Phenotype of infiltrating cells in an ex vivo model of human antiporcine hyperacute cardiac xenograft rejection.
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Animals↗
Biomedical subjects
S Ibrahim
Publications and source records attributed to S Ibrahim.
Trend of consents for donation by relatives of cadaveric donors in the Kingdom of Saudi Arabia.
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Cadaver↗
Moyamoya disease of childhood as a cause of recurrent cerebral ischemic attacks--a case report.
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Anticonvulsants↗
Immunohistochemical manifestations of unilateral kidney ischemia.
Events in the early post-transplant period have been correlated with increased renal allograft loss. Immunologic reactions and ischemic injury have been implicated in this process. While the immunologic aspects of allograft injury have been studied extensively, ischemic effects remain less well understood. To study the effects of ischemia in rats with different genetic backgrounds without the introduction of an alloimmune response, a clamp was placed on the vascular pedicle of the left kidney for 60 min. The short-term effects (1 wk) of ischemia were studied in groups of PVG (RT1c), LEW (RT1), DA (RT1a) and WR (RT1u) rats, Immunoperoxidase staining demonstrated limited infiltration of monocytes, macrophages, and T-cells accompanied by upregulation of low levels of MHC class II antigens on tubular epithelial cells, peritubular capillaries, and interstitial cells in kidneys of PVG and WF rats. Kidneys of LEW and DA rats had greater influxes of monocytes, macrophages, and T cells in addition to higher amounts of MHC class II antigens upregulation on tubular epithelium and interstitial cells. The long-term effects of ischemia were studied in kidneys of WF rats. These kidneys had a progressive increase in infiltrating T cells, monocytes, macrophages and MHC class II expression on the tubular epithelium and the interstitial cells at 14, 30, and 90 d after the ischemic insult. The differences in MHC class II expression between ischemic kidneys of PVG and LEW rats were not associated with differences in production of mRNA for IL-2, IFN-gamma, and TNF-alpha. In summary, transient renal ischemia in the absence of an allogeneic immune response triggers a progression of inflammatory responses, including leukocyte infiltration, cytokine production and MHC class II antigen upregulation which appears to be strain-dependent.
Animals↗
Predominant infiltration of rejecting human renal allografts with T cells expressing CD8 and CD45RO.
Subsets of T cells have been identified by the expression of different isoforms of CD45. Some T cells expressing CD45RA (gp220) have been characterized as "naive" in their response to antigens including alloantigens, whereas T cells expressing CD45RO (gp180) have been characterized as "memory" T cells. To examine the potential association between kidney allograft rejection and infiltration with these subsets, immunohistologic labeling of serial frozen sections from 17 nonrejecting and 18 rejecting kidney transplant biopsies was performed. Biopsies were selected on the basis of unambiguous clinical pathological diagnosis, no antirejection therapy within 1 month before biopsy, and enough tissue available for immunohistologic labeling. Sections were labeled for CD3, CD4, CD8, CD45RA, and CD45RO, and slides were evaluated in a masked manner. The numbers of cells were counted in 10 (400x) high power fields (HPF) in each section. The medians of average cell counts were significantly higher in the rejecting compared with nonrejecting group for CD3+, CD4+, CD8+, CD45RA+, and CD45RO+ T cells in both diffuse and aggregate patterns of infiltration. However, the numbers of infiltrating cells per HPF in rejecting grafts were most striking for CD8+ and CD45RO+ cells: 16/18 rejecting vs. 1/17 nonrejecting cases had more than 5 CD8+ cells/HPF. Likewise, 17/18 rejecting vs. 1/17 nonrejecting cases had more than 5 CD45RO+ cells/HPF. In both cases, the difference was most striking for cells infiltrating in a diffuse versus aggregate pattern. Significantly higher CD45RO+ to CD45RA+ ratios were observed in rejecting versus nonrejecting groups, both in the diffuse and aggregate patterns. Within the rejecting cases, the CD45RO+ to RA+ ratio was significantly higher in diffuse versus aggregate patterns of infiltration (P < 0.0002). These results indicate that a significant increase in CD8+, CD45RO+, and the ratio of CD45RO+ to CD45RA+ T cells in a diffuse pattern of infiltration is most characteristic of clinical renal allograft rejection.
Biopsy↗
Rejection of kidney allografts by MHC class I-deficient mice.
