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Biomedical subjects

A Antoniou

Publications and source records attributed to A Antoniou.

At least 37 records · Page 2Linked to original sources
PubMed1999

Anergic T cells act as suppressor cells in vitro and in vivo.

The potential suppressive effects of allospecific anergic T cells were investigated both in vitro and in vivo. Allospecific T cells were rendered unresponsive in vitro using immobilized anti-CD3 mAb. These anergic T cells profoundly inhibited proliferation of responsive T cells in an antigen-specific manner. The observed inhibition did not appear to be due to the release of inhibitory cytokines in that secretion of IL-2, IFN-gamma, IL-4, IL-10 and TGF-beta was greatly reduced following the induction of anergy, and neutralizing mAb specific for IL-4, IL-10 and TGF-beta failed to reverse the inhibition. Furthermore, the suppression mediated by anergic T cells required cell to cell contact. In vivo, adoptive transfer of anergic T cells into recipients of allogeneic skin grafts led to prolonged skin graft survival. Consistent with the lack of inhibitory cytokine production by the anergic cells, prolongation of skin allograft rejection was not influenced by the simultaneous administration of a neutralizing anti-IL-4 antibody. These results indicate that anergic T cells can function as antigen-specific suppressor cells both in vitro and in vivo.

Animals↗
PubMed1999

Endovaginal color Doppler sonographic evaluation of ectopic pregnancy in women after in vitro fertilization and embryo transfer.

The aim of this study was to evaluate the value of endovaginal color Doppler ultrasonography in the early diagnosis of ectopic pregnancy in women after in vitro fertilization and embryo transfer, and to correlate the sonographic findings with ss-hCG serum levels. Thirty-five patients had proven ectopic pregnancies and 4 other patients had heterotopic pregnancies. The diagnosis was disclosed correctly in all cases by endovaginal color Doppler US by identifying an adnexal mass with placental flow and a nongravid uterus called a "cold uterus". An intrauterine sac with "double ring sign" was found in all normal intrauterine pregnancies when the hCG levels exceeded 1000 IU/l but in none of the patients with ectopic pregnancy (EP). These findings suggest the efficacy of the discriminatory hCG serum level of 1000 IU/l in the investigation of EP. In conclusion, this study describes the diagnostic importance of transvaginal color Doppler US in correlation with hCG serum levels in the early detection of EP avoiding life-threatening complications and improving patient outcome.

Adult↗
PubMed1999

Selective arterial embolization in the management of symptomatic renal angiomyolipomas.

Current management of renal angiomyolipomas (AMLs) include observation, transcatheter embolization and partial or total nephrectomy. Patients symptoms and size of the lesion are the determinants for the choice of the treatment. In general symptomatic or greater than 8 cm masses require intervention. A retrospective study of five patients presented with symptomatic lesions and treated with selective transcatheter embolization, over a 3 year period was performed in our hospital. A total of eight embolizations were performed, all on an emergency basis due to retroperitoneal bleeding or significant hematuria. Surgical intervention was necessary in one case, due to massive rebleeding on the fourth post-procedural day. Two patients rebled within 6 months and 2 years respectively, and were managed successfully with additional embolization. The remaining two patients are still asymptomatic 26 and 18 months after the successful initial result. Experience with this procedure is reported on with emphasis to the clinical outcome. It is believed that selective arterial embolization should be the standard initial therapy for symptomatic renal AMLs.

Adolescent↗
PubMed1999

Carotid endarterectomy without protective measures in patients with occluded and non occluded contralateral carotid artery.

BACKGROUND: Comparison of carotid endarterectomy in patients with and without occluded contralateral carotid artery. METHODS DESIGN: evaluation of results without using shunt or patch. SETTING: < > Hospital, Medical School, University of Athens. SUBJECTS: 235 patients, divided into group I of 40 patients with and group II of 195 patients without occluded contralateral carotid artery. INTERVENTION: carotid endarterectomy under general anesthesia. MAIN OUTCOME MEASURES: heparin administration, stable hemodynamic status during clamping, short duration monitoring postoperatively. RESULTS: Postoperative morbidity of both groups was 2.5% (6/235) and mortality 1.7% (4/235). Group I: mortality rate was 2.5% (1/40) major and minor stroke each 2.5% (1/40) and group I: 1.5% (3/195) and 1% (2/195) respectively (NS). Four to 108 months later, 30% (12/40) of group I and 21% (41/195) of group II died. CONCLUSIONS: Endarterectomy of the carotid artery under general anesthesia without use of shunt and patch in patients with or without occlusion of the contralateral carotid artery presented the same comparative results. Candidates for carotid endarterectomy should be screened systematically for coronary disease preoperatively and annual stress testing postoperatively, tactics which may improve early and late mortality rate after carotid surgery.

