PubMed Health⌕ Search

Biomedical subjects

M Mach

Publications and source records attributed to M Mach.

At least 19 recordsLinked to original sources
PubMed2004

Direct liquid chromatography method for retinol, alpha- and gamma-tocopherols in rat plasma.

An HPLC method for Vitamins A and E in rat plasma has been developed. The main goals of the method are the small amount of sample, 50 microl, and the direct extraction of analytes in one step with acetone, which is a solvent compatible with the reverse-phase mobile phases. Recoveries, as compared with classical and more tedious methods, were near 100%. The method employs a Supelco Discovery C18 column and methanol/water (95:5, v/v) as mobile phase. After being developed, the method was validated following ICH guidelines, with UV, fluorescence and electrochemical detectors. It proved to be selective, lineal, accurate and precise. This method greatly simplifies sample treatment and that is a critical point when working with a large number of samples.

Animals↗
PubMed2004

Effect of melatonin on biochemical variables induced by phenytoin in organs of mothers, foetuses and offsprings of rats.

The present pre- and postnatal study was carried out to investigate the effect of melatonin (MEL), a potent antioxidant, on biochemical variables in the in vivo model of intrauterine hypoxia in rats. Chronic hypoxia was induced pharmacologically by the administration of the anticonvulsant phenytoin (PHT) during pregnancy. Rats were orally treated by PHT (150 mg/kg) from day 7 to 18 of gestation. MEL in drinking water (40 microg/ml) was administered from day 0 to 19 of gestation. The activity of the lysosomal enzyme N-acetyl-beta-D-glucosaminidase (NAGA) and the level of glutathione (GSH) were used as markers of tissue damage. In the prenatal study PHT-induced toxic damage was associated with an increase in NAGA activity and decrease of GSH level in placenta and in maternal serum and heart. MEL partially inhibited the changes of NAGA activity given above. MEL was able to increase only the decreased level of GSH in maternal heart. PHT decreased the level of GSH and increased the activity of NAGA in foetal organs, the improvement occurred in the liver and lungs, but not in foetal brain. In the postnatal study a significant increase of liver GSH level was found in all (control, MEL, PHT, MEL+PHT) groups of 1-day-old pups, while the activity of NAGA remained unchanged. We did not observe any significant differences in NAGA activity in the lungs and heart of pups. MEL increased the GSH level in lungs and heart. We concluded that administration of MEL during pregnancy partially inhibited the biochemical changes induced by PHT.

Acetylglucosaminidase↗
PubMed2004

Effect of melatonin and stobadine on maternal and embryofoetal toxicity in rats due to intrauterine hypoxia induced by phenytoin administration.

The aim of the present study was to test the hypothesis that the natural antioxidant melatonin (MEL) and the synthetic antioxidant stobadine (STO) could reduce the incidence of maternal and embryofoetal toxicity in rats due to intrauterine hypoxia. Chronic hypoxia was induced pharmacologically by the administration of the anticonvulsant phenytoin (PHT) during the entire period of pregnancy. PHT disturbed the normal course of pregnancy, affected reproductive parameters and increased the incidence of skeletal anomalies. MEL did not protect the PHT-induced development toxicity in rat. On the other hand, STO partially prevented PHT-induced reduction of foetal and placental weights. Administration of STO also decreased the frequency of pre- and post-implantation loss and resorptions in the PHT group. We concluded that pretreatment of pregnant rats with STO prevented to a certain extent reproductive and foetal development alterations caused by chronic intrauterine hypoxia.

Abnormalities, Drug-Induced↗
PubMed2003

Glycoprotein gpTRL10 of human cytomegalovirus is dispensable for virus replication in human fibroblasts.

Human cytomegalovirus (HCMV) has a coding capacity for glycoproteins which by far exceeds that of other herpesviruses. Few of these proteins have been characterized. Glycoprotein gpTRL10 represents a structural component of HCMV. The protein has no homologous counterparts in other herpesviruses. We have isolated bacterial artificial chromosomes (BACs) harboring the genome from the low passage clinical isolate PAN and constructed a deletion mutant in reading frame TRL10. Our results show that deletion of gpTRL10 has only minimal effects on viral replication in human fibroblasts.

Cells, Cultured↗
PubMed2003

Human cytomegalovirus glycoprotein N (gpUL73-gN) genomic variants: identification of a novel subgroup, geographical distribution and evidence of positive selective pressure.

