PubMed Health⌕ Search

Biomedical subjects

S Radulovic

Publications and source records attributed to S Radulovic.

At least 19 recordsLinked to original sources
PubMed2006

Cellular sensitivity to beta-diketonato complexes of ruthenium(III), chromium(III) and rhodium(III).

The aim of this study was to investigate cellular response to several ruthenium(III), chromium(III) and rhodium(III) compounds carrying bidentate beta-diketonato ligands: [(acac)--acetylacetonate ligand, (tfac)--trifluoroacetylacetonate ligand]. Cell sensitivity studies were performed on several cell lines (A2780, cisplatin-sensitive and -resistant U2-OS and U2-OS/Pt, HeLa, B16) using growth-inhibition assay. Effect of intracellular GSH depletion on cell sensitivity to the agents was analyzed in A2780 cells. Flow cytometry was used to assess apoptosis by Annexin-V-FITC/PI staining, and to analyze induction of caspase-3 activity. Possible DNA binding/damaging affinity was investigated, by inductively coupled mass spectrometry, and by 14C-thymidine / 3H-uridine incorporation assay. Cell sensitivity studies showed that the pattern of sensitivity to Ru(tfac)3 complex of the two cisplatin-sensitive/-resistant osteosarcoma cell lines, U2-OS and U2-OS/Pt, was similar to that of A2780 cells (72 h exposure), with the IC50 being around 40 microM. The growth-inhibitory effect of Ru(acac)3 ranged over 100 microM, while Cr(III) and Rh(III) complexes were completely devoid of antitumor action in vitro. Ru(tfac)3 exhibited strong potential for apoptosis induction on A2780 cells (up to 40%) and caused cell cycle arrest in the S phase as well as decrease of the percent of G1 and G2 cells. Ru(acac)3-induced apoptosis was slightly higher than 10%, whereas activation of caspase-3 in HeLa cells was moderate. DNA binding study revealed that only Cr(acac)3 was capable of binding DNA, while Cr(III) and Ru(III) compounds possess potential to inhibit DNA/RNA synthesis. In conclusion, only Ru(III) complexes showed potential for antitumor action.

Apoptosis↗
PubMed2002

Rickettsia-macrophage interactions: host cell responses to Rickettsia akari and Rickettsia typhi.

The existence of intracellular rickettsiae requires entry, survival, and replication in the eukaryotic host cells and exit to initiate new infection. While endothelial cells are the preferred target cells for most pathogenic rickettsiae, infection of monocytes/macrophages may also contribute to the establishment of rickettsial infection and resulting pathogenesis. We initiated studies to characterize macrophage-Rickettsia akari and -Rickettsia typhi interactions and to determine how rickettsiae survive within phagocytic cells. Flow cytometry, microscopic analysis, and LDH release demonstrated that R. akari and R. typhi caused negligible cytotoxicity in mouse peritoneal macrophages as well as in macrophage-like cell line, P388D1. Host cells responded to rickettsial infection with increased secretion of proinflammatory cytokines such as interleukin-1beta (IL-1beta) and IL-6. Furthermore, macrophage infection with R. akari and R. typhi resulted in differential synthesis and expression of IL-beta and IL-6, which may correlate with the existence of biological differences among these two closely related bacteria. In contrast, levels of gamma interferon (IFN-gamma), IL-10, and IL-12 in supernatants of infected P388D1 cells and mouse peritoneal macrophages did not change significantly during the course of infection and remained below the enzyme-linked immunosorbent assay cytokine detection limits. In addition, differential expression of cytokines was observed between R. akari- and R. typhi-infected macrophages, which may correlate with the biological differences among these closely related bacteria.

Animals↗
PubMed2002

Trans-platinum complexes as anticancer drugs: recent developments and future prospects.

