Transgene Expression in the Brain Stem Effected by Intramuscular Injection of Polyethylenimine/DNA Complexes

Gene delivery into the CNS without tissue destruction is challenging. As neurons are capable of taking up exogenous particulates from the muscles that they innervate, we investigated the feasibility of achieving gene transfer in CNS neurons by peripheral intramuscular injection of plasmid DNA complexed with the cationic polymer polyethylenimine (PEI) in the rat hypoglossal system. Using the luciferase reporter gene driven by a Rous sarcoma virus promoter, transgene expression of up to 4 x 10(6) RLU per brain stem at 20 microg of plasmid DNA was achieved after tongue injection. Using lacZ as a reporter gene, transgene expression in the brain stem was detected in hypoglossal motor neurons, a group of neurons that innervate tongue muscles. The plasmid DNA was detected by PCR analysis in the brain-stem samples, demonstrating that the PEI/DNA complexes had migrated by retrograde axonal transport to neuronal cell bodies in the brain stem after being internalized by nerve terminals in the tongue muscle. Using a therapeutic bcl-2 gene driven by a cytomegalovirus promoter and Western blotting, transgene expression was detectable in the brain stem as early as 18 h after tongue injection and lasted for at least 2 weeks. Two lipid transfection agents, GenePORTER and TransFast, mediated a weak gene expression in the hypoglossal system, but not two polymers, poly-l-lysine and chitosan. The nonviral neuronal gene delivery method established in this study bypasses the blood-brain barrier and suggests a possible therapeutic strategy for noninvasive CNS gene transfer.

Immunohistochemical demonstration of L-serine distribution in the rat brain

L-Serine has been suggested by in vitro studies to be an important neurotrophic factor which supports survival and neurite outgrowth of neurons. It is also a precursor of D-serine, a putative neurotransmitter. In the present study, we raised antibodies against L-serine in a rabbit and examined immunohistochemical distribution of the amino acid in the rat brain. In the hippocampus and the cerebellar cortex, where neurotrophic effects of L-serine have been indicated, L-serine immunoreactivity was found primarily in astrocytes. In the brain stem, where neuronal distribution of D-serine was reported, positive staining for L-serine was located primarily in neurons. Regional differences of cellular distribution of L-serine were indicated.

Theory of interlayer tunneling in bilayer quantum Hall ferromagnets

Spielman et al. [Phys. Rev. Lett. 84, 5808 (2000] recently observed a large and sharp Josephson-like zero-bias peak in the tunnel conductance of a bilayer system in a quantum Hall ferromagnet state. We argue that disorder-induced topological defects in the pseudospin order parameter limit the peak size and destroy the predicted Josephson effect. We predict that the peak would be split and shifted by an in-plane magnetic field in a way that maps the dispersion relation of the ferromagnet's Goldstone mode. We also predict resonant structures in the dc I-V characteristic under bias by an ac electric field.

Immunohistochemical evidences for localization and production of D-serine in some neurons in the rat brain

D-Amino acids are thought not to occur in mammalian tissues. However, previous studies reported D-serine was present only in astrocytes in the rat brain. In the present study, it was indicated by a highly sensitive immunocytochemical method with a D-serine specific antibody that D-serine was contained not only in astrocytes but also in some neurons, such as pyramidal neurons in the cerebral cortex, and neurons in the nucleus of the trapezoid body. Some amacrine cells also showed strong immunoreactivity for D-serine in the eyes which were injected with colchicine into the corpus vitreum.

Effective attraction between like-charged colloids in a two-dimensional plasma

The existence of attractions between like-charged colloids immersed in ionic solution has been discovered in recent experiments. This phenomenon contradicts the predictions of Derjaguin-Landau-Verwey-Overbeek and indicates a failure of mean-field theory. We study a toy model based on a two-dimensional one-component plasma, which is exactly soluble at one particular coupling constant. We show that colloidal interaction results from a competition between ion-ion repulsion and longer ranged ion-void attraction.

