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Papers by Vassilios Pappas

International Journal of Cardiology, 2005

Background: Intrapericardial drug delivery is a promising new technique, but the pharmacologic pr... more Background: Intrapericardial drug delivery is a promising new technique, but the pharmacologic properties of various agents delivered via this route are not known. Furthermore, the long-term safety of intrapericardial catheters has not been previously examined. Methods: Using a pericardial access device, a catheter connected to a drug-delivery system was implanted in five pigs. Plasma levels and electrocardiographic measurements were obtained after intravenous and intrapericardial administration of digoxin and procainamide. Histological examination was performed after the device had been implanted for a total of 6 months. Results: The QTc interval did not change significantly after digoxin or procainamide intravenous administration. QTc decreased by 47 F 23 ms ( p = 0.046) 8 h after digoxin intrapericardial administration and increased by 128 F 60 ms ( p = 0.002) 1 h after procainamide intrapericardial administration. The QRS duration did not change significantly after intravenous administration of either agent, but it increased by 17 F 9 ms ( p = 0.004) 1 h and by 15 F 4 ms ( p = 0.01) 8 h after procainamide intrapericardial administration. After intravenous procainamide the RR interval decreased, but it did not change significantly after intrapericardial administration of either agent. Histology showed moderate inflammatory infiltration and fibrosis adjacent to the catheter. Conclusions: Intrapericardial delivery of digitalis and procainamide produces unique electrophysiological properties. In contrast to satisfactory success of the implantation technique, long-term dwell of the catheter in the pericardium induces moderate, albeit probably clinically significant, fibrosis.

Abdominal Imaging, 1998

We present three patients with peritoneal metastases from transitional cell carcinoma of the urin... more We present three patients with peritoneal metastases from transitional cell carcinoma of the urinary tract. CT scan in one patient showed massive ascites with subtle peritoneal thickening and infiltration of omental fat. We had the opportunity to study the other patients with both CT and MR. Both examinations showed numerous large and small peritoneal implants in the abdomen and pelvis, mostly in the greater omentum.

Value in Health, 2008

English speaker; 4) comparison of original and back translation; and 5) review by a clinician. RE... more English speaker; 4) comparison of original and back translation; and 5) review by a clinician. RESULTS: Cultural and linguistic challenges emerged during the process. On the cultural level, the differences in the approach to suicide and its methods based on differences in tradition and availability of means required finding suitable alternatives in the target languages. On the linguistic level, it was important to differentiate between medical and psychiatric hospitalisation after a suicide attempt and appropriate solutions across languages had to be found. The process revealed an area of ambiguity in the original rating instructions which had to be clarified in the translations. Examples of these and other challenges and their solutions will be discussed in the presentation. CONCLUSIONS: The 45 language versions, of the C-SSRS (a total of over 90 translations now exist), were established according to a rigorous methodology to ensure conceptual equivalence and cultural relevance across languages. The translations may now be used in international studies to assess suicidal ideation and behaviour and facilitate the comparison and pooling of data. The analysis of the psychometric results will be necessary to see if and how suicidal ideation and behaviour compare across countries and cultures.

International Journal of Modelling, Identification and Control, 2008

In this paper, a study on how to perform simultaneous order and parameter estimation of multivari... more In this paper, a study on how to perform simultaneous order and parameter estimation of multivariate (MV) ARMA (autoregressive moving average) models under the presence of noise is addressed. The proposed method, which is computationally efficient, is an extension of a previously presented method for MV AR models and is based on the well established and widely applied multi-model partitioning theory. A series of computer simulations indicate that the method is infallible in selecting the correct model order in very few steps. The simultaneous estimation of the multivariate ARMA parameters is also another benefit of the proposed method. The results are compared with two other established order selection criteria namely Akaike's Information Crieterion (AIC) and Schwarz's Bayesian Information Criterion (BIC). Finally, it is shown that the method is also successful in tracking model order changes, in real time.

