Scatter factor and hepatocyte growth factor are indistinguishable ligands for the MET receptor.

Scatter Factor (SF) is a fibroblast-secreted protein which promotes motility and matrix invasion of epithelial cells. Hepatocyte Growth Factor (HGF) is a powerful mitogen for hepatocytes and other epithelial tissues. SF and HGF, purified according to their respective biological activities, were interchangeable and equally effective in assays for cell growth, motility and invasion. Both bound with identical affinities to the same sites in target cells. The receptor for SF and HGF was identified as the product of the MET oncogene by: (i) ligand binding and coprecipitation in immunocomplexes; (ii) chemical crosslinking to the Met beta subunit; (iii) transfer of binding activity in insect cells by a baculovirus carrying the MET cDNA; (iv) ligand-induced tyrosine phosphorylation of the Met beta subunit. SF and HGF cDNA clones from human fibroblasts, placenta and liver had virtually identical sequences. We conclude that the same molecule (SF/HGF) acts as a growth or motility factor through a single receptor in different target cells.     

Combined gut‐content and stable isotope trophic analysis of the pelagic stingray Pteroplaytrygon violacea (Bonaparte, 1832) diet from the western North Atlantic Ocean

The understanding of trophic relationships is vital for correctly modeling ecosystems and ecosystem effects of fisheries removals. The pelagic stingray is found in epipelagic sub‐tropical and tropical waters worldwide and is a common bycatch in pelagic longline fisheries. Between August 2008 and November 2011, 156 specimens (81 males; 75 females) were collected during pelagic longline fishing operations in the US South Atlantic Bight and Gulf of Mexico. Stomach content analyses found that the major prey items were cephalopod molluscs (59.18%), followed by actinopterygiian fishes (37.75%), and decapod crustaceans (35.71%). These concentrations of prey items found in the stomachs coincide with previous studies done in the Pacific Ocean. In contrast to previous studies that found high percentages of empty stomachs (63%), the current percentage of empty stomachs was much lower (25.6%), likely due to shorter times between collection and inspection. Stable isotope analysis (δ¹³C and δ¹⁵N) was performed on white muscle in order to correlate the trophic position with gut‐content analysis. The δ¹³C values ranged from ‐18.81‰ to ‐16.70‰, while the δ¹⁵N ranged from 6.11‰ to 11.88‰. Modeling of stable isotope data suggest that while squid are occasionally an important part of the pelagic stingray diet, prey usually consist of shrimp and other pelagic crustaceans. Pelagic stingrays fed within two trophic levels, but their prey appeared to feed on different carbon sources than those found in other pelagic elasmobranchs. A deeper understanding of the pelagic stingray diet sources can help fisheries management as it begins to transition into ecosystem‐based management.     

AT‐101 (R‐(−)‐gossypol acetic acid) enhances the effectiveness of androgen deprivation therapy in the VCaP prostate cancer model

Prostate cancer remains a leading cause of cancer death in American men. Androgen deprivation therapy (ADT) is the most common treatment for advanced prostate cancer patients; however, ADT fails in nearly all cases resulting in castration resistant or androgen‐insensitive (AI) disease. In many cases, this progression results from dysregulation of the pro‐survival Bcl‐2 family proteins. Inhibition of pro‐survival Bcl‐2 family proteins, therefore, may be an effective strategy to delay the onset of AI disease. Gossypol, a small molecule inhibitor of pro‐survival Bcl‐2 family proteins, has been demonstrated to inhibit AI prostate cancer growth. The apoptotic effect of gossypol, however, has been demonstrated to be attenuated by the presence of androgen in a prostate cancer xenograft mouse model (Vertebral Cancer of Prostate [VCaP]) treated with AT‐101 (R‐(?)‐gossypol acetic acid). This study was undertaken to better understand the in vitro effects of androgen receptor (AR) on AT‐101‐induced apoptosis. VCaP cells treated with AT‐101 demonstrated an increase in apoptosis and downregulation of Bcl‐2 pro‐survival proteins. Upon AR activation in combination with AT‐101 treatment, apoptosis is reduced, cell survival increases, and caspase activation is attenuated. Akt and X inhibitor of apoptosis (XIAP) are downregulated in the presence of AT‐101, and AR stimulation rescues protein expression. Combination treatment of bicalutamide and AT‐101 increases apoptosis by reducing the expression of these pro‐survival proteins. These data suggest that combination therapy of AT‐101 and ADT may further delay the onset of AI disease, resulting in prolonged progression‐free survival of prostate cancer patients. J. Cell. Biochem. 110: 1187–1194, 2010. Published 2010 Wiley‐Liss, Inc.     