Aged↗
PubMed1998

Multifactorial analysis of differences between sporadic breast cancers and cancers involving BRCA1 and BRCA2 mutations.

BACKGROUND: We have previously demonstrated that breast cancers associated with inherited BRCA1 and BRCA2 gene mutations differ from each other in their histopathologic appearances and that each of these types differs from breast cancers in patients unselected for family history (i.e., sporadic cancers). We have now conducted a more detailed examination of cytologic and architectural features of these tumors. METHODS: Specimens of tumor tissue (5-microm-thick sections) were examined independently by two pathologists, who were unaware of the case or control subject status, for the presence of cell mitosis, lymphocytic infiltration, continuous pushing margins, and solid sheets of cancer cells; cell nuclei, cell nucleoli, cell necrosis, and cell borders were also evaluated. The resulting data were combined with previously available information on tumor type and tumor grade and further evaluated by multifactorial analysis. All statistical tests are two-sided. RESULTS: Cancers associated with BRCA1 mutations exhibited higher mitotic counts (P = .001), a greater proportion of the tumor with a continuous pushing margin (P<.0001), and more lymphocytic infiltration (P = .002) than sporadic (i.e., control) cancers. Cancers associated with BRCA2 mutations exhibited a higher score for tubule formation (fewer tubules) (P = .0002), a higher proportion of the tumor perimeter with a continuous pushing margin (P<.0001), and a lower mitotic count (P = .003) than control cancers. CONCLUSIONS: Our study has identified key features of the histologic phenotypes of breast cancers in carriers of mutant BRCA1 and BRCA2 genes. This information may improve the classification of breast cancers in individuals with a family history of the disease and may ultimately aid in the clinical management of patients.

Adult↗
PubMed1998

Abdominal Takayasu's arteritis: imaging with color duplex sonography.

Takayasu's arteritis is a inflammatory process of unknown etiology affecting mainly the thoracic and abdominal aorta and producing steno-occlusive findings of various degrees in different sites. We present a case of Takayasu's disease in a young woman, studied by color duplex sonography and verified by angiography.

Adolescent↗
PubMed1998

Modulation by epitope-specific antibodies of class II MHC-restricted presentation of the tetanus toxin antigen.

Above a certain affinity the dissociation rate of monovalent antigen from antibody becomes slower than the time taken for antigen capture, endocytosis and processing by professional antigen presenting cells. Thus, when high affinity antibodies drive antigen uptake, either directly via B-cell membrane immunoglobulin or indirectly via Fc receptors, the substrate for processing may frequently be an antigen/antibody complex. Here we review studies using the tetanus toxin antigen which show that bound antibodies can dramatically affect proteolytic processing, dependent on the epitope specificity and multiplicity of antibodies bound. Certain antibodies protect or 'footprint' specific domains of the antigen during processing in B-cell clones resulting in modulation of loading of class II MHC-restricted T-cell epitopes. Processing and class II MHC loading of some T-cell epitopes within the footprinted region was hindered, as might be expected, but, surprisingly, presentation of other T-cell epitopes was boosted considerably. These studies show that protein/protein complexes can be processed in an unpredictable fashion by antigen presenting cells and indicate a possible mechanism whereby cryptic T-cell epitopes might be revealed in autoimmune disease.

Antibody Specificity↗
PubMed1998

Carotid atherosclerosis in adolescents and young adults with IDDM. Relation to urinary endothelin, albumin, free cortisol, and other factors.