Human cytomegalvirus (HCMV) ORF UL73 is a polymorphic locus, encoding the viral glycoprotein gpUL73-gN, a component of the gC-II envelope complex. The previously identified gN genomic variants, denoted gN-1, gN-2, gN-3 and gN-4, were further investigated in this work by analysing a large panel of HCMV clinical isolates collected from all over the world (223 samples). Sequencing and phylogenetic analysis confirmed the existence of the four gN genotypes, but also allowed the identification of a novel subgroup belonging to the gN-3 genotype, which was designated gN-3b. The number of non-synonymous (d(N)) and synonymous (d(S)) nucleotide substitutions and their ratio (d(N)/d(S)) were estimated among the gN genotypes to evaluate the possibility of positive selection. Results showed that the four variants evolved by neutral (random) selection, but that the gN-3 and gN-4 genotypes are maintained by positive selective pressure. The 223 HCMV clinical isolates were subdivided according to their geographical origin, and four main regions of gN prevalence were identified: Europe, China, Australia and Northern America. The gN variants were found to be widespread and represented within the regions analysed without any significant difference, and no new genotype was detected. Finally, for clinical and epidemiological purposes, a rapid and low-cost method for genetic grouping of the HCMV clinical isolates was developed based on the RFLP revealed by SacI, ScaI and SalI digestion of the PCR-amplified UL73 sequence. This technique enabled us to distinguish all four gN genomic variants and also their subtypes.

Amino Acid Sequence↗
PubMed2002

Molecular characteristics of some commercial high-molecular-weight hyaluronans.

Commercially available hyaluronan (HA) samples were investigated by the method of size exclusion chromatography (SEC). The fractions eluted from the SEC column were on-line molecularly characterized by using a multi-angle laser light scattering (MALLS) photometer. Along with the SEC-MALLS technique, the high-molecular-weight HA biopolymers were (off-line) analyzed by capillary viscometry.

Hyaluronic Acid↗
PubMed2002

Identification of glycoprotein gpTRL10 as a structural component of human cytomegalovirus.

Human cytomegalovirus (HCMV) has a coding capacity for glycoproteins which far exceeds that of other herpesviruses. Few of these proteins have been characterized. We have investigated the gene product(s) of reading frame 10, which is present in both the internal and terminal repeat regions of HCMV strain AD169 and only once in clinical isolates. The putative protein product is a 171-amino-acid glycoprotein with a theoretical mass of 20.5 kDa. We characterized the protein encoded by this reading frame in the laboratory strain AD169 and a recent isolate, TB40E. The results from both strains were comparable. Northern blot analyses showed that the gene was transcribed with early/late kinetics. Two proteins of 22 and 23.5-kDa were detected in virus-infected cells and in cells transiently expressing recombinant TRL10. Both forms contained only high-mannose-linked carbohydrate modifications. In addition, virus-infected cells expressed small amounts of the protein modified with complex N-linked sugars. Image analysis localized transiently expressed TRL10 to the endoplasmic reticulum. Immunoblot analyses as well as immunoelectron microscopy of purified virions demonstrated that TRL10 represents a structural component of the virus particle. Immunoblot analysis in the absence of reducing agents indicated that TRL10, like the other HCMV envelope glycoproteins, is present in a disulfide-linked complex. Sequence analysis of the TRL10 coding region in nine low-passage clinical isolates revealed strain-specific variation. In summary, the protein product of the TRL10 open reading frame represents a novel structural glycoprotein of HCMV and was termed gpTRL10.

Amino Acid Sequence↗
PubMed2001

Intrauterine transmission of cytomegalovirus to infants of women with preconceptional immunity.

BACKGROUND: Preconceptional immunity against cytomegalovirus (CMV) provides only partial protection against intrauterine transmission of the virus. Whether congenital CMV infection in the offspring of women who are seropositive for CMV can occur after maternal reinfection with a different strain of CMV is unknown. METHODS: Serum specimens from 46 women with preconceptional immunity against CMV that were obtained during the previous pregnancy and the current pregnancy were analyzed for antibodies against the strain-specific epitopes of CMV glycoprotein H. Virus-neutralizing activity in maternal serum samples was measured against the AD169 laboratory strain of CMV and the CMV isolates available from seven infected infants. In addition, the nucleotide sequences of the glycoprotein H gene from the seven CMV isolates were determined. RESULTS: Eleven of the 16 mothers with infected infants (69 percent) had antibodies against the glycoprotein H epitopes present on two laboratory strains of CMV, AD169 and Towne. Ten of the 16 mothers with infected children (62 percent) acquired new antibody specificities against glycoprotein H, as compared with only 4 of the 30 mothers of uninfected infants (13 percent, P<0.001). The samples obtained at the time of the current delivery from four of the seven mothers contained at least twice as many neutralizing antibodies against the CMV isolated from their infants as were present in the samples obtained at the previous delivery. The specificity of the newly acquired maternal antibodies reflected the amino acid sequence of the glycoprotein H epitope of CMV from these four infants. CONCLUSIONS: In women who are seropositive for CMV, reinfection with a different strain of CMV can lead to intrauterine transmission and symptomatic congenital infection.

