Severe hypoxemia in the absence of blood loss causes a gender dimorphic immune response

A gender dimorphic immune response has beenobserved after trauma and severe hemorrhage, a condition believed to beassociated with tissue hypoxia. Although studies have shown thathypoxemia per se in males causes a systemic inflammatory response, itis unclear if the inflammatory response to hypoxemia exhibits gender dimorphic characteristics. To study this, male and female C3H/HeN micein the proestrus state of the estrous cycle were subjected to hypoxemia(95% N₂-5% O₂) or sham hypoxemia (room air)for 60 min. Later (2 h), plasma interleukin (IL)-6 and tumor necrosis factor (TNF)- levels were determined along with splenic immune responses. Plasma IL-6 and TNF- concentrations after hypoxemia weresignificantly increased in males but not in females. Splenocyte proliferation was depressed in males after hypoxemia but not in females. A shift toward an immunosuppressive Th-2 cytokine profile wasobserved in males after hypoxemia [decreased interferon- (Th-1) andincreased IL-10 (Th-2)], whereas no such shift was observed infemales. Splenic macrophage IL-6, IL-10, and IL-12 production weresuppressed in males after hypoxemia; however, such suppression was notobserved in females. These findings therefore indicate that a genderdimorphic immune response also exists after hypoxemia in the absence ofblood loss and tissue trauma, similar to trauma-hemorrhage.Furthermore, because no systemic inflammatory response or alterationsin T lymphocyte or macrophage functions are observed in proestrusfemales but such parameters are markedly altered after severe hypoxemiain males, these studies indicate that proestrus females can toleratehypoxemia better than males.

     

Sex steroids regulate pro- and anti-inflammatory cytokine release by macrophages after trauma-hemorrhage

Studies indicate that macrophage immune responses in males aredepressed after trauma-hemorrhage, whereas they are enhanced in femalesunder such conditions. Nonetheless, the involvement of male and femalesex steroids in this gender-dependent dimorphic immune response aftertrauma-hemorrhage remains unclear. To study this, male C3H/HeN micewere castrated and treated with pellets containing either vehicle,5-dihydrotestosterone (DHT), 17-estradiol, or a combination ofboth steroid hormones for 14 days before soft tissue trauma (i.e.,laparotomy) and hemorrhagic shock (35 ± 5 mmHg for 90 min followed byadequate fluid resuscitation) or a sham operation. Twenty-four hourslater the animals were killed, plasma was obtained, and Kupffer celland splenic and peritoneal macrophage cultures were established. ForDHT-treated mice, we observed significantly decreased releases of theproinflammatory cytokines interleukin 1 (IL-1) and IL-6 bysplenic macrophage (50 and 57%, respectively) andperitoneal macrophage (51 and 52%, respectively)cultures after trauma-hemorrhage compared with releases by cultures ofcells from mice subjected to a sham operation; in contrast, responsesof splenic and peritoneal macrophage cultures from other groupssubjected to trauma-hemorrhage did not changesignificantly. In addition, only DHT-treated animals exhibited increased Kupffer cell IL-6 release (+634%). The release ofIL-10 in DHT-treated hemorrhaged animals was increased compared withthat in sham-operated animals but was decreased in estrogen-treated mice under such conditions. These results suggest that male and femalesex steroids exhibit divergent immunomodulatory properties with respectto cell-mediated immune responses after trauma-hemorrhage.

     

A Stress Management Program for Higher Risk Medical Students: Preliminary Findings

Approximately 10 % of first year medical students have clinically relevant anxiety or depression which may affect academic success and quality of life. This study tested the effects of a stress management intervention on indicators of anxiety, depression and self-efficacy in self-selected first year medical students. Forty two medical students volunteered to participate and provided informed consent. An eight session intervention was offered and focused on building relaxation skills, adaptive coping, and basic nutrition. Anxiety, depression, and self-efficacy were assessed pre and post intervention. This group of students had significantly higher baseline values of depression and anxiety but lower self-efficacy compared to a previous study of medical students at the same institution (p < 0.03). After the intervention, statistically significant improvements were observed in anxiety (p < 0.05), and self-efficacy (p < 0.05), but not in depression. The entering levels of anxiety and depression in this group suggested that these students were at risk for later clinical syndromes. Intervention directed to decreasing the effects of stress was associated with improvement in indicators of distress and may modify the longer term risk.     