Pace-pacing and Clinical Electrophysiology, 1997

The case of a 6-year-old boy with cytochrome oxidase (complex IV) deficiency and complete heart b... more The case of a 6-year-old boy with cytochrome oxidase (complex IV) deficiency and complete heart block, treated with permanent pacemaker implantation, is reported.

Gynecological Endocrinology, 2001

Hypothalamic amenorrhea is a treatable cause of infertility. Our patient was presented with secon... more Hypothalamic amenorrhea is a treatable cause of infertility. Our patient was presented with secondary amenorrhea and diabetes insipidus. Cortisol and prolactin responded normally to a combined insulin tolerance test (ITT) and thyrotropin-releasing hormone (TRH) challenge, while thyroid-stimulating hormone (TSH) response to TRH was diminished, and no response of growth hormone to ITT was detected. Both luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels increased following gonadotropin-releasing hormone (GnRH) challenge. No response of LH to clomiphene citrate challenge was detected. Magnetic resonance imaging findings demonstrated a midline mass occupying the inferior hypothalamus, with posterior lobe not visible and thickened pituitary stalk. Ovulation induction was carried out first with combined human menopausal gonadotropins (hMG/LH/FSH) (150 IU/day) and afterwards with pulsatile GnRH (150 ng/kg/pulse). Ovulation was achieved with both pulsatile GnRH and combine gonadotropin therapy. Slightly better results were achieved with the pulsatile GnRH treatment.

Gynecological Endocrinology, 2001

Hypothalamic amenorrhea is a treatable cause of infertility. Our patient was presented with secon... more Hypothalamic amenorrhea is a treatable cause of infertility. Our patient was presented with secondary amenorrhea and diabetes insipidus. Cortisol and prolactin responded normally to a combined insulin tolerance test (ITT) and thyrotropin-releasing hormone (TRH) challenge, while thyroid-stimulating hormone (TSH) response to TRH was diminished, and no response of growth hormone to ITT was detected. Both luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels increased following gonadotropin-releasing hormone (GnRH) challenge. No response of LH to clomiphene citrate challenge was detected. Magnetic resonance imaging findings demonstrated a midline mass occupying the inferior hypothalamus, with posterior lobe not visible and thickened pituitary stalk. Ovulation induction was carried out first with combined human menopausal gonadotropins (hMG/LH/FSH) (150 IU/day) and afterwards with pulsatile GnRH (150 ng/kg/pulse). Ovulation was achieved with both pulsatile GnRH and combine gonadotropin therapy. Slightly better results were achieved with the pulsatile GnRH treatment.

Journal of Cancer Research and Clinical Oncology, 2010

Aim The purpose of this study was to investigate the co-expression of survivin, c-erbB2, and COX-... more Aim The purpose of this study was to investigate the co-expression of survivin, c-erbB2, and COX-2 in endometrial cancer tissues and evaluate its prognostic significance in endometrial cancer Methods Tumor tissue biopsies from 110 patients with primary untreated endometrial carcinomas were studied by immunohistochemistry. Statistical analysis evaluated correlation of antigen expression with tumor stage, grade, myometrial invasion, and histologic type. Association with disease outcome was also investigated Results The results showed that expression of the three antigens was independently associated with histological grade, disease stage, and myometrial invasion. Clinicopathological parameters were also associated with the number of antigens expressed by each tumor, the expression of more antigens correlating with advanced stage disease and deep myometrial invasion. In a 10-year follow-up, patients with tumors expressing more of these three antigens had significantly lower survival rate that those with smaller expression score Conclusions Our results indicate that the co-expression score has independent prognostic value for endometrial cancer.

Online shopping purchase intention is influenced by several factors based on the literature revie... more Online shopping purchase intention is influenced by several factors based on the literature review. Effort expectancy, performance expectancy, trust and self-efficacy are some of the most widely used factors. An empirical study was undertaken to investigate the impact of various levels of these factors on consumer purchase intention. High levels of the above factors are shown to have highly significant impact on customers' intention to purchase. On the other hand lower levels of these factors do not have an impact on customer's intention. The paper contributes by highlighting the level where the impact of the factors is getting more significant.

