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Biomedical subjects

L Popova

Publications and source records attributed to L Popova.

At least 19 recordsLinked to original sources
PubMed2000

Pattern recognition receptors TLR4 and CD14 mediate response to respiratory syncytial virus.

The innate immune system contributes to the earliest phase of the host defense against foreign organisms and has both soluble and cellular pattern recognition receptors for microbial products. Two important members of this receptor group, CD14 and the Toll-like receptor (TLR) pattern recognition receptors, are essential for the innate immune response to components of Gram-negative and Gram-positive bacteria, mycobacteria, spirochetes and yeast. We now find that these receptors function in an antiviral response as well. The innate immune response to the fusion protein of an important respiratory pathogen of humans, respiratory syncytial virus (RSV), was mediated by TLR4 and CD14. RSV persisted longer in the lungs of infected TLR4-deficient mice compared to normal mice. Thus, a common receptor activation pathway can initiate innate immune responses to both bacterial and viral pathogens.

Animals↗
PubMed2000

Leptin expression during the differentiation of subcutaneous adipose cells of human embryos in situ.

In this study, the immunocytochemical expression of leptin in the developing subcutaneous tissue of human embryos at 6-10 weeks of gestation was investigated using the avidin-biotin peroxidase method. Immunocytochemical staining for leptin was observed in the cytoplasm of the differentiating preadipose cells. The other cells present in the embryonal subcutis (mesenchymal cells differentiating into fibroblasts, fibrocytes, endothelial cells) were leptin-negative. The developing skin epithelium lying above it and the blood cells in the capillaries also did not express leptin. The results suggest that the leptin is produced by the developing fat cells from the beginning of lipidogenesis and differentiation. It possibly acts as a hormonal factor regulating the embryonal growth, development and body fat storage.

Adipose Tissue↗
PubMed1999

Effect of dacarbazine (DTIC) on cultures from malignant melanoma of the choroid: an immunohistochemical and electron microscopic study.

INTRODUCTION: Dacarbazine (DTIC) is a very effective chemotherapeutic agent used in the treatment of cutaneous melanoma; it also could have a potential therapeutic value as an antimetastatic agent in the treatment of choroidal melanoma. OBJECTIVE: To study the HMB-45 and S100 protein expression in choroidal melanoma cultures with and without DTIC, and compare the immunohistochemical and electron microscopic changes in both groups. METHODS: Five- and seven-day cultures of choroidal melanoma (n = 21) were cultivated in diffusion chambers. The cultures were divided in two groups: I group (control group)--the cells were grown in 199-medium; II group--the cells were in 199-medium supplemented with 0.03 mg/ml of DTIC. Immunohistochemical studies were performed with paraffin-embedded material of the cultures by the avidin-biotin-alkaline phosphatase technique. Araldit-embedded material was studied by electron microscopy. RESULTS: The expression of HMB-45 and S100 protein in the cultures with DTIC ranged from slightly positive to negative. The tumor cells were severely damaged. Electron microscopy in this group showed presence only of cellular fragments. In the DTIC-free group the HMB-45 and S100 expressions were strongly positive. There were no electron microscopic evidence of cellular death. CONCLUSION: DTIC suppresses the growth of choroidal melanoma in vitro. These results indicate that further studies are warranted to elucidate the effect of DTIC in vivo.

Antigens, Neoplasm↗
PubMed1999

Immunocytochemical expression of p75LNGFR and trkA in Leydig cells of the human testis.

The authors demonstrate for the first time the immunocytochemical expression of the low-affinity neurotrophic growth factor (NGF) receptor p75LNGFR and the high-affinity NGF receptor trkA in the human testis. Employing the polyclonal anti-p75LNGFR antibody and the polyclonal anti-trkA antibody they report strong immunoreactivity for those antigens in the interstitial Leydig cells. Sertoli cells and some cellular elements of the germinative epithelium were also trkA-positive. These findings implicate the neurotrophic factor NGF and its receptors p75LNGFR and trkA in the autocrine and paracrine regulation of the steroidogenic activity of Leydig cells of the human testis.

Adult↗
PubMed1998

Na+-ATPase from the plasma membrane of the marine alga Tetraselmis (Platymonas) viridis forms a phosphorylated intermediate.

