Contractility of single human dermal myofibroblasts and fibroblasts

Human dermal myofibroblasts, characterised by the expression of alpha-smooth muscle actin, are part of the granulation tissue and implicated in the generation of contractile forces during normal wound healing and pathological contractures. We have compared the contractile properties of single human dermal fibroblasts and human dermal myofibroblasts by culturing them on flexible silicone elastomers. The flexibility of the silicone substratum permits the contractile forces exerted by the cells to be measured [Fray et al., 1998: Tissue Eng. 4:273-283], without changing their expression of alpha-smooth muscle actin. The mean contractile force produced by myofibroblasts (2.2 microN per cell) was not significantly different from that generated by fibroblasts (2.0 microN per cell) when cultured on a substrata with a low elastomer stiffness. Forces produced by fibroblasts were unaffected by increases in elastomer stiffness, but forces measured for myofibroblasts increased to a mean value of 4.1 microN/cell. This was associated with a higher proportion of myofibroblasts being able to produce wrinkles on elastomers of high stiffness compared to fibroblasts. We discuss the force measurements at the single cell level, for both fibroblast and myofibroblasts, in relation to the proposed role of myofibroblasts in wound healing and pathological contractures.     

The Bacillus subtilis cell division proteins FtsL and DivIC are intrinsically unstable and do not interact with one another in the absence of other septasomal components

The bacterial septum appears to comprise a macromolecular assembly of essential cell division proteins (the 'septasome') that are responsible for physically dividing the cell during cytokinesis. FtsL and DivIC are essential components of this division machinery in Bacillus subtilis. We used yeast two-hybrid analysis as well as a variety of biochemical and biophysical methods to examine the proposed interaction between Bacillus subtilis FtsL and DivIC. We show that FtsL and DivIC are thermodynamically unstable proteins that are likely to be unfolded and therefore targeted for degradation unless stabilized by interactions with other components of the septasome. However, we show that this stabilization does not result from a direct interaction between FtsL and DivIC. We propose that the observed interdependence of DivIC and FtsL stability is a result of indirect interactions that are mediated by other septasomal proteins.     

Tranexamic acid for the prevention of postpartum bleeding in women with anaemia: study protocol for an international,randomised, double-blind,placebo-controlled trial

Background

Postpartum haemorrhage (PPH) is responsible for about 100,000 maternal deaths every year, most of which occur in low- and middle-income countries. Tranexamic acid (TXA) reduces bleeding by inhibiting the enzymatic breakdown of fibrin blood clots. TXA decreases blood loss in surgery and reduces death due to bleeding after trauma. When given within 3 h of birth, TXA reduces deaths due to bleeding in women with PPH. However, for many women, treatment of PPH is too late to prevent death. Over one third of pregnant women in the world are anaemic and many are severely anaemic. These women have an increased risk of PPH and suffer more severe outcomes if PPH occurs. There is an urgent need to identify a safe and effective way to reduce postpartum bleeding in anaemic women.

Methods/design

The WOMAN-2 trial is an international, multicentre, randomised, double-blind, placebo-controlled trial to quantify the effects of TXA on postpartum bleeding in women with moderate or severe anaemia. Ten thousand women with moderate or severe anaemia who have given birth vaginally will be randomised to receive 1?g of TXA or matching placebo by intravenous injection immediately (within 15?min) after the umbilical cord is cut or clamped. The primary outcome is the proportion of women with a clinical diagnosis of primary PPH. The cause of PPH will be described. Data on maternal health and wellbeing, maternal blood loss and its consequences, and other health outcomes will be collected as secondary outcomes. The main analyses will be on an ‘intention-to-treat’ basis, irrespective of whether the allocated treatment was received. Results will be presented as appropriate effect estimates with a measure of precision (95% confidence intervals). Subgroup analyses will be based on the severity of anaemia (moderate versus severe) and type of labour (induced or augmented versus spontaneous). A study with 10,000 patients will have over 90% power to detect a 25% relative reduction from 10 to 7.5% in PPH. The trial will be conducted in hospitals in Africa and Asia.

Discussion

The WOMAN-2 trial should provide reliable evidence for the effects of TXA for preventing postpartum bleeding in women with anaemia.

Trial registration

ISRCTN, ISRCTN62396133. Registered on 7 December 2017;ClincalTrials.gov, ID: NCT03475342. Registered on 23 March 2018.

     

Ecological foundations for subsistence strategies among the Mbuti Pygmies

To date, no wholly satisfactory explanation has been proposed for the division of the Mbuti Pygmies into two types of hunting economies: net hunters to the southwest and archers to the northeast. Examination of the literature suggests that this economic subdivision may rest on differences in seasonality and overall patterns of wild food availability between the southwestern and northeastern sectors of the Ituri Forest. The southwestern sector is described as consisting of almost pure stands of the leguminous tree species, Gilbertiodendron dewevrei, growing on white sand soils. This area appears to be floristically (and probably faunistically) less diverse than the north-eastern area. Perhaps in response to relatively low availability of human food, Pygmy bands in the southwest have turned to net hunting and a subsistence economy resting on the meat trade in order to secure a dependable, high-quality source of dietary energy on a year-round basis. Conversely, in the less seasonal and apparently more diverse and dietarily productive north-east, Pygmy bands may face less variation in food availability and therefore be under less pressure to alter their traditional hunting and gathering lifestyle.     

