Cell extract-derived differentiation of embryonic stem cells

Various means have been used to encourage the differentiation of embryonic stem cells (ESCs) toward specific lineages, including growth factor administration, genetic modification, and coculture with relevant cells/tissues. Cell extract-based reprogramming has recently been used to derive mature cells from nonrelated phenotypes. In this communication, we tested whether this in vitro reprogramming approach can be used to direct ESC differentiation. Permeabilized murine ESCs exposed to extracts of murine type II pneumocytes showed increased expression of surfactant protein C and its corresponding mRNA, reflecting enhanced differentiation of pneumocytes. Subsequent differentiation to a type I phenotype was demonstrated by expression of aquaporin 5. Pneumocyte formation occurred quicker than with growth factor-induced differentiation. Our findings establish that ESCs can be differentiated in vitro using cellular extracts. This model provides a tool for analysis of the key factors involved in the differentiation of ESCs to type II pneumocytes.     

Virus-inhibiting surgical glove to reduce the risk of infection by enveloped viruses

Needle puncture and other accidents that occur during surgery and other procedures may lead to viral infections of medical personnel, notably by hepatitis C (HCV) and human immunodeficiency virus (HIV), now that hepatitis B can be prevented by vaccination. A new surgical glove called G-VIR, which contains a disinfecting agent for enveloped viruses, has been developed. Herpes simplex type 1 (HSV) was used as a standard enveloped virus in both in vitro and in vivo tests of the virucidal capacity of the glove. Bovine viral diarrhea virus (BVDV) and feline immunodeficiency virus (FIV) were used as models for HCV and HIV, respectively. For in vitro study, a contaminated needle was passed through a glove and residual virus was titrated; for in vivo studies, animals were stuck with a contaminated needle through a glove. Despite variation in virus enumeration inherent in the puncture technique, statistical evaluation showed that infection was reproducibly and substantially reduced by passage through the virucidal layer. For BVDV, the amount of virus passing through the virucidal glove was reduced in 82% of pairwise comparisons with control gloves that lacked the virucidal agent; when plaque counts were adjusted to a common dilution, the median count for the virucidal glove was on the average reduced >10-fold. In experiments in which the proportion of wells infected with FIV was measured, the ratio of TCID(50) values (control glove to G-VIR) was >15, and probably much higher. For HSV, the amount of virus passing through the virucidal glove was reduced in 81% of comparisons with control gloves; the median of adjusted plaque counts was reduced on the average approximately eightfold or ninefold. In vivo tests with FIV and HSV in cats and mice, respectively, found smaller percentage reductions in infection than the in vitro tests but confirmed the virucidal effect of the gloves.     

Minicircular DNA having sequence homologies with chloroplast DNA in a bleached mutant of Euglena gracilis

Summary Chloroplast DNA was isolated from total cellular DNA of a bleached mutant of Euglena gracilis (Y₃BUD) by enrichment of the light component (p = 1.686) by repeated CsCl equilibrium centrifugations. Electron microscope visualization of this DNA showed minicircular DNA molecules in addition to large circular molecules (42 pm) identical to wild type chloroplast DNA. They were heterogenous in size and their contour lengths ranged from 0.8 to 8.5 m. Fractionnation by agarose gel electrophoresis gave several discrete bands. Some of them hybridized with pure chloroplast DNA and with several cloned chloroplast DNA fragments, particularly to ribosomal fragments, while others did not show homology with chloroplast DNA being probably of extrachloroplatic origin.     

Recombinant VP9-based enzyme-linked immunosorbent assay for detection of immunoglobulin G antibodies to Banna virus (genus Seadornavirus)

Banna virus (BAV, genus Seadornavirus, family Reoviridae) is an arbovirus suspected to be responsible for encephalitis in humans. Two genotypes of this virus are distinguishable: A (Chinese isolate, BAV-Ch) and B (Indonesian isolate, BAV-In6969) which exhibit only 41% amino-acid identity in the sequence of their VP9.The VP7 to VP12 of BAV-Ch and VP9 of BAV-In6969 were expressed in bacteria using pGEX-4T-2 vector. VP9 was chosen to establish an ELISA for BAV, based mainly on two observations: (i). VP9 is a major protein in virus-infected cells and is a capsid protein (ii). among all the proteins expressed, VP9 was obtained in high amount and showed the highest immuno-reactivity to anti-BAV ascitic fluid.The VP9s ELISA was evaluated in three populations: French blood donors and two populations (blood donors and patients with a neurological syndrome) from Malaysia, representing the region where the virus was isolated in the past.The specificity of this ELISA was >98%. In mice injected with live BAV, the assay detected IgG-antibody to BAV infection 21 days post-injection, which was confirmed by Western blot using BAV-infected cells.The VP9 ELISA permits to determine the sero-status of a population without special safety precautions and without any requirements to propagate the BAV. This test should be a useful tool for epidemiological survey of BAV.     