To evaluate the requirement for CD8+ T cells in kidney transplant rejection, we studied class I-deficient (class I-) mice that had received vascularized renal allografts. Because of the absence of MHC class I expression, these mice are grossly deficient in CD4-CD8+ alpha beta TCR+ cells. Despite the deficiency of CD8+ T cells in naive class I- mice, kidney allografts transplanted into class I- recipients developed significant reductions in renal blood flow and glomerular filtration rate to levels comparable to allograft controls. This functional deterioration was associated with histologic changes consistent with cellular rejection. There were no significant differences in the pattern, severity, or phenotypic character of the cellular infiltrate in allografts transplanted into class I- recipients compared to controls. In fact, substantial numbers of CD8+ T cells were present in these allografts, and the intensity and pattern of anti-CD8 staining was not different from controls. Virtually all of the CD8+ cells in the kidney grafts were class I- and CD4- and co-expressed CD8 alpha and beta chains; the majority were alpha beta TCR+. The CD8+ infiltrating cells were cytotoxic to donor targets but also exhibited activity against class I+ cells bearing self-MHC. Despite the marked CD8+ T cell infiltration of grafts, CD8+ T cells could not be detected by flow cytometry in freshly isolated splenocytes from the class I- recipients of allografts. High levels of circulating anti-class I antibodies were present in the serum of class I- recipients of kidney allografts, and these antibodies had unusual specificity in that they appeared to recognize framework epitopes of MHC class I. Thus, class I- mice readily reject kidney allografts. Although the number of CD8+ alloreactive precursors is substantially reduced in class mice, and their specificities are atypical, the pattern and character of the intra-graft CD8+ cellular response is not significantly altered. Thus, factors unrelated to precursor frequency determine the dimension of the intra-graft CD8+ response. Such factors might include cellular and/or biochemical properties of microenvironment within the graft.
Animals↗
The contribution of terminal complement components to acute and hyperacute allograft rejection in the rat.
Acute rejection and antibody-mediated hyperacute allograft rejection are affected by activation of the complement cascade. Split products of early complement components influence the localization, activation, and effector functions of platelets, granulocytes, monocytes, and lymphocytes, while the formation of membrane attack complex (C5b-C9) can lead to rapid cell destruction. Therefore, we compared acute and Ab-mediated hyperacute allograft rejection in a recently described model of C6 deficient PVG (C-) (RT1c) rats and their normal counterpart PVG (C+) (RT1c) rats. Cardiac allografts from fully MHC disparate ACI donors were heterotopically grafted into naive and skin graft sensitized PVG (C-) and PVG (C+) rats. ACI cardiac allografts were rejected acutely (8.3 +/- 2 days; n = 7) by naive PVG (C+) recipients, but survived significantly longer in PVG (C-) recipients (22 +/- 10 days; n = 10). Presensitized PVG (C+) rats rejected ACI cardiac allografts hyperacutely in 6.1 +/- 2.4 hr (n = 5). In contrast, ACI cardiac allografts transplanted into presensitized (PVG (C-) rats had markedly longer survival of 91 +/- 14 hr (n = 5). The alloantibody responses of naive PVG (C+) and PVG (C-) recipients 7 days after cardiac allografting, and of presensitized PVG (C+) and PVG (C-) recipients at time of cardiac allografting were not significantly different as measured by flow cytometry against ACI lymphocytes. Immunofluorescence demonstrated deposition of IgM, IgG and C3 in ACI allografts in PVG (C-) as well as in PVG (C+) recipients. Deposition of C6 was only found in grafts rejected by PVG (C+). The significantly longer survival of ACI cardiac allografts in C6-deficient PVG (C-) rats indicates that the membrane attack complex contributes to acute as well as antibody-mediated hyperacute allograft rejection.
Acute Disease↗
Glutathione reductase (EC 1.6.4.2.) in experimental trypanosomiasis.
The activity of glutathione reductase (GHSR) in extracts of kidney, liver and testis of rats infected with Trypanosoma congolense decreased with every wave of parasitemia. The implications of these observations as they relate to the risk of oxidative stress are discussed.
Animals↗
Protein-bound pyrroles in rat hair following subchronic intraperitoneal injections of 2,5-hexanedione.
