PubMed Health⌕ Search

Biomedical subjects

H Benediktsson

Publications and source records attributed to H Benediktsson.

At least 19 recordsLinked to original sources
PubMed2005

Protective effects of PG490-88 on chronic allograft rejection by changing intragraft gene expression profiles.

Our previous study showed that PG490-88 effectively ameliorated both functional and histological changes of chronic rejection in the rat. In this experiment, we investigated the intragraft gene expression profiles of PG490-88 under successful prevention of chronic rejection in rat kidney allografts. Kidneys of F344 rats were transplanted into bilaterally nephrectomized LEW recipients. Recipients with a brief course of low-dose FK506 (1 mg/kg per day for 10 days) were dosed with PG490-88 0.5 mg/kg per day, which was predetermined and defined as the effective dose of preventing chronic allograft rejection in this model, for 90 days after grafting. Kidney grafts were harvested on day 90 after transplantation and subjected to gene expression analysis by real-time RT-PCR. Overall, the expression levels of all genes tested were upregulated in the brief course of low-dose FK506 control. PG490-88 treatment exhibited significant inhibition of intragraft m RNA levels of iNOS, IL-6, and perforin and marginal downregulation of IL-2, IFNgamma, IRF-1, TNFalpha, and TGFbeta. There was no change in IL-10, granzyme B, and PDGFalpha, when compared to the brief course of low-dose FK506 control. These results suggested that downregulation of multiple intragraft gene expression by mainly suppression of iNOS, IL-6, and perforin might be responsible for successful prevention of chronic kidney allograft nephropathy by PG490-88 in rats.

Animals↗
PubMed2005

Down-regulation of TGF-beta and VCAM-1 is associated with successful treatment of chronic rejection in rats.

We measured the expression levels of transforming growth factor-beta (TGF-beta) and vascular cell adhesion molecule (VCAM-1) in rat kidney grafts undergoing chronic rejection and treated the rats with six different regimens in order to determine correlation between their expression levels and severity of chronic rejection. F344 or Lewis kidneys were transplanted into Lewis recipients to generate allograft or isograft groups, respectively. Graft recipients were treated with one of the following regimens: (1) untreated isograft, (2) untreated allograft, (3) tacrolimus (FK506), 1 mg/kg/d for 10 days, (4) triptolide (PG490-88), 0.5 mg/kg/d for 10 days, and (5) leflunomide analogue (FK778), 10 mg/kg/d for 10 days. Kidneys were harvested on day 90 after transplantation and subjected to histological analysis and gene expression analysis by real-time reverse transcriptase polymerase chain reaction (RT-PCR) for TGF-beta and VCAM-1. Gene expression values were compared to measurements of chronic rejection by linear regression analysis. Modified Banff score for transplant pathology show that chronic rejection was mild in the FK778 group, moderate in the PG490-88 group, and severe in the FK506 and allograft control groups. Overall, the expression levels of TGF-beta and VCAM-1 show high correlations with histological changes of chronic rejection. Suppression of the expression levels of TGF-beta and VCAM-1 is associated with the amelioration of chronic rejection by various drugs, suggesting that these molecules are important key molecules in chronic rejection.

Animals↗
PubMed2004

Anti-C1q autoantibodies in murine lupus nephritis.

Autoantibodies against C1q can be found in the circulation of patients with several autoimmune diseases including systemic lupus erythematosus (SLE). In SLE there is an association between the occurrence of these antibodies and renal involvement. How anti-C1q autoantibodies contribute to renal disease is currently unknown. Cohorts of MRL-lpr mice, which are known to develop age-dependent SLE-like disease, were used to study the relationship between levels of anti-C1q autoantibodies and renal disease. We collected serum, urine and renal tissue and analysed autoantibodies, complement levels and renal deposition as well as renal function. At 2 months of age all mice already had elevated levels of anti-C1q autoantibodies, and elution of kidneys revealed the presence of these antibodies in renal immune deposits in MRL-lpr mice and not in control MRL+/+ mice. In conclusion, anti-C1q antibodies are already present in serum and immune deposits of the kidney early in life and therefore can play a role in nephritis during experimental SLE-like disease in mice.