DNA damage in peripheral blood of patients with chronic obstructive pulmonary disease (COPD)

Chronic obstructive pulmonary disease (COPD) is a condition characterized by chronic airway inflammation and remodeling, lung parenchymal inflammation, and destruction resulting in expiratory airflow obstruction, hyperinflation of the lung with loss of elastic recoil, and impairment of gas exchange. Skeletal muscles in individuals with COPD generate free radicals at rest, and production increases during contractile activity. Overproduction of free radicals may result in oxidant-antioxidant imbalance in favor of oxidants. This study evaluated the levels of genetic damage in peripheral blood of patients with COPD using the cytokinesis-blocked micronucleus (CBMN) and the comet assays. The study was conducted with 25 patients with COPD and 25 controls matched for age and sex. Results of both comet and CBMN assays showed an increase in the level of DNA damage. In the group of patients with COPD, the mean frequency of binucleate cells with micronuclei was 6.72+/-3.02, and in the control group, 4.20+/-2.08 (p=0.00233). Mean comet value was 26.84+/-19.61 in patients with COPD and 7.25+/-7.57 in the control group (p=0.00004). The increased frequency of micronuclei in patients with COPD was primarily assigned to clastogenic events and DNA amplification because the frequency of nucleoplasmic bridges and buds was also increased. Oxidative stress in lung cells is a constant source of free radicals that damage genetic material of both lung and circulating cells.     

Near Surface Swimming of Salmonella Typhimurium Explains Target-Site Selection and Cooperative Invasion

Targeting of permissive entry sites is crucial for bacterial infection. The targeting mechanisms are incompletely understood. We have analyzed target-site selection by S. Typhimurium. This enteropathogenic bacterium employs adhesins (e.g. fim) and the type III secretion system 1 (TTSS-1) for host cell binding, the triggering of ruffles and invasion. Typically, S. Typhimurium invasion is focused on a subset of cells and multiple bacteria invade via the same ruffle. It has remained unclear how this is achieved. We have studied target-site selection in tissue culture by time lapse microscopy, movement pattern analysis and modeling. Flagellar motility (but not chemotaxis) was required for reaching the host cell surface in vitro. Subsequently, physical forces trapped the pathogen for ∼1.5–3 s in “near surface swimming”. This increased the local pathogen density and facilitated “scanning” of the host surface topology. We observed transient TTSS-1 and fim-independent “stopping” and irreversible TTSS-1-mediated docking, in particular at sites of prominent topology, i.e. the base of rounded-up cells and membrane ruffles. Our data indicate that target site selection and the cooperative infection of membrane ruffles are attributable to near surface swimming. This mechanism might be of general importance for understanding infection by flagellated bacteria.     

Host Gut Motility Promotes Competitive Exclusion within a Model Intestinal Microbiota

The gut microbiota is a complex consortium of microorganisms with the ability to influence important aspects of host health and development. Harnessing this “microbial organ” for biomedical applications requires clarifying the degree to which host and bacterial factors act alone or in combination to govern the stability of specific lineages. To address this issue, we combined bacteriological manipulation and light sheet fluorescence microscopy to monitor the dynamics of a defined two-species microbiota within a vertebrate gut. We observed that the interplay between each population and the gut environment produces distinct spatiotemporal patterns. As a consequence, one species dominates while the other experiences sudden drops in abundance that are well fit by a stochastic mathematical model. Modeling revealed that direct bacterial competition could only partially explain the observed phenomena, suggesting that a host factor is also important in shaping the community. We hypothesized the host determinant to be gut motility, and tested this mechanism by measuring colonization in hosts with enteric nervous system dysfunction due to a mutation in the ret locus, which in humans is associated with the intestinal motility disorder known as Hirschsprung disease. In mutant hosts we found reduced gut motility and, confirming our hypothesis, robust coexistence of both bacterial species. This study provides evidence that host-mediated spatial structuring and stochastic perturbation of communities can drive bacterial population dynamics within the gut, and it reveals a new facet of the intestinal host–microbe interface by demonstrating the capacity of the enteric nervous system to influence the microbiota. Ultimately, these findings suggest that therapeutic strategies targeting the intestinal ecosystem should consider the dynamic physical nature of the gut environment.     

The labeling of lipoproteins for studies of cellular binding with a fluorescent lipophilic dye.