Adenoviral p53 gene therapy promotes heat-induced apoptosis in a nasopharyngeal carcinoma cell line

BACKGROUND

It has previously been demonstrated that Ad5CMV-p53 gene transfer, either used alone or delivered concomitantly with ionizing radiation, resulted in cytotoxicity mediated by apoptosis in nasopharyngeal carcinoma (NPC) cell lines. In this study, a novel approach was evaluated of combining Ad5CMV-p53 gene therapy with hyperthermia (HT), in the CNE-1 NPC cell line, which harbours a mutation in codon 249 of the p53 gene.

MATERIALS AND METHODS

CNE-1 cells were infected using either Ad5CMV-p53 or Ad5CMV-B-gal, followed, 24 h later, by HT (43 degrees C x 0-2 h). Protein was extracted for Western blot analysis, and apoptosis was evaluated using acridine-orange ethidium bromide staining, followed immediately by fluorescent microscopy examination for the proportion of cells displaying morphologic features of apoptosis.

RESULTS

Ad5CMV-p53 gene therapy combined with HT resulted in a dose-dependent cytotoxicity with less than 1% clonogenic survival when 10 pfu/cell of Ad5CMV-p53 was combined with 2 h heating at 43 degrees C. Western blotting demonstrated that treatment with Ad5CMV-p53 resulted in the rapid expression of p53, which was minimally affected by HT. The inducible form of hsp70 was maximally expressed at 48 h post-HT, with minimal effect when cells were additionally treated with Ad5CMV-p53. Clonogenic cytotoxicity was associated with the development of apoptosis, with up to 70% of CNE-1 cells displaying morphologic features of apoptosis after the combination treatments.

CONCLUSION

Based on the shapes of the clonogenic survival curves, Ad5CMV-p53 gene therapy and HT appear to interact in an additive manner, suggesting the therapeutic potential of this combined treatment approach for patients with NPC.

Cell damage of microcarrier cultures as a function of local energy dissipation created by a rapid extensional flow

Microcarrier cultures of Chinese hamster ovary cells were subjected to a range of energy dissipations created by an abrupt contraction. These flow conditions can be characterized as a rapidly transient, extensional, and shear flow. Cell damage was measured using a lactate dehydrogenase assay. The laminar flow in the device was modeled using two commercial, computation fluid-dynamic codes: POLYFLOW and FLUENT. Cell damage was correlated to numerical values of energy dissipation. The magnitude of energy dissipation at which cell damage began to be detected, 10(4) ergs cm(-3) s(-1) (10(4) cm(2) s(-3)), is consistent with values of energy dissipation estimated in bioreactors operated under conditions which result in cell damage. This magnitude of energy dissipation is orders of magnitude lower than those values reported to cause damage to suspended animals cells which is also consistent with generally accepted experimental observations. Finally, an analysis and discussion of the presence and relative importance with re- spect to cell damage of shear vs. extensional flow is included.

Upregulation of COX-2 during cardiac allograft rejection

BACKGROUND

The hypothesis that cyclooxygenase-2 (COX-2) is involved in the myocardial inflammatory response during cardiac allograft rejection was investigated using a rat heterotopic abdominal cardiac transplantation model.

METHODS AND RESULTS

COX-2 mRNA and protein in the myocardium of rejecting cardiac allografts were significantly elevated 3 to 5 days after transplantation compared with syngeneic controls (n=3, P<0.05). COX-2 upregulation paralleled in time and extent the upregulation of iNOS mRNA, protein, and enzyme activity in this model. COX-2 immunostaining was prominent in macrophages infiltrating the rejecting allografts and in damaged cardiac myocytes. Prostaglandin (PG) levels in rejecting allografts were also higher than in native hearts. Because NO has been reported to modulate PG synthesis by COX-2, additional transplants were performed using animals treated with a selective COX-2 inhibitor (SC-58125) and a selective inhibitor of the inducible nitric oxide synthase (iNOS) N-aminomethyl-L-lysine. At posttransplant day 5, inhibitor administration resulted in a significant reduction of COX-2 mRNA expression (3764+/-337 versus 5110+/-141 arbitrary units, n=3, P<0.05) and iNOS enzymatic activity (1.7+/-0.4 versus 22.8+/-14. 4 nmol/mg protein, n=3, P<0.01) compared with vehicle-treated allogeneic transplants. Allograft survival in treated animals was increased modestly from 5.4 to 6.4 days (P<0.05). However, apoptosis of cardiac myocytes (TUNNEL method) was only marginally reduced relative to vehicle controls in treated graft recipients. The intensity of allograft rejection was also similar in the treated and untreated allografts.

