Interaction of B7RP-1 with ICOS Negatively Regulates Antigen Presentation by B Cells

Stimulation of T cells through the T cell receptor is insufficient for optimal T cell activation. A second activation signal is necessary, being usually provided by the costimulatory molecule CD28. Recently, additional costimulatory pathways have been identified, including inducible costimulator (ICOS) and its ligand B7RP-1. We have examined the role of the B7RP-1/ICOS costimulatory pathway on antigen presentation by B cells, using the I-A^k and I-E^k-positive CH27 B cell line and several different T cell lines. We found that CH27 expressed B7RP-1 and PD-L1 whereas the T cell lines expressed ICOS and PD-1. In the presence of HEL, the T cell hybridomas C10 and 3A9 released IL-2, which is indicative of antigen-specific T cell activation by the CH27 cells. Unexpectedly, blocking antibodies for B7RP-1 and ICOS enhanced the IL-2 response in both T cells. As expected, an increase in the production of IL-2 was seen when blocking antibodies for PD-1 were used. Blocking with antibodies for I-A^k, CD28, B7.1, and B7.2 lead to a decrease in IL-2 production. Additionally we tested a Th1 and a Th2 T cell clone. Blockade of B7RP-1/ICOS lead to an increased IFN- response in Th1 cells (A.E7) and an increased IL-4 response in Th2 cells (D10.G4.1). Intracellular staining also showed an increase in cytokine production when the B7RP-1/ICOS pathway was blocked. In conclusion, the B7RP-1/ICOS pathway is negatively regulating T cell activation by B cells and may play a role similar to that of the PD-L1/PD-1 pathway.     

Differential histochemical peanut agglutinin stain in benign and malignant human prostate tumors: Relationship with prostatic specific antigen immunostain and nuclear DNA content

The histochemical binding pattern of the peanut (Arachis hypogaea) lectin (PNA) was quantitatively described by means of computer-assisted microscope analysis in 28 benign prostatic hyperplasias (BPH), 15 prostatic intraepithelial neoplasias (PIN), and 119 prostatic adenocarcinomas. PNA exhibits noninunune but selective binding to glycoproteins with β-D-galactosyl(1,3)-N-acetyl-D-galactosamine residues. We also investigated whether a relationship existed between the number of histochemical-related PNA acceptors and the histochemical prostate-specific antigen (PSA) stain intensity, and between the number of PNA receptors and DNA ploidy level. The results show that neoplastic prostate tissues and high-grade intraepithelial prostatic neoplasias (PIN2_3) exhibit a significantly higher number of PNA acceptors than benign prostatic hyperplasias and low (PIN1) grade prostatic intraepithelial neoplasias. A statistically significant correlation was observed between the number of histochemically related PNA acceptors and PSA immunostain intensity. Lastly, diploid prostatic tumors, whether benign or malignant, exhibited a significantly higher number of PNA acceptors than aneuploid ones. These results suggest that PNA acceptors play an important role in the biology of prostate tumors.     

Mutational pattern of influenza B viruses adapted to high growth replication in embryonated eggs

Improved replication of influenza viruses in embryonated chicken eggs (CE) permits increased vaccine production and availability. We investigated the growth properties of influenza B viruses in relation to specific mutations occurring after serial passage in CE. In serial passage experiments yielding high growth variants of B/Victoria/504/2000, mutations predicted to alter amino acid (AA) composition occurred only near the receptor-binding pocket of the hemagglutinins (HA) and in no other genes. Two B/Victoria/504/2000 high growth variants had the same AA substitutions in HA (R162M and D196Y), but the higher yield variant had a third substitution (G141E), which also altered antigenic characteristics. In a serial passage experiment yielding a high growth variant of B/Hong Kong/330/2001, mutations predicted to alter AA composition occurred only in PB2 and NP in domains predicted to relate to RNP formation and function. Our results indicate that adaptation of influenza B viruses to high-yield replication by serial passage in CE requires few mutations either in internal or external genes. Specific modifications of genes or a combination of genes could be used to optimize or create influenza B viruses for specific growth substrates.     

Genetic linkage analysis identifies new proximal and distal flanking markers for the X-linked agammaglobulinemia gene locus, refining its localization in Xq22

Genetic linkage analysis has been instrumental in mapping thegene for X-linked agammaglobulinemia (XLA) to the proximal longarm of the human X chromosome, to Xq22. Due to the relativerarity of this disease the localization of the gene within Xq22has remained imprecise. We have investigated twenty-nine familiesaffected by XLA and have found no recombinants with the DXS178locus in over 30 informative meioses. DXS178 is now the mostreliable and informative locus for use in pre-natal diagnosisand carrier detection of XLA. In addition, we have identifiednew closely linked proximal and distal flanking markers forXLA, DXS442 and DXS101, respectively. These loci are separatedby 2cM, considerably reducing the extent of DNA within whichthe XLA locus can be contained. This will open up the way formore directed positional cloning efforts for the isolation ofthe XLA gene.     

