Quantifying cell turnover using CFSE data

The CFSE dye dilution assay is widely used to determine the number of divisions a given CFSE labelled cell has undergone in vitro and in vivo. In this paper, we consider how the data obtained with the use of CFSE (CFSE data) can be used to estimate the parameters determining cell division and death. For a homogeneous cell population (i.e., a population with the parameters for cell division and death being independent of time and the number of divisions cells have undergone), we consider a specific biologically based "Smith-Martin" model of cell turnover and analyze three different techniques for estimation of its parameters: direct fitting, indirect fitting and rescaling method. We find that using only CFSE data, the duration of the division phase (i.e., approximately the S+G2+M phase of the cell cycle) can be estimated with the use of either technique. In some cases, the average division or cell cycle time can be estimated using the direct fitting of the model solution to the data or by using the Gett-Hodgkin method [Gett A. and Hodgkin, P. 2000. A cellular calculus for signal integration by T cells. Nat. Immunol. 1:239-244]. Estimation of the death rates during commitment to division (i.e., approximately the G1 phase of the cell cycle) and during the division phase may not be feasible with the use of only CFSE data. We propose that measuring an additional parameter, the fraction of cells in division, may allow estimation of all model parameters including the death rates during different stages of the cell cycle.     

Autoantibodies and hepatitis C virus genotypes in chronic hepatitis C patients in Estonia

AIM: To determine the prevalence of several autoantibodies in chronic hepatitis C patients, and to find out whether the pattern of autoantibodies was associated with hepatitis C virus (HCV) genotypes. METHODS: Sera from 90 consecutive patients with chronic hepatitis C were investigated on the presence of anti-nuclear (ANA), anti-mitochondrial (AMA), anti-smooth muscle (SMA), anti-liver-kidney microsomal type 1 (LKMA1), anti-parietal cell (PCA), anti-thyroid microsomal (TMA), and anti-reticulin (ARA) autoantibodies. The autoantibodies were identified by indirect immunofluorescence. HCV genotypes were determined by a restriction fragment length polymorphism analysis of the amplified 5' noncoding genome region. RESULTS: Forty-six (51.1%) patients were positive for at least one autoantibody. Various antibodies were presented as follows: ANA in 13 (14.4%) patients, SMA in 39 (43.3%), TMA in 2 (2.2%), and ARA in 1 (1.1%) patients. In 9 cases, sera were positive for two autoantibodies (ANA and SMA). AMA, PCA and LKMAI were not detected in the observed sera. HCV genotypes were distributed as follows: 1b in 66 (73.3%) patients, 3a in 18 (20.0%), and 2a in 6 (6.7%) patients. CONCLUSION: A high prevalence of ANA and SMA can be found in chronic hepatitis C patients. Autoantibodies are present at low titre (1:10) in most of the cases. Distribution of the autoantibodies show no differences in the sex groups and between patients infected with different HCV genotypes.     

Defective generation but normal maintenance of memory T cells in old mice

The ability to maintain memory after encounter with antigen is one of the central features of the immune system. Immune memory generated during young age can be maintained well into old age. However, we know little about maintenance of immune memory generated during old age. In this study, we compared generation and maintenance of memory CD8 T cells in young (2-3-month-old) and aged (22-24-month-old) mice following acute lymphocytic choriomeningitis virus infection. We found that young mice made a more vigorous primary T cell response and generated higher levels of memory cells than old mice. However, once generated, memory CD8 T cells were maintained at stable levels in both young and old mice for more than 5 months. Interestingly, the generation of a secondary effector response in vivo was again slightly compromised in the old mice. Taken together, these results show that generation of T cell responses is compromised in old age, but maintenance of the pool of memory T cells is not affected by the aging process.     

Inflicted traumatic brain injury (ITBI) or shaken baby syndrome (SBS) in Estonia

Background: Inflicted traumatic brain injury (ITBI) or shaken baby syndrome (SBS) is recognized as a major cause of disability and death in the paediatric population. Aim: To find out the incidence of ITBI in Estonia. Methods: 26 cases of ITBI were recognized: four children died, 22 survived. Results: Of 26 children, 20 (77%) were boys and six (23%) were girls. Median age at admission to hospital was 3.9 mo, and the boys were younger than the girls. Conclusion: The overall incidence of ITBI was 28.7 per 100 000 infants. In the prospective group the incidence was 40.5 per 100 000, and in retrospective group 13.5 per 100 000. ITBI is not rare but not always a recognized form of child abuse. Healthcare professionals should be more aware of this condition.     