Cytomegalovirus Inhibits the Engraftment of Donor Bone Marrow Cells by Downregulation of Hemopoietin Gene Expression in Recipient Stroma

Cytomegalovirus (CMV) disease after bone marrow (BM) transplantation is often associated with BM graft failure. There are two possible reasons for such a correlation. First, a poor hematopoietic reconstitution of unrelated etiology could promote the progression of CMV infection by the lack of immune control. Alternatively, CMV infection could interfere with the engraftment of donor BM cells in recipient BM stroma. Evidence for a causative role of CMV in BM aplasia came from studies in long-term BM cultures and from the murine in vivo model of CMV-induced aplastic anemia. A deficiency in the expression of essential stromal hemopoietins, such as stem cell factor (SCF), has indicated a functional insufficiency of the stromal microenvironment. It remained open to question whether CMV mediates a negative regulation of hemopoietin gene expression (the downregulation model) or whether it causes the default of a positive regulator (the lack-of-induction model). Further, even though implicitly assumed, it has never been formally documented that CMV directly interferes with the engraftment of a BM cell transplant. We addressed these problems in a murine model of CMV infection after experimental male-into-female BM transplantation. The data indicate that the downregulation model applies. Quantitation of the male-sex-determining gene tdy demonstrated an impaired engraftment of donor BM cells in the BM stroma of the female recipients. This graft failure was reflected by a diminished population of SCF-receptor-expressing hematopoietic progenitor cells and correlated with a reduced level of stromal SCF gene expression. Interestingly, high doses of BM cells protected against stromal insufficiency by a mechanism unrelated to control of infection.     

Redox control of proton transfers in membrane b-type cytochromes: an absorption and resonance Raman study on bis(imidazole) and bis(imidazolate) model complexes of iron-protoporphyrin

Optical absorption spectra and resonance Raman (RR) spectra, obtained with Soret excitation, are reported for bis(imidazole) and bis(imidazolate) complexes of iron(II)- and iron(III)-protoporphyrin IX, prepared in aqueous conditions. Perdeuteration experiments on the axial ligands permitted the assignment of the symmetric Fe-(ligand)₂ stretching mode of Fe[x]PP(L)₂ to RR bands at 203 (x = II; L = ImH), 212 (x = II; L = Im^–), 201 (x = III; L = ImH) and 226 cm^–1 (x = III; L = Im^–). These frequency differences indicate a strengthening of the axial bonds when the imidazole deprotonations occur. The larger difference observed for the ferric derivatives reflects the stronger -donor capability of the Im^– anion for iron(III) over iron(II). For the ferrous derivatives, the frequencies of several skeletal porphyrin modes (₄, ₁₀, ₁₁ and ₃₈) are downshifted by 2–10 cm^–1 upon deprotonation of the ligands. This effect corresponds to an increased back-bonding from the metal atom to the porphyrin ring when the axial ligand decreases its -acid strength. Bringing further support to this interpretation, an inverse linear relationship is established between the frequencies of (Fe(Il)-L₂) and ₁₁. This correlation is expected to monitor the overall H-bonding state of histidine ligands of reduced cytochromes b. On the other hand, absorption measurements have characterized large pK_a differences for the sequential imidazole ionizations of Fe[x]PP(ImH)₂ in aqueous cetyltrimethylammonium bromide (9.0 and 10.8 for x = 111; 13.0 and 14.1 for x = II). These titrations show that Fe(II)PP(Im^–)₂ and Fe(III)PP(ImH)₂ are good proton-acceptor and proton-donor, respectively, and suggest a model by which heme, located in a favorable environment inside a cytochrome, could couple a cycle of electron transfer with a proton transfer. Based on sequence data and structural models, it is further proposed that, in several membrane cytochromes b (b, b ₆, b ₅₅₉), a positively charged amino acid residue and an imidazolate ligand of the ferriheme could form an ion pair involved in a redox control of proton transfer.Abbreviations RR resonance Raman - EPR electron paramagnetic resonance - PP protoporphyrin IX - ImH imidazole - Im^– imidazolate - Im* imidazole or imidazolate - 1MeIm 1-methylimidazole - HisH histidine - His^– histidinate - CTABr cetyltrimethylammonium bromide - NaDS sodium dodecylsulphate - VLP very low potential - LP low potential - HP high potential     

Clinical observations on behavioral treatment of a patient with insulin-dependent diabetes mellitus

This report uses a single case format to describe clinical observations on the use of biofeedback-assisted relaxation in Type I insulin-dependent diabetes mellitus. It is suggested that treatment based on relaxation training may be utilized in diabetics provided that certain conditions are met and that the relaxation procedure is modified to conform to the special requirements of persons taking insulin. Since both client characteristics and type of training protocol can markedly affect outcome, it may be especially important to tailor the training protocol for each insulin-dependent diabetic patient, based on careful and continuous monitoring of treatment effects.     

