Mechanical measures during maximal velocity knee extension exercise and their relation to fibre composition of the human vastus lateralis muscle

Summary A method for measuring the maximal velocity of knee extension exercise is described using a very light lever arm. Instrumentation of the lever arm with a potentiometer and accelerometer also allows for the measurement of peak acceleration, time to peak acceleration, the average rate of development of acceleration (jerk) and peak torque. With this apparatus and surface electromyography, electromechanical delay (EMD) was also determined. This apparatus was tested using 17 female and 10 male subjects, and the measures obtained were related to the percentage of fast twitch fibres (% FT) and the relative area of fast twitch fibres (% FTA) in the vastus lateralis determined from duplicate muscle biopsy samples. Peak velocity of unloaded knee extension averaged 12.1±1.2 and 12.2±1.7 rad · s^–1 for females and males, respectively, and were not significantly different. As well, peak acceleration, time to peak acceleration jerk and EMD values were not significantly different between the female and male subjects, but the mean peak torque for the female subjects (73.5±14.7 N · m) was significantly lower than that for the males (98.4±31.5 N · m). Peak acceleration was significantly correlated with %FT (r=0.40,P=0.04) for the total subject population. None of the other measures was significantly related to either %FT or %FTA for the male and female subjects or the combined population of subjects.     

Thermal responses of men and women during cold-water immersion: influence of exercise intensity

Summary The influence of exercise intensity on thermoregulation was studied in 8 men and 8 women volunteers during three levels of arm-leg exercise (level I: 700 ml oxygen (O₂) · min^–1; level II: 1250 ml O₂ · min^–1; level III: 1700 ml O₂ · min^–1 for 1 h in water at 20 and 28°C (T _w). For the men inT _w 28°C the rectal temperature (T _re) fell 0.79°C (P<0.05) during immersion in both rest and level-I exercise. With level-II exercise a drop inT _re of 0.54° C (P < 0.05) was noted, while at level-III exerciseT _re did not change from the pre-immersion value. AtT _w of 20°C,T _re fell throughout immersion with no significant difference in finalT _re observed between rest and any exercise level. For the women at rest atT _w 28°C,T _re fell 0.80°C (P<0.05) below the pre-immersion value. With the two more intense levels of exercise,T _re did not decrease during immersion. InT _w 20°C, the women maintained higherT _re (P<0.05) during level-II and level-III exercise compared to rest and exercise at level I. The_{T re} responses were related to changes in tissue insulation (I _t) between rest and exercise with the largest reductions inI _t noted between rest and level-I exercise acrossT _w and gender. For men and women of similar percentage body fat, decreases inT _re were greater for the women at rest and level-I exercise inT _w 20°C (P< 0.05). With more intense exercise, the women maintained a higherT _re than the men, especially in the colder water. These findings indicate that exercise is not always effective in offsetting the decrease inI _t and facilitated heat loss in cool or cold water compared to rest. The factors of exercise intensity,T _W, body fat, and gender influence the thermoregulatory responses.     

Distribution of circulation-derived endothelial progenitors following systemic delivery.

Cells with an endothelial phenotype can be cultured from peripheral blood. These cells include cells of a monocytic origin with endothelial features (culture-modified mononuclear cells, CMMCs) and, at later time points, blood outgrowth endothelial cells (BOECs). Both are promising candidates for systemic cell-based cardiovascular therapies and each may have unique capabilities. Indeed, the combined use of both cell types has been shown to have synergistic therapeutic features requiring simultaneous delivery. However, the majority of preclinical studies of cell delivery have used splenectomized animals to increase systemic distribution. The goal of this study was to directly compare the distribution of these two cell types following systemic delivery in an intact animal model. A similar pattern of delivery was seen following delivery of both cell types with detection in the lung, liver, bone marrow, and spleen. Taken together, the data suggest that strategies using systemic delivery of circulation-derived cells must consider the distribution and efficiency of delivery in intact animals.     

Immunophenotypic changes and clinical outcome in B-cell lymphomas treated with rituximab.

Rituximab is a chimeric monoclonal antibody that recognizes the CD20 antigen and is used to treat B-cell non-Hodgkin lymphoma (B-NHL). Few studies have been published examining the use of antibody panels to evaluate B-NHL treated with rituximab. The authors performed a retrospective analysis of immunophenotypic changes and clinical outcome in 18 patients with B-NHL following rituximab therapy. The intensity of CD20 expression was evaluated by flow cytometry and/or immunohistochemistry, before and after rituximab therapy; the latter samples were taken 5 to 12 months after initiating rituximab therapy (median 7 months). Nine of the 18 patients (50%) achieved complete or partial clinical remission and did not have morphologic evidence of lymphoma in the post-therapy samples. The other nine patients (50%) had persistent disease. Two patterns of CD20 expression were noted in the post-therapy samples: unchanged expression of CD20 in neoplastic cells (4/9 cases) and loss of or a significant decrease in detected CD20 expression in neoplastic cells (5/9 cases). These results show that in many cases of B-NHL persisting after rituximab therapy, CD20 expression decreases or is lost, raising the possibility of deletion or expression modulation of the CD20 gene in neoplastic cells. This study also underscores the importance of using a panel of antibodies to evaluate rituximab-treated B-NHL.     

