A membrane cofactor protein transgenic mouse model for the study of discordant xenograft rejection

Background:  In recent years, interest has been revived in the possibility of transplanting organs into humans from a phylogenetically disparate species such as the pig (xenotransplantation). Such discordant xenografts, however, are subject to hyperacute rejection (HAR) and activation of host complement plays a major role in this rejection. This problem may be solved through the use of transgenic technology by providing the grafted tissue with molecules that down-regulate the action of host complement.
Results: Transgenesis with a yeast artificial chromosome (YAC) was used to produce transgenic mice with the complete genomic gene of the human complement regulator membrane cofactor protein (MCP). Transgenic mice were obtained that exhibit full regulation of MCP as normally observed in humans. Hearts from these mice were shown to be significantly protected from HAR caused by human serum in an in vivo experimental procedure.
Conclusions:  We conclude that MCP can protect discordant xenografts from HAR caused by human serum and that transgenic mice can be used effectively as in vivo models for the study of the role of human complement regulatory molecules in xenotransplantation.     

Aspartylglucosaminuria in the United States

Aspartylglucosaminuria (AGU) was diagnosed in two unrelated males with progressive mental retardation, coarse facies and skeletal abnormalities. Until now, this disorder has been described in predominantly Finnish populations with only one previous case reported in the U.S. We conclude that AGU may be more common in nowFinnish populations than the number of reported cases would indicate and should be included in the differential diagnosis in patients with suspected lysosomal storage disorders regardless of their geographical or ethnic backgrounds.     

Differential Effects of Left versus Right Monaural Biofeedback for Heart Rate Increase

Cerebral lateralization in the voluntary increase of heart rate was investigated in a biofeedback experiment involving 20 right-handed female subjects randomly assigned to one of two groups: right or left ear input of stimulus and biofeedback information. The stimulus was a 1000 Hz tone which signalled the start and duration of 30 20-sec training trials. Feedback was a click presented every time an interbeat interval was shorter than a criterion established through a shaping schedule. A monetary bonus provided additional reinforcement at the end of each trial. Subjects given right ear feedback increased their heart rate significantly more than subjects given left ear feedback. The largest difference between the group means (7 bpm) was recorded after the first 20 training trials. The results are discussed in terms of hemispheric perceptual and functional differences.     

Modulating parameters of excitability during and after transcranial direct current stimulation of the human motor cortex

Weak transcranial direct current stimulation (tDCS) of the human motor cortex results in excitability shifts which occur during and after stimulation. These excitability shifts are polarity-specific with anodal tDCS enhancing excitability, and cathodal reducing it. To explore the origin of this excitability modulation in more detail, we measured the input–output curve and motor thresholds as global parameters of cortico-spinal excitability, and determined intracortical inhibition and facilitation, as well as facilitatory indirect wave (I-wave) interactions. Measurements were performed during short-term tDCS, which elicits no after-effects, and during other tDCS protocols which do elicit short- and long-lasting after-effects. Resting and active motor thresholds remained stable during and after tDCS. The slope of the input–output curve was increased by anodal tDCS and decreased by cathodal tDCS. Anodal tDCS of the primary motor cortex reduced intracortical inhibition and enhanced facilitation after tDCS but not during tDCS. Cathodal tDCS reduced facilitation during, and additionally increased inhibition after its administration. During tDCS, I-wave facilitation was not influenced but, for the after-effects, anodal tDCS increased I-wave facilitation, while cathodal tDCS had only minor effects. These results suggest that the effect of tDCS on cortico-spinal excitability during a short period of stimulation (which does not induce after-effects) primarily depends on subthreshold resting membrane potential changes, which are able to modulate the input-output curve, but not motor thresholds. In contrast, the after-effects of tDCS are due to shifts in intracortical inhibition and facilitation, and at least partly also to facilitatory I-wave interaction, which is controlled by synaptic activity.     

HLA transgenic mice as models of human autoimmune diseases

MHC class II alleles have been linked to several human autoimmune diseases such as rheumatoid arthritis (RA), Type I diabetes, and multiple sclerosis (MS). Although the mechanisms by which expression of certain MHC class II molecules predispose an individual to a particular autoimmune disease are not known, it is clear that increased susceptibility is associated with the polymorphic regions unique to these predisposing HLA alleles. These polymorphic differences may influence susceptibility by selecting potential autoreactive T cells during thymic education. Alternatively, nonsusceptible alleles may either delete or fail to select these potential autoimmune T cells, thus reducing the possibility of developing disease. In the periphery, the unique specificity of the HLA molecule derived from a susceptible allele may then recognize and present an autoantigenic peptide or foreign peptide that may cross-react with an autoantigen, activating these autoreactive T cells and leading to disease. To dissect these possibilities and to determine the exact role of particular HLA-DR or DQ molecules in disease susceptibility, we have generated several lines of HLA-DR and DQ transgenic mice. In this review, we present data summarizing the functions of these HLA class II molecules using well-established mouse models for autoimmune diseases.     

Circadian clock and cell cycle gene expression in mouse mammary epithelial cells and in the developing mouse mammary gland.

Mouse mammary epithelial cells (HC-11) and mammary tissues were analyzed for developmental changes in circadian clock, cellular proliferation, and differentiation marker genes. Expression of the clock genes Per1 and Bmal1 were elevated in differentiated HC-11 cells, whereas Per2 mRNA levels were higher in undifferentiated cells. This differentiation-dependent profile of clock gene expression was consistent with that observed in mouse mammary glands, as Per1 and Bmal1 mRNA levels were elevated in late pregnant and lactating mammary tissues, whereas Per2 expression was higher in proliferating virgin and early pregnant glands. In both HC-11 cells and mammary glands, elevated Per2 expression was positively correlated with c-Myc and Cyclin D1 mRNA levels, whereas Per1 and Bmal1 expression changed in conjunction with beta-casein mRNA levels. Interestingly, developmental stage had differential effects on rhythms of clock gene expression in the mammary gland. These data suggest that circadian clock genes may play a role in mouse mammary gland development and differentiation.     

Gender-related cytokine patterns in sera of schistosomiasis patients with Symmers' fibrosis

Cytokine levels were compared between schistosomiasis patients affected by intense fibrosis defined by ultrasound examination and graded from F-0 to F-3. The concentrations of interleukin-1beta (IL-1beta), IL-4, IL-5, IL-10, IL-13, gamma interferon, and tumor necrosis factor alpha (TNF-alpha) were determined by enzyme-linked immunosorbent assay of serum samples. Levels of IL-4, IL-5, and TNF-alpha in the sera of F-3 patients were significantly higher than those found in F-0 individuals, while levels of IL-13 were lower. Levels of IL-4, IL-5, and TNF-alpha in serum were significantly higher in F-3 males than in F-0 males or F-3 females. Conversely, levels of IL-13 were significantly lower in F-3 females than in F-0 females and males.