Cisplatin represents one of the most potent drugs available in the cancer chemotherapy for several solid tumors, such as germ cell tumors, ovarian, lung, head and neck, and bladder cancers. Structure-activity relationship studies showed that leaving groups (generally chlorine) and two amine ligands in platinum complexes must be in the cis orientation and that the corresponding trans compounds are inactive. During the 1990's, several groups have reported trans-platinum compounds with in vitro growth inhibitory and in vivo antitumor properties. Some of these complexes were active against tumor cells resistant to cisplatin. More interestingly, there is a difference in cellular and biochemical pharmacology between trans-platinum complexes and cisplatin. Thus, monofunctional adducts might be related to the cytotoxicity of the trans-platinum-iminoether compounds against cis-DDP sensitive/resistant cell lines; unusual structure of long-range interstrand cross-links might be relevant for great effectivity of bifunctional polinuclear trans-platinum(II) compounds against cis-DDP resistant variants. Trans-platinum compounds, appear to follow different pattern of cell killing in comparison to cisplatin, thus giving a reason for optimism in their development as a new class of platinum-based antitumor drugs.

Animals↗
PubMed2002

Antiproliferative activity of some cis-/trans-platinum(II) complexes on HeLa cells.

Purpose of this work was to synthesize several cis-/trans- isomer pairs of the platinum(II) complexes, and study the extent and the mode of their antiproliferative activity on HeLa cells. Six platinum(II) isomer pairs have a general formula cis-/trans-[PtA2X2], where A is ligand: ammonia (NH3), pyridine (Py); and X is ligand: chloride ion (Cl-), bromide ion (Br-), iodide ion (I-), thiocyanato ion (SCN-); four compounds have different structural formulas, and these are cis-/trans-[Pt(NH2OH)2(NH3)2]Cl2, and cis-/trans-Pt(Gly)2, where Gly is bidentate glycinato ligand. Results of the MTT assay, showed that six cis- and one trans-platinum(II) complexes exhibited cytotoxicity (IC50) ranging between 5 and 33 microM. Most of the cis-platinum(II) isomers caused significant alteration of cell cycle phases progression, and induced apoptosis in degree that varied among different compounds, as evaluated using flowcytometry and morphological study. Spectrophotometric analysis (AAS) indicated that there is no correlation between intracellular platinum(II) accumulation and cytotoxicity of tested complexes.

Antineoplastic Agents↗
PubMed2000

Inhibition of human epithelial ovarian cancer cell growth in vitro by somatostatin analog RC-160.

In this study, we investigated the effects of somatostatin analog RC-160 on the growth of the OV-1063 human epithelial ovarian cancer cell line in vitro. RC-160 inhibited cell proliferation, as measured by cell number, and [(3)H]thymidine incorporation into DNA at 10(-9)-10(-5) M. In OV-1063 cells, (125)I-labeled RC-160 was bound to one class of specific, saturable binding sites with high affinity (K(d) = 0.2 +/- 0.03 nM) and low capacity (5,500 binding sites per cell). (125)I-labeled RC-160 could be displaced by unlabeled RC-160. Ligand binding was dependent on time and temperature. Receptor internalization assay showed that the ligand-receptor complex was internalized at 37 degrees C, which indicates the presence of biologically active somatostatin receptors on OV-1063 cells. These results suggest that somatostatin analog RC-160 can suppress the growth of OV-1063 human epithelial ovarian cancer cells by a direct action and that the inhibitory effect of somatostatin analog is mediated through the high-affinity somatostatin receptors.

Antineoplastic Agents↗
PubMed1999

Identification and molecular analysis of the gene encoding Rickettsia typhi hemolysin.

Rickettsia typhi, the causative agent of murine typhus, grows directly within the host cell cytoplasm, accumulating a large number of progeny, and eventually lyses the cells. Typhus group rickettsiae (R. typhi and R. prowazekii) adhere to and lyse human and sheep erythrocytes. However, the molecular mechanism underlying erythrocyte lysis by R. typhi has not been defined. Here we describe the cloning and nucleotide sequence analysis of the gene (tlyC) encoding a hemolysin from R. typhi. DNA sequence analysis of R. typhi tlyC revealed an open reading frame of 912 bp, which encodes a protein of 304 amino acids with a predicted molecular mass of 38 kDa. To associate the R. typhi tlyC gene product with hemolytic activity, we performed complementation studies with hemolysin-negative Proteus mirabilis WPM111 (a HpmA(-) mutant of BA6163) transformed with R. typhi tlyC or R. typhi GFPuv-tlyC constructs. We demonstrated that the cloned tlyC gene conferred a hemolytic phenotype on an otherwise nonhemolytic mutant of P. mirabilis. The availability of the cloned R. typhi tlyC will permit further characterization and definition of its role in rickettsial virulence.

