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Biomedical subjects

A Kostakis

Publications and source records attributed to A Kostakis.

At least 37 records · Page 2Linked to original sources
PubMed2002

Definition of permissible and immunogenic HLA antigens based on epitope analysis of the HLA specific antibodies produced in sensitized patients.

The goal of this study was to develop an accurate protocol whereby detection of acceptable HLA-A and -B mismatches is based on epitope analysis of HLA class I specific antibodies detected in the serum of highly sensitized patients awaiting a kidney retransplant. A total of 400 serum samples from 44 highly sensitized patients with panel reactive antibodies (PRA) of > or = 60% were collected during a 3-year follow-up period. All patients had been sensitized from a previous graft. In order to define the specificities of the HLA class I specific antibodies, two techniques were used in parallel: the antihuman globulin augmented complement-dependent cytotoxicity (CDC) technique and an enzyme-linked immunoabsorbent assay (ELISA) technique. Epitope identification was based on class I HLA antigen sequencing, where the unique epitope configuration on one HLA antigen represented the private epitope of the specific HLA antigen, and epitopes shared by more than one HLA antigen represented public determinants. The epitope prediction for the immunogenic HLA epitopes was based on an MHC database. For each highly sensitized patient, antibody specificities against actual and 'at risk' epitopes were defined. Following epitope analysis, all HLA antigens that did not express the actual and/or 'at risk' immunogenic epitopes were considered as acceptable mismatches of epitope analysis. The cytotoxicity of highly sensitized patients was determined using two different panels of selected, separated T lymphocytes. HLA class I specific IgG antibodies against 69 actual and 86 'at risk' epitopes were detected. In all patients, a large number of acceptable mismatches were defined. These included a large number of HLA antigens, corresponding to both HLA-A and -B loci. Our study introduces an accurate protocol for the detection of acceptable mismatches in highly sensitized patients. According to this protocol, the detailed description of immunogenic HLA specific epitope targets, against which HLA class I specific antibodies are directed, is a useful tool for the detection of acceptable mismatches in highly sensitized patients. This may lead to reduced production of HLA class I specific antibodies and, consequently, improved graft survival.

Adolescent↗
PubMed2001

Cholestatic syndrome with bile duct damage and loss in renal transplant recipients with HCV infection.

BACKGROUND/AIMS: Bile duct cells are known to be susceptible to hepatitis B and C virus, while it has been recently suggested that hepatitis B virus (HBV) and hepatitis C virus (HCV) infection may have a direct role in the pathogenesis of vanishing bile duct syndrome (VBDS) after liver transplantation. We report the development of a cholestatic syndrome associated with bile duct damage and loss in four HCV-infected renal transplant recipients. METHODS: All four patients were followed up biochemically, serologically and with consecutive liver biopsies. Serum HCV RNA was quantitatively assessed and genotyping was performed. RESULTS: Three patients were anti-HCV negative and one was anti-HCV/HBsAg positive at the time of transplantation and received the combination of methylprednisolone, azathioprine and cyclosporine A. Two patients became anti-HCV positive 1 year and one patient 3 years post-transplantation. Elevation of the cholestatic enzymes appeared simultaneously with seroconversion, or 2-4 years later, and was related to lesions of the small-sized interlobular bile ducts. Early bile duct lesions were characterized by degenerative changes of the epithelium. Late and more severe bile duct damage was associated with bile duct loss. The progression of the cholestatic syndrome coincided with high HCV RNA serum levels, while HCV genotype was 1a and 1b. Two patients (one with HBV co-infection) developed progressive VBDS and died of liver failure 2 and 3 years after biochemical onset. One patient, despite developing VBDS within a 10-month period, showed marked improvement of liver function after cessation of immunosuppression because of graft loss. The fourth patient, who had mild biochemical and histological bile duct changes, almost normalized liver function tests after withdrawal of azathioprine. CONCLUSION: A progressive cholestatic syndrome due to bile duct damage and loss may develop in renal transplant patients with HCV infection. The occurrence of the lesions after the appearance of anti-HCV antibodies and the high HCV RNA levels are indicative of viral involvement in the pathogenesis. Withdrawal of immunosuppressive therapy may have a beneficial effect on the outcome of the disease.

Adult↗
PubMed2001

Autoimmune thyroid disease in women with breast carcinoma.

