Biomedical subjects

M Simeonova

Publications and source records attributed to M Simeonova.

At least 19 recordsLinked to original sources

PubMed2006

[Terminated pregnancy following prenatal diagnosis of congenital anomalies--a part of register of congenital anomalies].

UNLABELLED: The most of European registries of congenital anomalies (CA) collected information of CA in livebirths, stillbirths and terminated pregnancies following prenatal/ultrasound diagnosis. OBJECTIVES: to assess terminated pregnancies after prenatal/ ultrasound diagnosis of CA as a part of register of CA performed in University Hospital-Pleven. Among 21 202 births monitored during the study period (1996-2005), 679 CA were detected. The total prevalence of CA was 32/ 1000 births. The outcome of pregnancy for all cases of selected CA by register was 620 livebirths (91.3%), 36 stillbirths (5.3%), 23 terminated pregnancies (TP) (3.4%). The percentage of pregnancy termination was higher in the case of isolated anomalies, mainly lethal and CA associated with a low survival rate (61%), than with multiple ones. The most common CA detected after prenatal/ ultrasound diagnosis were neural tube defects (NTD) - the main reason for TP (52% of cases). The low proportion of these CA in TP (1/3) compared to their proportion in livebirths (50%) demonstrated an insufficiency of prenatal diagnosis of NTD as a part of register of CA performed in University Hospital-Pleven. Prenatal diagnosis of CA allows an early genetic counseling of mother presenting information on neonatal prognosis and recurrence risk for subsequent pregnancies. It helps family to take an adequate decision for termination of pregnancy with bad prognosis about heavy fetal CA.

Abortion, Induced↗

PubMed2004

Study on the role of 5-fluorouracil in the polymerization of butylcyanoacrylate during the formation of nanoparticles.

The possible involvement of 5-fluorouracil (5FU) in the initiation process of the polymerization of n-butylcyanoacrylate monomer during nanoparticle formation was investigated. 5FU in acidic solution (pH 2-3) may interfere in the initiation process through its amino groups via the formation of zwitterions. The proposed zwitterionic mechanism of initiation was supported by the molecular weight profiles of the polymer, determined by gel permeation chromatography, and the covalent linkage of the cytostatic to the main polymer chain. H NMR analyses clearly demonstrated that a significant fraction of 5FU was covalently bonded to the poly(butylcyanoacrylate) chains through its amino groups preferentially through one of the two nitrogen atoms. In vitro release study performed shows that the investigated 5FU-loaded PBCN are suitable for sustaining delivery of 5FU.

Antimetabolites, Antineoplastic↗

PubMed2004

[Active screening for genetic pathology in newborns. I. Registration of congenital abnormalities].

Active screening for genetic pathology over a period of 12 years (1990-2001) involved examination of 29,629 newborns at the Clinic of Obstetrics and Gynaecology. Congenital anomalies were detected in 1244 cases (live-, stillbirths and terminated pregnancies) which gives an average incidence rate of 42.0 per 1000 among the studied population. Congenital cardiac anomalies and CA of the central nervous system were the most common types of isolated CA. They provided frequencies of 7.76 per 1000 and 6.85 per 1000 cases respectively. The incidence of the neural tube defects (NTD), particularly, varied throughout the years (t = 2.69; p < 0.01) but stated high--on average 2.12 per 1000 with the highest rate of 3.89 per 1000 in 1993. A reduction in the incidence of NTD is possible with a recommendation of periconceptional folic acid supplementation. Registration of CA is a strategy for identifying families at risk to give births of child with CA. This approach enabled us to provide more accurate genetic counselling and prenatal diagnosis for genetic pathology. Active screening of newborn population is likely to be an effective and necessary service.

Bulgaria↗

PubMed2004

[Active screening for genetic pathology in newborns. II. Genetic counseling and prenatal diagnosis in high risk families].

Active screening for genetic pathology over a period of 12 years (1990-2001) involved examination of 29629 newborns at the Clinic of Obstetrics and Gynaecology. Congenital anomalies were detected in 1244 cases (live-, stillbirths and terminated pregnancies) which gives an average incidence rate of 42.0 per 1000 among the studied population. Chromosomal abnormalities were diagnosed in 70 cases (5.6%), single gene conditions--in 164 cases (13.2%), multifactorially determined conditions--in 449 cases (36.1%). The total genetic contribution of all recognized cases with genetic conditions was 54.9% (683 cases). Genetic counseling was provided to 560 out of 1244 (45%) couples who given births to affected children. During that period prenatal diagnosis was performed on 110 (44%) pregnancies and most of them (90%) ended successfully (healthy child was born). Our strategy for identifying CD by active screening enabled us to provide more accurate genetic counselling and prenatal diagnosis for genetic diseases. Screening of newborn population is likely to be an effective and necessary service.

