Expression of superoxide dismutase and xanthine oxidase in myometrium, fetal membranes and placenta during normal human pregnancy and parturition

Superoxide, an agent which attenuates the half-life of nitric oxide, is metabolized and synthesized by superoxide dismutase (SOD) and xanthine oxidase, respectively. Over the last few years much work has focused on the role of nitric oxide in human parturition. The aim of this study was to determine whether the onset of human parturition is associated with a change in the expression of copper/zinc superoxide dismutase (Cu/Zn SOD), manganese superoxide dismutase (Mn SOD) or xanthine oxidase within the uterus. Samples of myometrium, placenta, decidua and fetal membranes were obtained from women before and after the onset of labour at term. Immunocytochemistry was used to localize Cu/Zn SOD, Mn SOD and xanthine oxidase and measure SOD enzyme activity. Cu/Zn and Mn SOD-like immunoreactivity was detected in syncytiotrophoblast cells, villous stromal cells and endothelial cells of blood vessels in the placenta. In the myometrium Cu/Zn and Mn SOD were localized to myocytes and endothelial cells and to some vascular smooth muscle cells. In the fetal membranes we observed staining for Cu/Zn SOD and Mn SOD in the amnion, chorion, extravillous trophoblast and decidua. There was no difference in SOD enzyme activity or staining intensity for SOD between different cell types before and during labour. Xanthine oxidase immunoreactivity was identified in each of the tissues examined and again there was no difference in immunostaining in tissues obtained from women delivered before or after the onset of labour. These results show that the pregnant uterus is capable of both synthesizing and degrading superoxide and suggest that superoxide dismutase and xanthine oxidase may play a role in the maintenance of uterine quiescence during pregnancy, but not in the initiation of parturition.      

Mechanical properties of abdominal aortic aneurysm wall

There is a need to understand why and where the abdominal aortic aneurysm may rupture. Our goal therefore is to investigate whether the mechanical properties are different in different regions of the aneurysm. Aorta samples from five freshly excised whole aneurysms, > or = 5 cm in diameter, from five patients, average age 71 +/- 10 years, were subjected to uniaxial testing. We report the wall thickness, yield stress and strain, and parameters that describe nonlinear stress-strain curves for the anterior, lateral and posterior regions of the aneurysm. The posterior region was thicker than the anterior region (2.73 +/- 0.46 mm versus 2.09 +/- 0.51 mm). The stress-strain curves were described by sigma = a epsilon(b), where sigma is true stress and epsilon is engineering strain. In the circumferential direction, the wall stiffness increased from posterior to anterior to lateral. In the longitudinal direction, the lateral and anterior regions showed greater wall stiffness than the posterior region. The wall stiffness was greater in the circumferential than longitudinal direction. The anterior region was the weakest, especially in the longitudinal direction (yield stress sigmaY = 0.38 +/- 0.18 N mm(-2)). For a less complex model the aneurysmal wall could be considered orthotropic with sigma = 12.89epsilon(2.92) and 4.95epsilon(2.84) in the circumferential and longitudinal directions. For the isotropic model, sigma =7.89epsilon(2.88). In conclusion, different regions of the aneurysm have different yield stress, yield strains, and other mechanical properties, and this must be considered in understanding where the rupture might occur.     

The transplacental toxicity of methyl mercury to fetal rat liver mitochondria. Morphometric and biochemical studies.

Ultrastructural morphometric and biochemical changes in liver mitochondria of fetal rats whose mothers were exposed to methyl mercury hydroxide in their drinking water at concentrations of 0, 3, 5, or 10 p.p.m. for 4 weeks prior to mating and through day 19 of pregnancy are described. A dose-related decrease in the volume density of mitochondria was observed in fetal hepatocytes of dams given the 5- and 10-p.p.m. dose levels. This finding was associated with decreased mitochondrial protein synthesis, which appeared to result primarily from decreased synthesis of mitochondrial structural proteins. Loss of respiratory control was observed in mitochondria from animals in the 3-p.p.m. dose group whereas state 3 respiration was abolished in animals exposed to the 5- and 10-p.p.m. dose levels. The specific activities of monoamine oxidase and cytochrome oxidase, outer and inner mitochondrial membrane marker enzymes respectively, showed dose-related decreases of up to 62 and 78 per cent of control, respectively. delta-Aminolevulinic acid synthetase, which is loosely bound to the inner mitochondrial membrane, also showed dose-related decreases of up to 68 per cent of control. Malate dehydrogenase, a mitochondrial matrix marker enzyme, showed no change in activity at any dose level tested. These observations were correlated with dose-related tissue concentrations of methyl and inormpaired mitochondrial biogenesis and functional development is one basis for explaining the sensitivity of fetal animals to methyl mercury toxicity.     