Amino Acid Sequence↗
PubMed2001

Effect of repeated administration of the antioxidant stobadine on the behavior of singly-housed male mice in intraspecies conflict.

The aim of the present study was to assess the effect of repeated oral administration of stobadine (70 mg/kg) on the occurrence of selected behavioral elements during exposure to an intraspecies conflict between singly-housed and group-housed male mice. Isolation induced timidity (defensive-escape behavior without attacks) in most mice (87%). This isolation-induced timidity was reduced after stobadine treatment. In the stobadine-treated group, sociable activities (following, climbing) were also decreased. After discontinuation of the treatment (18 days), aggressive behavior tended to increase in the stobadine-treated group. The results of this study are indicative of an inhibitory effect of repeated administration of stobadine on some behavioral activities of singly-housed male mice in an intraspecies conflict.

Aggression↗
PubMed2001

Characterization of antibody response to human cytomegalovirus in Indian renal transplant patients.

BACKGROUND & OBJECTIVES: Cytomegalovirus (CMV) disease in seroendemic transplant populations is due to reactivation of the virus, or reinfection. In this context, the antibody response is likely to influence presentation, clinical severity and outcome of the disease, and may provide a diagnostic and prognostic marker. This study was carried out in Indian renal transplant patients and healthy adults to characterize the antibody response to cytomegalovirus. METHODS: Thirty three transplant recipients with CMV illness (symptomatology with IgM and/or nPCR positive status), 20 recipients who were asymptomatic in the 6 months of follow up after transplantation and 62 healthy controls were investigated for markers of CMV infection. These individuals were tested for IgG avidity and neutralizing antibody by ELISA techniques. RESULTS: All 53 transplant recipients were found to have an IgG avidity index of > 50 per cent. Antibody to a CMV envelope glycoprotein gB/AD-1 (putative neutralizing antibody) was expressed as S/N ratio and was > or = 5 in asymptomatic (65%) and symptomatic (27%) immunosuppressed renal transplant recipients. However, none of the 53 CMV IgG positive healthy controls were positive for neutralizing antibodies S/N ratio > or = 5 (S/N ratio = sample mean OD/mean OD of 3 negative controls in each run). We observed the simultaneous presence of CMV PCR signal in leukocytes and neutralizing antibody (S/N ratio > or = 5) in the plasma in 22 (41.5%) of the 53 renal transplant recipients. INTERPRETATION & CONCLUSIONS: In this study among the immunosuppressed transplant patients we observed an association between symptomatic disease and the relative absence of neutralizing antibodies. The neutralizing antibodies are less frequently demonstrable among controls; while appearance in a higher proportion of asymptomatic recipients especially in association with high IgG avidity (> 90%) is suggestive of its role in control of CMV disease despite reactivation as evidenced by DNAemia while on immunosuppressive therapy.

Adult↗
PubMed2000

Dense bodies of human cytomegalovirus induce both humoral and cellular immune responses in the absence of viral gene expression.