CONCLUSIONS

The data indicates that COX-2 expression is enhanced in parallel with iNOS in the myocardium during cardiac allograft rejection.

[B7 and DC vaccines induced anti-tumor immunity against murine T-lymphocyte leukemia L615]

OBJECTIVE

To study the effect of B7 and DC vaccines in inducing anti-tumor immunity in murine T-lymphocyte leukemia L615.

METHODS

In vivo, murine mortality and survival were observed to compare the difference between B7 and DC vaccine in inducing immunoprotection against the subsequent challenge of live L615 cells;in vitro, specific cytotoxic assay and MLR were performed to test the specific cytotoxicity and proliferative activity of effective T cells.

RESULTS

Both vaccines could efficiently improve T cell mediated anti-leukemic immunity in syngenic hosts, and DC vaccine was revealed to be more efficient. In vitro observations showed that both vaccines could induce tumor specific cytotoxicity and proliferative activity of effective T cells.

CONCLUSION

DC vaccine is promising in tumor immunotherapy owing to its safety, efficiency and convenience.

Noncollinear-pumped KTP optical parametric oscillator

A theoretical analysis and an experimental study are presented on the phase-matching condition of noncollinearly pumped optical parametric oscillators (OPO's) based on a noncritical phase-matching potassium titanyl phosphate (KTP) OPO. It is shown that noncollinearly pumped, double-pass, singly resonant optical parametric oscillators maintain the advantage of round-trip parametric gain in a collinear pump, since in this case the two generated signal waves are coherent, which results in high conversion efficiency and low pump threshold. With this KTP OPO we achieved 31% energy conversion efficiency from a 1064-nm pump wave to 1572-nm eye-safe output. In addition, because the incident pump beam is not perpendicular to the OPO cavity mirrors and consequently no reflected beam flows back into the pump source, we can avoid employing optical isolators.

[A study on tumor necrosis factor alpha, macrophage inflammatory protein-2 and myeloperoxidase in blood, broncho-alveolar fluid and lung tissues of rat chronic bronchitis model]

OBJECTIVE

To study the nature and mechanisms of airway inflammation in chronic bronchitis and observe the effects of inhaled glucocorticoids on inflammatory indices.

METHODS

Rat chronic bronchitis model was established by intratracheal instillation of small dose of lipopolysaccharide (LPS, 1 g/L). Experiments were performed in 28 male Sprague-Dawley rats, which comprised four groups in random, i.e. chronic bronchitis model group, normal saline treated group, dexamethasone treated group and healthy control group. The levels of myeloperoxidase (MPO) of blood and lung tissues, and tumor necrosis factor (TNF)alpha and macrophage inflammatory protein-2 (MIP-2) of plasma, broncho-alveolar fluid (BALF) and lung tissues were determined by biochemical and ELISA methods. Total and differential white blood cell counts of BALFwere carried out.

RESULTS

(1) The levels of TNFalpha and MIP-2 in BALF and lung tissues, and MPO in lung tissues of chronic bronchitis model group were significantly increased than those of control group (P < 0.05). (2) More significant increase in total white blood cell count and neutrophils in BALF was found in rat chronic bronchitis group than in control group (P < 0.001). (3) Significant positive correlations were observed between the level of MPO and MIP-2 of lung tissues, the level of MPO and TNFalpha of lung tissue and the total cell counts and the level of MIP-2 of BALF and lung tissue. (4) More significant decrease in total cell counts and neutrophils of BALF and levels of MPO in lung tissue was found in dexamethasone-treated group as compared to those of chronic bronchitis group.

CONCLUSION

Recruitment and activation of neutrophils seem to be the characteristics of chronic bronchitis. TNFalpha and MIP-2 may be involved in the process of chemotaxis and activation in airway inflammation in chronic bronchitis. Inhaled steroids might have some effects on chronic bronchitis by limiting the airway inflammation.

