CD4+ T cell responses in mice lacking MHC class II molecules specifically on B cells

The role of B lymphocytes in initiating and maintaining a CD4+ T cell response has been examined using a variety of strategies, but remains controversial because of weaknesses inherent to each of the approaches. Here, we address this issue by measuring CD4+ T cell priming both in mutant mice devoid of B cells and in chimeric animals lacking major histocompatibility complex class II molecules specifically on B cells. We find that peptide and some protein antigens do not require B cells expressing class II molecules, nor B cells themselves, to efficiently prime. This could be demonstrated by the usual lymph node proliferation assay, a rather indirect in vitro measure of priming, and by a direct ex vivo assay of population expansion and activation marker expression. Interestingly, one protein antigen, conalbumin, could not prime in the absence of B cells, but could in the presence of B cells devoid of class II molecules. This finding constrains the possible mechanisms whereby B lymphocytes contribute to the initiation of a CD4+ T cell response, arguing against the importance of surface immunoglobulin-mediated antigen presentation by B cells.     

Isolation of xanthan from Xanthomonas campesteris B-1459 in mechanically agitated fermentors

Xanthan production from Xanthomonas campestris was studied by a mechanically shaken fermentor. Influence of glucose concentration, aeration of culture media, rheology of broths and pH control was evaluated. Different aeration conditions based on variation of stirring rates were assayed. Substrate concentration was determined according to the Miller method, and polymer production was performed by the Cadmus method. The higher xanthan levels (i.e. 2.3%) were obtained at 750 rpm, with 1 v/v. min. In such conditions, viscosity ranges about 7000 cPoise and a low level of dissolved oxygen were detected in the culture medium. Xanthan production was influenced by the glucose concentration and the presence of amaranth within the culture medium. In the processes wherein an automatic control of pH was performed, the polymer concentration did not increase regarding to processes involving regular pH evolution.     

Biased suppression of hematopoiesis and multiple developmental defects in chimeric mice containing Shp-2 mutant cells

Shp-2 is a cytoplasmic tyrosine phosphatase that contains two Src homology 2 (SH2) domains at the N terminus. Biochemical data suggests that Shp-2 acts downstream of a variety of receptor and cytoplasmic tyrosine kinases. A targeted deletion mutation in the N-terminal SH2 (SH2-N) domain results in embryonic lethality of homozygous mutant mice at midgestation. In vitro embryonic stem (ES) cell differentiation assays suggest that Shp-2 might play an important role in hematopoiesis. By aggregating homozygous mutant (Shp-2(-/-)) ES cells and wild-type (WT) embryos, we created Shp-2(-/-)-WT chimeric animals. We report here an essential role of Shp-2 in the control of blood cell development. Despite the widespread contribution of mutant cells to various tissues, no Shp-2(-/-) progenitors for erythroid or myeloid cells were detected in the fetal liver and bone marrow of chimeric animals by using the in vitro CFU assay. Furthermore, hematopoiesis was defective in Shp-2(-/-) yolk sacs. In addition, the Shp-2 mutation caused multiple developmental defects in chimeric mice, characterized by short hind legs, aberrant limb features, split lumbar vertebrae, abnormal rib patterning, and pathological changes in the lungs, intestines, and skin. These results demonstrate a functional involvement of Shp-2 in the differentiation of multiple tissue-specific cells and in body organization. More importantly, the requirement for Shp-2 is more stringent in hematopoiesis than in other systems.     

Influence of timing on the dosimetric analysis of transperineal ultrasound-guided, prostatic conformal brachytherapy

