Neuronal differentiation in cultures of weaver (wv) mutant mouse cerebellum

In the present study we report for the first time a weaver (wv) gene dose effect on neuron survival and neurite formation in vitro. Dissociated cerebellar cells from postnatal 7- and 8-day-old normal ( + / + ), heterozygous weaver ( + /wv) and homozygous weaver (wv/wv) mice were cultured as monolayers on poly-L-lysine coated glass. Cell death occurred rapidly in wv/wv cultures. Cell counts showed that less than 20% of the total neurons and neuronal precursors (identified by “birthday” radiolabeling techniques) survived by Day 3. Cell death was less extensive in + /wv cultures with 65% of the total neurons and 80% of the precursors surviving by Day 3. In contrast to wv/wv cultures, younger neurons survive better than the total population in + /wv cultures. The impairment of neurite formation over the first week is also proportional to the number of mutant genes as shown by quantitation of (a) the percentage of cells with neurites; (b) the percentage of cells with neurites of a given length class with time; (c) the lengths of the longest processes formed per cell. The mean longest neurite lengths obtained by computer digitization at 6 days in vitro were 41.8, 26.8, and 9.0 μm for + / +, + /wv, and wv/wv granule cells, respectively.     

Systematic review and meta-analysis: rapid diagnostic tests versus placental histology, microscopy and PCR for malaria in pregnant women

Background

To prepare field sites for malaria vaccine trials, it is important to determine baseline antibody and T cell responses to candidate malaria vaccine antigens. Assessing T cell responses is especially challenging, given genetic restriction, low responses observed in endemic areas, their variability over time, potential suppression by parasitaemia and the intrinsic variability of the assays.

Methods

In Part A of this study, antibody titres were measured in adults from urban and rural communities in Ghana to recombinant Plasmodium falciparum CSP, SSP2/TRAP, LSA1, EXP1, MSP1, MSP3 and EBA175 by ELISA, and to sporozoites and infected erythrocytes by IFA. Positive ELISA responses were determined using two methods. T cell responses to defined CD8 or CD4 T cell epitopes from CSP, SSP2/TRAP, LSA1 and EXP1 were measured by ex vivo IFN-γ ELISpot assays using HLA-matched Class I- and DR-restricted synthetic peptides. In Part B, the reproducibility of the ELISpot assay to CSP and AMA1 was measured by repeating assays of individual samples using peptide pools and low, medium or high stringency criteria for defining positive responses, and by comparing samples collected two weeks apart.

Results

In Part A, positive antibody responses varied widely from 17%-100%, according to the antigen and statistical method, with blood stage antigens showing more frequent and higher magnitude responses. ELISA titres were higher in rural subjects, while IFA titres and the frequencies and magnitudes of ex vivo ELISpot activities were similar in both communities. DR-restricted peptides showed stronger responses than Class I-restricted peptides. In Part B, the most stringent statistical criteria gave the fewest, and the least stringent the most positive responses, with reproducibility slightly higher using the least stringent method when assays were repeated. Results varied significantly between the two-week time-points for many participants.

Conclusions

All participants were positive for at least one malaria protein by ELISA, with results dependent on the criteria for positivity. Likewise, ELISpot responses varied among participants, but were relatively reproducible by the three methods tested, especially the least stringent, when assays were repeated. However, results often differed between samples taken two weeks apart, indicating significant biological variability over short intervals.     

Experimental in vitro mechanical characterization of porcine Glisson's capsule and hepatic veins

Understanding the mechanical properties of human liver is the most critical aspect of numerical modeling for medical applications and impact biomechanics. Many researchers work on identifying mechanical properties of the liver both in vivo and in vitro considering the high liver injury percentage in abdominal trauma and for easy detection of fatal liver diseases such as viral hepatitis, cirrhosis, etc. This study is performed to characterize mechanical properties of individual parts of the liver, namely Glisson's capsule and hepatic veins, as these parts are rarely characterized separately. The long term objective of this study is to develop a realistic liver model by characterizing individual parts and later integrating them. In vitro uniaxial quasi-static tensile tests are done on fresh unfrozen porcine hepatic parts for large deformations at the rate of 0.1mm/s with a Bose Electroforce 3200 biomaterials test instrument. Results show that mean values of small strain and large strain elastic moduli are 8.22 ± 3.42 and 48.15 ± 4.5 MPa for Glisson's capsule (30 samples) and 0.62 ± 0.41 and 2.81 ± 2.23 MPa for veins (20 samples), respectively, and are found to be in good agreement with data in the literature. Finally, a non-linear hyper-elastic constitutive law is proposed for the two separate liver constituents under study.     

In vivo liver tissue mechanical properties by Transient Elastography: comparison with Dynamic Mechanical Analysis

Understanding the mechanical properties of human liver is one of the most critical aspects of its numerical modeling for medical applications or impact biomechanics. Generally, model constitutive laws come from in vitro data. However, the elastic properties of liver may change significantly after death and with time. Furthermore, in vitro liver elastic properties reported in the literature have often not been compared quantitatively with in vivo liver mechanical properties on the same organ. In this study, both steps are investigated on porcine liver. The elastic property of the porcine liver, given by the shear modulus G, was measured by both Transient Elastography (TE) and Dynamic Mechanical Analysis (DMA). Shear modulus measurements were realized on in vivo and in vitro liver to compare the TE and DMA methods and to study the influence of testing conditions on the liver viscoelastic properties. In vitro results show that elastic properties obtained by TE and DMA are in agreement. Liver tissue in the frequency range from 0.1 to 4 Hz can be modeled by a two-mode relaxation model. Furthermore, results show that the liver is homogeneous, isotropic and more elastic than viscous. Finally, it is shown in this study that viscoelastic properties obtained by TE and DMA change significantly with post mortem time and with the boundary conditions.     