Animals↗
PubMed2003

Glomerular deposition of C1q and anti-C1q antibodies in mice following injection of antimouse C1q antibodies.

Anti-C1q autoantibodies are present in the serum of patients with different autoimmune diseases such as systemic lupus erythematosus (SLE). The occurrence of these autoantibodies correlates with renal involvement. In the present study we examined whether injection of rabbit antimouse C1q antibodies in mice leads to deposition in kidneys. Injection of healthy mice with a single dose of rabbit IgG antimouse C1q antibodies resulted in deposition of both C1q and IgG anti-C1q in glomeruli. The pattern of deposition observed in the glomeruli of mice injected with antimouse C1q antibodies both at 24 h and 2 weeks was both glomerular basement membrane (GBM)-associated and mesangial. Injection of control IgG did not have a detectable effect on circulating C1q levels, and no deposition of either C1q or rabbit IgG was seen at 24 h. The deposition of rabbit antimouse C1q and C1q in glomeruli resulted in complement activation, as assessed by C3 deposition, and influx of leucocytes associated with albuminuria in some, but not all mice. In none of the control mice was albuminuria observed. This report is the first to show that anti-C1q antibodies deposit in the healthy glomerulus together with autologous C1q. This deposition is stable for at least 2 weeks, causes complement activation, leucocyte influx and can lead to mild albuminuria.

Albuminuria↗
PubMed2001

Peritubular capillary basement membrane reduplication in allografts and native kidney disease: a clinicopathologic study of 278 consecutive renal specimens.

BACKGROUND: An association has been found between transplant glomerulopathy (TG) and reduplication of peritubular capillary basement membranes (PTCR). Although such an association is of practical and theoretical importance, only one prospective study has tried to confirm it. METHODS: We examined 278 consecutive renal specimens (from 135 transplants and 143 native kidneys) for ultrastructural evidence of PTCR. In addition to renal allografts with TG, we also examined grafts with acute rejection, recurrent glomerulonephritis, chronic allograft nephropathy and stable grafts ("protocol biopsies"). Native kidney specimens included a wide range of glomerulopathies as well as cases of thrombotic microangiopathy, malignant hypertension, acute interstitial nephritis, and acute tubular necrosis. RESULTS: We found PTCR in 14 of 15 cases of TG, in 7 transplant biopsy specimens without TG, and in 13 of 143 native kidney biopsy specimens. These 13 included cases of malignant hypertension, thrombotic microangiopathy, lupus nephritis, Henoch-Schonlein nephritis, crescentic glomerulonephritis, and cocaine-related acute renal failure. Mild PTCR in allografts without TG did not predict renal failure or significant proteinuria after follow-up periods of between 3 months and 1 year. CONCLUSIONS: We conclude that in transplants, there is a strong association between well-developed PTCR and TG, while the significance of mild PTCR and its predictive value in the absence of TG is unclear. PTCR also occurs in certain native kidney diseases, though the association is not as strong as that for TG. We suggest that repeated endothelial injury, including immunologic injury, may be the cause of this lesion both in allografts and native kidneys.

Basement Membrane↗
PubMed2001

[Side effects after lumbal myelography. A prospective study of outpatients.].

INTRODUCTION: Since myelography was first introduced, hospitalization has been considered necessary. The incidence of side effects and their severity is considerably less since the introduction of water-soluble contrast media, and today the procedure is carried out on outpatients in many X-ray departments. The aim of this study was to examine the incidence of side effects after lumbal myelography performed at the Radiological Department of Reykjavík City Hospital. MATERIAL AND METHODS: Patients referred for lumbal myelography during a five month period from January to May 1995 were included in the study group. All data were prospectively collected. All procedures were carried out in the same way. The injection was most often between the lumbar vertebrae L3/L4. The same quantity of iodine was used in each case. After the examination, patients were permitted to sit in the waiting room and move about freely, but remained under the supervision of the department for three hours. Patients answered three questionnaires regarding their condition before the examination, after, and again two days later, to obtain a general assessment of the total discomfort and also to see whether they had followed directions. RESULTS: Ninety nine patients were included in the study. The total response rate was 89-97%. Most patients were given instructions at the end of the procedure and followed those directions. At the end of the procedure totally 44% of the patients had complaints of headache, 23% of nausea and 44% of pain at the injection site. Before the procedure 93% of the patients had complaints of pain in the back, 86% in the thighs and 77% had complaints of pain in the calves. Immediately after the procedure 54%, 71% and 66% had complaints of pain in the back, thighs or calves. Two days days later 75% had complainst of pain in the back. The large majority of the patients, or 83%, viewed the procedure as having caused little discomfort. CONCLUSIONS: The incidence of side effects from lumbal myelography performed at the X-Ray Department of Reykjavík City Hospital is within acceptable limits.