European Journal of Vascular and Endovascular Surgery, 1998

International Journal of Cardiology, 2005

Background: Intrapericardial drug delivery is a promising new technique, but the pharmacologic pr... more Background: Intrapericardial drug delivery is a promising new technique, but the pharmacologic properties of various agents delivered via this route are not known. Furthermore, the long-term safety of intrapericardial catheters has not been previously examined. Methods: Using a pericardial access device, a catheter connected to a drug-delivery system was implanted in five pigs. Plasma levels and electrocardiographic measurements were obtained after intravenous and intrapericardial administration of digoxin and procainamide. Histological examination was performed after the device had been implanted for a total of 6 months. Results: The QTc interval did not change significantly after digoxin or procainamide intravenous administration. QTc decreased by 47 F 23 ms ( p = 0.046) 8 h after digoxin intrapericardial administration and increased by 128 F 60 ms ( p = 0.002) 1 h after procainamide intrapericardial administration. The QRS duration did not change significantly after intravenous administration of either agent, but it increased by 17 F 9 ms ( p = 0.004) 1 h and by 15 F 4 ms ( p = 0.01) 8 h after procainamide intrapericardial administration. After intravenous procainamide the RR interval decreased, but it did not change significantly after intrapericardial administration of either agent. Histology showed moderate inflammatory infiltration and fibrosis adjacent to the catheter. Conclusions: Intrapericardial delivery of digitalis and procainamide produces unique electrophysiological properties. In contrast to satisfactory success of the implantation technique, long-term dwell of the catheter in the pericardium induces moderate, albeit probably clinically significant, fibrosis.

Abdominal Imaging, 1998

We present three patients with peritoneal metastases from transitional cell carcinoma of the urin... more We present three patients with peritoneal metastases from transitional cell carcinoma of the urinary tract. CT scan in one patient showed massive ascites with subtle peritoneal thickening and infiltration of omental fat. We had the opportunity to study the other patients with both CT and MR. Both examinations showed numerous large and small peritoneal implants in the abdomen and pelvis, mostly in the greater omentum.

Value in Health, 2008

English speaker; 4) comparison of original and back translation; and 5) review by a clinician. RE... more English speaker; 4) comparison of original and back translation; and 5) review by a clinician. RESULTS: Cultural and linguistic challenges emerged during the process. On the cultural level, the differences in the approach to suicide and its methods based on differences in tradition and availability of means required finding suitable alternatives in the target languages. On the linguistic level, it was important to differentiate between medical and psychiatric hospitalisation after a suicide attempt and appropriate solutions across languages had to be found. The process revealed an area of ambiguity in the original rating instructions which had to be clarified in the translations. Examples of these and other challenges and their solutions will be discussed in the presentation. CONCLUSIONS: The 45 language versions, of the C-SSRS (a total of over 90 translations now exist), were established according to a rigorous methodology to ensure conceptual equivalence and cultural relevance across languages. The translations may now be used in international studies to assess suicidal ideation and behaviour and facilitate the comparison and pooling of data. The analysis of the psychometric results will be necessary to see if and how suicidal ideation and behaviour compare across countries and cultures.

International Journal of Modelling, Identification and Control, 2008

In this paper, a study on how to perform simultaneous order and parameter estimation of multivari... more In this paper, a study on how to perform simultaneous order and parameter estimation of multivariate (MV) ARMA (autoregressive moving average) models under the presence of noise is addressed. The proposed method, which is computationally efficient, is an extension of a previously presented method for MV AR models and is based on the well established and widely applied multi-model partitioning theory. A series of computer simulations indicate that the method is infallible in selecting the correct model order in very few steps. The simultaneous estimation of the multivariate ARMA parameters is also another benefit of the proposed method. The results are compared with two other established order selection criteria namely Akaike's Information Crieterion (AIC) and Schwarz's Bayesian Information Criterion (BIC). Finally, it is shown that the method is also successful in tracking model order changes, in real time.