The early phase of experimental acute renal failure

Experiments were conducted to establish whether diminished solute reabsorption in the loop of Henle during acute renal failure could explain the loss of urinary concentration and participate in generating a tubuloglomerular feedback-mediated reduction in filtration rate. The electrolyte content of the fluid in the ascending limb of the loop of Henle was determined in situ by monitoring its electrical conductivity after propulsion into the distal tubule with a sudden burst perfusion. The value of the minimum electrolyte concentration decreased exponentially with increasing equilibration time, reaching a steady-state value equivalent to 27±9 mM NaCl in normal kidneys, 34±15 mM in mercuric chloride kidneys and 53±22 mM following ischaemia. A mathematical model was derived to describe the process of sodium chloride dilution from which it was possible to calculate both the permeability and transport velocity of the cortical thick ascending limb. In the normal kidney, the transport velocity was calculated to be 4.65±0.92 ·10^–5 cm/s, a value not significantly different from that of the mercuric chloride or ischaemic kidneys, and the estimated permeability was 1.13±0.52·10^–5 cm/s, not different from that of the mercuric chloride kidneys but significantly lower than that calculated for the ischaemic kidneys. It is concluded that for the more severely damaged ischaemic model, the loss of urinary concentrating ability was accompanied by a reduction in diluting ability of the ascending limb of the short loop of Henle, which appears to be due, at least in part, to an elevation of the passive permeability to sodium chloride in this segment.     

On the peripheral bladder control system of the dog and urodynamics:In vivo characterisation and hybrid computer simulation

A quantitative model of the peripheral bladder control system of the dog is developed. This model is based on the experimental characterisation of the detrusor muscle and the urethra in 25 female dogs. Intravesical pressure, urinary flow and bladder volume were simultaneously recorded during electrical bladder stimulation, and, from these data, a dynamic model of the bladder control system has been deduced. A general equation for predicting urinary flow patterns is developed, and the hybrid computer EAI-690 is used to simulate the evacuation of the bladder. The effect of different parameters of the system on the micturition pattern is investigated in detail. This work may have interesting clinical applications: for example, in the development of adequate techniques for the evacuation of the paraplegic bladder. Also, the experimental procedures elaborated in this study could be applied in the diagnosis of bladder function and urethral obstruction. Indeed, we have been able to characterise the detrusor muscle and the urethra independently using clinically accessible variables.     

Functional magnetic resonance imaging evidence for binocular interactions in human visual cortex

Using functional magnetic resonance imaging (fMRI), we explored the binocular interactions occurring when subjects viewed dichoptically presented checkerboard stimuli. A flickering radial checkerboard was presented to each eye of the subject, while T2*-weighted images were acquired over the visual cortex with gradient-echo, echoplanar sequences. We compared responses in striate and extrastriate visual cortex under four conditions: both eyes were stimulated at the same time (binocular condition), each eye was stimulated in alternation (monocular condition) or first the one eye then the other eye was stimulated (left eye first - right eye trailing, or vice versa). The results indicate that only the striate area, in and near the calcarine fissure, shows significant differences for these stimulation conditions. These differences are not evident in more remote extrastriate or associational visual areas, although the BOLD response in the stimulation-rest comparison was robust. These results suggest that the effect could be related to inhibitory interactions across ocular dominance columns in striate visual cortex.     

Neuronal apoptosis in the dentate gyrus in humans with subarachnoid hemorrhage and cerebral hypoxia

Apoptosis of dentate granule cells is a typical feature of several animal models of disease. In 20 autopsy cases of subarachnoid hemorrhage (SAH) and global cerebral hypoxia caused by protracted shock or respiratory failure, we evaluated by light microscopy and in situ tailing whether this pattern of neuronal damage also occurs in humans. In subarachnoid hemorrhage, 4.0/mm2 (0-13.0/mm2) apoptotic neurons were observed in the dentate gyrus, in cerebral hypoxia 3.6/mm2 (0-19.9/mm2) (p>0.05), and in 10 aged-matched control cases dying rapidly from non-neurological diseases 0/mm2 (0-0/mm2) (median [range]) (p<0.001 versus SAH and hypoxia). Neuronal apoptosis in the dentate gyrus was most frequent, when death occurred later than 24 hours and less than 11 days after disease onset. Neuronal damage in the hippocampus was always necrotic. It was more severe in hypoxia than in SAH (median neuronal damage score 3 [range: 0-3] versus 0 [0-3], p<0.001). Apoptosis appears to be the predominant mechanism of death in dentate granule cells irrespective of the underlying disease, whereas neuronal death in the hippocampus generally is of necrotic morphology.