Time-related contact angle measurements with human plasma on biomaterial surfaces

Axisymmetric drop shape analysis by profile (ADSA-P) was used to assess in time contact angle changes of human plasma drops placed on four different biomaterials. Results were related with conventional blood compatibility measurements: albumin adsorption, fibrinogen adsorption and platelet adhesion. While contact angle measurements with water are material-related but constant in time, contact angle measurements with plasma changed over time owing to protein adsorption on the solid-liquid interface. The contact medium plasma did not influence the initial contact angle. Contact angles on PDMS decreased most in time (41 degrees) and demonstrated highest levels of conventionally measured albumin and fibrinogen adsorption and platelet adhesion. PTFE, with the lowest contact angle decrease over a 500 minutes period (19 degrees), showed low fibrinogen and albumin adsorption as well as low platelet adhesion. PU and HDPE demonstrated almost similar initial contact angles with plasma and contact angle decreases (26 and 27 degrees), intermediate protein adsorption, and platelet adhesion. We conclude that biocompatibility properties of the tested materials may be more related to the behaviour of their contact angles in time, than to the initial hydrophobic or hydrophilic state.     

Involvement of serotonin in intestinal mastocytopoiesis and inflammation during a Trichinella spiralis infection in mice

The involvement of serotonin in the regulation of intestinal mastocytopoiesis and inflammation has been investigated in mice infected with Trichinella spiralis. Two serotonin antagonists, methysergide and ketanserin, were examined for their ability to interfere with jejunal pathology comprising the influx of mucosal mast cells and other inflammatory cells during an infection with T. spiralis and with worm expulsion. In vitro analysis of the frequency of mast cell precursors in bone marrow, blood, spleen and intestinal tissue suggested that the mucosal mast cell response during a T. spiralis infection is probably due to invasion and local maturation in the gut of mast cell precursors, and may be mediated by T-cell-derived mast cell growth factors. Since both serotonin antagonists inhibited the mucosal mast cell response in T. spiralis-infected mice and diminished the influx of eosinophilic granulocytes, goblet cell hyperplasia, and villous atrophy, it was concluded that during a T. spiralis infection in mice release of serotonin may provide an environment that facilitates the local influx in the gut of inflammatory cells. Since worm expulsion was not affected by the serotonin antagonists, these results suggest that worm expulsion can occur without a mast cell and or eosinophilic granulocyte influx. The role of serotonin release by as yet unidentified serotonin-containing cells in the gut in relation with T cell regulation is discussed.     

Cell-bound IgE and increased expression of Fc epsilon-receptors on dendritic cells in cutaneous infiltrates of mycosis fungoides.

Skin biopsies of 31 non-atopic patients, 20 with mycosis fungoides, six with psoriasis and five with contact dermatitis, and of five non-atopic healthy controls were compared for the presence of cell-bound IgE and vacant IgE binding sites. IgE+ cells were demonstrated in the cutaneous infiltrate of nine (45%) patients with mycosis fungoides, two (33%) with psoriasis and one (20%) with contact dermatitis. Following pre-incubation of skin sections with IgE myeloma protein to saturate vacant IgE-binding sites, 14 out of 16 patients (88%) with stage I mycosis fungoides, five (83%) patients with psoriasis and one (20%) with contact dermatitis showed an increase in the number of IgE+ cells. While cell-bound IgE was positively related to serum IgE levels the expression of IgE-binding sites was not. All IgE+ cells were HLA-DR+ dendritic cells identified as either macrophages (CD68+, CD14+) or Langerhans cells (CD1+). Skin biopsies of non-atopic healthy controls or clinically uninvolved skin in mycosis fungoides had neither any IgE+ cells nor any vacant binding sites. Inhibition studies with IgG1, IgG4 and IgE myeloma proteins as well as with several enzymatic fragments of IgE demonstrated that IgE interacted with Fc epsilon-receptors through isotype-specific structures on the Fc epsilon-fragment. Four anti-CD23 monoclonal antibodies, however, were unable to stain vacant Fc epsilon-receptors nor could they block IgE-binding. We hypothesize that locally-secreted lymphokines, like IL-4 or interferon-gamma, induce Fc epsilon-receptors on dendritic cells in the cutaneous infiltrate and that these receptors become occupied in parallel with elevated serum IgE levels.     