Infection of fibroblast cell cultures with human cytomegalovirus (HCMV) leads to the production of significant amounts of defective enveloped particles, termed dense bodies (DB). These noninfectious structures contain major antigenic determinants which are responsible for induction of both the humoral and the cellular immune response against HCMV. We tested the hypothesis that, by virtue of their unique antigenic and structural properties, DB could induce a significant immune response in the absence of infectious virus. Mice were immunized with gradient-purified DB, which were either left untreated or subjected to sequential rounds of sonication and freeze-thawing to prevent cellular entry. Titers of neutralizing antibodies induced by DB were in a range comparable to levels present in convalescent human sera. The virus-neutralizing antibody response was surprisingly durable, with neutralizing antibodies detected 12 months following primary immunization. The HCMV-specific major histocompatibility complex class I-restricted cytolytic T-cell (CTL) response was assayed using mice transgenic for the human HLA-A2 molecule. Immunization with DB led to high levels of HCMV-specific CTL in the absence of de novo viral protein synthesis. Maximal total cytolytic activity in mice immunized with DB was nearly as efficient as the cytolytic activity induced by a standard immunization with murine cytomegalovirus. Furthermore, DB induced a typical T-helper 1 (Th1)-dominated immune response in mice, as determined by cytokine and immunoglobulin G isotype analysis. Induction of humoral and cellular immune responses was achieved without the concomitant use of adjuvant. We thus propose that DB can serve as a basis for the future development of a recombinant nonreplicating vaccine against HCMV. Finally, such particles could be engineered for efficient delivery of antigens from other pathogens to the immune system.

3T3 Cells↗
PubMed2000

Complex formation by human cytomegalovirus glycoproteins M (gpUL100) and N (gpUL73).

The envelope glycoproteins of human cytomegalovirus (HCMV) virions are incompletely characterized. We have analyzed complex formation between glycoprotein M (gM or gpUL100) and a second glycoprotein. gM-homologous proteins are conserved throughout the herpesvirus family and represent type III membrane proteins containing multiple hydrophobic sequences. In extracellular HCMV particles, gM was found to be complexed through disulfide bonds to a second protein with an apparent molecular mass of 50 to 60 kDa. The 50- to 60-kDa protein was found to be derived from reading frame UL73 of HCMV strain AD169. UL73-homologous genes are also conserved within herpesviruses. When transiently expressed by itself, the UL73 gene product consisted of a protein of 18 kDa. However, in the presence of gM, the UL73 gene product was posttranslationally modified to the 50- to 60-kDa species. Thus, gM and the UL73 gene product, which represents the gN homolog of herpesviruses, form a disulfide-linked complex in HCMV virions. Transient expression of gM and gN followed by fluorescence imaging with monoclonal antibodies against either protein demonstrated that complex formation was required for transport of the proteins from the endoplasmic reticulum to the Golgi and trans-Golgi compartments. Finally, we tested the gM-gN complex for reactivity with sera from HCMV-seropositive donors. Whereas most sera failed to react with either gM or gN when expressed alone, 62% of sera were positive for the gM-gN complex. Because a murine monoclonal antibody reactive with gN in the gM-gN complex efficiently neutralizes infectious virus, the gM-gN complex may represent a major antigenic target of antiviral antibody responses.

Antibodies, Monoclonal↗
PubMed1999

Strain-specific neutralization of human cytomegalovirus isolates by human sera.

Induction of an effective antibody response against human cytomegalovirus (HCMV) is an important defense mechanism since it is potentially capable of neutralizing infectious viruses. We have analyzed the extent of HCMV strain-specific neutralization capacity in human sera. Nine recent HCMV isolates and their corresponding sera were investigated in cross-neutralization assays. We observed differences, independent of the overall neutralization capacity, in the 50% neutralization titers of the sera against individual strains, differences that ranged from 8-fold to more than 60-fold. For one isolate, complete resistance to neutralization by two human sera was observed. The neutralization capacity of human sera was not influenced by the presence of various concentrations (up to 100-fold excess) of noninfectious envelope glycoproteins, an inherent contamination of virus preparations from recent HCMV isolates. This indicated that the decisive parameter for neutralization is the titer of the neutralizing antibodies and that neutralization is largely independent of the concentration of virus. Analysis with transplant patients revealed that during primary infection strain-specific and strain-common antibodies are produced asynchronously. Thus, our data demonstrate that the induction of strain-specific neutralizing antibodies is a common event during infection with HCMV and that it might have important implications for the course of the infection and the development of anti-HCMV vaccines.

Antibodies, Viral↗
PubMed1999

Immunohistochemical studies of productive rhesus cytomegalovirus infection in rhesus monkeys (Macaca mulatta) infected with simian immunodeficiency virus.

