Amyloid-beta Interactions with ABC Transporters and Resistance Modifiers.

BACKGROUND/AIM: Failure of cancer chemotherapy caused by multidrug resistance (MDR) of tumor cells is mediated by ABC transporters that reduce the uptake of cytotoxic agents. Similar transporters are responsible for amyloid clearance in nerve cells in Alzheimer's disease (AD). The aim of this study was to compare the biological effects of amyloid complexes of some known ABC transporter inhibitors e.g. disiloxanes. One of the most active fragments of the pathological "endogen" substrate responsible for AD was investigated in the presence of amyloid-beta fragment on the reversal of multidrug resistance and apoptosis induction on multidrug-resistant tumor cells in model experiments. MATERIALS AND METHODS: The efflux pump activity of the cells treated with amyloid-beta complexes was studied by Rhodamin-123 accumulation. Apoptosis induction was measured by staining of treated cells by Annexin-V and propidium iodine. The fluorescent activity FL-1 and FL-2 of the cells was measured and analyzed on a PARTEC FACScan instrument. RESULTS: The resistance modifiers: disiloxanes and memantine complexed with amyloid-beta 1-42 reduced the activity of ABC transporter in MDR tumor cells. Early apoptosis was moderately increased by amyloid-beta complexes. Late apoptosis and the number of total viable cells were not changed. CONCLUSION: Amyloid-beta and its complexes inactivate the efflux pump of tumor cells resulting in accumulation of amyloid. It is supposed that reduced membrane transport can explain the lower incidence of cancer in AD.

Putative supramolecular complexes formed by carotenoids and xanthophylls with ascorbic acid to reverse multidrug resistance in cancer cells.

BACKGROUND: The molecular basis of interaction of selected carotenoids and xanthophylls with ascorbic acid on cancer cells was studied to determine their anticancer effects. MATERIALS AND METHODS: Drug accumulation was measured in a human ABCB1 gene-transfected mouse lymphoma cell line and in a human lung cancer cell line by flow cytometry; furthermore, their anticancer effects were determined in mice in vivo. RESULTS: Several carotenoids inhibited the multidrug resistance of cancer cells. Ascorbic acid improved the effect of certain xanthophylls, but the effect of capsanthin was not modified. Capsanthin had weak (12%) but capsorubin (85%) had a remarkable antiproliferative effect on A549 lung cancer cells. Capsorubin reduced immediate-early tumor antigen expression, while capsanthin was not effective. Capsorubin accumulates selectively in the nuclei of cancer cells. CONCLUSION: The Authors suggest a special complex formation between membrane-bound capsorubin and ascorbic acid, which can be exploited in experimental chemotherapy.

Antitumor-promoting activity of lignans: inhibition of human cytomegalovirus IE gene expression.

BACKGROUND: Chemoprevention is a promising new approach to cancer prevention. Since the beginning of chemoprevention studies, short-term in vitro models used in the study of carcinogenesis have been applied in the identification of antitumor-promoting agents. MATERIALS AND METHODS: The lignans threo-4,4'-dihydroxy-3-methoxylignan, (-)-dihydroguaiaretic acid, 4'-hydroxy-3,3',4-trimethoxylignan, 3,3',4,4'-tetramethoxylignan, 4,4'-diacetyl-3,3'-dimethoxylignan, talaumidin, heliobuphthalmin, (-)-dihydro-cubebin, and hinokinin were evaluated for their ability to inhibit human cytomegalovirus (HCMV) IE-antigen expression in lung cancer cells (A549). RESULTS: Most of the evaluated compounds reduced IE-antigen expression of HCMV, the best result being obtained with 4,4'-dihydroxy-3-methoxylignan. However, a dose-dependent significant increase of IE-antigen expression was found for the derivative (-)-dihydrocubebin. CONCLUSION: The results of this study suggest that some of these lignans might be valuable as potential cancer chemopreventive agents.

[Cytomegalovirus infection in pregnancy]. / Cytomegalovirus-fertôzés terhességben.