AIMS: Estimation of prevalence of autoimmune thyroid disorders in Greek breast cancer patients (prospective study). METHODS: The prevalence of autoimmune thyroiditis was estimated in 310 Greek breast cancer patients, in 100 women with benign breast disease and in 190 women without any breast disease, by submitting them to clinical examination, ultrasound thyroid evaluation, serum thyroid antibody determination and fine needle aspiration (FNA) of the thyroid gland. RESULTS: Autoimmune thyroiditis was found in 136/310 (43.9%) breast cancer women: 95 were diagnosed by positive autoantibodies, 19 had positive FNA findings and 22 had both positive autoantibodies and positive FNA findings. In 117 cases, thyroid autoantibodies were positive (37.7% whereas the control groups had respective rates of 19% and 18.4% autoantibody positivity). CONCLUSIONS: There is evidence of high incidence of autoimmune thyroiditis in Greek breast cancer patients, increasing in relation to cancer stage.

Adult↗
PubMed2001

Obstructive uropathy in the transplanted kidney: definitive management with percutaneous nephrostomy and prolonged ureteral stenting.

BACKGROUND AND PURPOSE: Renal transplantation is an effective treatment for end-stage renal disease. Ureteral stenosis is the most frequent urologic complication. We report our experience with percutaneous nephrostomy and antegrade ureteral stenting, which may offer a primary and definitive alternative to open surgery. PATIENTS AND METHODS: Fifteen patients with renal allograft obstructive uropathy were managed with percutaneous nephrostomy and prolonged ureteral stenting. RESULTS: Percutaneous nephrostomies were successfully performed in all 15 kidneys: In 13 patients, antegrade ureteral stenting was attempted, this being successful in 11 (85%). After prolonged ureteral stenting (mean duration 15 months), the stent was removed in eight patients, and six of them (75%) did not have recurrences. During follow-up, urea, creatinine, sodium, and potassium determinations and ultrasound scans were performed, and success was confirmed by the decline of creatinine and reduction in hydronephrosis. No major complication was observed. CONCLUSION: Percutaneous nephrostomy and ureteral stenting is a safe and effective treatment for renal allograft obstructive uropathy. Prolonged ureteral stenting may offer a definitive treatment with low morbidity.

Follow-Up Studies↗
PubMed2001

Paratesticular liposarcoma in a transplanted patient.

A case of paratesticular liposarcoma in a transplanted patient is presented. Liposarcomas of the urogenital system are very rare tumors and have never before been reported in an immunosuppressed transplanted patient. We present a case of considerable clinical interest, our therapeutic approach and the final outcome.

Genital Neoplasms, Male↗
PubMed2001

Extragonadal seminoma after renal transplantation and immunosuppression; treatment in the presence of renal dysfunction: a case report and literature review.

A 37-yr-old man who had undergone renal transplantation for end-stage renal failure presented with a large right pelvic mass obstructing the transplanted kidney. Initially, this was diagnosed as an anaplastic tumor while he had been on immunosuppressive treatment for kidney allograft rejection after transplantation. Despite difficulties of classic histopathology to reveal the origin of his tumor, FISH analysis revealed the presence of chromosome 12p abnormalities, strongly indicative of a germ-cell tumor-more likely seminoma-with extragonadal presentation. Because of renal dysfunction, he was treated with carboplatin (dose adjusted according to renal clearance) and etoposide, and when he experienced a rather atypical progression with bone metastases, he was treated with single-agent paclitaxel, and died almost 13 mo after initial presentation. The case adds further to the existing small list of seminoma/GCTs developing in transplant recipients, points to the unusual presentation patterns and diagnostic histopathology challenges, and presents the difficulty in therapeutic options, as a result of frequent renal dysfunction and intercurrent immunosuppressive therapy. All of these issues together with an extensive literature review are discussed in detail.

Adult↗
PubMed2000

Epitope analysis of HLA class I donor specific antibodies in sensitized renal transplant recipients.