Oribatid Mite Communities on Lichens in Heavily Contaminated Post-Smelting Dumps

In this study, we examined oribatid fauna of strongly contaminated post-smelting dumps (southern Poland) that exist in the substrate and are associated with the most frequent lichen, Cladonia rei. Due to artificial origin of the substrate and the extremely high contamination with heavy metals, the studied dumps are unique in Europe in terms of unfavourable life conditions. In total, 2,936 specimens of Oribatida, representing 50 oribatid species, were sampled on 10 dumps and a reference site. Thalli of C. rei act as an island for soil oribatid mites on extremely contaminated post-smelting dumps. Both abundance and species richness of oribatid fauna collected from C. rei thalli were significantly greater than those recorded in the dump’s substrate. The pool of oribatid species that was able to persist in extremely high doses of heavy metals was comparatively broad. However, only one species, Tectocepheus velatus, was able to achieve high abundances on all dumps. Three different responses of species (tolerant, sensitive, and indifferent) to heavy-metal contamination were recognised. Redundancy analysis indicated that highly increased levels of heavy metals, as well as K content, C/N ratio, and pH value, were the main factors that influence the composition and distribution of species. The concentrations of heavy metals (both essential elements (zinc) as well as xenobiotics (lead, cadmium) in T. velatus from the most contaminated dumps were not increased compared with those observed in moderately contaminated soils.     

The association between pelvic floor muscle function and pelvic girdle pain--a matched case control 3D ultrasound study

There is uncertainty regarding the association between the function of the pelvic floor muscles (PFM) and pelvic girdle pain (PGP), and whether exercises to strengthen the PFM should be recommended for patients with PGP. This one-to-one matched case-control study examined whether there is any difference in voluntary PFM function between women with and without clinically diagnosed PGP. PFM function was assessed by manometry and three-dimensional ultrasound. Images were saved anonymously and analyses were performed offline by one investigator. A special Cox regression model was used to fit a conditional logistic regression procedure for one-to-one matched case-control studies. Forty-nine pairs of women were successfully matched according to age and parity. The study showed no difference in voluntary PFM function measured by palpation, manometry or ultrasound. The size of the levator hiatus area, together with BMI, was significantly associated with PGP. Women with PGP had statistically significantly smaller levator hiatus areas and a tendency for higher vaginal resting pressure compared to the control group. A significantly smaller levator hiatus and a tendency for higher vaginal resting pressure may indicate increased activity of the PFM. Hence, no evidence was found to recommend strengthening exercises for the PFM in patients with PGP. It is important to note that in this study we examined only voluntary contractions and not an automatic response of the PFM to a functional activity.     

Compensatory contribution of Cav2.3 channels to acetylcholine release at the neuromuscular junction of tottering mice

Tottering (Tg) mice carry the mutation P601L in their Cacna1a encoded Cav2.1 channels. Transmitter release at the wild-type neuromuscular junction (NMJ) is almost exclusively mediated by Cav2.1 channels, and we used this model synapse to study synaptic consequences of the Tg mutation. With electrophysiology, and using subtype-specific Cav2 channel-blocking toxins, we assessed a possible compensatory contribution of non-Cav2.1 channels to evoked acetylcholine (ACh) release at Tg NMJs. Release was reduced by approximately 75% by the Cav2.1 channel blocker omega-agatoxin-IVA, which was less than the approximately 95% reduction observed in wild-type. Release at Tg NMJs, but not at wild-type synapses, was reduced by approximately 15% by SNX-482, a Cav2.3 channel blocker. No Cav2.2 channel involvement was found. Probably, there is a small reduction in functional presynaptic Cav2.1 channels at Tg NMJs, which is compensated for by Cav2.3 channels. The remaining Cav2.1 channels are likely to convey enlarged Ca2+ flux, because evoked ACh release at Tg NMJs, at low extracellular Ca2+ concentration, was approximately sixfold higher than at wild-type NMJs. This is the first report of compensatory expression of non-Cav2.1 channels at NMJs of mice with a single amino acid change in Cav2.1.