Postoperative computed tomography (CT)-based dosimetric analysis of transperineal ultrasound-guided conformal prostate brachytherapy provides detailed information regarding the coverage and uniformity of the implant. However, there is no generally accepted standard for the optimal timing of the postoperative dosimetry. This report details dosimetric analysis and the effect of timing based upon CT and orthogonal film evaluation for ten unselected patients implanted with either iodine-125 (125I) or palladium-103 (103Pd). Within 2 hours after implantation, patients underwent a CT scan and the first of four sequential sets of orthogonal films. Subsequent orthogonal films were obtained on days 3, 14, and 28 postimplant. CT-based dosimetry revealed coverage of the prostate to the prescribed minimal peripheral dose (mPD) at 93.1 +/- 3.6% of the volume, the prostate volume receiving 150% of mPD was 38.2 +/- 8.7%, and the urethral and rectal doses were 114 +/- 12% and 78 +/- 19% of mPD, respectively. The implanted seeds seen on orthogonal films acted as markers for temporal changes in prostate dimensions, and the standard deviation of each dimension was used as input in an ellipsoidal volume calculation. Seed coordinates were self normalized to the center of gravity of each two-dimensional view and were measured relative to the linear regression line in the superior-inferior direction. The reproducibility of the anteroposterior (AP) film setup in terms of temporal variation in the angle of the regression line was markedly better than that of the lateral films, 1.8 degrees +/- 1.2 degrees vs. 4.3 degrees +/- 2.6 degrees, respectively. Dimensional contraction from day 0 to day 28 averaged 11.3% in the superior-inferior direction, 8.5% in the AP/PA (posteroanterior) direction, and 2.5% in the right-left lateral direction. This translated into a volume change of 20.9% (ranged 11.6-31.6%), which was determined by using the ellipsoid method. The half-life for edema resolution was 10.6 +/- 1.8 days (range 8.6-14.3 days). However, because of variability in the degree and extent of edema and its rate of resolution, we believe that it may be futile to define a single point in time as the most accurate indicator of the postoperative dose distribution. Rather, it may be preferable to accept universal standardization of timing and methodology for CT-based postoperative dosimetry, which would facilitate comparison of results between centers and maximize the information content of that single measurement. We conclude that day 0 represents the optimal time, because dosimetric evaluation at that time minimizes patient discomfort and inconvenience (a catheter is already in place), provides information about edema when it is near its maximum extent, and provides prompt closure of the learning loop and, as such, hopefully will result in improved implantation techniques and results.     

Validation of the in vivo intravascular ultrasound measurement of in-stent neointimal hyperplasia volumes

OBJECTIVES: This study was undertaken to validate the in vivo intravascular ultrasound (IVUS) measurement of in-stent neointimal hyperplasia (IH) volumes. BACKGROUND: Because stents reduce restenosis compared to balloon angioplasty, stent use has increased significantly. As a result, in-stent restenosis is now an important clinical problem. Serial IVUS studies have shown that in-stent restenosis is secondary to intimal hyperplasia. To evaluate strategies to reduce in-stent restenosis, accurate measurement of in-stent neointimal tissue is important. METHODS: Using a porcine coronary artery model of in-stent restenosis, single Palmaz-Schatz stents were implanted into 16 animals with a stent:artery ratio of 1.3:1. Intravascular ultrasound imaging was performed at 1 month, immediately prior to animal sacrifice. In vivo IVUS and ex vivo histomorphometric measurements included stent, lumen and IH areas; IH volumes were calculated with Simpson's rule. RESULTS: Intravascular ultrasound measurements of IH (30.4+/-11.0 mm3) volumes correlated strongly with histomorphometric measurements (26.7+/-8.5 mm3, r=0.965, p < 0.0001). The difference between the IVUS and the histomorphometric measurements of IVUS volume was 4.1+/-2.7 mm3 or 15.8+/-11% (standard error of the estimate=0.7). Both histomorphometry and IVUS showed that IH was concentric and uniformly distributed over the length of the stent. Intravascular ultrasound detected neointimal thickening of < or =0.2 mm in 5 of 16 stents. Sample size calculations based on the IVUS measurement of IH volumes showed that 12 stented lesions/arm would be required to show a 50% reduction in IVUS-measured IH volume and 44 stented lesions/arm would be required to show a 25% reduction in IH volume. CONCLUSION: In vivo IVUS measurement of IH volumes correlated strongly with ex vivo histomorphometry. Using volumetric IVUS end points, small sample sizes should be necessary to demonstrate effectiveness of strategies to reduce in-stent restenosis.     