OBJECTIVE: To investigate 1) alterations of carotid intimal-plus-medial thickness (IMT) in subjects with IDDM and 2) the relation of IMT to indexes of diabetic angiopathy and to risk factors of atherosclerosis. RESEARCH DESIGN AND METHODS: IMT was assessed by ultrasound B-mode imaging in 39 subjects with IDDM (23 male, 16 female young adults aged 17.5 +/- 5.2 years, diabetes duration 8.8 +/- 5.9) and in 22 control subjects (healthy siblings of the IDDM subjects) of comparable age. Urinary endothelin (UET1) and urinary free cortisol (UFC) were determined by radioammunoassay (RIA), urinary albumin by nephelometry, HbA1c by high-performance liquid chromatography (HPLC), and plasma renin by immunoradiometric assay (IRMA). RESULTS: The IMT values were greater in IDDM subjects than in control subjects (0.49 +/- 0.1 mm, 0.44 +/- 0.09 mm, respectively; P = 0.048) and greater in IDDM male subjects than in control male subjects (0.52 +/- 0.09 and 0.44 +/- 0.06 mm, respectively; P = 0.015), with no difference between IDDM and control female subjects. The IMT values were greater in diabetic male subjects than in female subjects (0.52 +/- 0.09 and 0.45 +/- 0.1 mm, respectively; P = 0.017). In IDDM subjects, but not in control subjects, there was a positive correlation of IMT to urinary albumin (P = 0.008), systolic blood pressure (P = 0.023), UET1 (P = 0.016), UFC (P = 0.002), and BMI (P = 0.021). Multiple regression analysis demonstrated that in IDDM subjects the variable that interacts independently with IMT was the BMI (P = 0.001). CONCLUSIONS: IMT, an index of atherosclerosis (macroangiopathy), is increased in IDDM subjects quite early (already in adolescence), and it is positively related to urinary albumin, UET1, blood pressure, and UFC.

Adolescent↗
PubMed1997

Contraction-excitation feedback in human atrial fibrillation.

BACKGROUND: Contraction-excitation feedback, that is, electrophysiologic changes that are caused or preceded by mechanical changes of the myocardium, has been extensively studied in the ventricles. The role of contraction-excitation feedback in the atria, and more particularly in the genesis and maintenance of atrial fibrillation, has been less adequately investigated. HYPOTHESIS: The aim of the present study was to determine whether increased right atrial pressure (RAP) facilitates the induction of atrial fibrillation (AF) in patients with a history of lone AF. METHODS: Sixteen patients with a history of paroxysmal AF but without structural heart disease were included in the study. All patients underwent electrophysiologic study at both a lower (3.1 +/- 2.0 mmHg) and (in 13 cases) a higher (6.4 +/- 2.5 mmHg) RAP. "Higher" was considered the pressure following rapid (in about 30 min) intravenous administration of normal saline or before the administration of a diuretic. RESULTS: Rapid atrial pacing induced AF in 19 of 29 attempts. At a lower pressure, rapid pacing induced brief (3 s to 3 min) AF in 3 of 16 patients, long-lasting (> 3 min) AF in 3 of 16 patients, and no AF in 10 of 16 patients. At a higher pressure, brief AF was induced in 3 of 10 patients in whom no AF could be induced at a lower pressure, and long-lasting AF in 10 patients in whom either brief AF (3 cases) or no AF (7 cases) was induced at a lower pressure. In 11 patients, in whom Wenckebach periodicity was determined at both higher and lower pressure, the critical cycle length at which atrioventricular block appeared was significantly (p < 0.001, paired t-test) longer (349.1 +/- 44.4 ms, i.e., +15.5 +/- 11.3 ms) at higher than at lower atrial pressure (333.6 +/- 41.0 ms). In nine patients, in whom Wenckebach periodicity was determined and two rhythms occurred at different pressures, the critical cycle length was 332.2 +/- 45.8 ms when associated with sinus rhythm, and significantly (p < 0.01) longer (344.4 +/- 48.0 ms, i.e., +12.2 +/- 8.3 ms) when associated with induction of AF. CONCLUSION: In patients with lone atrial fibrillation, modest increases in atrial pressure may facilitate the induction of atrial fibrillation.

Atrial Fibrillation↗
PubMed1996

T cell tolerance and activation to a transgene-encoded tumor antigen.

Much has been learned in recent years concerning the nature of tumor antigens recognized by T cells. To apply this knowledge clinically, the nature of the host response to individual and multiple tumor antigens has to be characterized. This will help to define the efficacy of immune surveillance and the immune status of the host following exposure to tumor antigens expressed on pre-neoplastic tissue. To approach these questions, we have developed a transgenic mouse which expresses the tumor-specific antigen P91A. The single amino acid substitution in P91A results in the expression of a new MHC class I (H-2Ld)-binding peptide. In transgenic tissue, the H-2Ld/P91A complex is expressed in isolation from other tumor-associated antigens, allowing definition of the immune response to a single defined tumor antigen, a situation closely analogous to events during tumorigenesis. We show that CD8+ T cell immune surveillance of P91A is ineffective without the introduction of a helper determinant operating through stimulation of CD4+ T cells. Recognition of the isolated P91A tumor antigen on normal tissue by CD8+ T cells is a tolerogenic process. Induction of T cell tolerance suggests tumor antigen-T cell interactions occurring during tumorigenesis may elicit T cell tolerance and hence confound some immunotherapeutic approaches.