Bulgaria↗

PubMed2003

Poly(butylcyanoacrylate) nanoparticles for topical delivery of 5-fluorouracil.

Poly(butylcyanoacrylate) nanoparticles (PBCN) as a drug carrier of 5-fluorouracil (5FU) intended for topical treatment of skin lesia were investigated. The presence of 5FU (as saline solution, pH 10-11) in the polymerization medium affected the polymerization as well as the nanoparticle formation by influencing the initiation of the polymerization reaction. 5FU acted as an initiator in the anionic polymerization of n-butylcyanoacrylate monomer through its nucleophilic nitrogen centers. The results obtained by GPC, 1H NMR, and X-ray diffraction allude to a possible mechanism of cytostatic immobilization in the polymer matrix, with evidence for both free and bound forms of the drug.

Administration, Topical↗

PubMed2003

Study on the effect of polybutyl-2-cyanoacrylate nanoparticles and their metabolites on the phagocytic activity of peritoneal exudate cells of mice.

The phagocytic activity of peritoneal exudate cells (PECs) harvested from peritoneal cavity of mice after a single intraperitoneal (i.p.) treatment with poly(butylcyanoacrylate) nanoparticles (PBCN) and their probable metabolites [poly(cyanoacrylic acid) (PCAA) and n-butanol] was investigated in an in vitro phagocytic assay. Polymer suspension of PBCN was given as a single i.p. injection at doses of 200 and 10 mgkg(-1), 3, 18, 72 and 120 h before the performance of the phagocytic assay. PCAA and n-butanol were given at the same manner at doses of 126.8 and 96.8 mgkg(-1), respectively (equivalent to a dose of 200 mgkg(-1) of intact PBCN after enzyme hydrolysis) 3, 18 and 120 h before the test performance. The phagocytic assay was performed in vitro in tubes with sheep red blood cells (SRBC). Phagocytic index (percentage of PECs ingested more than 3 sheep erythrocytes), phagocytic number, and ingestion capacity (number of erythrocytes ingested per cell) were the parameters used for evaluation of the phagocytic activity. The alterations of phagocytic activity of the PECs observed were strongly time- and dose-dependent. Administration of all tested compounds shortly before the test performance resulted in a considerable decrease in the capability of PECs to ingest SRBC. The alterations of phagocytic activity decreased when the time between the treatment of mice and the phagocytic assay is on the increase. The dose of 200 mgkg(-1) of PBCN administered 120 h before the phagocytic assay led to the significant increase of the phagocytic index of PECs. The phagocytic function of assayed PECs was temporary impeded and 5 days were completely enough for their restoration.

Animals↗

PubMed2002

Cellular absorption of electric field energy: influence of molecular properties of the cytoplasm.

Molecular dispersions may significantly alter the frequency dependence of structural polarizations. Consequently, the molecular properties cannot be neglected when the energy absorption is calculated with a subcellular resolution. Our example presents calculations that explain the absorption in single human red blood cells. The molecular properties of the cytoplasm have been derived from literature data on the impedance of Hb suspensions. The resulting cell properties were then compared to own data obtained by single cell dielectric spectroscopy.

Cytoplasm↗

PubMed2002

Estimating the subcellular absorption of electric field energy: equations for an ellipsoidal single shell model.

An oriented single shell model is used to describe the absorption of electric field energy for a cell of the general ellipsoidal shape exposed to a homogeneous AC-field. A finite element approach allowed us to derive characteristic equations describing the dependence of the field distribution on the cell geometry, the electric properties of the structural media, membrane and bulk solutions, as well as on the field frequency with a subcellular resolution. Finally, equations were derived for the absorption at certain sites of the model. The model allows for the introduction of frequency-dependent cellular media properties. Experimentally, the new cell parameters can be verified by dielectric single-cell spectroscopy.

Adsorption↗

PubMed2001

[Osteogenesis imperfecta - diagnostic challenges].

