On the course of goal pursuit: The influence of goal progress on explicit judgments of self-agency

The experience of causing our own actions and resulting outcomes (i.e., self-agency) is essential for the regulation of our actions during goal pursuit. In two experiments, participants indicated experienced self-agency over presented outcomes, which varied in distance to their goal in an agency-ambiguous task. In Study 1, progress was manipulated at trial level (i.e., stimuli moved randomly or sequentially towards the goal). In Study 2, progress was constant at trial level (sequential), but varied at task level (i.e., goal discrepancy of the outcomes was random or decreased over trials). Study 1 showed that self-agency gradually increased in the progress condition as unsuccessful outcomes were objectively closer to the goal, while self-agency increased exponentially upon full goal attainment in the absence of progress. The gradual pattern for the progress condition was replicated in Study 2. These studies indicate that explicit judgments of self-agency are more flexible when there is goal progress.

Embitterment in patients with a rheumatic disease after a disability pension examination: occurrence and potential determinants

OBJECTIVES

Health care and vocational professionals regularly encounter patients with rheumatic diseases who are embittered after a disability pension examination. People who are embittered typically feel victimised, experience resentment and injustice, resist help, and have difficulty coping. Our objective was to examine the occurrence of embitterment in patients with rheumatic diseases after a disability pension examination and the association of embitterment with its possible determinants helplessness and illness invalidation at work.

METHODS

The Illness Cognition Questionnaire (ICQ), Illness Invalidation Inventory (3*I), and Bern Embitterment Inventory were completed by patients who had 9 to 12 weeks earlier received the result of a disability pension examination. Diagnoses were fibromyalgia (n=103), rheumatoid arthritis (n=46), osteoarthritis (n=158), another rheumatic disease (n=62), and more than one rheumatic disease (n=187). Scores were compared to scores of reference groups. Hierarchical regression analyses were conducted.

RESULTS

Eighteen to 27 percent of patients had high levels of embitterment with no differences between diagnostic groups (p=0.71). Helplessness (p<0.001), the two invalidation dimensions discounting and lack of understanding (p<0.001), and the combination of helplessness with these invalidation dimensions (p<0.01), were predictive of more embitterment.

CONCLUSIONS

Our results suggest that, after a disability pension examination, embitterment is present in about one out of five patients with a rheumatic disease. This is problematic insofar as embitterment limits well-being, functioning, and the potential to reintegrate to work. To the extent that helplessness and invalidation at work are causal determinants of embitterment, interventions targeting these aspects may be key to reduce embitterment.

Production of plant growth modulating volatiles is widespread among rhizosphere bacteria and strongly depends on culture conditions

Recent studies have suggested that bacterial volatiles play an important role in bacterial-plant interactions. However, few reports of bacterial species that produce plant growth modulating volatiles have been published, raising the question whether this is just an anecdotal phenomenon. To address this question, we performed a large screen of strains originating from the soil for volatile-mediated effects on Arabidopsis thaliana. All of the 42 strains tested showed significant volatile-mediated plant growth modulation, with effects ranging from plant death to a sixfold increase in plant biomass. The effects of bacterial volatiles were highly dependent on the cultivation medium and the inoculum quantity. GC-MS analysis of the tested strains revealed over 130 bacterial volatile compounds. Indole, 1-hexanol and pentadecane were selected for further studies because they appeared to promote plant growth. None of these compounds triggered a typical defence response, using production of ethylene and of reactive oxygen species (ROS) as read-outs. However, when plants were challenged with the flg-22 epitope of bacterial flagellin, a prototypical elicitor of defence responses, additional exposure to the volatiles reduced the flg-22-induced production of ethylene and ROS in a dose-dependent manner, suggesting that bacterial volatiles may act as effectors to inhibit the plant's defence response.

CEPHEUS SA: a South African survey on the undertreatment of hypercholesterolaemia

AIM

The aim of the CEntralised Pan-South African survey on tHE Under-treatment of hypercholeSterolaemia (CEPHEUS SA) was to evaluate the current use and efficacy of lipidlowering drugs (LLDs), and to identify possible patient and physician characteristics associated with failure, if any, to achieve low-density lipoprotein cholesterol (LDL-C) targets.