Primary and recurrent infections of human cytomegalovirus (HCMV) can occur during pregnancy. Both can result congenital infection, the leading infectious cause of mental retardation, sensorineural deafness and visual impairment. Intrauterine transmission of HCMV and adverse outcome are mainly related to primary maternal infection. However, there is an increasing evidence that incidence of symptomatic infections in infants born to immune mothers is higher than previously thought. Therefore the option of prenatal diagnosis has a crucial role in the management of pregnancy complicated by active HCMV infection. In spite of the potentially devastating consequence of congenital HCMV infection, little information is available concerning antiviral therapy as prophylactic treatment for women at high risk of the transmission of HCMV during pregnancy. Passive immunization for prevention of vertical transmission of the virus seems to be promising. Until a HCMV vaccine is available, education regarding the risk and strategies for prevention of HCMV infection during pregnancy is needed.

Chemoprevention and inhibition of P-glycoprotein in cancer cells by Chinese medicinal herbs.

Many of the herbal extracts used in the Chinese clinical medical routine inhibit the growth of tumor cells. In the present work, extracts of 12 selected herbs were prepared with methanol, chloroform, ethyl acetate and water, and the effects of these on the multidrug resistance (MDR) and P-glycoprotein of mouse lymphoma cells transfected with the human mdr1 gene and on a human lung alveolar epithelial cell line were investigated. The extracts were tested for antiproliferative effects, and the reversal of MDR in mouse lymphoma cells. The possible chemopreventive effect of the chloroform extracts was studied on the expression of cytomegalovirus (CMV) immediate-early (IE) antigen in human lung cancer cells (A549). The antimicrobial effects of the extracts were tested on some representative micro-organisms. Certain of the chloroform extracts of the plant materials were the most effective compounds on the reversal of MDR. Two of the chloroform extracts enhanced the antiproliferative effect of doxorubicin on MDR mouse lymphoma cells. The selected extracts did not show any antibacterial effect with the agar diffusion method. Certain chloroform extracts decreased the intermediate IE antigen expression of CMV in A459 cells.

Genotypic analysis of two hypervariable human cytomegalovirus genes.

Most human cytomegalovirus (HCMV) genes are highly conserved in sequence among strains, but some exhibit a substantial degree of variation. Two of these genes are UL146, which encodes a CXC chemokine, and UL139, which is predicted to encode a membrane glycoprotein. The sequences of these genes were determined from a collection of 184 HCMV samples obtained from Africa, Australia, Asia, Europe, and North America. UL146 is hypervariable throughout, whereas variation in UL139 is concentrated in a sequence encoding a potentially highly glycosylated region. The UL146 sequences fell into 14 genotypes, as did all previously reported sequences. The UL139 sequences grouped into 8 genotypes, and all previously reported sequences fell into a subset of these. There were minor differences among continents in genotypic frequencies for UL146 and UL139, but no clear geographical separation, and identical nucleotide sequences were represented among communities distant from each other. The frequent detection of multiple genotypes indicated that mixed infections are common. For both genes, the degree of divergence was sufficient to preclude reliable sequence alignments between genotypes in the most variable regions, and the mode of evolution involved in generating the genotypes could not be discerned. Within genotypes, constraint appears to have been the predominant mode, and positive selection was detected marginally at best. No evidence was found for linkage disequilibrium. The emerging scenario is that the HCMV genotypes developed in early human populations (or even earlier), becoming established via founder or bottleneck effects, and have spread, recombined and mixed worldwide in more recent times.

Inhibition of human cytomegalovirus IE gene expression by dihydro-beta-agarofuran sesquiterpenes isolated from Euonymus species.

The development of strategies intended to inhibit human cytomegalovirus (HCMV) immediate-early (IE) antigen expression is an important goal in research designed to prevent and treat certain forms of cancer. The aim of this study was to identify potent IE antigen-targeting natural compounds as antitumor promoters in an in vitro model of tumor promotion. Nineteen dihydro-beta-agarofuran sesquiterpenes isolated from Euonymus species were evaluated for their ability to inhibit HCMV IE antigen expression in human lung adenocarcinoma (A549) cells. Five esters of penta- and hexahydroxydihydro-beta-agarofuran proved to be active components in these Euonymus species, inhibiting the IE antigen expression of HCMV. The highest activity was displayed by 2beta,6alpha,15-triacetoxy1beta-benzoyloxy-9alpha-nicotinoyloxydihydro-beta-agarofuran. These effective compounds may be regarded as prototypes of antitumor promoters, as secondary chemopreventive agents which can modify or halt tumor promotion in general.

