of the cell.

Enhanced proteolysis of pre-mRNA splicing factors in myeloid cells.

OBJECTIVE: Molecular identification and characterization of the bone marrow nuclear protein detected by the B92 monoclonal antibody. MATERIALS AND METHODS: The protein was purified to homogeneity from acute myeloid leukemia cells and was subjected to peptide digestion and amino acid sequencing. Identified sequences were used to screen a bone marrow cDNA library in search of matching transcripts. The protein was further studied in different cells and tissues by examination of protease inhibitors and harsh lytic conditions and during apoptosis in HL-60 cells. RESULTS: We found that the apparent bone marrow specific protein is a 47 kD proteolytic cleavage product of PSF, an essential pre-mRNA splicing factor. PSF is completely cleaved to p47 during lysis of immature myeloid cells due to potent proteolytic activity found in these cells but is rare in other cells and tissues. Furthermore, p47 is abundant in intact normal and tumor myeloid cells while in other cell types it is undetectable. The cleavage of PSF is accompanied by digestion of the PTB splicing regulator but not other proteins tested. In contrast, during apoptosis PTB is degraded while PSF remains intact. CONCLUSIONS: The bone marrow 47 kD protein is a fragment constituting the N-terminal, protease-resistant half of the splicing factor PSF. Proteolytic degradation of PSF specifically occurs in intact myeloid cells and this process is enhanced upon myeloid cell lysis.