METHODS

The survey was conducted in 69 study centres in South Africa and recruited consecutive consenting patients who had been prescribed LLDs for at least three months. One visit was scheduled for data collection, including fasting plasma lipid and glucose levels. Physicians and patients completed questionnaires regarding their knowledge, awareness and perceptions of hypercholesterolaemia and the treatment thereof.

RESULTS

Of the 3 001 patients recruited, 2 996 were included in the final analyses. The mean age was 59.4 years, and 47.5% were female. Only 60.5 and 52.3% of patients on LLDs for at least three months achieved the LDL-C target recommended by the NCEP ATP III/2004 updated NCEP ATP III and the Fourth JETF/South African guidelines, respectively. Being male, older than 40 years, falling into the lower-risk categories, compliance with the medication regimen, and patient knowledge that the LDL-C goal had been reached, were associated with the highest probability of attaining LDL-C goals.

CONCLUSION

The results of this survey highlight the sub-optimal lipid control achieved in many South African patients taking lipid-lowering therapy.

Preparation and structural analysis of carbon-supported Co core/Pt shell electrocatalysts using electroless deposition methods

Cobalt core/platinum shell nanoparticles were prepared by the electroless deposition (ED) of Pt on carbon-supported cobalt catalyst (Co/C) and verified by HRTEM images. For a 2.0 wt % Co/C core, the ED technique permitted the Pt loading to be adjusted to obtain a series of bimetallic compositions with varying numbers of monolayers (ML). The tendency for corrosion of Co and the electrochemical (i.e., oxygen reduction reaction (ORR)) activity of the structures were measured. The results from temperature-programmed reduction (TPR) analysis suggest that a single Pt ML coverage is formed at a Pt weight loading between 0.5 and 0.7% on the 2.0% Co/C. HRTEM analysis indicates that the continuity of the Pt shell on the Co core depends on the precursor Co particle size, where "large" Co particles (>10 nm) favor noncontinuous, three-dimensional Pt structures and "small" Co particles (<6 nm) favor layer-by-layer growth. For these larger core-shell particles, Co was observed to quickly corrode in 0.3 M H(2)SO(4). Surface area specific ORR activity, measured by chemisorption techniques, revealed that the Pt-Co/C catalysts performed better than a commercial Pt/C catalyst; however, on a Pt mass basis, only the lower Pt:Co atomic ratio Pt-Co/C catalysts outperformed the Pt/C catalyst.

Inhaled corticosteroids during acute bronchiolitis in the prevention of post-bronchiolitic wheezing

BACKGROUND

Acute bronchiolitis in infants and young children is associated with long-term airway disease also known as post-bronchiolitic wheezing. Two major hypotheses have been proposed to explain the association between bronchiolitis and PBW. The first hypothesis considers bronchiolitis to be the first manifestation of recurrent wheezing in infants and children who are susceptible to obstructive airway disease. The second hypothesis suggests that the infection and concomitant inflammatory reaction in the acute phase leads to airway epithelium injury resulting in long-term obstructive airway disease. In line with the latter hypothesis, corticosteroids may have a beneficial effect on the prevention of post-bronchiolitic wheezing.

OBJECTIVES

The objective of this review was to evaluate the effect of inhaled corticosteroids, started during the acute phase of bronchiolitis, on the prevention of post-bronchiolitic wheezing.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 3, 2006) which contains the Cochrane Acute Respiratory Infections Group's trials register, MEDLINE (1966 to September 2006), EMBASE (1980 to September 2006) and Current Contents (September 2006). Abstracts and reports of congresses (ERS 1999 to September 2005, ATS 1999 to September 2005) were obtained. We contacted experts in the field and pharmaceutical companies for ongoing or unpublished studies.

SELECTION CRITERIA

Randomised placebo-controlled trials studying the effect of inhaled corticosteroids in children younger than two years of age with the clinical diagnosis of acute bronchiolitis were included.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed trial quality using the Jadad 5-point scale.

MAIN RESULTS

Five studies matched the inclusion criteria, with a median Jadad score of 4 (Inter Quartile Range 3 to 4), involving 374 infants. Pooling of the data was limited, due to the clinical diversity of the studies. However, no effect of inhaled corticosteroids in the prevention of wheezing (diary records or GP diagnosed), hospital re-admissions or use of corticosteroids or bronchodilators could be demonstrated. Duration of therapy, length of follow up or causative agent (respiratory syncytial virus or not) did not influence the pooled effect. In the three studies that also evaluated the adverse events, none were reported.

