Adult heart transplantation under tacrolimus (FK506) immunosuppression: histopathologic observations and comparison to a cyclosporine-based regimen with lympholytic (ATG) induction

BACKGROUND: Tacrolimus (FK506) is an effective immunosuppressant for human heart transplantation, but information about its effects on cardiac allograft and nonallograft kidney and liver histopathologic study is limited. METHODS: We therefore reviewed 1145 endomyocardial biopsy specimens and eight autopsy results from 80 heart transplant recipients who received tacrolimus as baseline immunosuppression. These were compared with 619 endomyocardial biopsy specimens and four autopsy results from 51 patients treated with cyclosporine-based immunosuppression with lympholytic induction (CLI) by use of rabbit anti-thymocyte globulin. Twenty-one histologic features including the International Society for Heart and Lung Transplantation histopathologic grade were retrospectively assessed without knowledge of the treatment regimen. The lymphocyte growth index on biopsy specimens obtained from these patients was also compared. RESULTS: In general, there were no qualitative differences in the histopathologic appearance of various allograft syndromes between tacrolimus- and CLI-treated patients. Thus histopathologic criteria used to diagnose various graft syndromes are applicable under tacrolimus immunosuppression. However, early (between 10 and 30 days) after transplantation, biopsy specimens from patients treated with tacrolimus showed a significantly higher percentage of inflamed fragments (p = 0.02), the inflammation tended to be more severe (p = 0.09), and the rejection grade tended to be slightly higher (p = 0.08). In contrast, during the late transplantation period (275 to 548 days), biopsy specimens from patients treated with CLI showed a significantly higher percentage of inflamed fragments (p = 0.03), more severe inflammation (p = 0.03), higher rejection grades (p = 0.01), and a higher frequency of Quilty lesions (p = 0.05). Although overall freedom from any grade 3A or higher rejection was greater in the CLI-treated arm, tacrolimus was successfully used to treat refractory rejection in three patients from the CLI-treated arm. Concern has been raised in the literature about the possibility of tacrolimus being a direct hepatotoxin and an accelerant of allograft obliterative arteriopathy. However, no evidence to support either of these contentions was detected in this patient population. In contrast, tacrolimus is clearly nephrotoxic, although similar to cyclosporine in this regard. CONCLUSIONS: Tacrolimus is an effective immunosuppressive drug for heart transplantation. The cardiac allograft histopathologic study of patients treated with tacrolimus immunosuppression does not significantly differ from those given conventional, cyclosporine-based triple therapy with lympholytic induction.     

High flow/low resistance cannulas for percutaneous arteriovenous carbon dioxide removal

Percutaneous cannulas with low resistance are necessary for arteriovenous carbon dioxide removal (AVCO2R) to allow highest flow at lowest pressure to maximize CO2 removal. Commercially available arterial (A) and venous (V) percutaneous cannulas (8-18 Fr) were tested for pressure/flow characteristics under conditions that simulated percutaneous AVCO2R at clinically pertinent flow rates between 200-1000 ml/min to obtain the M number previously described by Delius, et al. The Bio-Medicus (Bio-Medicus, Grand Rapids, MI) 17F A, Research Medical, Inc (RMI) (Model FEM II, Research Medical, Inc., Midvale, UT) 16F A, and RMI 18F V cannulas exhibited the lowest M numbers that correlated with low resistance to flow. The four most clinically favorable arterial cannulas (8, 10, 12, and 14 Fr), coupled with a venous cannula four French sizes larger, were used in an AVCO2R circuit in adult sheep (n = 3) at varying mean arterial pressures (MAP) between 65-105 mmHg. The 8, 10, 12, and 14 Fr arterial cannulas allowed an arteriovenous flow of 208 +/- 72, 530 +/- 37, 848 +/- 66, and 944 +/- 96 ml/min, respectively, at a MAP of 65 mmHg. An increase in MAP to 105 mmHg was associated with approximately a 41, 30, 32, and 27% increment in blood flow, respectively. In summary, an arterial percutaneous cannula of 10 Fr or larger will allow AVCO2R blood flow greater than 500 ml/min, as previously shown by Brunston et al. to achieve total CO2 removal without incurring hypercapnia.     

Local secretion of corticotropin-releasing hormone by enterochromaffin cells in human colon

BACKGROUND/AIMS: Corticotropin-releasing hormone (CRH) is a regulator of the hypothalamic-pituitary-adrenal axis and a coordinator of the gastrointestinal response to stress. In addition to its central effects, CRH has peripheral effects on the immune system. CRH is present in several human tissues, such as the brain, spinal cord, adrenal medulla, lung, liver, peripheral blood leukocytes, as well as the gastrointestinal tract. The current study examined the local production of CRH in the normal human colon. METHODS: Normal human colonic tissues obtained by endoscopic biopsy were immunostained with anti-CRH and anti-5-hydroxytryptamine antibody and analyzed for CRH messenger (m)RNA by a reverse-transcribed polymerase chain reaction method and by in situ hybridization. RESULTS: Immunoreactive CRH and CRH mRNA were detected in the colonic mucosal cells in the neighborhood of the base of the crypts. The mucosal cells that expressed CRH mRNA also immunostained with anti-5-hydroxytryptamine antibody. CONCLUSIONS: Normal human colonic mucosal enterochromaffin cells produce CRH. CRH in the colonic mucosa may play a role in the modulation of the intestinal immune system and/or other gastrointestinal functions basally during stressful conditions.     