Quantitative and qualitative differences in HLA-DR molecules correlated with antigen-presentation capacity

The monoclonal antibodies 7.3.19.1 (anti-DRw52-like) and B8.11.2 (anti-DR framework) were used for the isolation and characterization of HLA class II molecules expressed by HLA-DR3 and DR5 homozygous B cell lines. Sequential immunoprecipitation studies demonstrated that from these cells class II molecules can be isolated which are characterized by the presence or absence of DR framework (DR) and DRw52-like (DRw62) determinants: (DR+, DRw52+), (DR+, DRw52-) and (DR-, DRw52+). The DR3 donor cells appeared to express only the (DR+, DRw52+) and (DR-, DRw52+) class II molecules whereas DR5-positive cells express only the (DR+, DRw52+) and (DR+, DRw52-) class II molecules. Besides qualitative differences some of the above-mentioned molecules appeared to differ in their levels of expression. To investigate whether this might have functional implications, cells with the HLA-DR3 and -5 haplotypes were used to present antigen purified protein derivative of tuberculin (PPD) to PPD-specific T cell lines and the blocking capacity of the two monoclonal antibodies 7.3.19.1 and B8.11.2 was determined. A remarkable correlation was observed between the type of class II molecule blocked by these monoclonal antibodies and its quantitative expression. However, (DR-, DRw52+) molecules, clearly expressed by DR3 cells, were not involved in the presentation of PPD. This indicates that not only quantitative but also qualitative aspects may play a role in the selection of the type of class II molecule that will be involved in antigen presentation.     

Frightening maternal behavior linking unresolved loss and disorganized infant attachment

Main and Hesse's (1990) model in which frightening (threatening, frightened, or dissociated) parental behavior explains why infants of parents with unresolved loss develop disorganized attachment relationships was tested. Unresolved loss using the Adult Attachment Interview in a nonclinical middle-class sample of 85 mothers who had experienced the loss of someone important was assessed. Disorganized attachment was examined in the Strange Situation. Parental behavior was recorded during 22-hr home visits. The model applied to mothers with currently insecure attachment representations. Secure mothers with unresolved loss displayed less frightening behavior than other mothers, and unresolved loss in secure mothers did not predict disorganized attachment of their infants. Frightening behavior predicted infant disorganized attachment irrespective of maternal security.     

Fertilization, pregnancy and embryo implantation rates after ICSI with fresh or frozen-thawed testicular spermatozoa

This study aimed to determine whether fertilization and implantation rates after intracytoplasmic sperm injection (ICSI) with fresh or frozen-thawed testicular spermatozoa were comparable. Between 1 January 1996 and 31 December 1996, 65 ICSI cycles with testicular spermatozoa and 35 cycles with frozen-thawed testicular spermatozoa were carried out. In 50 out of 65 ICSI cycles, testicular spermatozoa could be retrieved and in 34 out of 35 cycles carried out with frozen-thawed testicular spermatozoa, motile spermatozoa could be recovered. The fertilization rate after ICSI with frozen-thawed testicular spermatozoa was significantly lower (71.1%; P < or = 0.008) than with fresh testicular spermatozoa (79.3%). The pregnancy rate was similar for both groups (38.2 and 26.5 %). The implantation rate per transferred embryo, however, was significantly lower in the frozen-thawed rather than in the fresh testicular sperm group (9.1 versus 24.6%; P = 0.001). The live birth rate per transferred embryo was also higher in the group in which fresh testicular spermatozoa were used (18.8 versus 7.9% P = 0.043). This retrospective study shows that is possible to achieve a high fertilization rate after ICSI with both fresh and frozen-thawed testicular spermatozoa but implantation and live birth rates per transferred embryo, however, are significantly lower after ICSI with frozen-thawed than with fresh testicular spermatozoa.      

GTP-related difference in cyclic AMP production between resident and inflammatory human peritoneal macrophages.