AUTHORS' CONCLUSIONS

This review does not demonstrate an effect of inhaled corticosteroids given during the acute phase of bronchiolitis in the prevention of post-bronchiolitic wheezing. The small number of included participants and the inability to pool all clinical outcomes precludes us from making strong recommendations.

Correlation of radiographic and manometric findings in patients with ineffective esophageal motility

BACKGROUND

Ineffective esophageal motility disorder (IEM) is a new, manometrically defined, esophageal motility disorder, associated with severe gastroesophageal reflux disease (GERD), GERD-associated respiratory symptoms, delayed acid clearance, and mucosal injury. Videoesophagram is an important, inexpensive, and widely available tool in the diagnostic evaluation of patients with esophageal pathologies. The efficacy of videoesophagography has not been rigorously examined in patients with IEM. The aim of this study was to determine the diagnostic value of videoesophagography in patients with IEM.

METHODS

The radiographic and manometric findings of 202 consecutive patients presenting with foregut symptoms were evaluated. IEM was defined by strict manometric criteria. All other named motility disorders such as achalasia were excluded. Videoesophagography was performed according to a standard protocol.

RESULTS

Of patients in this cohort, 16% (33/202) had IEM by manometric criteria. Of IEM patients, 55% (18/33) had an abnormal videoesophagram, while in 45% (15/33) this test was read as normal. Only 11% (15/137) of patients with a normal videoesophagram were found to have IEM. Sensitivity of videoesophagram was 54.6%, specificity 72.2%, positive predictive value only 27.7%, and negative predictive value 89.1% in the diagnosis of IEM.

CONCLUSIONS

These data show that videoesophagram is relatively insensitive in detecting patients with IEM and should not be considered a valid diagnostic test for this disorder. We conclude that esophageal manometry is an indispensable diagnostic modality in the workup of a patient with suspected of IEM.

Redefining gastroesophageal reflux (GER)

BACKGROUND

The detection of gastroesophageal reflux (GER) has to date been limited to acid exposure observed on 24-h pH monitoring. It is clear, however that nonacid reflux can be a significant clinical problem. Recently, as impedance technology with the capacity to detect all types of reflux (acid, nonacid, liquid, mixed, and air) has been developed.

METHODS

Seventeen asymptomatic healthy volunteers underwent combined 24-h pH and impedance testing. In all patients, pH was measured at 5 cm above the lower esophageal sphincter (LES), and simultaneous impedance changes were recorded at 3, 5, 7, 9, 15, and 17 cm above the LES. Refluxes were classified as acid (drop in pH <4 for >5 sec), Nonacid, short acid, or nonacid delta based on chemical properties; they were further classified as liquid, mixed, or gas based on the physical refluxate detected by impedance changes. The height of the reflux entering the esophagus was classified as distal (<5 cm), intermediate (5-9 cm), or proximal (9-17 cm).

RESULTS

A total of 868 reflux events were characterized. Fifty-nine percent of them were not conventional acid reflux and could only be detected by impedance changes. Less than 2% of the events that were detected by a fall in pH to <4 were not detected by impedance changes. Pure liquid reflux was seen in 35.4%, a mixed pattern in 36.3%, and a gas reflux in 26.7%. Liquid was confined to the distal esophagus in 30%; it reached the midesophagus in 58% and the proximal esophagus in 11%.

CONCLUSIONS

Over half of GER events are not detected by pH studies. Liquid reflux reaches the mid and proximal esophagus 69% of the time and gas nearly always does (92%). The additional information provided by impedance technology is likely to have a major impact on the understanding and clinical management of patients with gastroesophageal reflux disease (GERD).