English Abstract↗
PubMed1999

Specific mucosal immunity in the pathophysiology of bacterial prostatitis in a rat model.

Mucosal immunity was established in the rat prostate by stimulating the common mucosal system through serosal exposure of formalin-killed Escherichia coli. Immunized but not sham-immunized rats developed bacterial specific IgG and IgA in prostatic fluid, and IgA in urine. Immunized (n = 21) and sham-immunized control rats (n = 30) were challenged by transurethral injection of E. coli into the prostate ducts. Mortality, gross and microscopic pathology, tissue bacterial counts, bacterial associated immunoglobulins, and antibody titers in serum and urine were assessed at 7 days following the challenge. Increased E. coli specific immunoglobulin titers were seen in immunized rats, and E. coli, but not Proteus, found in the prostates of immunized animals were coated with IgG and IgA. Immunization protected against toxaemia and septicemia, seen as a rare complication of acute prostatitis, but did not protect against acute prostatitis, nor alter the degree of tissue damage seen in the rat model.

Acute Disease↗
PubMed1998

Effect of misoprostol on myocardial contractility in rats treated with cyclosporin A.

The nephrotoxic side effects of the immunosuppressant cyclosporin A in animals and humans are well known. Misoprostol, a prostaglandin E analog, is used clinically in organ-transplant recipients taking cyclosporin A to protect against these side effects. We reported previously that long-term treatment of rats with cyclosporin A causes a diminution in myocardial peak contractile stress. There is an associated spontaneous sarcomere activity and rest depression of force in the absence of a change in myofilaments sensitivity to intracellular Ca2+. Here we investigated the potential protective effects of misoprostol on the myocardium of cyclosporin A-treated rats. Rats were treated with either cyclosporin A, misoprostol, or their combination. Force-[Ca2+]o and -[Sr2+]o, and force-interval relations as well as the sarcomere length were studied in trabeculae isolated from the right ventricles. At suboptimal [Ca2+]o, cyclosporin A shifted the force-[Ca2+]o relation to the left but reduced peak contractile stress by approximately 35% at the highest (optimal) [Ca2+]o. Co-treatment with misoprostol prevented the leftward shift, and treatment with misoprostol alone did not cause a leftward shift. The diminution of peak stress, however, did not recover with misoprostol treatment, and stress was further reduced. Treatment with only misoprostol also reduced stress generated by the muscles more than that by cyclosporin A alone. Intriguingly, activation of the myofilaments by Sr2+ failed to recover peak stress to control levels in any group treated with misoprostol. Unlike cyclosporin A, however, rest potentiation of force was more pronounced, and spontaneous sarcomere activity was absent with misoprostol. No histopathologic changes were observed with cyclosporin A or misoprostol treatment. Misoprostol modifies the cyclosporin A-induced changes in the Ca2+ handling, but further decreases the stress generated by the muscles.

Animals↗
PubMed1996

Antihypertensive drug treatment in chronic renal allograft rejection in the rat. Effect on structure and function.