A panel of antibodies for the immunostaining of Bouin's fixed bone marrow trephine biopsies.

AIMS: To assess a panel of antibodies on Bouin's fixed bone marrow trephine (BMT) biopsies. These biopsies are widely used in routine diagnosis of various haematological malignancies and may be the sole material available in many centres; however, information regarding the immunostaining of this material is lacking. METHODS: Biopsies were taken from 72 patients presenting with various haematological malignancies (leukaemia, 38; lymphoma, 14; multiple myeloma, 20). A panel of antibodies was assessed on Bouin's fixed BMT biopsies by the alkaline phosphatase-antialkaline phosphatase method. RESULTS: Three B (MB2, LN-2, Ki-B5) and two T cell lineage antibodies (UCHL-1, CD3-r) reliably identified lymphoid cells, while MPO-r, Leu-M1/CD15, and KP-1/CD68 recognised cells from the myeloid or histiocytic/macrophage series. Reed-Sternberg cells were stained by LN-2, Leu-M1, and CD30. Antibodies specific for plasma cells (VS38) and hairy cells (DBA.44) gave a variable pattern of staining. Among the proliferation markers, proliferative cell nuclear antigen but not Ki-67 related antibodies were effective. CONCLUSION: This study presents a panel of antibodies with reactivity not restricted to common fixatives that are also suitable for Bouin's fixed BMT biopsies.     

Proprioception does not quickly drift during visual occlusion

Several perceptual studies have shown that the ability to estimate the location of the arm degrades quickly during visual occlusion. To account for this effect, it has been suggested that proprioception drifts when not continuously calibrated by vision. In the present study, we re-evaluated this hypothesis by isolating the proprioceptive component of position sense (i.e., the subjects were forced to rely exclusively on proprioception to locate their hand, which was not the case in earlier studies). Three experiments were conducted. In experiment 1, subjects were required to estimate the location of their unseen right hand, at rest, using a visual spot controlled by the left hand through a joystick. Results showed that the mean accuracy was identical whether the localization task was performed immediately after the positioning of the hand or after a 10-s delay. In experiments 2 and 3, subjects were required to point, without vision of their limb, to visual targets. These two experiments relied on the demonstration that biases in the perception of the initial hand location induced systematic variations of the movement characteristics (initial direction, final accuracy, end-point variability). For these motor tasks, the subjects did not pay attention to the initial hand location, which removed the possible occurrence of confounding cognitive strategies. Results indicated that movement characteristics were, on average, not affected when a 15-s or 20-s delay was introduced between the positioning of the arm at the starting point and the presentation of the target. When considered together, our results suggest that proprioception does not quickly drift in the absence of visual information. The potential origin of the discrepancy between our results and earlier studies is discussed.     

Neutralizing antibodies in gene-defective hosts

In a host with a normal immune system and a complete gene defect, the nondefective gene product will be immunogenic. Consequently, neutralizing antibodies against the respective protein can arise either 'spontaneously' or after immunization, as shown in patients and in animal models, such as knockout mice. Accordingly, patients with X-linked or homozygous autosomal gene defects are at risk of developing neutralizing antibodies, in particular after protein substitution or gene therapy. This Review compares and exemplifies the various genetic and immunological contexts that lead to 'neutralizing and generated by gene defect' or 'nagged' antibodies, and outlines implications and solutions for therapeutic strategies.     

Dynamic responses of oxygen uptake at the onset and end of moderate and heavy exercise in trained subjects.

Inconsistencies about dynamic asymmetry between the on- and off-transient responses in VO2 are found in the literature. Therefore the purpose of this study was to examine VO2 on- and off-transients during moderate- and heavy-intensity cycling exercise in trained subjects. Ten men underwent an initial incremental test for the estimation of ventilatory threshold (VT) and, on different days, two bouts of square-wave exercise at moderate (VT) intensities. VO2 kinetics in exercise and recovery were better described by a single exponential model (VT). For moderate exercise, we found a symmetry of VO2 kinetics between the on- and off-transients (i.e., fundamental component), consistent with a system manifesting linear control dynamics. For heavy exercise, a slow component superimposed on the fundamental phase was expressed in both the exercise and recovery, with similar parameter estimates. But the on-transient values of the time constant were appreciably faster than the associated off-transient, and independent of the work rate imposed (VT). Our results do not support a dynamically linear system model of VO2 during cycling exercise in the heavy-intensity domain.     

Presence of a linear plasmid-like DNA molecule in the fungal pathogen Ceratocystis fimbriata Ell. & Halst.

Summary A plasmid-like molecule was detected in a strain of the ascomycete Ceratocystis fimbriata Ell. & Halst., a pathogenic fungus of Populus spp. The DNA replicon, designated pFQ501, was found to have a linear structure with a length of 6.0 kb (3.9 × 10⁶ daltons) and a density of 1.685 g/cc. This molecule was found to be associated with the mitochondria and was isolated from the gel; its restriction map was deduced from single and double digestions.