Osteogenesis imperfecta (OI) is one of the commonest skeletal disorders with an incidence about one in 10,000. It is characterized by clinical and genetic heterogeneity. Congenital lethal OI (OI type II) is the most severe from with a possibility of the early prenatal sonographic diagnosis. The authors present two clinical cases of antenatal diagnosis of OI in 26 and 24 weeks of gestation. The pregnancies were terminated. The accurate specific diagnosis was based on the clinical examination and radiographic features. In case N 2 additional findings were ascites and hydrothorax, that may occasionally be found in literature. The accurate prenatal sonographic diagnosis of lethal skeletal dysplasias and particularly of OI is possible and based on the specific sonographic findings during the second trimester of pregnancy. Ultrasound screening of all pregnant women in early second trimester is an efficient method for detection of many fetal malformations. It requires a participation of the both clinician sonographer and geneticist in a team in order to achieve a specific genetic diagnosis.

Abortion, Induced↗

PubMed2000

[Congenital anomalies among live-birth infants and their place in the structure of neonatal mortality--the Higher Medical Institute, Pleven (1993-97)].

The aim of the study was to determine the frequency of the congenital anomalies (CA) among the live-born (LB), the structure of the neonatal mortality (NM) and the impact of congenital anomalies on it. Congenital anomalies were found in 171 (2.71%) of 11,902 infants born and hospitalized at the Clinics of Neonatology--Pleven between 1993 and 1997. 171 (14.4% o) of all LB died in 28 day after delivery. Noninfectious lung pathology and CA were responsible for respectively 28.7% and 27.5% of these deaths and were the main causes of NM. Multiple congenital anomalies and CA of cardio-vascular system were the most frequent CA that caused these deaths. The major part of the CA with genetic basis (64%) emphasizes the importance of the registration of CA and the genetic counselling for declining the NM rate.

Bulgaria↗

PubMed1998

Study of the effect of polybutylcyanoacrylate nanoparticles and their metabolites on the primary immune response in mice to sheep red blood cells.

Polybutylcyanoacrylate nanoparticles (PBCN) and their metabolites (polycyanoacrylic acid--PCAA, and n-butanol) were compared with respect to their effects on the primary immune response of mice to sheep red blood cells (SRBC). PCAA was synthetized via a Knoevenagel reaction. Antibody production (hemagglutinins) and E-rosette-forming cells (E-RFC) were used to document the induction of antigen-specific immune response to SRBC in all immunized mice. PBCN showed a time- and dose-dependent effect on the immune response, both humoral and cellular. The inductive phase of immune response was affected preferably. The high dose of PBCN (200 mg kg(-1)) tended to suppress the immune response. This was expressed more in mice treated before antigenic stimulation. Lower dose (10 mgkg(-1)) stimulated the immune response. A significant difference was found in the effects of PBCN and their metabolites on the immune response. PCAA and n-butanol administered at doses equivalent (after lysosomal hydrolysis) to the doses applied of intact PBCN did not impair significantly the immune response. A clear time dependence and dose dependence were not observed. The study led to the hypothesis that the greater suppressive effect of PBCN, relative to either PCAA or n-butanol, or a mixture of them, is probably due to the blocking of the immunopresenting function of macrophages instead of some toxicity towards the immunocompetent cells.

Animals↗

PubMed1998

[Postnatal screening for congenital anomalies--the possibility of detecting families at high genetic risk].

The aim of the study was to present out experience with the registration of congenital anomalies (CA) and to assess the effect of the preventive genetic-consultative activities in affected families. In the period 1990-1996, 19174 infants born or hospitalized at the Clinic of Obstetrics, Pleven were screened for CA, showing frequency of 26.1%. Structural analysis of the CA is presented. 226 out of 500 (45%) families with and affected child were consulted by a geneticist. Data an prenatal diagnosis (PD) offered to 142 families at high risk and their reproductive decision are submitted. The low rate of families made use of invasive PD is pointed out; the real benefits of ultrasonography as a screening test for detection of fetal anomalies has been recommended.

Abnormalities, Multiple↗

PubMed1996

[The testicular feminization syndrome combined with disseminated hemangiomatosis].

It is described a new born child with many hemangiomas on the liver. It is made a karyogram to exclude. The possibility of chromosome disease. We fixed male karyotype 46 XY--syndrome Morris. We found out that it is a rare combination of testicular feminization with disseminated hemangiomatosis. After the medical treatment with high doses of cortisone the hemangiomas decreased their sizes.