Studies were initiated to ascertain whether body hair could be used to develop a biological marker for chronic exposure to industrial neurotoxicants that yield the metabolite 2,5-hexanedione (2,5-HD), that is, n-hexane and methyl n-butyl ketone. Rats were injected daily with a 50 mg/kg ip dose of 2,5-HD for 45 d. At intervals, body hair and individual vibrissae were removed (under general anesthesia) and tested for the presence of pyrrole substances with p-N,N-dimethylaminobenzaldehyde (DMAB, Ehrlich's reagent). Vibrissae and body hair were stained a reddish color that was distinctly different from that observed with the hair taken from control animals. Solubilized body hair protein from the treated animals gave a positive Ehrlich's test, while that from control animals was negative. Spectral analysis of the DMAB-treated hair from experimental animals disclosed a maximum absorbance at 530 nm, which indicated the presence of pyrrole substituents. Serial analysis of individual nose hairs taken during 2,5-HD administration showed a progression with time of the region staining positively for pyrroles, thus indicating that the process can proceed in growing hair. These findings suggest the potential utility of hair as an indicator for chronic exposure to this class of industrial chemicals possessing neurotoxicity potential. This could complement urinary analysis, which is now used to confirm recent exposure.
Animals↗
Pyridinium crosslinks in patients on haemodialysis and continuous ambulatory peritoneal dialysis.
BACKGROUND: The urine excretion of the pyridinium crosslinks of collagen, pyridinoline (PYD) and deoxypyridinoline (DPD) closely reflect bone resorption and their assay has been used as specific markers of mature collagen turnover. The aims of this study were to evaluate the use of these markers to predict the severity of osteodystrophy in patients with chronic renal failure. METHODS: Using an isocratic ion-paired reverse-phase high-performance liquid chromatography, PYD and DPD were determined in the serum, urine and dialysate of 48 patients with chronic renal failure undergoing haemodialysis (n = 28) or continuous ambulatory peritoneal dialysis (n = 20). Nineteen apparently healthy subjects were studied as controls. RESULTS: In all groups, serum and urine crosslinks excretion showed poor correlation with age. In the patients urine PYD/creatinine and DPD/creatinine were significantly (P < or = 0.03 and < or = 0.001 respectively) higher than normal; urine PYD and DPD levels were highly correlated with each other (r = 0.98) and with serum PTH (r = 0.84 and 0.83 respectively). The mean (SD) predialysis serum PYD, 269 (334) nmol/l, was significantly (P < or = 0.003) elevated compared with normal patients, 4.1 (0.6) and pre-dialysis serum DPD was 82.9 (93.7) nmol/l. DPD was below the detection limit of the assay in normal sera. In the patients postdialysis decreases in serum PYD and DPD were statistically significant (P < 0.0002 and P < 0.0007 respectively). PYD and DPD were found in the dialysate of patients on haemodialysis as well as 24-h dialysate in patients on CAPD. Dialysate PYD and DPD were highly correlated with each other (r = 0.80) and with dialysate creatinine (r = 0.76 and r = 0.62 respectively). In the patients, the mean serum, urine and dialysate PYD and DPD increased with the duration on dialysis. These findings confirm that metabolic bone disease increases in patients with duration of chronic renal failure. CONCLUSION: Estimation of serum crosslinks levels has potential as an additional tool in the diagnosis and monitoring of renal osteodystrophy. The ability to determine crosslink levels in serum and dialysate should be particularly useful in patients who are unable to produce urine.
Adult↗
A comparison of techniques used to estimate the amount of resuspended soil on plant surfaces.
The objectives of this study were to compare four common techniques used to estimate soil mass loadings on plant surfaces and to assess the need to account for particle-size distributions of both the soil tracer and contaminant of concern within the soil. Soil loadings (g soil kg-1 dried plant) from split samples collected in a pasture near Chernobyl were estimated using soil tracers of plutonium analyzed via alpha spectroscopy (mean +/- standard error; 1.0 +/- 0.2), titanium analyzed with an inductive coupled plasma spectrometer; (3.6 +/- 0.6), and neutron activation analysis for scandium (8.1 +/- 1.6), as well as simply washing the soil off the vegetation (34.1 +/- 5.6) Differences were significant at p < 0.001. We also found that soil loading estimates from any one technique varied by a factor of 10 depending on the soil particle size used in the calculations. This was because soil loadings decreased when smaller-sized soil fractions dominated the resuspension process. However, the percent of the plant's total contamination attributable to soil loading increased with smaller soil particles. Smaller soil particles apparently contribute less to the mass of soil loading (g soil kg-1 dry plant), but more to the total plant contamination (Bq) because of the higher concentration of contaminant found in the smaller-sized soil fractions. Differences in mass loading estimates due to the technique chosen (a factor of 10), or due to differences in elemental concentration as a result of the soil particle size used in the calculation (also a factor of 10), were greater than the natural variability observed in the field (2.5).
Alpha Particles↗
Leukotrienes in renal transplant rejection in rats. Distinct roles for leukotriene B4 and peptidoleukotrienes in the pathogenesis of allograft injury.