Pace-pacing and Clinical Electrophysiology, 1997

The case of a 6-year-old boy with cytochrome oxidase (complex IV) deficiency and complete heart b... more The case of a 6-year-old boy with cytochrome oxidase (complex IV) deficiency and complete heart block, treated with permanent pacemaker implantation, is reported.

Gynecological Endocrinology, 2001

Hypothalamic amenorrhea is a treatable cause of infertility. Our patient was presented with secon... more Hypothalamic amenorrhea is a treatable cause of infertility. Our patient was presented with secondary amenorrhea and diabetes insipidus. Cortisol and prolactin responded normally to a combined insulin tolerance test (ITT) and thyrotropin-releasing hormone (TRH) challenge, while thyroid-stimulating hormone (TSH) response to TRH was diminished, and no response of growth hormone to ITT was detected. Both luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels increased following gonadotropin-releasing hormone (GnRH) challenge. No response of LH to clomiphene citrate challenge was detected. Magnetic resonance imaging findings demonstrated a midline mass occupying the inferior hypothalamus, with posterior lobe not visible and thickened pituitary stalk. Ovulation induction was carried out first with combined human menopausal gonadotropins (hMG/LH/FSH) (150 IU/day) and afterwards with pulsatile GnRH (150 ng/kg/pulse). Ovulation was achieved with both pulsatile GnRH and combine gonadotropin therapy. Slightly better results were achieved with the pulsatile GnRH treatment.

Gynecological Endocrinology, 2001

Hypothalamic amenorrhea is a treatable cause of infertility. Our patient was presented with secon... more Hypothalamic amenorrhea is a treatable cause of infertility. Our patient was presented with secondary amenorrhea and diabetes insipidus. Cortisol and prolactin responded normally to a combined insulin tolerance test (ITT) and thyrotropin-releasing hormone (TRH) challenge, while thyroid-stimulating hormone (TSH) response to TRH was diminished, and no response of growth hormone to ITT was detected. Both luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels increased following gonadotropin-releasing hormone (GnRH) challenge. No response of LH to clomiphene citrate challenge was detected. Magnetic resonance imaging findings demonstrated a midline mass occupying the inferior hypothalamus, with posterior lobe not visible and thickened pituitary stalk. Ovulation induction was carried out first with combined human menopausal gonadotropins (hMG/LH/FSH) (150 IU/day) and afterwards with pulsatile GnRH (150 ng/kg/pulse). Ovulation was achieved with both pulsatile GnRH and combine gonadotropin therapy. Slightly better results were achieved with the pulsatile GnRH treatment.

Journal of Cancer Research and Clinical Oncology, 2010

Aim The purpose of this study was to investigate the co-expression of survivin, c-erbB2, and COX-... more Aim The purpose of this study was to investigate the co-expression of survivin, c-erbB2, and COX-2 in endometrial cancer tissues and evaluate its prognostic significance in endometrial cancer Methods Tumor tissue biopsies from 110 patients with primary untreated endometrial carcinomas were studied by immunohistochemistry. Statistical analysis evaluated correlation of antigen expression with tumor stage, grade, myometrial invasion, and histologic type. Association with disease outcome was also investigated Results The results showed that expression of the three antigens was independently associated with histological grade, disease stage, and myometrial invasion. Clinicopathological parameters were also associated with the number of antigens expressed by each tumor, the expression of more antigens correlating with advanced stage disease and deep myometrial invasion. In a 10-year follow-up, patients with tumors expressing more of these three antigens had significantly lower survival rate that those with smaller expression score Conclusions Our results indicate that the co-expression score has independent prognostic value for endometrial cancer.

Online shopping purchase intention is influenced by several factors based on the literature revie... more Online shopping purchase intention is influenced by several factors based on the literature review. Effort expectancy, performance expectancy, trust and self-efficacy are some of the most widely used factors. An empirical study was undertaken to investigate the impact of various levels of these factors on consumer purchase intention. High levels of the above factors are shown to have highly significant impact on customers' intention to purchase. On the other hand lower levels of these factors do not have an impact on customer's intention. The paper contributes by highlighting the level where the impact of the factors is getting more significant.

European Journal of Vascular and Endovascular Surgery, 1998