To gain insight into the contribution of immunologic and hemodynamic factors in the progressive demise of structure and function in chronic renal allograft dysfunction, we studied the histological changes, the immunostainable glomerular anionic sites, and glomerular capillary hydrostatic pressures of rat renal allografts with chronic rejection. Recipient animals were left untreated, received 8 weeks of treatment with the immunosuppressive drug cyclosporine, or received antihypertensive drugs consisting of the combination of reserpine, hydralazine and hydrochlorothiazide, the angiotensin-converting enzyme inhibitor cilazapril, or the angiotensin II receptor blocker L-158,809. Grafts in untreated recipients developed chronic interstitial inflammation, as well as vascular and glomerular lesions consistent with chronic rejection. These lesions were associated with immunohistochemical loss of the negatively charged heparan sulfate proteoglycan side chain. All treatment regimens decreased the systemic and glomerular capillary pressures and were associated with no loss of function, decreased proteinuria, and a tendency to improved graft function. Cyclosporine prevented all histological manifestations of rejection, and antihypertensive drugs decreased the extent of glomerular mesangiolysis and glomerulosclerosis; L-158,809 and cilazapril also inhibited graft atherosclerosis and tubular atrophy. We conclude that chronic rejection is primarily an immune-mediated process, but hemodynamic and angiotensin II-mediated effects may play a pivotal role in the expression of immune-mediated lesions.

Animals↗
PubMed1996

Nitric oxide synthase inhibition is associated with decreased survival of cardiac allografts in the rat.

Nitric oxide is a biological mediator that regulates blood vessel wall tonus, enhances macrophage cytotoxicity, and inhibits cellular immune reactivity. Primary acute rejection is associated with increased intragraft production of NO but it is unknown whether this delays or enhances the loss of graft function. The aim of the current study was to determine the effect of L-NAME, a nitric oxide synthase inhibitor, on the course and histopathology of rat cardiac allografts with primary acute rejection. L-NAME decreased the graft survival time from 9.4+/-1.5 to 6.9+/-0.3 days; the histopathology at asystole showed predominantly ischemic necrosis. L-NAME combined with antihypertensive drugs restored the rejection time (from 8.6+/-0.4 to 14.2+/-3.2 days) and resulted in an acute rejection pattern. We conclude that blocking of nitric oxide formation during acute rejection of a vascularized cardiac graft results in a decreased graft survival time and ischemic graft necrosis, very likely secondary to unopposed vasoconstriction.

Animals↗
PubMed1996

Anti-integrin (LFA-1, VLA-4, and Mac-1) antibody treatment and acute cardiac graft rejection in the rat.

Cell adhesion molecules mediate interactions with other cells and extracellular matrix, control cell infiltration in sites of inflammation, and regulate cell activation. Previous studies have shown that treatment of rat cardiac transplant recipients with a combination of antibodies against the T-cell integrins LFA-1 and VLA-4 gave a modest prolongation of graft survival. Current experiments were designed to examine the effect of blocking Mac-1, an important monocyte adhesion receptor and mediator of monocyte migration, together with anti-LFA-1 and anti-VLA-4 antibodies on cardiac graft survival and on the graft rejection pattern. The anti-Mac-1, CD11b-specific antibody OX-42 did not affect graft survival time although it did decrease the graft infiltration by rounded, ED-2-positive macrophages.

Acute Disease↗
PubMed1996

Growth factor transcripts in rat renal transplants.

Locally produced cytokines and growth factors may mediate tissue remodelling processes, as observed in renal transplants exposed to ischemia or acute rejection episodes. The present study was designed to investigate mRNA transcript levels of platelet-derived growth factor (PDGF)-receptor beta, PDGF-A, PDGF-B, fibroblast growth factor-1, and transforming growth factor beta 1 in normal rat kidneys, in kidneys following contralateral nephrectomy and in renal transplants with acute or chronic rejection. Platelet-derived growth factor-receptor beta mRNA levels increased significantly in syngeneic and allogeneic transplants in the first week after transplantation and in allogeneic transplants with chronic rejection. Immunohistochemistry showed induction of PDGF-receptor beta protein expression on vascular wall cells in such grafts. Platelet-derived growth factor-A chain mRNA levels increased in day 3 allografts and in syngeneic LEW grafts, while PDGF-B chain mRNA levels showed no significant changes with transplantation. Fibroblast growth factor-1 mRNA levels were detectable in normal kidneys, tended to decrease with acute rejection, and increased significantly in chronic rejection. Transforming growth factor-beta 1 transcripts increased in acute and chronic rejection; immunohistochemistry showed predominantly glomerular localization of the transforming growth factor-beta 1 protein. We conclude that transplantation and rejection are associated with changes in the intragraft mRNA levels for several growth factors; chronic rejection is characterized by an increase in fibroblast growth factor-1 and transforming growth factor-beta 1 transcript levels.