Expression of ATP6V1C1 during oral carcinogenesis

We investigated the gene and protein expressions of V-type ATPase protein subunit C1 (ATP6V1C1) in cases of oral squamous cell carcinoma (OSCC) and contralateral normal mucosa in smokers, nonsmokers and former smokers. Subjects were separated into five groups of 15: group 1, smokers with OSCC; group 2, normal contralateral mucosa of OSCC patients; group 3, chronic smokers; group 4, former smokers who had stopped smoking 1 year earlier; group 5, individuals who had never smoked. Exfoliative cytology specimens from oral mucosa of smokers, former smokers and nonsmokers showed normal gene and protein expression. We found significantly greater gene expression in the OSCC group than in the nonsmoker groups. No difference in gene expression was observed between normal contralateral mucosa and nonsmoker groups, smoker and nonsmoker groups or former smoker and nonsmoker groups. We observed intense immunostaining for ATP6V1C1 protein in all cases of OSCC and weak or no staining in smoker, former smoker and nonsmoker groups. Significantly greater expression of ATP6V1C1 protein was observed in the OSCC group compared to the other groups, which supports the role of ATP6V1C1 in effecting changes associated with oral cancer. Analysis of the mucosae of chronic smokers, former smokers and the normal contralateral mucosa of patients with OSCC showed unaltered ATP6V1C1 gene and protein expression. Early stages of carcinogenesis, represented by altered epithelium of chronic smokers, had neither gene nor protein alterations as seen in OSCC. Therefore, we infer that the changes in ATP6V1C1 occur during later stages of carcinogenesis. Our preliminary study provides a basis for future studies of using ATP6V1C1 levels for detecting early stage OSCC.     

Evaluation of apoptosis markers in different cell lines infected with equine arteritis virus

Equine arteritis virus (EAV) induces apoptosis in infected cells. Cell death caused by EAV has been studied mainly using three cell lines, BHK-21, RK-13 and Vero cells. The mechanism of apoptosis varies among cell lines and results cannot be correlated owing to differences in EAV strains used. We evaluated different markers for apoptosis in BHK-21, RK-13 and Vero cell lines using the Bucyrus EAV reference strain. Acridine orange/ethidium bromide staining revealed morphological changes in infected cells, while flow cytometry indicated the extent of apoptosis. We also observed DNA fragmentation, but the DNA ladder was detected at different times post-infection depending on the cell line, i.e., 48, 72 and 96 h post-infection in RK-13, Vero and BHK-21 cells, respectively. Measurement of viral titers obtained with each cell line indicated that apoptosis causes interference with viral replication and therefore decreased viral titers. As an unequivocal marker of apoptosis, we measured the expression of caspase-3 and caspases-8 and -9 as extrinsic and intrinsic markers of apoptosis pathways, respectively. Caspase-8 in BHK-21 cells was the only protease that was not detected at any of the times assayed. We found that Bucyrus EAV strain exhibited a distinctive apoptosis pathway depending on the cell line.     

Fifty years of brain tissue mechanical testing: from in vitro to in vivo investigations

Beginning in the 1960s many studies have been performed to investigate the mechanical properties of brain. In this paper we point out the difficulties linked with in vitro experimental protocols as well as the advantages of using recently developed non-invasive in vivo techniques, such as magnetic resonance elastography. Results of in vitro and in vivo work are compared, emphasizing the specificities and disparities of the in vitro as well as the in vivo results. In particular, a detailed discussion of the results obtained from dynamic shear experiments and magnetic resonance elastography is given before arriving at a tentative conclusion on the state of knowledge of the mechanical properties of brain.     

Selective sequestration of iridoid glycosides from their host plants in Longitarsus flea beetles

We investigated in eight species of the flea beetles genus Longitarsus (Coleoptera, Chrysomelidae) whether the beetles take up iridoid glycosides from their host plants of the Lamiaceae, Plantaginaceae, and Scrophulariaceae. Five of the beetle species, L. australis, L. lewisii, L. melanocephalus, L. nigrofasciatus, and L. tabidus, could be shown to sequester iridoid glycosides in concentrations between 0.40 and 1.55% of their dry weight. Eight different iridoid glycosides, acetylharpagide, ajugol, aucubin, catalpol, 8-epi-loganic acid, gardoside, geniposidic acid, and harpagide could be identified in the host plants, yet only aucubin and catalpol are sequestered by the beetles. No iridoid glycosides could be detected in the beetles if neither aucubin nor catalpol were present in the host plant, as in L. minusculus on Stachys recta (acetylharpagide only) and in L. salviae on Salvia pratensis (no iridoid glycosides). In one beetle species, L. luridus, we could not detect any iridoid glycosides although its field host, Plantago lanceolata, had considerable amounts of aucubin and catalpol plus two further iridoids. The five sequestering Longitarsus species differ in their capacity to store the compounds and in their affinity for catalpol relative to aucubin.     

叶绿素b聚集体和它的能化态的性质

叶绿素b由单体聚合成多聚体后吸收光谱明显红移。叶绿素b聚集体膜在光下产生150 mV的光电位,停止照光后此电位消失速度比叶绿素a聚集体膜的慢。叶绿素b聚集体吸收光能后形成相当稳定的能化态,半生命期约几分钟。当聚集体解聚时所吸收的光能又以光的形式辐射出来。叶绿素b聚集体能化态的能量可快速而有效地传给叶绿素a聚集体,以叶绿素a的延迟发光形式释放出来。