In humans infected with the human immunodeficiency virus (HIV), clinical disease due to human cytomegalovirus (HCMV) infection is one of the AIDS-defining diseases; HCMV is the most common opportunistic infection found postmortem. Histologically, the typical lesions are characterized by "owl's eye cells." In rhesus monkeys infected with simian immunodeficiency virus (SIV), comparable lesions are caused by an infection with the rhesus CMV (RhCMV). The aim of this study was to investigate the incidence of productive and latent RhCMV infection in monkeys infected with SIV macaques (SIVmac). Eleven SIVmac-infected rhesus monkeys, which were euthanatized after developing AIDS-like disease, and 11 clinically healthy and uninfected animals comprised the study. The monkeys were screened serologically for RhCMV by western-blot analysis. Immunohistochemistry was performed by an indirect immunoperoxidase technique with a polyclonal rabbit RhCMV-antiserum. Lesions characteristic of RhCMV-associated diseases were detected histologically. All animals were latently RhCMV-infected. Seven of eleven (63.6%) SIV-infected macaques were productively RhCMV infected according to immunohistochemistry. RhCMV antigen was identified in the gastrointestinal tract, the hepatobiliary system, the lungs, and the testicles. Two of these seven animals showed characteristic inflammatory lesions associated with productive infection. Consequently, the CMV prevalence in SIVmac-infected rhesus monkeys and human AIDS patients is comparable.

Animals↗
PubMed1998

Kinetics of the antibody response against human cytomegalovirus-specific proteins in allogeneic bone marrow transplant recipients.

The humoral immune response against human cytomegalovirus (CMV) was retrospectively investigated in >800 serum samples from 31 recipients of allogeneic bone marrow transplants. To this end, an ELISA was performed that allowed the individual analysis of IgG antibodies against known antigenic domains of CMV-derived phospho- and glycoproteins and nonstructural polypeptides. Twenty-nine patients developed active CMV infection after transplantation, as determined by repeatedly positive samples in polymerase chain reaction (PCR) assays. Seventeen patients responded serologically to viral replication by producing CMV-specific antibodies against a variety of antigens. The response was detectable concomitantly with PCR positivity and was seen as early as 20 days after transplantation. High titers of glycoprotein-specific neutralizing antibodies were correlated with the absence of viral DNA in blood (P<.002). Nineteen patients developed CMV disease. Survival was associated with the production of high titers of CMV glycoprotein-specific antibodies in response to viral replication.

Antibodies, Viral↗
PubMed1997

The humoral immune response against human cytomegalovirus is characterized by a delayed synthesis of glycoprotein-specific antibodies.

An individual analysis of IgG antibodies against 12 known antigenic domains of human cytomegalovirus (HCMV)-derived structural phospho- and glycoproteins and nonstructural polypeptides was performed. In HCMV-seropositive healthy persons, the separate determination of antibody titers against the various antigens resulted in an antibody profile that was characteristic for each individual. Profiles were qualitatively stable over a period of >4 years. However, quantitative changes were observed in some persons. During primary HCMV infection, a delay of 50-100 days in the appearance of glycoprotein-specific antibodies was observed, whereas immunoglobulins directed against other HCMV-specific antigens were promptly synthesized. In contrast, during reactivation or reinfection, a synchronized production of antibodies was found. Levels of glycoprotein-specific antibodies and detection of viral DNA in peripheral blood inversely correlated. Precursor B cell analyses showed no significant differences between glycoprotein-specific and phosphoprotein-specific B cells.

Antibodies, Viral↗
PubMed1997

Identification of the gene coding for rhesus cytomegalovirus glycoprotein B and immunological analysis of the protein.

The nucleotide sequence of the gene encoding glycoprotein B (gB) of rhesus cytomegalovirus (RhCMV) was determined and the protein characterized. The open reading frame of gB encoded a protein of 854 amino acids with 60% identity and 75% similarity at the amino acid level to human cytomegalovirus (HCMV) gB. Cysteine residues in the extraluminal part of the protein are perfectly conserved. Out of the 16 potential N-linked glycosylation sites present in HCMV gB, 15 are conserved in RhCMV gB. Immunoblot analyses with antisera detected three bands of 150 kDa, 90-110 kDa and 55 kDa representing the full-length gB as well as the proteolytic cleavage products. Cross-reactivity and cross-neutralization of a number of HCMV gB-specific monoclonal antibodies with RhCMV gB indicated sharing of immunogenic epitopes between the two molecules. The RhCMV gB regions corresponding to antigenic domains AD-1, 2 and 3 of HCMV gB were immunogenic during natural RhCMV infection with the AD-1 region being the immunodominant domain. The data indicate that RhCMV might represent a useful model to investigate pathogenesis and immune surveillance of cytomegaloviruses.

Amino Acid Sequence↗