Animals↗
PubMed1996

Enhanced glomerular retrieval for renal biopsies.

A substantial number of glomeruli were found to become dislodged from renal biopsy cores during the biopsy procedure. These "lost" glomeruli can be retrieved and immobilized on membrane substrates; the morphology of these membrane-immobilized glomeruli is of diagnostic quality. Hence, this technique of glomerular retrieval offers an opportunity to maximize the number of glomeruli obtained at biopsy and also makes available additional material for diagnostic studies, physiology studies, and archiving.

Animals↗
PubMed1995

Reproducibility of the Banff classification of renal allograft pathology. Inter- and intraobserver variation.

The present study was undertaken to investigate the inter- and intraobserver variation in use of the scoring system for glomerulitis, vasculitis, interstitial inflammation, tubulitis and arteriolar hyalinosis that is an essential part of the recently proposed Banff classification of renal allograft biopsies. Seventy-seven biopsies done less than 90 days after transplantation were included. The scoring was done blindly by five pathologists on biopsies stained with H&E and PAS. The volume fraction of interstitial inflammation was estimated. Spearman rank correlation coefficient and kappa values were used for the evaluation of reproducibility. The results of both inter- and intraobserver variability showed a good correlation and reasonable kappa values for vasculitis, interstitial inflammatory infiltration, and tubulitis. Less-good correlation was found for glomerulitis and arteriolar hyalinosis. The interobserver kappa score for grading of the rejection severity was 0.40 overall but 0.56 when only presence or absence of acute rejection was considered and 0.66 for presence or absence of vasculitis. Weighted kappa values for interobserver vasculitis score and rejection grading were 0.58 and 0.55, respectively. A strong association existed between the volume fraction of interstitial inflammation and the semiquantitative scoring for interstitial inflammation. In conclusion, the good correlations for the key elements in the grading of the allograft biopsies in the present classification system, confirmed the utility of the defined criteria for grading rejection. More precisely defined criteria or simplification of the scoring system are needed for glomerulitis and arteriolar hyalinosis--parameters not used in the diagnosis of rejection.

Biopsy↗
PubMed1995

Lithium chloride enhances survival of NZB/W lupus mice: influence of melatonin and timing of treatment.

Daily administration of 4 mg 6LiCl to groups (15 mice/group) of female NZB/W mice starting at 8 weeks of age led to long-term survival (44 weeks of age) of 73% of the mice when injections were performed between 08:00 and 10:00 h and 67% of mice when injections were performed between 17:00 and 19:00 h. Untreated controls were dead by 34 weeks of age and the differences between untreated and treated groups was significant (P < or = 10(-4)). In contrast daily administration of melatonin (100 micrograms/mouse) did not significantly enhance survival when injections were performed between 17:00 and 19:00 h but did enhance survival when given between 08:00 and 10:00 h (P < or = 10(-3)). Differences between the two melatonin groups was also significant (P < or = 0.05). Mice treated with Li plus melatonin exhibited survival curves identical to mice treated with Li alone. Therefore, the Li effect was dominant and survival was not altered by melatonin. Cessation of treatment in long-term survivors at 44 weeks of age led to the rapid death of 80% of the mice previously treated between 17:00 and 19:00 h (Li, Li + melatonin). In contrast, only 40% of the long-term survivors in the other groups had died by 66 weeks of age (22 weeks post-treatment). Thus the p.m. groups were less protected from disease reactivation than were the a.m. groups. Neither Li, melatonin, nor Li+melatonin influenced anti-gp70 or anti-ssDNA levels in serum, but Li treatment maintained renal function as determined by proteinuria scores. These findings indicate that the effectiveness of Li is probably not related to melatonin metabolism and immunomodulating influences, but the influence of other neuroendocrine variables cannot be eliminated.

Adjuvants, Immunologic↗