Cloning and characterization of two guide RNA-binding proteins from mitochondria of Crithidia fasciculata: gBP27, a novel protein, and gBP29, the orthologue of Trypanosoma brucei gBP21

In kinetoplastid protozoa, mitochondrial (mt) mRNAs are post-transcriptionally edited by insertion and deletion of uridylate residues, the information being provided by guide (g)RNAs. Currently popular mechanisms for the editing process envisage a series of consecutive 'cut-and-paste' reactions, carried out by a complex RNP machinery. Here we report on the purification, cloning and functional analysis of two gRNA-binding proteins of 28.8 (gBP29) and 26.8 kDa (gBP27) from mitochondria of the insect trypanosome Crithidia fasciculata. gBP29 and gBP27 proved to be similar, Arg + Ala-rich proteins, with pI values of approximately 10.0. gBP27 has no homology to known proteins, but gBP29 is the C.fasciculata orthologue of gBP21 from Trypanosoma brucei, a gRNA-binding protein that associates with active RNA editing complexes. As measured in UV cross-linking assays, His-tagged recombinant gBP29 and gBP27 bind to radiolabelled poly(U) and synthetic gRNAs, while competition experiments suggest a role for the gRNA 3'-(U)-tail in binding to these proteins. Immunoprecipitates of mt extracts generated with antibodies against gBP29 also contained gBP27 and vice versa. The immunoprecipitates further harbored a large proportion of the cellular content of four different gRNAs and of edited and pre-edited NADH dehydrogenase subunit 7 mRNAs, but only small amounts of mt rRNAs. In addition, the bulk of gBP29 and gBP27 co-eluted with gRNAs from gel filtration columns in the high molecular weight range. Together, these results suggest that the proteins are part of a large macromolecular complex(es). We infer that gBP29 and gBP27 are components of the C.fasciculata editing machinery that may interact with gRNAs.

Risk factors and the prevalence of trocar site herniation after laparoscopic fundoplication

BACKGROUND

Although there have been case reports describing trocar site herniation after laparoscopic fundoplication, its overall prevalence and the risk factors for its development are unclear.

METHODS

The records of 320 patients undergoing primary laparoscopic fundoplication as treatment for gastroesophageal reflex disease (GERD) or hiatal hernia between 1991 and 1999 were reviewed retrospectively. Placement of the initial supraumbilical trocar was by the open Hassan technique in all patients.

RESULTS

Nine patients (five male) with a mean age 54 years (range, 37-75) developed trocar site herniation, for an overall prevalence of 3%. The mean interval between surgery and diagnosis was 12 months (range, 4-21). In all patients, the hernia occurred at the supraumbilical camera port site. Patients with trocar hernias tended to have a higher body mass index (BMI) than those without hernias (mean BMI, 29.4 kg/m2 vs 27.2 kg/m2, p = 0.13). None of the patients developed intestinal obstruction as a consequence of herniation. To date, all but one of the hernias have been repaired. Six of them required the insertion of a prosthetic mesh.

CONCLUSIONS

The prevalence of trocar site herniation after laparoscopic fundoplication was minimal at 3%. All hernias occurred at the midline supraumbilical port, the only site where open trocar insertion was employed. As a consequence of these observations, we have developed a new method of open trocar placement. This method utilizes a paramedian skin incision and separate fascial incisions through anterior and posterior rectus sheathes, with retraction of the rectus abdominis muscle laterally.

Surgical treatment and outcomes in carcinoma of the extrahepatic bile ducts: the University of Rochester experience

HYPOTHESIS

To our knowledge, few individual surgeons and only a handful of institutions have gained a meaningful experience with the treatment of adenocarcinoma of the extrahepatic bile ducts or cholangiocarcinoma. The purpose of this study was to critically evaluate the experience of a single center in the treatment of these tumors.

DESIGN

Retrospective cohort study with a median follow-up of 48 months.

SETTING

Department of surgery at a university referral center.

PATIENTS

Seventy-seven patients with biopsy-confirmed adenocarcinoma of the extrahepatic bile ducts evaluated and treated between January 1980 and February 1998.

MAIN OUTCOME MEASURES

Prognostic variables, resectability rates, morbidity, and survival.

RESULTS

Thirty-eight male and 39 female patients were studied (median age, 71 years). Twenty-three patients (30%) underwent curative resections, 32 patients (41%) underwent palliative surgery, and 22 patients (29%) received nonoperative therapies. The 30-day perioperative morbidity rate was 18%, and mortality was 6%. Overall median survival was 11 months; 4 months for patients receiving nonoperative therapy; 8 months for patients receiving palliative surgery; and 72 months for curative resection. Five-year survival rates were 23%, 0%, 10%, and 55%, respectively. Curative resection was the only prognostic variable to have a statistically significant effect on survival.