Animals↗
PubMed1996

Unicompartmental knee arthroplasty with patelloplasty.

Patellofemoral arthritis is generally regarded as a contraindication to unicompartmental knee arthroplasty. A retrospective review of 52 patients (60 knees) who underwent this operation together with nonresurfacing excisional patelloplasty was carried out. The patellar facets were resected through subchondral bone retaining the triangular shape of the bone. There were 90% good and excellent results at an average follow-up of 6 years with no patellofemoral pain, despite marked to moderate patellofemoral crepitus in 98%. Patellofemoral arthroplasty can extend the indications for unicompartmental knee arthroplasty, providing an alternative to total knee replacement.

Arthritis↗
PubMed1996

Development of a hypoplastic uterus in a patient with testicular feminization syndrome 21 years after gonadectomy.

We describe a case of hypoplastic uterus, identified by transrectal ultrasonography and magnetic resonance imaging, which developed 21 years after gonadectomy for testicular feminization syndrome. Its likely origin was Müllerian-fusion remnant resulting from a deficiency in functional Müllerian inhibiting substance (MIS) and/or desensitization of the Müllerian tract to MIS, caused by diethylstilbestrol administration to the patient's mother during the sensitive period of the 6th and 9th gestational weeks of her pregnancy. This Müllerian-fusion remnant remained latent, due to insufficient estrogen stimulation both endogenously (until gonadectomy) and exogenously during hormone replacement therapy. Initial growth was possible induced in response to high doses of estrogen that the patient received over the last 3 years for the treatment of osteoporosis.

Adolescent↗
PubMed1996

Ornidazole in the treatment of active Crohn's disease: short-term results.

The object of this work was to test the efficacy of ornidazole in patients with active Crohn's disease. Twenty-five patients with active Crohn's disease (Crohn's disease activity index greater than 150 points) participated in this open study. The analysis of results was based on changes in the severity of the Crohn's disease activity index measured at entry and at the end of the first, second, and third and fourth week. Analysis of variance, correlation analysis, multiple regression analyses and chi-square test were used for statistical evaluation of results. The results showed that the Crohn's disease activity index fell gradually from week 0 to week 4 (p < 0.001), while the number of patients going into remission increased gradually from week 0 to week 4 (18/25 patients, 75%). Sex, location of disease, age at onset, first attack or recurrence and duration of disease were not statistically related to response to treatment. Presence and severity of abdominal pain both decreased and bowel movements were also reduced. General well-being improved significantly, the loss of weight stopped and an increase in body weight was noted at the end of the fourth week. Side effects were minimal. It is concluded that ornidazole is an effective and safe drug for the treatment of active Crohn's disease.

Adult↗
PubMed1994

I-123 metaiodobenzylguanidine--thallium-201 mismatch following myocardial infarction.

Experimental data show that myocardial infarction (MI) results in regional depletion of myocardial catecholamines more extensively than necrosis. To investigate the extent of adrenergic denervation post MI in humans, we examined 16 patients, 59 +/- 12 years old, with recent (7-12 days) MI. Resting thallium-201 (201Tl) single photon emission computerized tomography (SPECT) imaging was performed to assess necrosis; metaiodobenzylguanidine I123 (MIBG) SPECT was used to evaluate adrenergic denervation. 201Tl and I123 MIBG defects were evaluated quantitatively using polar maps, and differences in defects were expressed as percent of total polar map. In all patients, I123 MIBG defect was larger than 201Tl defect, and difference ranged from 19 to 61% (39.5 +/- 13.2%). Thrombolysis and age > 60 did not influence the difference. Anterior MI showed larger differences (44 +/- 13 vs. 32 +/- 11%, p < 0.05); patients with ischemic electrocardiographic (ECG) changes in leads without abnormal Q waves had larger differences (45 +/- 9 vs. 33 +/- 14%, p < 0.05). It was concluded that (a) patients with recent MI present denervation larger than 201Tl perfusion defect, and (b) patients with anterior MI and ischemic ECG changes present a larger area of denervation.

3-Iodobenzylguanidine↗