Macrocyclic lathyrane diterpenes as antitumor promoters.

Human cytomegalovirus (CMV) preferentially infects tumor tissues and the accumulated CMV immediate-early (IE) antigen may lead to tumor promotion and progression. The development of strategies to inhibit human CMV IE antigen expression and/or function is an important goal to prevent and treat certain forms of cancers associated with human CMV. The aim of this study was to search for antitumor promoters from plant sources. The effect of six macrocyclic lathyrane-type diterpenoids, latilagascenes A-E (1-5) and jolkinol B (6), isolated from the methanol extract of Euphorbia lagascae, on the expression of IE antigen in lung cancer cells (A549) infected by CMV was studied. All the compounds, except latilagascene D (4), decreased IE antigen expression of CMV.

Prevalence and avidity of human herpesvirus-6 specific IgG antibodies in pregnant women in Hungary.

The prevalence, the level and the avidity of human herpesvirus-6 (HHV-6) specific IgG were examined in pregnant women and age-matched female blood donors. The study group consisted of 180 women (age 14-45); 60 women with normal pregnancy, 60 pregnant women with fetuses suspected of having any viral infection and 60 healthy blood donors with no history of pregnancy. Plasma or serum samples were tested for HHV-6 IgG antibodies by an immunofluorescence assay. Ninety-eight percent of blood donors and 97% of 120 pregnant women had IgG antibodies to HHV-6. The rate of seropositivity in women with normal pregnancies and women with fetuses suspected to have viral infection was the same. Pregnant women (n = 120) had significantly lower antibody titer than blood donors. No significant differences were found in the same respect between the two groups of pregnant women. Low avidity of IgG antibodies to HHV-6 was detected in 5% of pregnant women.

Opposite effects of serotonin and interferon-alpha on the membrane potential and function of human natural killer cells.

In an earlier article, we reported that serotonin (5-hydroxytryptamine, 5-HT) inhibits the natural killer cell (NK) cytotoxicity of human whole blood in a dose-dependent manner and that natural human interferon-alpha (IFN-alpha) partially eliminates this effect. Because natural IFN-alpha might contain factors other than IFN, we repeated these experiments with recombinant human interferon-alpha (rhIFN-alpha) and separated blood lymphocytes enriched with NK cells and then demonstrated that IFN really is responsible for this effect. Furthermore, this investigation was carried out to clarify the mechanisms of the action of 5-HT and of rhIFN-alpha on NK cells. The inhibition of the cytotoxicity was pronounced when 5-HT was added at the onset of the cytotoxic assay, whereas the pretreatment of lymphocytes for 18 h only led to a slight inhibition. Moreover, rhIFN-alpha applied 1 h before or 1 h after the addition of 5-HT decreased the inhibitory effect of 5-HT. Flow cytometric analysis involving the use of a voltage-sensitive dye, oxonol, revealed that 5-HT depolarized, whereas rhIFN-alpha hyperpolarized the plasma membrane of the lymphocytes. Thus, it seems likely that the inhibitory effect of 5-HT on the cytotoxicity of peripheral human lymphocytes is due to the depolarization on the plasma membrane of the effector cells and that rhIFN-alpha antagonizes this ability via its hyperpolarizing activity.

[Possibilities of postnatal diagnosis in congenital cytomegalovirus infection]. / A congenitalis cytomegalovirus-fertózés postnatalis diagnosztikájának lehetóségei két eset kapcsán.

The authors review two cases of suspected congenital cytomegalovirus (CMV) infections in which modern laboratory approaches were applied to establish the diagnosis postnatally. In the first case, intrauterine infection was suggested by ventriculomegaly, detected by means of a head ultrasonographic scan. The postnatal cranial ultrasonography and computed tomographic scans revealed intracerebral calcifications. CMV was detected in the blood and urine of the newborn. The postnatal serological tests proved that the mother had experienced a primary CMV infection during gestation. Abnormal neurological signs developed in the infant by the age of 9 months. In the second case, the mother had had an active CMV infection at 29 weeks of gestation involving a twin pregnancy. The CMV-specific serological tests demonstrated that this was a recurrent infection. The twins were born without signs or clinical symptoms and CMV was not detected in their urine samples. At 5 months of age, one of the twins excreted CMV in his urine, which must have been a consequence of a postnatal infection. The general screening of young women by CMV serology at the beginning of gestation is recommended. This would establish a CMV serostatus and provide an opportunity for the gynecologist to provide advice concerning the avoidance of infection, especially in cases where the patient is seronegative and therefore at risk of primary CMV infection.