Complement C1q and C3 are critical for the innate immune response to Streptococcus pneumoniae in the central nervous system

Previous studies suggest that the complement system can contribute to limiting pneumococcal outgrowth within the CNS. In this study, we evaluated the role of the complement system in the activation of the innate immune response and the development of the prognosis-relevant intracranial complications in a murine model of pneumococcal meningitis. Thereby, we used mice deficient in C1q, lacking only the classical pathway, and C3, lacking all three complement activation pathways. At 24 h after intracisternal infection, bacterial titers in the CNS were almost 12- and 20-fold higher in C1q- and C3-deficient-mice, respectively, than in wild-type mice. Mean CSF leukocyte counts were reduced by 47 and 73% in C1q- and C3-deficient-mice, respectively. Intrathecal reconstitution with wild-type serum in C3-deficient mice restored both the ability of mice to combat pneumococcal infection of the CSF and the ability of leukocytes to egress into the CSF. The altered recruitment of leukocytes into the CSF of C3-deficient mice was paralleled by a strong reduction of the brain expression of cytokines and chemokines. The dampened immune response in C3-deficient mice was accompanied by a reduction of meningitis-induced intracranial complications, but, surprisingly, also with a worsening of short-term outcome. The latter seems to be due to more severe bacteremia (12- and 120-fold higher in C1q- and C3-deficient-mice, respectively) and, consecutively, more severe systemic complications. Thus, our study demonstrated for the first time that the complement system plays an integral role in mounting the intense host immune response to Streptococcus pneumoniae infection of the CNS.     

Directional Trans-Synaptic Labeling of Specific Neuronal Connections in Live Animals

Understanding animal behavior and development requires visualization and analysis of their synaptic connectivity, but existing methods are laborious or may not depend on trans-synaptic interactions. Here we describe a transgenic approach for in vivo labeling of specific connections in Caenorhabditis elegans, which we term iBLINC. The method is based on BLINC (Biotin Labeling of INtercellular Contacts) and involves trans-synaptic enzymatic transfer of biotin by the Escherichia coli biotin ligase BirA onto an acceptor peptide. A BirA fusion with the presynaptic cell adhesion molecule NRX-1/neurexin is expressed presynaptically, whereas a fusion between the acceptor peptide and the postsynaptic protein NLG-1/neuroligin is expressed postsynaptically. The biotinylated acceptor peptide::NLG-1/neuroligin fusion is detected by a monomeric streptavidin::fluorescent protein fusion transgenically secreted into the extracellular space. Physical contact between neurons is insufficient to create a fluorescent signal, suggesting that synapse formation is required. The labeling approach appears to capture the directionality of synaptic connections, and quantitative analyses of synapse patterns display excellent concordance with electron micrograph reconstructions. Experiments using photoconvertible fluorescent proteins suggest that the method can be utilized for studies of protein dynamics at the synapse. Applying this technique, we find connectivity patterns of defined connections to vary across a population of wild-type animals. In aging animals, specific segments of synaptic connections are more susceptible to decline than others, consistent with dedicated mechanisms of synaptic maintenance. Collectively, we have developed an enzyme-based, trans-synaptic labeling method that allows high-resolution analyses of synaptic connectivity as well as protein dynamics at specific synapses of live animals.     

Attenuation of Immune-Mediated Influenza Pneumonia by Targeting the Inducible Co-Stimulator (ICOS) Molecule on T Cells

Inducible Co-stimulator (ICOS) plays a critical role in mediating T cell differentiation and function and is considered a key player in balancing T effector and T regulatory (T_reg) cell responses. Here we show that activation of the ICOS signalling pathway during acute influenza A virus (IAV) infection by application of an agonistic ICOS antibody reduced the frequency of CD8⁺ T cells in the respiratory tract of IAV infected animals and delayed pathogen elimination. In line with this, immune-mediated influenza pneumonia was significantly ameliorated in mice that received ICOS agonist as indicated by significantly reduced alveolar infiltrations and bronchointerstitial pneumonia, while at the same time virus-related pathology remained unaffected. Importantly, ICOS agonist treatment resulted in expansion of CD4⁺Foxp3⁺ T_regs in IAV infected mice, which was associated with elevated levels of the immunosuppressive cytokine IL-10 in the alveolar space. Together, our findings suggest a prominent role of ICOS signaling during acute IAV infection by increasing the T_reg/CD8⁺ T cell ratio with beneficial outcome on immune-mediated pneumonia and underline the suitability of ICOS as potential therapeutic target for immune intervention in those infectious conditions characterized by strong immunopathology rather than virus-mediated cytopathic effects.