A potential role for beta- and gamma-crystallins in the vascular remodeling of the eye.

We demonstrate that expression of beta- and gamma-crystallins is associated with intraocular vessels during normal vascular development of the eye and also in the Nuc1 rat, a mutant in which the hyaloid vascular system fails to regress normally. Real-Time RT PCR, Western blot and metabolic labeling studies indicate an increased expression of beta- and gamma-crystallins in Nuc1 retina. The increased expression of crystallins was localized to the astrocytes surrounding the intraocular vessels. A similar pattern of crystallin expression was also observed in the retinal vessels during normal development. Cultured human astrocytes exposed to 3-nitropropionic acid, an established model of neuronal hypoxia, increased VEGF expression, as expected, but also increased expression of crystallins. Our data suggest that crystallins may function together with VEGF during vascular remodeling. Interestingly, in human PFV (persistent fetal vasculature) disease, where the hyaloid vasculature abnormally persists after birth, we show that astrocytes express both VEGF and crystallins.     

LcrV plague vaccine with altered immunomodulatory properties

Yersinia pestis, the causative agent of plague, secretes LcrV (low-calcium-response V or V antigen) during infection. LcrV triggers the release of interleukin 10 (IL-10) by host immune cells and suppresses proinflammatory cytokines such as tumor necrosis factor alpha and gamma interferon as well as innate defense mechanisms required to combat the pathogenesis of plague. Although immunization of animals with LcrV elicits protective immunity, the associated suppression of host defense mechanisms may preclude the use of LcrV as a human vaccine. Here we show that short deletions within LcrV can reduce its immune modulatory properties. An LcrV variant lacking amino acid residues 271 to 300 (rV10) elicited immune responses that protected mice against a lethal challenge with Y. pestis. Compared to full-length LcrV, rV10 displayed a reduced ability to release IL-10 from mouse and human macrophages. Furthermore, the lipopolysaccharide-stimulated release of proinflammatory cytokines by human or mouse macrophages was inhibited by full-length LcrV but not by the rV10 variant. Thus, it appears that LcrV variants with reduced immune modulatory properties could be used as a human vaccine to generate protective immunity against plague.     

Expression of luminal and basal cytokeratins in human breast carcinoma

We have examined basal and luminal cell cytokeratin expression in 1944 cases of invasive breast carcinoma, using tissue microarray (TMA) technology, to determine the frequency of expression of each cytokeratin subtype, their relationships and prognostic relevance, if any. Expression was determined by immunocytochemistry staining using antibodies to the luminal cytokeratins (CKs) 7/8, 18 and 19 and the basal markers CK 5/6 and CK 14. Additionally, assessment of alpha-smooth muscle actin (SMA) and oestrogen receptor status (ER) was performed. The vast majority of the cases showed positivity for CK 7/8, 18 and 19 indicating a differentiated glandular phenotype, a finding associated with good prognosis, ER positivity and older patient age. In contrast, basal marker expression was significantly related to poor prognosis, ER negativity and younger patient age. Multivariate analysis showed that CK 5/6 was an independent indicator for relapse free interval. We were able to subgroup the cases into four distinct phenotype categories (pure luminal, mixed luminal/basal, pure basal and null), which had significant differences in relation to the biological features and the clinical course of the disease. Tumours classified as expressing a basal phenotype (the combined luminal plus basal and the pure basal) were in a poor prognostic subgroup, typically ER negative in most cases. These findings provide further evidence that breast cancer has distinct differentiation subclasses that have both biological and clinical relevance.     

Sensitivities of Human Monocytes and Epithelial Cells to Pneumolysin Are Different

The Streptococcus pneumoniae pore-forming toxin, pneumolysin, is an important virulence factor in pneumococcal pneumonia. The effect of pneumolysin on human lung epithelial and monocyte cell viability was compared. Pneumolysin caused a dose-dependent loss of viability of human lung epithelial (A549 and L132) and monocyte (U937 and THP-1) cell lines. Analysis of the dose-response curves revealed similar log 50% inhibitory concentration (pIC(50)) values for A549, L132, and THP-1 of 0.12+/- 0.1, 0.02+/- 0.04, and 0.12+/- 0.13 hemolytic units (HU), respectively, but U937 cells showed a significantly greater pIC(50) of 0.42+/- 0.12 HU. Differentiation of A549 and L132 with phorbol ester or THP-1 with gamma interferon had no effect on their sensitivity to pneumolysin. However, a significant decrease in the potency of pneumolysin against U937 cells followed gamma interferon treatment. The Hill slopes of the inhibition curves were greater than unity, indicating that pneumolysin may act with positive cooperativity. Analysis of pneumolysin-treated THP-1 cells by electron microscopy revealed membrane lesions of between 100 and 200 nm in diameter.