Mother-to-fetus transmission of cytomegalovirus. A review.

Congenital human cytomegalovirus (CMV) infection is the leading infectious cause of mental retardation, sensorineural deafness and visual impairment. It is mainly related to a primary maternal infection. The placenta should be considered the most important site of both the protection of the fetus from CMV infection and the transmission of CMV from mother to fetus. The control of the passage of CMV across the placenta probably involves a cascade of regulatory events. Roles are played by factors relating to the host immune-selective pressures, such as local cytokines and maternal CMV-specific neutralizing antibodies. The presence of other pathogens at the maternal-fetal interface also influences the outcome of CMV infection. Further investigations are needed in which clinical CMV strains are applied in in vitro studies to unravel the molecular mechanism of the intrauterine transmission of CMV and to elucidate the complex regulation that leads to prevention of the in utero transmission of CMV in vivo.

Incidence and outcome of congenital cytomegalovirus infection in selected groups of preterm and full-term neonates under intensive care.

Congenital cytomegalovirus (CMV) infection is the leading cause of mental retardation and hearing impairment. Examination for the presence of CMV infection was carried out in a selected population of 70 neonates. Urine samples were tested for CMV by means of a nested polymerase chain reaction. CMV was detected in 6 (16.7%) of the 36 preterm newborns and in 5 (14.7%) of the 34 full-term newborns. One preterm neonate died and the remaining 10 newborns were followed up. Two children born at full-term did not excrete CMV at 2 years of age and were symptom-free. Of 8 CMV-excreting children (5 preterm and 3 full-term), 2 were symptom-free (1 preterm and 1 term). Symptomatic CMV disease developed in 6 children (4 preterm and 2 full-term), with mental retardation (n=4), hearing loss (n=1), strabismus (n=2) or bronchial asthma (n=1). Screening of such neonates is important; those identified as congenitally CMV-infected can be monitored to correct any sequelae immediately.

[Cytotrophoblast cells from human first-trimester placental villi: isolation, characterization, cultivation and research applications]. / Elsó trimeszterból származó humán placentabolyhokból nyert cytotrophoblastsejtek: izolálás, jellemzés, tenyésztés és alkalmazás a kutatásban.

INTRODUCTION: Successful implantation and placentation are essential for the normal intrauterine development of the fetus. Trophoblast cell proliferation, differentiation, invasive behaviour and interaction with the maternal immune system are known to have an impact on these processes. Trophoblast cells do not only physically anchor the developing fetus to the uterus, but they give rise to the syncytiotrophoblast. This is the principal endocrine component of the placenta, and participates in essential metabolic processes and in the defence against transplacentally transmitted infections. Therefore, placental trophoblasts play an important role in the establishment and maintenance of pregnancy. AIM OF THE STUDY: The authors summarize their experience with the isolation, characterization and culture of cytotrophoblast cells from first-trimester human placentae. MATERIALS AND METHODS: The simultaneous preparation of highly enriched human placental trophoblast populations from first-trimester placental villi (6-12 weeks of gestation) by sequential trypsinization, Percoll gradient centrifugation, and negative selection with anti-CD45 or HLA-ABC and HLA-DP, DQ, DR immunomagnetic separation is described. Characterization of freshly isolated and cultured cytotrophoblast cells has been performed by immunohistochemistry, immunofluorescent staining, measurement of hCG production and analysis of matrix metalloproteinase production by substrate gel zymography. RESULTS AND CONCLUSION: On the basis of immunohistochemical and functional data the isolated cells proved to be cytotrophoblasts. This method of isolation and cultivation should facilitate in vitro studies of trophoblast differentiation, invasion, endocrine function, virus interaction, and immunology.