Plasma membranes isolated from the marine unicellular alga Tetraselmis (Platymonas) viridis were phosphorylated by [gamma-32P]ATP, and membrane proteins were then analyzed by PAGE in SDS, under acidic conditions. Three radioactive components with apparent molecular masses of 100 kDa, 76 kDa, and 26 kDa were detected. The phosphorylation of one of them, the 100 kDa polypeptide, was specifically stimulated by Na+. Vanadate almost completely inhibited the Na+-mediated phosphorylation of the peptide. The phosphate bound to this peptide underwent rapid turnover and was discharged by hydroxylamine. The 100 kDa phosphopeptide was sensitive to ADP. The conclusion is drawn that the 100 kDa phosphopeptide is a phosphorylated intermediate of the Na+-transporting ATPase in the T. viridis plasma membrane.

Adenosine Diphosphate↗
PubMed1997

The HsdR subunit of R.EcoR124II: cloning and over-expression of the gene and unexpected properties of the subunit.

Type I restriction endonucleases are composed of three subunits, HsdR, HsdM and HsdS. The HsdR subunit is absolutely required for restriction activity; while an independent methylase is composed of HsdM and HsdS subunits. DNA cleavage is associated with a powerful ATPase activity during which DNA is translocated by the enzyme prior to cleavage. The presence of a Walker type I ATP-binding site within the HsdR subunit suggested that the subunit may be capable of independent enzymatic activity. Therefore, we have, for the first time, cloned and over-expressed the hsdRgene of the type IC restriction endonuclease EcoR124II. The purified HsdR subunit was found to be a soluble monomeric protein capable of DNA- and Mg2+-dependent ATP hydrolysis. The subunit was found to have a weak nuclease activity both in vivo and in vitro, and to bind plasmid DNA; although was not capable of binding a DNA oligoduplex. We were also able to reconstitute the fully active endonuclease from purified M. EcoR124I and HsdR. This is the first clear demonstration that the HsdR subunit of a type I restriction endonuclease is capable of independent enzyme activity, and suggests a mechanism for the evolution of the endonuclease from the independent methylase.

Adenosine Triphosphatases↗
PubMed1996

Proteinase inhibitors and pemphigus vulgaris. An in vitro and in vivo study.

The aim of this study was to determine the inhibitory effect of clinically usable proteinase inhibitors p-aminomethylbenzoic acid (PAMBA), and aprotinin on acantholysis in skin organ culture and in clinical trials with pemphigus patients. PAMBA added to the culture medium at a concentration of 1 mg/ml fully prevented the acantholysis, while Contrykal at 10 ATrE/ml reduced acantholysis. Subsequently, we treated 12 patients (groups 1) with PAMBA 100-200 mg daily for 7 to 26 days in combination with a moderate dose of corticosteroid (mean dose 36.1 mg prednisolone equivalent) or immunosuppressive drugs. A second group of 12 patients (group 2) were treated with a high dose of corticosteroid (mean 94.2 mg prednisolone equivalent) and immunosuppressive drugs. Evaluation was performed before treatment, after 3 weeks and on discharge using a clinical scoring system. The inclusion of PAMBA in the treatment protocol of group 1 resulted in active disease being brought under control with lower corticosteroid doses. As a result, fewer side effects were observed in group 1 than in group 2. In our opinion, protease inhibitors may be useful as adjuvant drugs in the combination therapy of pemphigus.

4-Aminobenzoic Acid↗
PubMed1996

Pathogenic in vitro studies of pemphigus vulgaris. I. Experimental model of pemphigus vulgaris in cultures in diffusion chambers.

Normal human skin, cultivated in diffusion chambers with biological membranes in the presence of serum from pemphigus vulgaris patient in the culture, developed all microscopic signs of an acantholytic process. An experimental model of pemphigus was thus created for the first time in our country and proposed by the authors as suitable basis for further studies on the disease pathogenesis and treatment.

Culture Techniques↗
PubMed1989

Ultraviolet light-induced confluent and reticulated papillomatosis.

A 16-year-old girl initially had an eruption consisting of dark gray, flat, pin-sized, confluent papules with a slight hyperkeratotic surface. The lesions appeared after her summer holidays and were restricted to the tanned skin of sun-exposed areas, mainly the abdomen and back. Clinical and histologic findings were consistent with confluent and reticulated papillomatosis. If a basic disorder of keratinization is the cause of confluent and reticulated papillomatosis, it seems likely that the development of the disease in our patient may be due to an abnormal epidermal response to ultraviolet light.

Adolescent↗
PubMed1989

[Thrombokinetic study of patients with idiopathic thrombocytopenic purpura].

The kinetics of 111In-oxine-labeled platelets was studied in 37 patients with idiopathic thrombocytopenic purpura and in 12 control subjects using gamma-chamber. A comparison was made of the parameters of the kinetics, survival and sequestration type of platelets, as well as their recovery and exchange. In less severe processes the splenic type, while in more severe disease--the hepatic type of sequestration prevailed.