OBJECTIVE: The goal of this study was to evaluate the epitope specificity of donor-specific HLA class I antibodies detected in the serum of alloimmunized from a previous renal graft patients. METHOD: A total of 410 serum samples from 87 patients who had lost a previous graft, were collected every 4 months during a 2-year follow-up period. All recipients and donors were typed for class I HLA-antigens by a standard lymphocytotoxicity technique. To define the specificities of the HLA class I antibodies, two techniques were used in parallel: the antihuman globulin augmented CDC (AHG-CDC) technique and an ELISA technique. The mismatched HLA-antigens and the detected HLA class I antibodies were categorized as intra-cross-reactive group mismatches (intra-CREGs-MMs) and other-CREG-MMs. For each sensitized patient actual and at risk epitope specificities were defined. RESULTS: Thirty-eight patients (43.7%) had developed IgG HLA class I-specific antibodies with stable specificities against mismatched alloantigens from the previous graft. A total of 60 antibody reactivity patterns and 82 specificities against private and public epitope were recognized. Patients with only intra-CREGs-MMs produced HLA class I-specific antibodies less frequently than patients with only other-CREG-MMs, although the difference was nearly statistically significant (P=0.053). All HLA class I donor-specific antibodies were considered to have specificities against the private epitopes of the mismatched graft HLA-antigens. In the cases where HLA class I alloreactivity was spreading to more than one donor antigens, we considered that the detected antibodies had specificities against the private and the shared between the alloantigens epitope(s). No epitope-specific antibodies were detected against shared epitopes between the mismatched alloantigens and the HLA-antigens of the patients. In 11/38 cases (28.9%) HLA class I alloreactivity spreading to non-graft antigens was detected. These antibodies were directed against HLA-antigens that share epitope(s) and have strong serological reactivity with the immunogenic alloantigens. CONCLUSION: Our data show that a small number of private and public alloepitopes seem to be responsible for antibody production in patients sensitized from a previous graft. A detailed description of these HLA-epitopes, in the context of clinical graft complications, may lead to an improved organ allocation strategy.

Antibody Specificity↗
PubMed2000

Cholestatic syndromes in renal transplant recipients with HCV infection.

We present two distinct types of cholestatic syndrome identified in eight renal transplant (RTx) patients with HCV infection. Four patients developed fibrosing cholestatic hepatitis (FCH) and four, vanishing bile duct syndrome (VBDS). All patients with FCH were anti-HCV (-) at the time of Tx and developed a cholestatic profile 1-4 months post-Tx, with high HCV-RNA levels. Immunosuppressive therapy was drastically reduced. Two patients died of sepsis and liver failure 16 and 18 months post-Tx, and the other two showed marked improvement and seroconverted to anti-HCV. Regarding the patients with VBDS, three were anti-HCV (-) and one was anti-HCV (+)/HBsAg (+) at the time of RTx. Two patients became anti-HCV (+) 1 year, and one patient, 3 years post-Tx. Two patients developed progressive VBDS and died of liver failure 2 and 3 years after onset, and two showed marked improvement after withdrawal of immunosuppression. In two of the patients, the progression of the disease coincided with elevation in serum HCV RNA levels. We concluded that a progressive cholestatic syndrome acquiring features of FCH or VBDS may develop in HCV-infected RTx patients. The association with high viral load implicated the virus in the pathogenesis. Drastic reduction of immunosuppression may favourably affect the outcome.

Adult↗
PubMed2000

A limited number of HLA epitopes are recognized from HLA class I-specific antibodies detected in the serum of sensitized patients.

The goal of this study was to evaluate the epitope specificity of HLA class I-specific antibodies detected in the serum of sensitized patients awaiting retransplantation. The study group consisted of 22 sensitized from previous graft patients, who produced stable IgG HLA class I-specific antibodies. A total of 60 serum samples were screened and analyzed by two techniques in parallel: the antihuman globulin augmented CDC (AHG-CDC) technique and an ELISA technique. All recipients and donors were typed for class I HLA antigens by a standard lymphocytotoxicity technique. The epitope identification was based on class I HLA antigens sequencing, where the multiple immunogenic epitopes are differentially shared among various HLA antigens. The unique epitope configuration on one HLA antigen represents the private epitope of the specific HLA antigen while epitopes shared by more than one HLA antigen represent public determinants. In some HLA antigens (HLA-A1), more than one private epitope has been defined, while in others (HLA-B35, -B51), the private epitopes are not yet known. In a total of 36 antibody reactivity patterns, the majority of the definable IgG HLA class I-specific antibodies corresponded to the A-locus (75%), and only 25% had specificities against the B-locus antigens, although the number of incompatibilities concerning both loci were almost identical (29 for the HLA antigens of the A-locus and 26 for those of B-locus). All patients produced HLA class I-specific antibodies with specificities against the private epitopes of the immunogenic mismatched HLA antigen(s). In 6/21 cases (28.6%), HLA class I alloreactivity spreading to nongraft HLA antigens was detected and 9 public (shared) immunogenic alloepitopes were recognized. In conclusion, appling the epitope analysis of HLA class I-specific antibodies produced by sensitized from previous graft patients, we were able to define the immunogenic alloepitopes. We consider that the immunogenic alloepitopes, during transplantation course, are mainly private epitopes of mismatched HLA antigens and, in certain cases, shared epitopes between the donor alloantigens and other HLA antigens. This knowledge may offer the potential of transplanting sensitized patients through improved donor selection.