Amino Acid Sequence↗
PubMed1999

Green fluorescent protein as a marker in Rickettsia typhi transformation.

Transformation of rickettsiae is a recent accomplishment, but utility of this technique is limited due to the paucity of selectable markers suitable for use in this intracellular pathogen. We chose a green fluorescent protein variant optimized for fluorescence under UV lights (GFPUV) as a fluorometric marker and transformed Rickettsia typhi with an rpoB-GFPUV fusion construct. The rickettsiae were subsequently grown in Vero cells, and cultures were screened by PCR and restriction fragment length polymorphism (RFLP) to confirm incorporation of the rpoB-GFPUV construct. Cultures were then analyzed by flow cytometry for detection of GFPUV expression, and transformed R. typhi were isolated in a fluorescence-activated cell sorter. This is the first report of transformation of rickettsiae with a nonrickettsial (GFPUV) gene.

Biomarkers↗
PubMed1999

Concomitant radiotherapy and carboplatin in locally advanced bladder cancer.

OBJECTIVE: The aim of the study was to assess the efficacy and safety of concomitant radiotherapy (CRT) and carboplatin. PATIENTS AND METHODS: From 1992 until 1997, 67 patients with T3 invasive bladder cancer (IBC) were treated using CRT and carboplatin. X-Ray radiotherapy (10 MeV) was applied using LINAC in a locoregional technique, with a total tumor dose of 65 Gy in 32 fractions. Carboplatin was administered as a bolus infusion once a week, on day 5, up to a total dose of 900 mg. RESULTS: The most frequent toxicity was hematological. Of the 67 treated patients, 92.5% achieved a clinically complete response, and 7.5% developed progressive disease during therapy. The 5-year overall survival was 55% and disease-free survival was 35%. CONCLUSION: CRT and carboplatin appear to be safe and extremely active in the treatment of T3 IBC, but the results should be confirmed in a randomized study.

Adult↗
PubMed1998

Attitudes of oncologists, family doctors, medical students and lawyers to euthanasia.

The purpose of this survey was to define attitudes and opinions of two types of physicians, medical students and lawyers in the area of euthanasia and related issues and problems. A questionnaire was used as the source of data. There were four groups of test persons: oncologists, home care physicians (family doctors), third-year medical students and lawyers. The questionnaire included 22 questions, 4 of which concerned general characteristics of tested persons (including religious belief), while 18 referred to the problems of euthanasia. The total number of tested persons was 123, 55 men and 68 women with a median age of 38 +/- 11 years ( +/- SD). There were 30 test persons in the group of oncologists, 31 in the group of family doctors, 31 in the group of third-year students, and 31 in the group of lawyers. Between 97% and 100% of individuals gave scored responses to most items. More than half of the individuals (57%) were against euthanasia, and 61% are against the legalization of euthanasia. The views of doctors and medical students were similar (2/3 against) and significantly different from the view of lawyers (2/3 for, P < 0.01). The legalization of euthanasia is favored by 61% of lawyers, in contrast to 43%, 30% and 23% of oncologists, family doctors and medical students, respectively. Overall, 31% sais they would apply euthanasia if they were asked for it, and 36% that would if it had been legalized. Lawyers are twice as willing to perform euthanasia as students or physicians. The least ready to apply euthanasia are physicians working as oncologists (only 1 in 5). Compared with oncologists, one-third of home-care physicians would perform euthanasia anyway, whether legalized or not. Most of the test persons were of the opinion that euthanasia should be performed in the case of children born with a severe anomaly. None of the tested groups considered invalidity or being a burden to the family important reasons for the termination of somebody's life. Approximately 40% of responders believed that the decision for euthanasia should be made by the patient alone. Only lawyers were of the opinion that the misuse of euthanasia could be controlled. Our study shows that it is probably more important to determine factors associated with behavior pertaining to euthanasia in physicians working closely with suffering patients. Reducing suffering and launching a hospice movement and palliative care services might be the most appropriate way to deal with the problem of euthanasia.