Adolescent↗
PubMed1989

[Lennert's lymphoma].

The epithelioid cell Lennert's lymphoma is a rare form of malignant lymphomas. The authors present the cases of 4 patients, aged 50-71 years, 3 men and 2 women, with histologically proved Lennert's lymphoma. In two of the patients the diagnosis was proved at post mortem, too. The cases were characterized by a great variety of the clinico-hematologic data, the course of the disease and the therapeutic response. In all patients the disease was expressed in the III stage and in three of the patients it progressed to the IV stage. The therapeutic conduct is discussed because an early occurrence of cytopenia was found.

Aged↗
PubMed1989

[Autoimmune hemolytic anemia in malignant lymphomas].

The incidence, evolution and prognostic importance of hemolytic anemia in malignant lymphomas are not yet well studied and clarified. The study includes a four-year period, 1985-1988, during which in 5 patients with malignant lymphoma an autoimmune hemolytic anemia was found. In two of the patients the hemolytic anemia preceded the lymphoproliferative disease. An attempt is made to assess the importance of the hemolytic process in the evolution of malignant lymphoma. The need of a detailed examination and a long term follow up of the patients with autoimmune anemia in view of improving the early diagnosis of malignant lymphoproliferative diseases is pointed out.

Adolescent↗
PubMed1989

[Endocrine localization of Hodgkin's disease].

Among 130 patients with Hodgkin's disease hospitalized for a 13 year period were established two cases of primary extranodular localization in the thyroid gland and an extremely rare case of affection of the neurohypophysis as a manifestation of hematogenous dissemination. The clinical manifestations, therapeutic approach and the effect of the endocrine localization on the survival of the patients are presented. The prognosis was comparatively good in the patients with thyroid localization but in the patients with hypophyseal localization it was unfavourable. The diagnostic and therapeutic possibilities in Hodgkin's disease with endocrine localization are discussed.

Adult↗
PubMed1989

[15 patients with myelodysplastic syndrome].

15 patients (10 men and 5 women) with myelodysplastic syndrome, treated in a Hematologic Clinic during the last three years, are studied. The patients are classified in the following groups: with a refractory anemia (4 patients), with an acquired idiopathic sideroblast anemia (3 patients), with a refractory anemia with an excess of blast cells (8 patients). The diagnosis is proved by morphologic examinations, in some of the patients by isotopic examinations and in 5 patients a cytogenetic analysis is made. 7 patients died and in 5 of them the post mortem examination confirms the clinical diagnosis of myelodysplastic syndrome passed in acute leukosis. 4 patients are still alive and are under active observation. For the remaining 4 patients there are no data. The shortest survival is 6 months and the longest one is 9 years. The prognostic importance of the number of blast cells in the bone marrow is pointed out. The patients with refractory anemia with an excess of blast cells are treated with mercaptopurine or small doses of cytosine arabinoside in addition to the conventional blood-stimulating therapy applied in the other forms of myelodysplastic syndrome.

Adult↗
PubMed1988

Psoriasis and drugs: influence of tetracyclines on the course of psoriasis.

Patients with psoriasis vulgaris (462) were studied by questionnaire to find the effect on psoriasis of drug therapy for intercurrent diseases or focal infections. Of 462 patients with psoriasis, in 76 (16.45%) the disease became more severe during drug therapy. Of these, 19 worsened after administration of tetracyclines, and in five psoriasis was precipitated after therapy with drugs of the tetracycline family. We suggest that tetracyclines should be avoided in patients with psoriasis and in healthy persons with a genetic predisposition (positive family history, human leukocyte antigens B13, B17, B27).

Ampicillin↗
PubMed1988

[The use of metamizole as a risk factor in the occurrence of agranulocytosis].

The risk of agranulocytosis following the use of metamizole was studied by the method of controlled cases. All cases of agranulocytosis and their control cases in Sofia for the period 1982-1986 were included in the study. The mean agranulocytosis morbidity for this period was 3.16 cases for one million population for one year. The etiologic fraction was 7.1%. The relative risk of agranulocytosis following the use of metamizole is 1.25, the maximal risk is 0.03 cases for one million persons using metamizole for one year and the maximal lethal risk is 0.007 cases for one million persons using metamizole for one year. The use of metamizole in Bulgaria for the same period was studied, too. The data presented as a number of defined daily doses used by 1000 population for one day show that the use of metamizole in this country is high. A tendency toward an increase of 7.3% per year was found during the investigation. At the same time the agranulocytosis morbidity remained constant during the period of investigation. The results of the study lead to the conclusion that the use of metamizole is not related to a higher risk of agranulocytosis.

Agranulocytosis↗