Androgen-Insensitivity Syndrome↗

PubMed1995

[The role of chromosome anomalies in the origin of reproductive failures].

The results from chromosomal analysis of 185 couples, studied on the occasion of reproductive failures (RF), such as sterility, spontaneous abortions, stillbirths and malformed children are presented. Twenty nine couples (15.68%) with one of spouses--a carrier of a chromosomal anomaly (CA) are established. CA types include: aneuploidy--2, mosaic--5, Robertson's translocation--3, non-Robertson's translocation--7, and pericentric inversion--12. Recognition of genetic conditions is vital for accurate assessment of recurrence risks and in order in some instances, to provide specific prenatal diagnosis.

Abnormalities, Multiple↗

PubMed1994

Tissue distribution of polybutylcyanoacrylate nanoparticles loaded with spin-labelled nitrosourea in Lewis lung carcinoma-bearing mice.

The tissue distribution of polybutylcyanoacrylate nanoparticles (PBCN) with a diameter of 127 nm, loaded with 1-(2-chloroethyl)-3-(1-oxyl-2,2,6,6-tetramethylpiperidinyl)-1- nitrosourea (spin-labelled nitrosourea, SLCNU) is described. PBCN-suspensions were intraperitoneally (i.p.) injected into Lewis lung carcinoma bearing mice. The biodistribution of PBCN in the visceral organs, blood and tumor was studied by electron spin resonance (ESR) spectroscopy. A relatively low accumulation of nanoparticles in the liver and spleen was found. The accumulation was negligible in the i.m. implanted primary tumor. SLCNU-loaded nanoparticles were mainly found in the lungs, kidneys, and heart. The highest content of the particles studied was observed in the lungs of tumor bearing experimental animals damaged by metastases. These findings suggest that PBCN offer some opportunities in the targeting of SLCNU to lung metastases.

Animals↗

PubMed1994

In vitro study of cytotoxic activity of vinblastine in a free form and associated with nanoparticles.

The cytotoxic activities of unloaded polybutylcyanoacrylate nanoparticles (PBCN), free vinblastine, vinblastine-loaded nanoparticles (by incorporation and adsorption processes) and a mixture of vinblastine-free and unloaded PBCN were compared in vitro on human erythroleukemic K-562 cells. Enhanced cytotoxicity was observed when vinblastine was either adsorbed on PBCN or mixed with them rather than free. When vinblastine was incorporated into polymer matrix of nanoparticles, a lag period and postponed cytotoxic effect on K-562 cells were observed.

Antineoplastic Agents↗

PubMed1991

Nanoparticles as drug carriers for vinblastine. Acute toxicity of vinblastine in a free form and associated to polybutylcyanoacrylate nanoparticles.

The possibility of reducing toxicity of Vinblastine by fixing it in polybutyl-2-cyanoacrylate nanoparticles was studied. A significant reduction of mortality of mice was recorded after a single intraperitoneal (i. p.) injection of nanoparticle-associated Vinblastine. A wide range of doses of Vinblastine (1.04-6.25 mg/kg) were used. There was a considerable decrease of leucopenia caused by Vinblastine-loaded polybutyl-2-cyanoacrylate nanoparticles as compared to that induced by free Vinblastine.

Animals↗

PubMed1989

Cytogenetic investigations of human subjects occupationally exposed to chemicals from the petroleum-processing industry.

A cytogenetic investigation was carried out of 55 workers from the petroleum-processing industry and of 30 control subjects. The frequencies of both structural and numerical chromosome aberrations and of sister chromatid exchanges were determined simultaneously and the relationship among these cytogenic indices were analyzed. The incidence of chromosome aberrations and sister chromatid exchanges among the petroleum workers was higher than that among the controls. The cytogenic indices demonstrated a clear dependence on the working environment of the subjects and a correlation with the existence of some reproductive failures in the families of the exposed workers. Our results indicate the presence of some mutagenic risk in the working environment of some of the divisions in the petroleum-processing industry due to the genotoxic influence on the somatic cells of the exposed workers at a cytogenetic level. This potential risk is mainly associated with the presence of some heavy oil-fractions and polycyclic aromatic hydrocarbons in the working environment.

Adult↗