Antibodies↗
PubMed1999

Fibrosing cholestatic hepatitis in renal transplant recipients with hepatitis C virus infection.

Fibrosing cholestatic hepatitis (FCH) has been described as a specific manifestation of hepatitis B virus (HBV) infection in liver allograft recipients characterized by a rapid progression to liver failure. Only sporadic cases have been reported in other immunocompromised groups infected with HBV and in a few transplant recipients with hepatitis C virus (HCV) infection. We present the occurrence of FCH in 4 HCV-infected renal transplant recipients within a series of 73 renal transplant recipients with HCV infection followed up closely serologically and with consecutive liver biopsies. All 4 patients received the triple-immunosuppressive regimen (azathioprine, cyclosporine A, methylprednisolone). The interval from transplantation to the appearance of liver dysfunction was 1 to 4 months and to histological diagnosis, 3 to 11 months. The biochemical profile was analogous to a progressive cholestatic syndrome in 3 patients, whereas the fourth patient had only slightly increased alanine aminotransferase and gamma-glutamyl transferase (gammaGT) levels. Liver histological examination showed the characteristic pattern of FCH in 2 patients, whereas the other 2 patients had changes compatible with an early stage. All patients were anti-HCV negative at the time of transplantation, whereas 2 patients, 1 with incomplete and 1with complete histological FCH features, seroconverted after 3 and 31 months, respectively. The patients were HCV RNA positive at the time of the first liver biopsy and showed high serum HCV RNA levels (14 to 58 x 10(6) Eq/mL, branched DNA). HCV genotype was 1b in 3 patients and 3a in 1 patient. After histological diagnosis, immunosuppression was drastically reduced. Two patients died of sepsis and liver failure 16 and 18 months posttransplantation, whereas the seroconverted patients showed marked improvement of their liver disease, which was histologically verified in 1 patient. In conclusion, FCH can occur in HCV-infected renal transplant recipients. It seems to develop as a complication of a recent HCV infection during the period of maximal immunosuppression and is associated with high HCV viremia levels. There are indications that drastic reduction of immunosuppression may have a beneficial effect on the outcome of the disease.

Adult↗
PubMed1999

Visceral leishmaniasis in renal transplant recipients: successful treatment with liposomal amphotericin B (AmBisome).

Visceral leishmaniasis (VL) is a rare disease in renal transplant recipients. Liposomal amphotericin B (AmBisome) is known to be effective against VL. However, previously there has been no experience with administration of such treatment to renal transplant recipients. We report herein four patients with VL complicating renal transplantation who were treated successfully with liposomal amphotericin B (total dose, 23-40 mg/kg). Neither adverse reactions nor clinical relapses of VL were observed.

Adult↗
PubMed1998

Assignment of HLA-antigens in CREGs facilitates the detection of acceptable mismatches in highly sensitized patients.

The purpose of this study was to investigate whether in highly sensitized patients (HSPs) the acceptable HLA-A and -B mismatches (AMs) can be predicted on the basis of patients' HLA-phenotype. To this affect, 1000 historical serum samples obtained from 50 HSPs (PRA > 60%), panel reactive antibodies (PRA) value and the specificity of class I anti-HLA-antibodies were detected by two techniques in parallel: An anti-human globulin augmented cytotoxicity (AHG-CDC) and an Elisa technique. Thereafter, class I HLA-antigens of the nonreactive cells in the screening panel and class I HLA-antigens of the patients were assigned to CREGs. The AMs for each one of the patients were detected using a separate cell panel, which was prepared in a way to include almost all the HLA-antigens belonging to the CREGs of the patients as well as to those of the nonreactive cells in the screening panel. It was found that the AMs in HSPs, detected with this protocol were more, compared to those we usually detect using only the HLA-antigens of the nonreactive cells in the screening panel (up to 8 versus 2-5). Both, the definitively detected AMs, and the HLA-specificities of the nonreactive cells of the screening panel belonged to the same CREGs. These CREGs were equivalent to the CREGs of class I HLA-phenotypes of each patient. The data presented in this paper introduce a new, rapid and easier way for the detection of AMs in HSPs. According to this proposed protocol, the assignment of patients' standard class I private HLA-phenotypes in CREGs, not only greatly facilitates the detection of AMs, but the detected AMs are also in fact significantly more than those determined by the conventional methodology. We have also confirmed that the majority of antibodies induced by HLA alloimmunization are directed against mismatched shared or public group epitopes CREGs. Moreover, we have confirmed that prospective matching for major CREGs would be feasible on a national level and would not significantly prolong waiting time, which could result in a significant augmentation of the potential donor pool.

Adult↗