The Arabidopsis blue light receptor cryptochrome 2 is a nuclear protein regulated by a blue light-dependent post-transcriptional mechanism

Cryptochrome 2 is a flavin-type blue light receptor mediating floral induction in response to photoperiod and a blue light-induced hypocotyl growth inhibition. cry2 is required for the elevated expression of the flowering-time gene CO in response to long-day photoperiods, but the molecular mechanism underlying the function of cry2 is not clear. The carboxyl domain of cry2 bears a basic bipartite nuclear localization signal, and the cry2 protein was co-fractionated with the nucleus. Analysis of transgenic plants expressing a fusion protein of CRY2 and the reporter enzyme GUS (GUS-CRY2) indicated that the GUS-CRY2 fusion protein accumulated in the nucleus of transgenic plants grown in dark or light. The C-terminal domain of cry2 that contains the basic bipartite nuclear localization signal was sufficient to confer nuclear localization of the fusion protein. Phenotypic analysis of transgenic plants expressing the fusion protein GUS-CRY2 demonstrated that GUS-CRY2 acts as a functional photoreceptor in vivo, mediating the blue light-induced inhibition of hypocotyl elongation. These results strongly suggest that cry2 is a nuclear protein. Although no obvious light regulation was found for the nuclear compartmentation of GUS-CRY2 fusion protein, the abundance of GUS-CRY2 was regulated by blue light in a way similar to that of cry2.

VEGF increases retinal vascular ICAM-1 expression in vivo

PURPOSE

Intraocular injections of vascular endothelial growth factor (VEGF), a peptide implicated in the pathogenesis of diabetic retinopathy, can induce retinal ischemia. Diabetic retinal ischemia may be caused, in part, by the adhesion of leukocytes to the retinal vasculature. In this study, the ability of VEGF to increase the expression of intercellular adhesion molecule-1 (ICAM-1) and other adhesion molecules in capillary endothelium and the retinal vasculature was examined.

METHODS

The expression of ICAM-1, vascular cell adhesion molecule-1 (VCAM-1), E-selectin, and P-selectin on human brain capillary endothelial cell monolayers exposed to VEGF was quantitated by immunoassay. The effect of VEGF on retinal vascular ICAM-1 expression was determined in ICAM-1 immunofluorescence studies of retinal flat-mounts and in RNase protection assays.

RESULTS

VEGF increased capillary endothelial cell ICAM-1 levels in a dose- and time-dependent manner (6-24 hours, plateau after 6 hours; EC50, 25 ng/ml). VEGF failed to alter E-selectin, P-selectin, or VCAM-1 levels under the conditions tested. Intravitreal injections of pathophysiologically relevant concentrations of VEGF increased ICAM-1 protein and mRNA levels in the retinal vasculature.

CONCLUSIONS

VEGF increases retinal vascular ICAM-1 expression. VEGF-induced increases in ICAM-1 may promote retinal leukostasis in diabetic eyes.

T cell immunity induced by allogeneic microglia in relation to neuronal retina transplantation

Microglia share a lineage relationship with bone marrow-derived monocytes/macrophages and dendritic cells, and their inclusion in retinal and brain transplants may function as "passenger leukocytes. " In other solid allografts, passenger leukocytes are the primary sources of immunogenicity, triggering alloimmune rejection. We have conducted a series of in vitro and in vivo studies examining the capacity of microglia cultured from forebrain to activate alloreactive T cells and to induce and elicit alloimmunity. Cultured microglia expressed class II MHC molecules and costimulatory molecules (B7-1, B7-2, and CD40), and they secreted IL-12. Cultured microglia injected s.c. into naive recipients induced allospecific delayed hypersensitivity and elicited delayed hypersensitivity directed at alloantigens. Cultured microglia differed from conventional APCs by secreting significant amounts of mature TGF-beta2, but smaller amounts of IL-12. Moreover, while both cultured microglia and conventional APC stimulated T cell proliferation in vitro, microglia directed the responding T cells toward the Th2 pathway in which IL-4, but not IL-2 and IFN-gamma, was secreted. The abilities of microglia to secrete TGF-beta2, to stimulate alloreactive Th2 cells, and to induce anterior chamber associated immune deviation when injected into the eye of naive allogeneic mice suggest that they are not typical passenger leukocytes. The unique functional properties of cultured microglia may account for the capacity of neonatal retinal tissue transplanted into the eye to alter the systemic alloimmune response in a manner that delays, but does not prevent, graft rejection.