Adult↗
PubMed1998

Molecular identification of Rickettsia typhi and R. felis in co-infected Ctenocephalides felis (Siphonaptera: Pulicidae).

Rickettsia typhi and R. felis, 2 closely related rickettsial species, often have been identified in cat fleas, Ctenocephalides felis (Bouché) from the same geographical location. However, no fleas have been found to be naturally infected concurrently with both rickettsial species. To examine whether one rickettsial species can develop simultaneously with another species in the same flea host, cat fleas, naturally infected with R. felis, were allowed to feed on blood containing R. typhi (Ethiopian strain, 10(7) PFU/ml). Experimental controls consisted of uninfected cat fleas, fleas infected with only R. typhi; and fleas naturally infected with only R. felis. After 9 d at 28 degrees C, the fleas were examined by PCR amplification and subsequent restriction digest analysis and dot blot hybridization of PCR products. Results from these studies demonstrated that R. felis and R. typhi are capable of co-existing in the same flea host. Subsequent isolation of R. typhi from dually infected fleas by tissue culture indicated that R. typhi was viable and capable of being maintained in fleas naturally infected with R. felis. As more studies confirm the presence of R. felis and R. typhi in domestic pets and peridomestic vertebrates in urban areas, the ability of the individual cat fleas, which live on these animals, to support both rickettsial species could be an epidemiologically important consideration.

Animals↗
PubMed1996

Isolation of Rickettsia akari from a patient in a region where Mediterranean spotted fever is endemic.

Rickettsia akari was isolated from blood collected from a patient in Croatia in 1991. We believe this is the first human isolate of R. akari to be reported in more than 40 years and the first ever from southern Europe. The Croatian isolate was antigenically and genetically indistinguishable from the prototype American strain and a Ukrainian strain. In all probability, rickettsialpox would be diagnosed more frequently and over a wider geographic area if physicians gave greater consideration to the diagnosis and if laboratory diagnostic methods were better able to distinguish among spotted fever group rickettsioses.

Adult↗
PubMed1996

Presence of calreticulin in vector fleas (Siphonaptera).

Calreticulin has been defined in the cat flea, Ctenophalides felis (Bouché), and oriental rat flea, Xenopsylla cheopis (Rothschild). Calreticulin, a major endoplasmic reticulum protein, was previously identified as a component of ixodid tick saliva. Using a riboprobe generated from tick calreticulin complementary DNA (cDNA), we distinguished 2 transcripts for calreticulin in cat fleas by Northern blot analysis. Increased expression of calreticulin was not evident in fed versus unfed adult fleas. We were able to amplify a calreticulin flea product from fed female messenger RNa (mRNA) using primers designed from the tick calreticulin gene. One of these products hybridized to the tick riboprobe. Localization of specific antibody to cat flea tissues showed calreticulin in the midgut with no detection in the salivary glands. We also observed specific labeling of calreticulin with antibody in the ovaries of fed females. Several cat flea polypeptides appear to crossreact with anticalreticulin antibody in Western blots. We did not detect a calreticulin using antibody to the tick-secreted protein in cat flea salivary glands. This antibody did recognize a protein in the rate flea salivary glands. Our results show that fleas have calreticulin and, possibly, several isoforms. It appears that the salivary glands of the cat and oriental rat flea differ in detectable levels of calreticulin. The specific antibody labeling of the ovaries is interesting and remains to be understood. Calreticulin's appearance in the midgut suggests a possible source of calreticulin as a flea secretion. Further studies are in progress to complete the sequencing of the flea polymerase chain reaction (PCR) product to compare to tick-secreted calreticulin. Comparisons to other blood-feeding arthropods at the protein and gene level are also being done. We hope to define further the expression of calreticulin in fleas, and in general, blood-feeding arthropods, with respect to its role in feeding and pathogen transmission.