CONCLUSIONS

Curative resection could be achieved in approximately one third of patients who had cholangiocarcinoma, and should be the goal of treatment. Survival is significantly improved in those patients who are considered to have resectable tumors and who undergo removal of all gross disease. Palliative surgical treatments also revealed a survival advantage over nonoperative therapies.

Surgery, radiotherapy, and chemotherapy in carcinoma of the esophagus

Esophageal carcinoma remains a highly lethal disease that has shown a recent profound increase in prevalence and an equally dramatic epidemiologic shift. There is a well recognized causal association between gastroesophageal reflux disease and adenocarcinoma of the esophagus, and the molecular events underlying this progression from mucosal injury, to metaplasia, to dysplasia, to carcinoma are now becoming clear. Current diagnostic modalities and preoperative staging systems all have significant limitations. Fortunately, chemoprevention strategies and the identification of clinically useful molecular biomarkers that may be used to stage disease and select appropriate therapy are on the horizon. The extent of surgical resection for esophageal carcinoma remains an area of great controversy. Disease that is confined to the mucosa is being diagnosed more commonly, and endoscopic ablative techniques have been proposed. To date, however, preoperative discrimination of tumor depth and presence of regional nodal metastases remains inadequate in these very early lesions, and caution is urged before adopting therapies that may compromise cure. For disease penetrating the mucosa, the extent of surgical therapy must be tailored by the objectives of treatment (cure vs palliation) and preoperative stage. Surgical resection is the current standard of care, with combined-modality therapy reserved for prohibitive surgical candidates. No clear survival benefit has been documented for neoadjuvant radiotherapy or chemotherapy alone. The results of preoperative combined-modality therapy, including three prospective, randomized trials, are encouraging but to date have not shown a definite benefit.

A more versatile and reliable method for renal transplantation in the rat

This study describes the authors' experience with a new method of orthotopic renal transplantation in the rat. This technique combines previously described modifications with the use of the donor inferior vena cava as a conduit to perform an end-to-side venous anastomosis. Survival was 87% and 80% at 3 and 120 days, respectively. Patency was 80% at 120 days, and histologic examination revealed normal renal architecture and parenchyma, with no evidence of ischemic injury. This technique offers a refinement of previous techniques and is reliable, flexible, and can be easily learned by novice microvascular surgeons.

Mitochondrial minicircles in the free-living bodonid Bodo saltans contain two gRNA gene cassettes and are not found in large networks

In trypanosomatids, the majority of the guide (g) RNAs that provide the information for U-insertion/deletion RNA editing are encoded by minicircles that are catenated into large networks. In contrast, in the distantly related cryptobiid Trypanoplasma borreli, gRNA genes appear to reside in large 180-kb noncatenated DNA circles. To shed light on the evolutionary history and function of the minicircle network, we have analyzed minicircle organization in the free-living bodonid Bodo saltans, which is more closely related to trypanosomatids than T. borreli. We identified 1.4-kb circular DNAs as the B. saltans equivalent of minicircles via sequence analysis of 4 complete minicircles, 14 minicircle fragments, and 14 gRNAs. We show that each minicircle harbors two gRNA gene cassettes of opposite polarity residing in variable regions of about 200 nt in otherwise highly conserved molecules. In the conserved region, B. saltans minicircles contain a putative bent helix sequence and a degenerate dodecamer motif (CSB-3). Electron microscopy, sedimentation, and gel electrophoresis analyses showed no evidence for the existence of large minicircle networks in B. saltans, the large majority of the minicircles being present as circular and linear monomers (85-90%) with small amounts of catenated dimers and trimers. Our results provide the first example of a kinetoplastid species with noncatenated, gRNA gene-containing minicircles, which implies that the creation of minicircles and minicircle networks are separate evolutionary events.