Saturation mutagenesis of the E. coli RecA loop L2 homologous DNA pairing region reveals residues essential for recombination and recombinational repair

The disordered mobile loop L2 of the Escherichia coli RecA protein is known to play a central role in DNA binding and pairing. To investigate the local chemical environment in relation to function we performed saturation mutagenesis of the loop L2 region (amino acid positions 193-212) using a site-directed mutagenesis procedure, and determined the recombinational proficiency of the 380 mutants using genetic assays for homologous recombination and recombinational repair. Residues Asn193, Gln194, Arg196, Glu207, Thr209, Gly211, and Gly212 were identified as stringently required for recombinational events in bacterial cells. In addition, our findings suggest the involvement of loop L2 in the ATPase activity of RecA, and a role for residues Gln194, Arg196, Lys198 and Thr209 in the DNA-dependent hydrolysis of ATP. Finally, since 20 residue peptides that comprise this region can pair homologous DNAs by forming filamentous beta-structures, we propose how the information from the mutant analysis might facilitate the use of a simplified amino acid alphabet to design beta-structure forming L2 peptides with improved RecA-like activities.

Contribution of microglia as passenger leukocytes to the fate of intraocular neuronal retinal grafts

PURPOSE

To determine whether donor-derived microglial cells play a role in dictating the immunogenicity of immature neuronal retinal tissue transplanted intraocularly.

METHODS

Neonatal neural retinas (aged <24 hours) from C57BL/6 or BALB/c mice were implanted in the anterior chamber or the subretinal space of adult syngeneic or allogeneic eyes. After 12 and 35 days of engraftment, retinal grafts were harvested and analyzed immunohistochemically with 20 microg/ml Griffonia simplicifolia (GS) isolectin to identify microglia and define their morphology, monoclonal antibodies to study expression of donor and recipient major histocompatibility complex (MHC) class I and II antigens, and anti-CD3 and -CD14 antibodies to distinguish microglia from T cells and macrophages.

RESULTS

Neonatal retinas were found to contain significant numbers of GS+ cells (microglia) at the time of grafting. By day 12 after grafting, markedly increased numbers of microglia were found in syngeneic and allogeneic grafts. Whereas most microglia in syngeneic grafts displayed a ramified (inactive) morphology at this time, most of the microglia in allografts displayed an ameboid (activated) configuration, with retracted processes and enlarged somas. By day 35 after grafting, although the density of microglia was reduced in syngeneic and allogeneic grafts, intensely labeled GS+ cells were localized in the centers of rosettes in syngeneic, but not in allogeneic, grafts. Instead, donor-derived microglia displayed intense expression of MHC class I and II antigens, and these grafts contained small numbers of recipient-derived T cells, but not macrophages.

CONCLUSIONS

Microglia within developing neuronal retinal transplants display morphologic features that are consistent with the ability to function as "passenger leukocytes," and they distribute themselves within rosettes as though performing surrogate support functions usually adopted by retinal pigment epithelial cells. Because this latter property causes activation of the microglia, it may also cause these cells to enhance the immunogenicity of the allograft.

CNI-1493 prolongs survival and reduces myocyte loss, apoptosis, and inflammation during rat cardiac allograft rejection

Cytokines and cytotoxic agents, including nitric oxide (NO) released by macrophages, play important roles during cardiac allograft rejection. In contrast to agents that suppress T-lymphocyte function, CNI-1493 is a multivalent guanylhydrazone compound that inhibits the synthesis and release of proinflammatory cytokines and NO from macrophages. This study investigated the effects of CNI-1493 on rejecting rat cardiac allografts by using Lewis to Wistar-Furth heterotopic cardiac transplants. CNI-1493 (2 mg/kg i.p., b.i.d.) or vehicle (water) was administered beginning the day before surgery. Rat cardiac allograft survival to cessation of heart beat, apoptosis of cardiac myocytes, degree of myocardial inflammation, and inducible nitric oxide synthase (iNOS) messenger RNA (mRNA), protein, and enzyme activity were studied at days 1, 3, 5, and 7 after transplantation. Allograft survival was increased significantly by 26% from 7.5 +/- 0.8 days in vehicle-treated rats (n = 6) to 9.5 +/- 1.2 days in CNI-1493-treated rats (n = 8, p < 0.05). Apoptotic cells per mm2 myocardium decreased from 2.25 +/- 1.25 to 0.84 +/- 0.49 at day 3 and 31.2 +/- 2.9 to 17.6 +/- 5.43 at day 5 after transplantation with CNI-1493 treatment (p < 0.05). The number of apoptotic myocytes and loss of cardiac muscle cells also decreased significantly at day 5 in the treated animals (p < 0.05). The reduction of myocyte loss at day 5 coincided with a significant decrease of the inflammatory response and reduced macrophage influx (p < 0.05). Myocardial iNOS mRNA, protein, and enzyme levels increased during the course of allograft rejection, and CNI-1493 did not significantly reduce iNOS expression in the rejecting rat allograft. CNI-1493 prolongs allograft survival and reduces myocyte loss, apoptosis, and inflammation during rat cardiac allograft rejection. These effects of CNI-1493 appear to be unrelated to altered NO synthesis but may be related to effects of the drug to inhibit macrophage synthesis of cytokines.