Animals↗
PubMed1996

Acquisition of the cat scratch disease agent Bartonella henselae by cat fleas (Siphonaptera:Pulicidae).

We assayed the ability of cat fleas to become infected with Bartonella henselae, using an artificial feeding device. Fleas fed a concentration of 1 x 10(5) cfu/ml in blood were examined using immunofluorescent antibody assay and polymerase chain reaction. Bacteria were present in the gut at 3 h, and persisted up to 9 d after infection. Qualitatively, the density of B. henselae was greater in the flea gut at 9 d, indicating that replication was occurring in the gut. B. henselae also was detected in the feces of infected fleas 9 d after infection, and produced viable colonies upon inoculation onto heart infusion agar/rabbit blood plates. Our results indicate that fleas can maintain infection with B. henselae, and may play a role in the transmission of this bacterium from infected cats to humans.

Animals↗
PubMed1996

Rickettsia felis: a new species of pathogenic rickettsia isolated from cat fleas.

A flea-borne rickettsia, previously referred to as ELB, has been implicated as a cause of human illness. Using sequence data obtained from a fragment of the citrate synthase gene, we compared ELB, Rickettsia australis, R. rickettsii, and R. akari with the louse-borne R. prowazekii. We tallied 24 base pair differences between ELB and R. prowazekii and 25 between R. rickettsii and R. prowazekii; there were 30 base pair differences between R. australis and R. prowazekii and 29 between R. akari and R. prowazekii. We observed 32 differences between Rickettsia typhi and ELB. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblot analyses of ELB, with typing sera against R. typhi indicate that ELB surface antigens are more closely related to the flea-borne R. typhi than to the mite-borne R. akari. On the basis of the results of citrate synthase gene sequence comparisons, as well as previous comparisons with 16S rRNA and 17-kDa-protein gene segments, we found that ELB is sufficiently genetically distinct from other rickettsiae to be designated a new species, Rickettsia felis.

Animals↗
PubMed1996

Modulation of cisplatin antitumor activity by short infusional high-dose cytosine arabinoside in advanced pretreated head and neck carcinoma: a phase II study.

The aim of the present study, which included 24 pretreated patients (both with radiotherapy and/or cisplatin-containing chemotherapy) with histological grade I/II head and neck cancer, was to investigate whether the enhancing action of cytosine arabinoside on cisplatin antitumor activity might be evidenced without excessive hematological toxicity with the administration of short infusional high-dose cytosine arabinoside, applied before cisplatin. Cytosine arabinoside was administered on day 1 of the treatment cycle at 0h and 12h at the dosage of 500 mg/m2 (1 hour infusion), and cisplatin at 6h and 18h of the same day with a dose of 20 mg/m2. On days 2, 3 and 4, only cisplatin 30 mg/m2/24h was administered. 19 patients were evaluable for activity including 14 patients pretreated with cisplatin-containing chemotherapy. 2/19 achieved complete response (CR), 2/19 a partial response (PR), 8/19 had stable disease and 7/19 progressive disease. Objective responses (2 CR and 1 PR) were evidenced in 3/14 patients previously resistant to cisplatin at the same dosage as in the present regimen. WHO grade IV toxicity for granulocytes was recorded in only one patient.

Adult↗
PubMed1995

Prevalence of antibodies to rickettsiae in the north-western part of Bosnia and Herzegovina.

The prevalence of rickettsial antibodies in north-western part of Bosnia and Herzegovina was studied. Among 231 sera tested by complement fixation (CF) positive were: 61.5% for Rickettsia typhi, 4.3% for R. prowazekii, 1.7% for R. conorii and 19.0% for Coxiella burnetii. Of 183 sera tested by indirect immunofluorescence assay (IFA) 37.7% reacted with R. typhi, 1.6% with R. conorii and 22.4% with C. burnetii. The results show that at least R. typhi and C. burnetii are highly endemic in this area.

Adolescent↗