To investigate the role of leukotrienes in renal allograft rejection, we studied the effects of specific leukotriene inhibitors in a rat kidney transplant model. The enhanced renal production of leukotrienes observed in allograft recipients was reduced in a dose-dependent manner by the specific 5-lipoxygenase inhibitor MK886. This suppression of leukotriene production caused a substantial improvement in renal function. Inhibition of 5-lipoxygenase also reduced the severity of vascular inflammation and endothelial injury in allografts, and profoundly inhibited expression of donor MHC class II Ag on kidney cells. Survival of renal allograft recipients was prolonged from 10 +/- 1 days in controls to 16 +/- 1 days in animals that received a 6-day course of MK886 (p < 0.05). To investigate the relative roles of LTB4 compared to peptidoleukotrienes in these processes, we treated a separate group of animals with the specific peptidoleukotriene receptor antagonist SKF106203. This agent inhibits the interaction of peptidoleukotrienes with their receptor(s) but does not affect the biologic actions of LTB4. In these studies, SKF106203 caused a modest improvement in renal allograft function that was of lesser magnitude than that seen with the 5-lipoxygenase inhibitor. SKF106203 also reduced vascular inflammation in allografts, but had no effect on expression of MHC class II Ag. We conclude that leukotrienes play a key role in the pathogenesis of renal allograft rejection. Furthermore, the detrimental effects of leukotrienes in rejection are mediated by distinct actions of LTB4 and peptidoleukotrienes.
Animals↗
The effect of soluble complement receptor type 1 on hyperacute rejection of porcine xenografts.
The use of xenografts (Xgs) from distantly related species to relieve the increasing shortage of organs for clinical transplantation is prevented by the occurrence of hyperacute rejection (HAR). This process, in which C activation plays a central role, cannot be inhibited with currently available immunosuppressants. In two clinically relevant xenotransplantation models, this study evaluated the effect of C inhibition using recombinant soluble complement receptor type 1 (sCR1) on HAR. In an ex vivo model in which porcine cardiac Xgs were perfused with human blood, cardiac function ceased within 34 min when the perfusate blood was untreated (n = 3). When the perfusate blood was treated with sCR1 (300 micrograms/ml), cardiac Xg function was maintained for up to 4 hr (n = 3). Immunohistologic examination of these Xgs demonstrated deposition of C3b/iC3b and C3d in Xgs perfused with untreated human blood but only C3d deposition in those Xgs perfused with sCR1-treated human blood. These findings are consistent with the cofactor activity of sCR1 for factor I-mediated degradation of deposited C3b/iC3b to C3d. Treatment with sCR1 also prevented the histopathologic changes of HAR observed when untreated blood was used as the perfusate. In an in vivo pig-to-primate heterotopic cardiac xenotransplantation model, in which porcine Xgs transplanted into untreated cynomolgus monkey recipients underwent HAR in 1 hr or less (n = 3), a single intravenous bolus of sCR1 (15 mg/kg) administered to the recipient immediately before Xg reperfusion markedly inhibited total and alternative pathway serum C activity and prolonged Xg survival to between 48 and 90 hr (n = 5). These studies confirm the important role of C activation in HAR of porcine cardiac Xgs by primates and indicate that sCR1 may be a useful agent for xenotransplantation.
Animals↗
Urinary phospholipids excretion in neonates treated with amikacin.
Aminoglycosides, among the most commonly used antibiotics in neonates, have frequently been implicated in nephrotoxic reaction. Studies in adults have indicated that phospholipiduria (PLU) is rapidly increased during aminoglycoside therapy, in relation to the renal phospholipidosis these drugs are known to induce in renal cortex. We studied the effect of amikacin (AK) on PLU in male prematurely-born neonates (gestational age > 34 weeks; postnatal age < or = 2 days) by assessing the urinary excretion of 4 enzymes (N-acetyl-beta-D-glucosaminidase [NAG], alkaline phosphatase, tau-glutamyltransferase and alanine aminopeptidase) and 4 low-molecular-weight proteins (beta-2-microglobulin, clara cell protein, microalbumin and retinol-binding protein) which are currently used to monitor the development and extent of renal tubular damage. Twenty-two patients and 8 healthy (as control) neonates were enrolled in the study. Patients were treated with AK (15 mg/kg per day) given in one (qd, n = 10) or two equal injections (b.i.d., n = 12) for durations of 7-11 days. PLU and proteinuria were determined in 24-h urine sample collections, and enzymes were assessed in spot urine collected at 9 a.m. We found that in neonates, AK causes a significant increase in PLU, and in enzymuria except for NAG in the qd group. Proteinuria showed no significant change due to AK treatment. No significant differences were observed between qd and b.i.d. administrations of AK for all parameters tested. We conclude that PLU could be used in neonates as well as in adults as a non-invasive method to monitor the development of the renal phospholipidosis during aminoglycoside therapy.