Contribution of carbon monoxide-producing cells in the gastric mucosa of rat and monkey

Recent studies have shown that carbon monoxide (CO) may function as a gaseous signaling molecule in a similar way to nitric oxide. In the gastrointestinal tract, immunoreactivity against a CO-producing enzyme, heme oxygenase-2 (HO-2), was reported in epithelial cells and neurons of submucosal and myenteric plexus. However, details of the epithelial cells in the gastric mucosa remain unknown. The aim of this study was to clarify if mRNA for HO-2 is expressed in the rat stomach, if HO-2 protein is present in the mucosa, and to define the cell types of the HO-2-immunoreactive cells. HO-2 mRNA and protein were detected in fundic and pyloric mucosa of rat stomach using an RNA protection assay and western blot analysis. Immunohistochemical study showed that HO-2 was localized in parietal cells of the fundic glands and gastrin cells of the pyloric glands of both rat and monkey. The results suggest that HO-2 enzyme is produced in the gastric mucosa, and that CO is released from parietal cells and gastrin cells.

Immunocytochemical localization of glutamate in normal and detached cat retina

PURPOSE

Glutamate immunoreactivity in the mammalian retina has generally been observed using immersion fixation. The authors investigated glutamate immunoreactivity in the detached cat retina and reevaluated this activity in the normal retina using rapid fixation by perfusion.

METHODS

Unilateral retinal detachment was produced in cats by injecting 0.25% sodium hyaluronate into the subretinal space using a glass micropipet. The eyes were fixed by perfusion with a mixture of 1% glutaraldehyde and 4% formaldehyde 10 minutes and 60 minutes after detachment, and then they were examined by conventional light and electron microscopic immunocytochemistry.

RESULTS

In contrast to previous reports based on immersion fixation, the inner segment was not glutamate immunopositive in the normal retina. The inner segment showed intense glutamate immunoreactivity 10 minutes and 60 minutes after retinal detachment.

CONCLUSIONS

Glutamate immunoreactivity in photoreceptor inner segments may be a postmortem change induced by strong ischemia. Perfusion fixation is of critical importance when studying the immunocytochemical distribution of glutamate in the retina.

Expression and distribution of heme oxygenase-2 mRNA and protein in rat kidney

Recent studies suggest that carbon monoxide (CO), which is formed by the enzyme heme oxygenase (HO) during the conversion of heme to biliverdin, shares some of the chemical and biological properties of nitric oxide (NO) and may play roles similar to those of NO. Heme oxygenase activity in the kidney has been reported for many years, and there are some reports on the expression of mRNA for two HO isozymes (HO-1 and HO-2) and cellular localization of HO-1 protein. However, cellular localization of HO-2 protein in the kidney under normal conditions has not been reported. In the present study we examined the expression and distribution of HO-2 mRNA and HO-2 protein in rat kidney using RNA protection assay and light and electron immunocytochemistry. RNA protection assay confirmed constitutive expression of HO-2 transcript in rat kidney. HO-2 immunoreactivity was selectively found in epithelial cells of the thick ascending limb and distal convoluted tubule, connecting tubule cells, and principal cells of the collecting duct. These results suggest that HO-2 is synthesized in the kidney and that HO-2 in the epithelial cells of renal tubules may serve as a source for CO generation under normal conditions.