Tolerance induction permits the development of graft-versus-host disease: donor-mediated attack following small bowel transplantation in mixed chimeras

The induction of tolerance to organ allografts would eliminate acute and chronic rejection as well as the need for nonspecific immunosuppression. We have shown that tolerance induced through the creation of mixed allogeneic bone marrow chimeras allows for the long-term engraftment of cardiac and small bowel allografts across strong multiple major histocompatibility barriers. The possibility that tolerance might render the host susceptible to graft-versus-host disease (GVHD) has not been investigated in this or other models of tolerance. To test this possibility chimeras were created by transplantation of T-cell depleted ACI and Lewis bone marrow into lethally irradiated Lewis rats. Chimerism was determined post bone marrow transplant (BMTx) by flow cytometry of lymphocytes from reconstituted animals. ACI/Lew chimeras (ALC), Lewis/ACI F1 (LACF1), and Lewis (LEW) rats all received heterotopic ACI vascularized small bowel grafts. A second group of chimeras received small bowel grafts from ACI rats pretreated with low dose irradiation to eliminate T-cells from the graft. LEW-->LEW small bowel isografts were also performed. Animals were examined for evidence of GVHD by clinical signs and histologic examination of biopsied tissues. GVHD was quantified using the popliteal lymph node enlargement assay. All LACF1 rats developed severe lethal GVHD following ACI small bowel transplant. Bone marrow chimeras, ALC (n = 6), developed fatal GVHD in a similar fashion after receiving a small bowel transplant. LEW-->LEW isografts and chimeras receiving bowel from irradiated ACI rats survived long term without GVHD while ACI-->LEW allogeneic transplants all underwent acute rejection. GVHD or its absence was confirmed histologically. Popliteal lymph node enlargement indices reflected the presence of GVHD in the chimeras (1.87) and LACF1 (5.4) receiving allografts, but not in isografts or chimeras receiving irradiated allogeneic transplants. Analysis of cytokines in the tongues of rats undergoing GVHD showed elaboration of Th1 type proinflammatory cytokines which was not seen in isografted rats or rats receiving preirradiated small bowel. These results demonstrate that tolerance induction through mixed chimerism results in susceptibility to small bowel induced GVHD. Preirradiating the donor bowel prior to SBTx can prevent GVHD.

RNA editing in the free-living bodonid Bodo saltans

In parasitic kinetoplastid protozoa, mitochondrial (mt) mRNAs are post-transcriptionally edited by insertion and deletion of uridylate residues, the information being provided by guide (g) RNAs. In order to further explore the role and evolutionary history of this process, we searched for editing in mt RNAs of the free-living bodonid Bodo saltans. We found extensive editing in the transcript for NADH dehydrogenase (ND) subunit 5, which is unedited in trypanosomatids. In contrast, B.saltans cytochrome c oxidase (cox) subunit 2 and maxicircle unidentified reading frame (MURF) 2 RNAs display limited editing in the same regions as their trypanosomatid counterparts. A putative intramolecular cox2 gRNA and the gene for gMURF2-I directing the insertion of only one U in the 5' editing domain of MURF2 RNA, are conserved in B.saltans. This lends (further) evolutionary support to the proposed role of these sequences as gRNAs. Phylogenetic analysis showed that B.saltans is more closely related to trypanosomatids than the cryptobiids Trypanoplasma borreli and Cryptobia helicis, in line with the trypanosomatid-like cox2 and MURF2 RNA editing patterns. Nevertheless, other features like the apparent absence of a catenated mtDNA network, are shared with bodonid and cryptobiid species. ND5 RNA editing may represent yet another example of editing 'on the way out' during kinetoplastid evolution, but in view of the fact that cox2 RNA is unedited in T. borreli and C.helicis, we infer that the editing of this RNA may have arisen relatively recently. Our results provide the first examples of RNA editing in a free-living kinetoplastid, indicating that there is no direct link between U-insertion/deletion editing and a parasitic lifestyle.

Tolerance induction by intrathymic inoculation prevents chronic renal allograft rejection

BACKGROUND

These experiments investigated the ability of the donor-specific unresponsiveness created by the intrathymic inoculation of donor alloantigen to effectively prevent chronic rejection in an established rat model of chronic renal allograft rejection.

METHODS

Three study groups were examined: (1) Allograft controls--F-344 rats received a Lewis renal allograft plus 10 days of low-dose cyclosporine (CsA); (2) isograft controls--F-344 rats received an F-344 renal isograft and low-dose CsA; (3) experimental group--F-344 rats received a T-cell depleted syngeneic bone marrow transplant and intrathymic injection of Lewis bone marrow. Twenty-one days after bone marrow transplant, these animals received a Lewis renal allograft.