N,N-dipentadecylaminostyrylpyridinium iodide is a dye that is approximately 100-fold more intensely fluorescent in a lipid than aqueous environment. This observation suggests its potential as a fluorescence stain for lipoproteins. This work reports the staining of LDL with this dye for use in studies of cellular binding. The staining procedure is simple, resulting in stable attachment of the dye as determined by transfer experiments, physical properties essentially identical to native LDL as demonstrated by virtually identical electrophoretic mobility, and consistent results in studies of cellular binding using flow cytometry. Increased signal to noise ratio over other dyes used for lipoprotein staining including the widely used Dil (3,3'-dioctadecylindocarbocyanine iodide) allows determinations of greater sensitivity and precision to be made. This is demonstrated by the flow cytometric determination of the 4 degrees C binding curve of LDL with freshly isolated human peripheral blood lymphocytes (i.e., cells not LDL receptor upregulated). Mediation of binding by the LDL receptor is demonstrated by correspondence between the LDL receptor dissociation constant derived from this work and literature values; increased specific binding in lymphocytes cultured in lipoprotein-deficient media to up-regulate the LDL receptor; and decreased specific binding in lymphocytes cultured in the presence of 25-hydroxy cholesterol for 48 h to suppress the LDL receptor.     

Why do women stop reproducing before menopause? A life-history approach to age at last birth

Evolutionary biologists have long considered menopause to be a fundamental puzzle in understanding human fertility behaviour, as post-menopausal women are no longer physiologically capable of direct reproduction. Menopause typically occurs between 45 and 55 years of age, but across cultures and history, women often stop reproducing many years before menopause. Unlike age at first reproduction or even birth spacing, a woman nearing the end of her reproductive cycle is able to reflect upon the offspring she already has—their numbers and phenotypic qualities, including sexes. This paper reviews demographic data on age at last birth both across and within societies, and also presents a case study of age at last birth in rural Bangladeshi women. In this Bangladeshi sample, age at last birth preceded age at menopause by an average of 11 years, with marked variation around that mean, even during a period of high fertility. Moreover, age at last birth was not strongly related to age at menopause. Our literature review and case study provide evidence that stopping behaviour needs to be more closely examined as an important part of human reproductive strategies and life-history theory. Menopause may be a final marker of permanent reproductive cessation, but it is only one piece of the evolutionary puzzle.     

Safety and Efficacy of At-Home Robotic Locomotion Therapy in Individuals with Chronic Incomplete Spinal Cord Injury: A Prospective,Pre-Post Intervention,Proof-of-Concept Study

Background

The compact Motorized orthosis for home rehabilitation of Gait (MoreGait) was developed for continuation of locomotion training at home. MoreGait generates afferent stimuli of walking with the user in a semi-supine position and provides feedback about deviations from the reference walking pattern.

Objective

Prospective, pre-post intervention, proof-of-concept study to test the feasibility of an unsupervised home-based application of five MoreGait prototypes in subjects with incomplete spinal cord injury (iSCI).

Methods

Twenty-five (5 tetraplegia, 20 paraplegia) participants with chronic (mean time since injury: 5.8 ± 5.4 (standard deviation, SD) years) sensorimotor iSCI (7 ASIA Impairment Scale (AIS) C, 18 AIS D; Walking Index for Spinal Cord Injury (WISCI II): Interquartile range 9 to 16) completed the training (45 minutes / day, at least 4 days / week, 8 weeks). Baseline status was documented 4 and 2 weeks before and at training onset. Training effects were assessed after 4 and 8 weeks of therapy.

Results

After therapy, 9 of 25 study participants improved with respect to the dependency on walking aids assessed by the WISCI II. For all individuals, the short-distance walking velocity measured by the 10-Meter Walk Test showed significant improvements compared to baseline (100%) for both self-selected (Mean 139.4% ± 35.5% (SD)) and maximum (Mean 143.1% ± 40.6% (SD)) speed conditions as well as the endurance estimated with the six-minute walk test (Mean 166.6% ± 72.1% (SD)). One device-related adverse event (pressure sore on the big toe) occurred in over 800 training sessions.

Conclusions

Home-based robotic locomotion training with MoreGait is feasible and safe. The magnitude of functional improvements achieved by MoreGait in individuals with iSCI is well within the range of complex locomotion robots used in hospitals. Thus, unsupervised MoreGait training potentially represents an option to prolong effective training aiming at recovery of locomotor function beyond in-patient rehabilitation.

Trial Registration

German Clinical Trials Register (DKRS) DRKS00005587