Importance of CD49d-VCAM interactions in human monocyte adhesion to porcine endothelium

By using a primate model of natural antibody depletion, we have previously shown that delayed rejection of porcine cardiac xenografts in unmodified primate recipients resulted from xenograft infiltration with monocyte/macrophage lineage cells. In the present study, we initially showed that human monocytes/macrophages demonstrated significantly greater adherence to unstimulated pig aortic endothelial cells (PAEC) than to human umbilical vein endothelial cells (HUVEC). Human TNF-alpha augmented monocyte adhesion to HUVEC by 5-fold higher levels than to PAEC. This effect could not be explained on the basis of incompatibility between human TNF-alpha and its receptor on PAEC since porcine VCAM expression increased by 75-85% after stimulation with TNF-alpha. TNF-augmented monocyte adherence was abrogated by either treatment of PAEC with an anti-VCAM Mab or monocytes with an anti-CD49d Mab. These results suggest that VCAM-CD49d interactions are important in adhesion of human monocytes to PAEC but may not be as effective as those between human monocytes and allogeneic endothelium, perhaps because of structural differences across species. Other interactions, as yet undefined, must explain the relative increase in adhesiveness of human monocytes for unstimulated PAEC versus HUVEC. In experiments investigating the functional consequences of this enhanced monocyte adherence, PAEC stimulation induced 10-fold higher levels of macrophage-derived IL-1 beta and 3-fold higher levels of T cell proliferation compared with HUVEC. Using an anti-DR Mab to interrupt antigen presentation by autologous macrophages markedly reduced the T cell proliferative response to PAEC. Together, these results indicate that the enhanced adherence of human monocytes to PAEC contributes to xenograft rejection beyond the hyperacute period by leading to tissue infiltration, elaboration of cytokines, and an augmented indirect pathway of T cell xenoantigen recognition.

The cardiac internuncial cell in Carassius auratus longsdorffii and other 19 teleost species: a fine-structural study

Thin-section studies of the sino-auricular border region in the hearts of 20 species of teleost fish revealed the cardiac internuncial cell (CIC), hitherto known only in Misgurnus, to occur also in 8 species (Acheilognathus lanceolatus, Carassius auratus longsdorffii, Cyprinus carpio, Girella punctata, Kareius bicoloratus, Rhodeus ocellatus ocellatus, Rhyncopelates oxyrhynchus, Tilapia nilotica), but to be absent in the other 12 species. There was an indication that the CIC was close in nature to myocardial cells because of the findings of Z band-like structures, especially myosin-like thick filaments (ca. 15 nm thick) in the cytoplasm. However, the myosin-like thick filaments were not associated with the actin-like thin filaments (ca. 5 nm thick) or Z band-like structures. Interestingly, the thick filaments showed considerable variation in their occurrence among individuals of a species (Carassius auratus longsdorffii); they were scarce in all of the CICs (Type I) observed in 12 out of 15 individuals studied, and very numerous in all of the CICs (Type II) in the remaining 3 individuals. All of the CICs in Kareius bicoloratus, Girella punctata, Rhodeus ocellatus ocellatus and Rhyncopelates oxyrhynchus were likely to be Type I and all of the CICs in Acheilognathus lanceolatus, Cyprinus carpio and Tilapia nilotica, Type II.

Increased c-fos expression in the brain during experimental murine cerebral malaria: possible association with neurologic complications

Cerebral expression of c-fos protein was studied by immunocytochemistry in murine cerebral malaria (CM) and malaria without cerebral involvement (non-CM). c-fos expression, low in the brains of uninfected mice, increased in frequency, intensity, and distribution during the course of fatal CM (e.g., a 70-fold increase on day 7 after inoculation). These changes paralleled the timing and degree of the neurologic complications and histopathologic changes. Only a slight increase in c-fos expression was detectable in non-CM mice on day 7 after inoculation. Dexamethasone treatment (days 0 and 1 after inoculation) of the CM mice largely prevented the increased cerebral c-fos expression, histopathologic changes, cerebral complications, and death. Increased c-fos expression may indicate the specific neuronal pathways activated by the immunopathologic process of fatal murine CM and could be associated with the behavioral changes and neurologic complications in this model.