Personality and social change: individual differences, life path, and importance attributed to the women's movement

This article identifies antecedent characteristics of individuals who found the women's movement important and then shows how finding it important was associated with personality change. Eighty-six women provided personality and life data as college seniors in 1958 or 1960, prior to the onset of the women's movement, and in 1981, after the movement gained momentum. A combination of openness, ambition, and dissatisfaction, as assessed by California Psychological Inventory (CPI; H. Gough, 1957/1966) in college, and subsequent life path from ages 28 to 43 significantly predicted importance attributed to the women's movement (IWM). On CPI scales, IWM was associated with significant increases on scales including Dominance, Self-Acceptance, Empathy, Psychological Mindedness, and Achievement via Independence. Correlates of IWM with self-reported feelings at ages 33 and 43 and observer-based personality ratings at age 43 supplemented analyses of personality change. Findings support the utility of examining the impact of social change on personality.     

Involvement of the Src homology 2-containing tyrosine phosphatase SHP-2 in growth hormone signaling

Growth hormone (GH) signaling requires activation of the GH receptor (GHR)-associated tyrosine kinase, JAK2. JAK2 activation by GH is believed to facilitate initiation of various pathways including the Ras, mitogen-activated protein kinase, STAT, insulin receptor substrate (IRS), and phosphatidylinositol 3-kinase systems. In the present study, we explore the biochemical and functional involvement of the Src homology 2 (SH2)-containing protein-tyrosine phosphatase, SHP-2, in GH signaling. GH stimulation of murine NIH 3T3-F442A fibroblasts, cells that homologously express GHRs, resulted in tyrosine phosphorylation of SHP-2. As assessed specifically by anti-SHP-2 coimmunoprecipitation and by affinity precipitation with a glutathione S-transferase fusion protein incorporating the SH2 domains of SHP-2, GH induced formation of a complex of tyrosine phosphoproteins including SHP-2, GHR, JAK2, and a glycoprotein with properties consistent with being a SIRP-alpha-like molecule. A reciprocal binding assay using IM-9 cells as a source of SHP-1 and SHP-2 revealed specific association of SHP-2 (but not SHP-1) with a glutathione S-transferase fusion incorporating GHR cytoplasmic domain residues 485-620, but only if the fusion was first rendered tyrosine-phosphorylated. GH-dependent tyrosine phosphorylation of SHP-2 was also observed in murine 32D cells (which lack IRS-1 and -2) stably transfected with the GHR. Further, GH-dependent anti-SHP-2 coimmunoprecipitation of the Grb2 adapter protein was detected in both 3T3-F442A and 32D-rGHR cells, indicating that biochemical involvement of SHP-2 in GH signaling may not require IRS-1 or -2. Finally, GH-induced transactivation of a c-Fos enhancer-driven luciferase reporter in GHR- and JAK2-transfected COS-7 cells was significantly reduced when a catalytically inactive SHP-2 mutant (but not wild-type SHP-2) was coexpressed; in contrast, expression of a catalytically inactive SHP-1 mutant allowed modestly enhanced GH-induced transactivation of the reporter in comparison with that found with expression of wild-type SHP-1. Collectively, these biochemical and functional data imply a positive role for SHP-2 in GH signaling.     

Perceptual significance of somatosensory cortical reorganization following peripheral denervation

The functional significance of reorganization in somatosensory cortex following peripheral denervation has not been thoroughly addressed. In this paper, two distinct hypotheses dealing with this issue are discussed. The first is the hypothesis of functional respecification. This influential view suggests that sets of partially deafferented cortical neurons, which respond to new peripheral inputs and acquire new receptive fields, undergo corresponding changes in perceptual meaning. Excitation of these neurons by stimulation of their novel receptive fields is thought to result in a change in referral of sensation from the original (now denervated) skin fields to the newly acquired skin fields. The second hypothesis is that of functional conservation. This equally plausible alternative is that sets of partially deprived neurons, although they respond to novel peripheral inputs, retain their original perceptual meaning. Excitation of these neurons by stimulation of their new receptive fields is thought to evoke sensation formerly mediated by those neurons, and hence is still projected to the original, now denervated skin regions or phantom. Behavioral evidence strongly suggests that cortical reorganization after peripheral denervation does not result in major functional respecification, but that the original perceptual function mediated by those neurons is preserved.