Delivery after caesarean section: review of 2176 consecutive cases.

A total of 2176 consecutive patients who had had one previous caesarean section were studied retrospectively. A repeat elective caesarean section was performed in 395 (18.2%). Labour started spontaneously in 1363 patients, 301 of whom were given oxytocin to accelerate inert labour, and was induced by amniotomy and infusion of oxytocin in 418 women; 1618 of these 1781 patients (90.8%) delivered vaginally. Patients who had had a previous vaginal delivery were more likely to deliver vaginally again. Those women in whom the initial caesarean section had been performed during labour before the cervix was 4 cm dilated were less likely to deliver vaginally than those who had progressed further in labour or those who had had an elective caesarean section. Similarly, those who received oxytocin to stimulate inert labour were more likely to require a repeat caesarean section than those who did not. The uterine scar ruptured in only eight (0.45%) of the 1781 patients allowed into labour. The risk of rupture of the scar was not increased by the use of oxytocin alone either to induce or to accelerate labour. The combination of oxytocin to accelerate labour and epidural analgesia to provide pain relief, however, was associated with an increased incidence of scar rupture. Labour may be safely allowed in women who have had a previous caesarean section, most of whom will deliver vaginally. Induction of labour does not increase the risk of either a repeat caesarean section or rupture of a uterine scar.     

Autophosphorylation of type II CaM kinase in hippocampal neurons: localization of phospho- and dephosphokinase with complementary phosphorylation site-specific antibodies.

We have visualized the distribution of autophosphorylated type II CaM kinase in neural tissue with the use of two complementary antibodies: a monoclonal antibody that binds to the alpha and beta subunits of the kinase only when they are autophosphorylated at threonine-286 (287 in beta) and affinity-purified rabbit antibodies that bind to both subunits only when they are not phosphorylated at these residues. We used these antibodies to double-label organotypic hippocampal cultures, detecting the mouse monoclonal antibody with rhodamine and the rabbit polyclonal antibodies with fluorescein. In double-exposed photographs, the ratios of intensities of the two fluorophores revealed the relative proportion of autophosphorylated and nonphosphorylated kinase in individual neurons throughout the cultures. We found that autophosphorylated and nonphosphorylated kinase are colocalized throughout most neurons rather than segregated within distinct cells or subcellular domains. However, the variations in intensity of the two fluorophores indicated that the proportion of autophosphorylated kinase is consistently higher in neuronal somas than in the neuropil. Incubation of the cultures in Ca2+ free medium dramatically reduced both the level of autophosphorylated kinase detected biochemically and the relative intensity of fluorescent staining with the phosphokinase specific monoclonal antibody. These results support the hypothesis that regulation of Ca(2+)-independent CaM kinase activity in vivo occurs by a dynamic equilibrium between autophosphorylation and dephosphorylation and that this equilibrium is maintained, at varying steady-state levels, in all parts of neurons.     

Genetic variability in the tumor necrosis factor-lymphotoxin region influences susceptibility to rheumatoid arthritis.

The major histocompatibility complex class III tumor necrosis factor-lymphotoxin (TNF-LT) region (6p21.3) was investigated as a possible susceptibility locus for rheumatoid arthritis (RA). Inheritance of five TNF microsatellite markers was determined in 50 multiplex families. Overall, 47 different haplotypes were observed. One of these, the TNF a6, b5, c1, d3, e3 (H1) haplotype, was present in 35.3% of affected, but in only 20.5% of unaffected, individuals (P < .005). This haplotype accounted for 21.5% of the parental haplotypes transmitted to affected offspring and only 7.3% not transmitted to affected offspring (P = .0003). The TNF a6 and TNF c1 alleles were individually associated with RA (P = .0005 and .0008, respectively), as were the HLA-DRB1 "shared epitope" (SE) (P = .0001) and HLA-DRB1*0401 (P = .0018). Both univariate and bivariate conditional logistic regression analysis showed significant effects of TNF c1 and SE in increasing risk to RA (P < .001). Stratification by the presence of SE indicated an independent effect of the TNFc1 allele (P = .0003) and the HLA A1, B8, DR3 extended haplotype (always TNFa2, b3, c1, d1, e3) (P = .0027) in SE heterozygotes, while the H1 haplotype was associated with RA in SE homozygotes (P = .0018). The TNF-LT region appears to influence susceptibility to RA, distinct from HLA-DR.     

Modified Behavior in Baculovirus-Infected Lepidopteran Larvae and Its Impact on the Spatial Distribution of Inoculum

Quantifying the rate of dispersal of target insects when infected with a disease agent will aid the development of biorational pest control programs. The effect of nucleopolyhedrovirus (NPV) infection on the mobility of second and fourth instarMamestra brassicaelarvae was investigated in the laboratory and field. NPV infection altered larval mobility, with the changes in behavior varying with the timecourse of infection. Diseased larvae moved three to five times further than healthy ones during the middle stages of infection. By the 7th day postinfection diseased larvae were less mobile than healthy counterparts. The same pattern of modified behavior was observed in both instars. Fourth instar larvae moved further than second instars under laboratory and field conditions. In the field, infected larvae tended to die on the apex of the cabbage leaves. Bioassay of the leaves showed a linear decrease in inoculum from central to peripheral plants within the plots, which occurred to the same extent for second and fourth instars. Leaves from plots where infected fourth instar larvae had been introduced had higher inoculum density than those from plots with second instars.