Acetylglucosaminidase↗
The trypanocidal effect of Cannabis sativa constituents in experimental animal trypanosomiasis.
The effect of Cannabis sativa on trypanosome-infected rats was examined. An aqueous extract of the seeds administered at a dose of 50 mg/kg/d cured animals infected with Trypanosome brucei brucei of blood stream parasites. Six fractions eluted from the crude extract by column chromatography were assessed for trypanocidal properties. Of these, only 2 fractions retained trypanocidal activity by curing mice infected with T brucei brucei.
Animals↗
V-region-mediated binding of human Ig by protein A.
The Fab-mediated "alternative" binding of Ig by staphylococcal protein A is a marker of a set of VH genes (a subset of family VH3 in man). We typed 115 monoclonal human Ig as alternative binders or nonbinders. The proportion of binders varied depending on the isotype, 35% in IgM but only 11-13% in IgA1 and IgG3. It was 28% among lambda-chain-bearing but 16% among kappa-bearing monoclonal Ig. Independent estimates of the proportions bound were obtained by studying polyclonal Ig of 10 healthy adults. The proportions bound were close to those observed in the study of monoclonal Ig (the means were IgM 32%, IgA1 13%, IgA2 24%, IgG3 14%). A higher proportion of infant than adult Ig was bound by protein A. Also, the proportion was less isotype-dependent in infants than in adults. At the age of 4 mo, 47% of IgM was bound (mean of 10 children), the values of other isotypes were: IgA1 35%, IgA2 39%, and IgG3 38%. At the age of 14 mo the proportion of alternative binders had decreased but was still far from adult values. We propose that ontogenically early ("virgin") B cells, besides being rich in IgM and lambda-chain producers, are rich in producers of alternative binders. A subsequent selection reduces the proportion of these B cells so that in ontogenically most developed B cell populations, e.g., those producing IgA1 kappa, such cells make up only about 10% of the total.
Adult↗
Improved renal function in mouse kidney allografts lacking MHC class I antigens.
The immunological responses that lead to rejection of organ and tissue transplants are triggered by the recognition of proteins encoded within the MHC. The relative contributions of responses directed toward MHC class I compared with class II in the loss of functional integrity of vascularized organ grafts have been difficult to define. The recent development of technologies which allow the generation of mice in which specific genes have been altered by gene targeting offers a new approach to addressing this question. We examine here the rejection of kidney allografts from mice lacking native MHC class I Ag. These mice were obtained from embryonic stem cells in which the beta 2 microglobulin (beta 2m) gene had been disrupted by homologous recombination. We found a significant improvement in function of renal allografts from MHC class I-deficient donors compared with allografts from donors with normal MHC class I expression. Surprisingly, the improved function of the MHC class I-deficient grafts was not associated with differences in mononuclear inflammatory cell infiltration of these grafts nor in differences in alloreactive proliferative or cytotoxic T cell responses. However, we did find differences in alloantibody response between the groups. Recipients of control allografts produced antibodies against both donor MHC class I and II, whereas recipients of MHC class I-deficient grafts formed alloantibodies primarily against donor MHC class II Ag. These studies confirm that immune responses directed toward donor MHC class I alloantigens contribute to kidney transplant dysfunction in this model. Also, these findings suggest that, at least for renal transplants, genetic manipulations which reduce MHC class I expression may be effective in overcoming some of the effects of MHC incompatibility.
Animals↗
Phospholipase A2 from Trypanosoma congolense: characterization and haematological properties.
Phospholipase A2 was isolated from Trypanosoma congolense and purified to electrophoretic homogeneity. The enzyme appeared to exist in a dimeric form with subunit molecular weights of 16,500 and 18,000. It had a pH optimum of 6.8. Kinetic analysis with different substrates, showed that the enzyme had exceptional specificity for 1,2,dimyristoyl-sn-phosphatidylcholine and 1,2,dioleoyl-sn-phosphatidylcholine with Km values of 1.85 x 10(-3) M and 2.12 x 10(-3) M respectively. The Arrhenius plot was linear with an activation energy of 5.8 kcal mol-1. Inhibition studies with parahydroxy-mercuribenzoate and tributyl-tin-oxide were positive thus implicating a thiol group at the catalytic site of the enzyme. The enzyme was stable to heat treatment and possessed haemolytic and anticoagulating properties.
Animals↗