Performance characteristics of HIV-1 culture and HIV-1 DNA and RNA amplification assays for early diagnosis of perinatal HIV-1 infection

A plasma HIV-1 RNA amplification assay (RNA assay), a quantitative peripheral blood mononuclear cell (PBMC) microculture (culture), and a PBMC HIV-1 DNA amplification assay (DNA assay) were compared for diagnosis of HIV-1 infection in infants receiving zidovudine in Pediatric AIDS Clinical Trials Group protocol 185; assays were performed for all 24 infected and 100 uninfected infants. HIV-1 infection was defined as >or=2 positive cultures or positive antibody to HIV-1 at >or=18 months. Cultures were performed at birth and 6 and 24 weeks of age; DNA and RNA assays were performed on cryopreserved specimens. The sensitivity of culture and DNA and RNA assays at birth was 20.8%, 10.5%, and 26.7%, respectively. At older ages, sensitivity typically exceeded 80%, remaining highest for the RNA assay (>85%). Assay specificity was >99%. Positive predictive values exceeded 93% for each assay at each age; negative predictive values were highest (>90%) for the RNA assay. At birth (P < 0.005) and age 6 weeks (P < 0.001), a significantly larger proportion of infected infants were identified by means of the RNA assay than by the other assays. The diagnostic performance of the RNA assay matched or exceeded that of culture and the DNA assay. Given that RNA assays require less blood volume and yield rapid results, our study adds to existing data suggesting that RNA assays may be used for early diagnosis of HIV-1 infection in infants.     

Physiological basis of the low calcium response in Yersinia pestis.

It is established that duplication in vitro of that amount of Ca2+ (2.5 mM) and Mg2+ (1.5 mM) present in blood permits vegetative growth of Yersinia pestis with repression of virulence factors encoded by the Lcr plasmid (Lcr+); similar simulation of intracellular fluid (no Ca2+ and 20 mM Mg2+) promotes bacteriostasis with induction of these virulence determinants. However, proliferation of yersiniae in mice occurs primarily within necrotic focal lesions (supplied by Ca(2+)-deficient host cell cytoplasm) within visceral organs rather than in Ca(2+)-sufficient blood. The present study addressed this enigma by defining conditions necessary for achieving vegetative growth of Lcr+ yersiniae at 37 degrees C in simulated intracellular fluid. Maximum optical densities were increased by substitution of K+ for Na+ and elimination of Cl-; the combination of Na+ plus L-glutamate was selectively toxic to Lcr+ cells. This phenomenon was attributed in part to the absence of aspartase in Y. pestis (a lesion known to facilitate massive accumulation of L-aspartate via transamination of the oxalacetate pool by L-glutamate). Replacement of L-glutamate by exogenous L-aspartate or alpha-ketoglutarate reversed this toxicity by favoring retention of oxalacetate. Proliferation of Lcr+ cells in a medium containing K+ and L-aspartate but lacking added Ca2+ and Na+ was markedly enhanced by increasing the concentration of fermentable carbohydrate. Accordingly, in the worst-case scenario (i.e., added Na+, Cl-, and L-glutamate), Lcr+ yersiniae underwent restriction of growth after one doubling, and in the best-case scenario (i.e., added K+ and L-aspartate), the organisms completed more than five doublings, thereby achieving full-scale growth. Both of these Ca(2+)-deficient media promoted maximum induction of Mg(2+)-induced V antigen, a virulence factor encoded by the Lcr plasmid.     

Preservation of 5-hydroxytryptamine1A receptor-G protein interactions in the cerebral cortex of patients with Alzheimer's disease.

The coupling of 5-hydroxytryptamine1A (5-HT1A) receptors to guanine nucleotide binding (G) proteins was investigated in membranes prepared from frontal and parietal cortices of control and Alzheimer's disease brains by characterising the effect of guanosine 5'-[beta gamma-imido]diphosphate (Gpp[NH]p) on [3H]8-hydroxy-2-(di-n-propylamino)-tetralin ([3H]8-OH-DPAT) binding parameters. In the absence of guanine nucleotides, [3H]8-OH-DPAT bound to a single high affinity binding site in all membrane types. The number of [3H]8-OH-DPAT binding sites was significantly decreased in the parietal cortex of Alzheimer's disease samples compared with controls, whereas in the frontal cortex the number of binding sites remained unchanged. Gpp[NH]p reduced the [3H]8-OH-DPAT binding affinity and the number of binding sites to the same degree in both regions in control and Alzheimer's disease cases. [3H]8-OH-DPAT binding was inhibited in a concentration dependent manner with an IC50 value of approximately 1 microM in all cases. These results suggest that the 5-HT1A receptor-G protein complex is functionally intact in these regions in Alzheimer's disease brain.     