RESULTS

Allograft controls demonstrated severe parenchymal fibrosis; isograft controls and intrathymic (IT) animals failed to develop this lesion. Immunohistochemical analysis revealed increased CD4+ T cells infiltrating the cortex of the allograft controls. Cytokine interferon-gamma and interleukin-2 transcripts were strongly positive in allograft controls and were absent from isograft controls and IT allografts as determined by reverse transcriptase-polymerase chain reaction. Analysis of tolerant grafts by flow microfluorimetry and genomic DNA amplification could not detect chimerism to a level of < 0.1%.

CONCLUSION

IT inoculation of donor alloantigen can confer long-term unresponsiveness and prevent the development of the characteristic lesions of chronic rejection.

Graft versus host disease in rats made tolerant for organ allografts

Tolerance for organ allografts would eliminate acute and chronic rejection as well as the need for nonspecific immunosuppression. A potential hazard of tolerance is the susceptibility to graft vs host disease (GVHD) due to unresponsiveness to alloantigen. This study sought to determine if our model of tolerance induction results in susceptibility to GVHD. Chimeras were created by transplantation of T-cell depleted ACI and Lewis bone marrow into lethally irradiated Lewis rats. Chimerism was determined post-BMTx by flow cytometric analysis of recipient spleens for the presence of ACI cells. ACI/Lew chimeras (ALC), animals that reconstituted only with syngeneic (Lewis) marrow (so-called failed chimeras), and ACI/Lew F1 (LACF1) hybrid rats were all given 200 x 10(6) ACI splenocytes i.v. Animals were examined for evidence of GVHD. GVHD was quantified using the popliteal lymph node enlargement assay. All LACF1 (n = 6) rats developed severe lethal GVHD following ACI splenocyte injection. Similarly, ALC (n = 6) developed fatal GVHD. Animals that reconstituted only with syngeneic Lewis marrow (failed chimeras) showed no signs of illness. GVHD was confirmed histologically and immunohistochemically. Failed chimeras receiving ACI splenocyte challenge showed no evidence of GVHD histologically. Popliteal lymph node enlargement indices reflected the presence of GVHD in the chimeras and hybrids but not in the failed chimeras. We conclude that tolerance induction by mixed chimerism results in susceptibility to GVHD if enough donor lymphoid tissue is given to the host at the time of organ transplant. Animals that are not mixed chimeras (failed bone marrow transplant) rejected the allogeneic splenocytes as evidenced by their lack of disease. Tolerance may therefore make the host defenseless against fatal GVHD.

Induction of specific tolerance through mixed hematopoietic chimerism prevents chronic renal allograft rejection in a rat model

BACKGROUND

Chronic rejection is the leading cause of late graft loss in kidney transplantation. We tested the ability of mixed hematopoietic chimerism to prevent chronic renal allograft rejection in an established rat model and described possible mechanisms responsible for this tolerance.

METHODS

Mixed hematopoietic chimerism was established in lethally irradiated F-344 rats by reconstitution with Lewis bone marrow. Four groups (n = 5 each) received orthotopic kidney transplants: (1) allograft controls, (2) isograft controls, (3) experimental chimeras, and (4) specificity control. After 120 days kidney grafts were examined histologically, immunohistochemically, and for cytokine interferon-gamma, interleukin-2 (IL-2), IL-4, and IL-10 gene transcripts by means of reverse transcriptase polymerase chain reaction techniques.

RESULTS

Allograft control group exhibited severe parenchymal fibrosis; isograft control and chimera groups failed to develop this lesion. Immunohistochemical analysis revealed increased CD8+ lymphocytes and ED-1+ monocyte-macrophages infiltrating the tubulointerstitium of control allografts. Interferon-gamma and IL-2 were absent in isografts. IL-4 was absent and IL-10 was positive in all grafts. Chimeras promptly rejected third-party allografts.

CONCLUSIONS

Induction of specific tolerance through mixed hematopoietic chimerism prevents chronic renal allograft rejection. These results support the hypothesis of an immunologic basis of chronic rejection and advance previous observations that the induction of specific tolerance enables long-term solid organ transplantation without the use of immunosuppression.