Crystal structure of the principal neutralization site of HIV-1

The crystal structure of a complex between a 24-amino acid peptide from the third variable (V3) loop of human immunodeficiency virus-type 1 (HIV-1) gp 120 and the Fab fragment of a broadly neutralizing antibody (59.1) was determined to 3 angstrom resolution. The tip of the V3 loop containing the Gly-Pro-Gly-Arg-Ala-Phe sequence adopts a double-turn conformation, which may be the basis of its conservation in many HIV-1 isolates. A complete map of the HIV-1 principal neutralizing determinant was constructed by stitching together structures of V3 loop peptides bound to 59.1 and to an isolate-specific (MN) neutralizing antibody (50.1). Structural conservation of the overlapping epitopes suggests that this biologically relevant conformation could be of use in the design of synthetic vaccines and drugs to inhibit HIV-1 entry and virus-related cellular fusion.     

Con: heparin-bonded cardiopulmonary bypass circuits do not represent a desirable and cost-effective advance in cardiopulmonary bypass technology

The p53 molecule might serve as a common tumor-associated antigen, as the tumor suppressor gene p53 is mutated and the p53 protein is often over-expressed in tumor cells. We report that effective immunity to p53 can be induced through an idiotypic network by immunization of mice with a monoclonal antibody (PAb-240) specific for mutated p53, or with a peptide derived from the complementarity determining region (CDR) 3 of the variable domain of the light chain (VL) of this antibody. The immunized mice produced IgG antibodies to p53 and mounted a cytotoxic reaction to a tumor line bearing mutated p53. The idiotypically immunized mice were resistant to challenge with the tumor cells. Thus antibodies to p53 might serve as immunogens for activating resistance to some tumors. At the basic level, these findings indicate that a network of p53 immunity may be organized naturally within the immune system.     

Evidence for the involvement of Fas ligand and perforin in the induction of vascular leak syndrome

Endothelial cell injury resulting in vascular leak syndrome (VLS) is one of the most widely noted phenomenons in a variety of clinical diseases. In the current study we used IL-2-induced VLS as a model to investigate the role of cytolytic lymphocytes in the cytotoxicity of endothelial cells. Administration of IL-2 (75,000 U/mouse, three times a day for 3 days) into BL/6 wild-type mice triggered significant VLS in the lungs, liver, and spleen. Interestingly, perforin-knockout (KO) mice exhibited a marked decrease in IL-2-induced VLS in all three organs tested. Also, Fas ligand-defective (gld) mice and Fas-deficient (lpr) mice exhibited decreased VLS in the liver and spleen, but not in the lungs. The decreased VLS seen in perforin-KO, gld, and lpr mice was not due to any defect in lymphocyte migration or homing to various organs because histopathologic studies in these mice demonstrated significant and often greater perivascular infiltration of lymphocytes compared with the IL-2-treated wild-type mice. Ultrastructural studies of the lungs demonstrated significant damage to the endothelial cells in IL-2-treated wild-type mice and decreased damage in perforin-KO mice. IL-2 administration caused up-regulation of CD44 in all strains of mice tested and triggered increased LAK activity against an endothelial cell line in wild-type and gld mice, but not in perforin-KO mice. The current study demonstrates for the first time that perforin and Fas ligand may actively participate in endothelial cell injury and induction of VLS in a variety of organs.     

Unusual properties of genomic DNA molecules spanning the euchromatic-heterochromatic junction of a Drosophila minichromosome

While investigating the copy number of minichromosome Dp(1;f)1187 sequences in the polyploid chromosomes of ovarian nurse and follicle cells of Drosophila melanogaster we discovered that restriction fragments spanning the euchromatic-heterochromatic junction of the chromosome and extending into peri-centromeric sequences had the unusual property of being selectively resistant to transfer out of agarose gels during Southern blotting, leading to systematic reductions in Dp1187-specific hybridization signals. This property originated from the peri-centromeric sequences contained on the junction fragments and was persistently associated with Dp1187 DNA, despite attempts to ameliorate the effect by altering experimental protocols. Transfer inhibition was unlikely to be caused by an inherent physical property of repetitive DNA sequences since, in contrast to genomic DNA, cloned restriction fragments spanning the euchromatic-heterochromatic junction and containing repetitive sequences transferred normally. Finally, the degree of inhibition could be suppressed by the addition of a Y chromosome to the genotype. On the basis of these observations and the fact that peri-centromeric regions of most eukaryotic chromosomes are associated with cytologically and genetically defined heterochromatin, we propose that peri-centromeric sequences of Dp1187 that are incorporated into heterochromatin in vivo retain some component of heterochromatic structure during DNA isolation, perhaps a tightly bound protein or DNA modification, which subsequently causes the unorthodox properties observed in vitro.     

Detection of cocaine exposure in the neonate. Analyses of urine, meconium, and amniotic fluid from mothers and infants exposed to cocaine

Cocaine and its metabolites were measured in urine, meconium, and amniotic fluid specimens collected from 30 maternal-infant pairs with histories of prenatal cocaine use. Cocaine, benzoylecgonine, and ecgonine methyl ester were measured by isotope dilution gas chromatography-mass spectrometry. Mothers were interviewed at delivery regarding their cocaine use during pregnancy. There was qualitative agreement between the results of drug determinations in maternal urine, amniotic fluid, infant urine, and meconium. Although all of the mothers in this study admitted to using cocaine during their pregnancy, cocaine or its metabolites were detected only in the 20 cases in which cocaine was used within 3 weeks before delivery. We conclude that when sufficiently sensitive analytic methods are used, maternal urine, infant urine, and meconium analyses yield equivalent results for detection of prenatal cocaine exposure. Importantly, neither meconium nor urinary drug measurements detected cocaine exposure when the last reported use was prior to 3 weeks before delivery.