Hydrosalpinges adversely affect markers of endometrial receptivity

While in-vitro fertilization (IVF) was initially developed in women with tubal factor infertility, recent clinical studies have suggested that the presence of hydrosalpinges lowers implantation and pregnancy rates. We postulated that these hydrosalpinges cause impaired endometrial receptivity. A total of 103 women with hydrosalpinges were prospectively evaluated, and compared with 55 infertile and 44 fertile controls. All women had endometrial biopsies during the window of implantation, analysed by conventional histological criteria, and also stained for three integrin markers of endometrial receptivity (alpha1beta1, alpha4beta1 and alpha vbeta3). Women with hydrosalpinges (cases) expressed significantly less of the alpha vbeta3 integrin compared with controls. There was no difference in expression of alpha1beta1 or alpha4beta1 among groups. A significantly greater number of cases had out of phase histology and missing alpha vbeta3 (type I defects) and absent integrin expression despite normal histological maturation (type II) defects, compared with controls. Of 20 women with impaired endometrial receptivity who were also biopsied after hydrosalpinx surgery, 70% demonstrated increased alpha vbeta3 expression. Seventy-seven percent of type I and 57% of type II defects were corrected postoperatively. Using markers of endometrial receptivity, this study demonstrates that inflammatory hydrosalpinges have an adverse effect on endometrial receptivity, which in some cases may be overcome by surgical treatment of the hydrosalpinx.      

B cell chronic lymphocytic leukaemia cells have reduced capacity to upregulate expression of MHC class I in response to interferon-gamma

AIMS: An important consideration in the design of a tumour vaccine is the ability of tumour-specific cytotoxic T lymphocytes (CTL) to recognise unmanipulated tumour cells in vivo. To determine whether B-CLL might use an escape strategy, the current studies compared B-CLL and normal B cell MHC class I expression. METHODS: Flow cytometry, TAP allele PCR and MHC class I PCR were used. RESULTS: While baseline expression of MHC class I did not differ, upregulation of MHC class I expression by B-CLL cells in response to IFN-gamma was reduced. No deletions or mutations of TAP 1 or 2 genes were detected. B-CLL cells upregulated TAP protein expression in response to IFN-gamma. Responsiveness of B-CLL MHC class I mRNA to IFN-gamma was not impaired. CONCLUSIONS: The data suggest that MHC class I molecules might be less stable at the cell surface in B-CLL than normal B cells, as a result of the described release of beta(2)m and beta(2)m-free class I heavy chains from the membrane. This relative MHC class I expression defect of B-CLL cells may reduce their susceptibility to CTL lysis in response to immunotherapeutic approaches.     

Isolation and characterization of interferon-producing reticuloendothelial cells from mouse epidermis

A homogeneous population of trypsin-resistant epidermal cells has been isolated from newborn ICR mice. These cells are characterized by adherence, receptors for Fc-IgG, ATPase activity, phagocytosis of latex particles and opsonized sheep erythrocytes, and secretion of lysozyme and interferon. The production of interferon by these cells suggests that they may be important in protection against viral infections of the skin as well as in regulation of immune responses. The ultrastructure of these trypsin-resistant epidermal cells shows striking similarity to that of reticuloendothelial cells.     

CTLA-4 expression on antigen-specific cells but not IL-10 secretion is required for oral tolerance

CD4(+) T cells play a vital role in mediating the tolerance induced at mucosal sites following exposure to non-pathogenic stimuli, and further understanding of the precise mechanisms by which these cells prevent aberrant responses is required. We have developed a model using transfer of DO11.10 TCR-transgenic bone marrow into irradiated recipients in which it has been possible to track antigen-specific CD4(+) cells in mesenteric lymph nodes (mLN), Peyer's patches (PP) and lamina propria following primary exposure to antigen. Using this model we have demonstrated initial activation in all three gut-associated lymphoid tissue compartments characterized by increases in the frequency of transgenic cells expressing CD69 and CD25. These cells subsequently enter a state of hyporesponsiveness both locally in the mLN and PP and in the periphery following feeding and challenge. Investigating the role of CTLA-4 either using anti-CTLA-4 mAb or by generating chimeras using DO11.10xCTLA-4(-/-) mice as donors we have clearly shown that antigen-specific cells require the expression of this regulatory molecule for oral tolerance. In contrast, oral tolerance was intact in chimeras generated using DO11.10xIL-10(-/-) cells, indicating that secretion of this cytokine by antigen-specific cells is not required.