In macrophages cyclic AMP (c-AMP) plays an important role in regulating many activities such as phagocytosis, migration and tumoricidal activity. High intracellular levels of c-AMP are negatively correlated with these activities. In earlier studies we have shown that c-AMP levels in inflammatory human peritoneal macrophages (IM) were markedly lower when compared to levels in resident macrophages (RM). This is in line with the fact that c-AMP down-regulates macrophage activity. To our knowledge no data are available on the mechanism underlying the difference in c-AMP production between RM and IM. In this study the difference in c-AMP production between RM and IM has been investigated on the level of receptor and G-protein-related mechanisms. Macrophage membranes were incubated with different agents i.e. prostaglandin E2 (PGE2), prostacyclin I2 (PGI2), isoprenalin (ISO) and sodium fluoride (SF). Additionally, the capacity of IM and RM to hydrolyse quanosine triphosphate (GTP) was measured. Only in the presence of GTP (10(-4) M) could the c-AMP difference be detected (RM = 51 +/- 4.4 pmol/mg protein/min +/- S.E., n = 22, IM = 32.8 +/- 5.2 pmol/mg protein/min +/- S.E., n = 10, p less than 0.01). After receptor stimulation with PGE2, PGI2 and ISO, c-AMP levels increased to the same extent in both IM and RM with no effect on the GTP-related difference. After SF stimulation, c-AMP levels in RM and IM increased to the same level (RM = 63 +/- 8 pmol/mg protein/min, n = 14, IM = 58 +/- 11 pmol/mg protein/min, n = 13).(ABSTRACT TRUNCATED AT 250 WORDS)     

Partial purification and characterization of anhydrotetracycline oxygenase of Streptomyces aureofaciens

Anhydrotetracycline oxygenase was purified both by affinity chromatography and by hydrophobic interaction chromatography. Molecular weight of anhydrotetracycline oxygenase was determined to be 115,000 by Sephadex G-200 gel filtration. Using preparative isoelectric focusing the isoelectric point of the enzyme was estimated to be 5.3. The enzyme showed a sensitivity to thiol-specific inhibitors. During the hydrophobic interaction purification step, the activity dropped considerably. Reactivation occurred when a heat treated crude extract was added to the reaction mixture.     

Induction of immunoglobulin synthesis by interleukin 2 is T4+/T8- cell dependent. A role for interleukin 2 in the pokeweed mitogen-driven system

The role of interleukin 2 (IL2) in the induction of human B cell differentiation in vitro was studied. IL2 was unable to induce immunoglobulin (Ig) production in non-T cells either in the presence or absence of pokeweed mitogen (PWM). However, IL2 alone could induce Ig production in non-T cells when irradiated T cells were present. Similar to the PWM-driven system helper activity was delivered by T4+ but not T8+ cells. Apparently, IL2 acts on T4+ cells and induces these cells to deliver the actual helper signal(s) for Ig production by B cells. Whereas in the PWM-driven system only T8+ cells suppress Ig synthesis, IL2-driven Ig synthesis was suppressed by both T4+ and T8+ cells added to a mixture of non-T cells and irradiated T4+ cells. This suppressor activity could be abrogated by irradiation. PWM was shown to induce IL2 production in both T4+ and T8+ cells. Moreover, PWM-induced Ig synthesis, like IL2-induced Ig synthesis, could be totally abrogated by a monoclonal antibody against the human IL2 receptor (anti-Tac). These findings, coupled to the innate Ig-inducing capacity of IL2, indicate a role for IL2 in the PWM-driven system. The mechanism of suppression in both the PWM- and the IL2-driven systems was not shortage of IL2 in the culture due to consumption or inhibition of production of IL2. Moreover, the T8+ cells produced IL2, despite their failure to help Ig synthesis. Helper T cell activity can thus be divided into two distinct activities: IL2 production and the ability to deliver the actual helper signal such as helper factors for B cell differentiation. This insight allows a better evaluation of the immunoregulatory activities of T cell subsets in health and disease.     

Characterization of the immunosuppression accompanying virus-induced avian osteopetrosis.

Infection of chickens with a myeloblastosis-associated virus which induced a high incidence of osteopetrosis was accompanied by immunosuppression. The immunosuppression was manifested in the following ways. The weight of the bursa, spleen, and thymus was depressed in infected chickens. Infected animals had a diminished capacity to form hemolytic plaques in a direct assay. Spleen cells from osteopetrotic animals did not respond to phytohemagglutinin, and the spleen and bursa had a decreased proportion of cells possessing surface immunoglobulin. Osteopetrotic animals failed to show an age-dependent increase in the proportion of cells demonstrating surface immunoglobulin that was observed in normal animals. However, several individual chickens with heavy osteopetrosis responded to antigenic stimulation in a normal fashion, indicating that although immunosuppression usually accompanies avian osteopetrosis, it may not contribute directly to abnormal bone proliferation.