PubMed Health⌕ Search

Biomedical subjects

R Toth

Publications and source records attributed to R Toth.

8 recordsLinked to original sources
PubMed2001

In situ derivatisation using pressurized liquid extraction to determine phenols, sterols and carboxylic acids in environmental samples and microbial biomasses.

Pressurized liquid extraction was combined with in-situ derivatisation to extract polar analytes such as phenols (including chlorophenols) sterols and carboxylic acids from environmental and microbial samples. This one-step protocol uses acetic anhydride as an acetylation agent, N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) as an silylation agent, and boron trifluoride-methanol, phenyltrimethyl ammoniumhydroxide and trimethyl sulfoniumhydroxide as methylation agents. It results in faster extraction rates and better or comparable extraction efficiencies when compared to classical approaches. The addition of a silylation agent also facilitates the extraction kinetics of analytes not accessible to silylation (e.g. polycyclic aromatic hydrocarbons or alkylbenzenes). This may be attributed to a dissociative action of the agent to weaken analyte-matrix interactions.

Acetylation↗
PubMed2000

Light-induced nuclear import of phytochrome-A:GFP fusion proteins is differentially regulated in transgenic tobacco and Arabidopsis.

Phytochromes (phy) are a family of photoreceptors that control various aspects of light-dependent plant development. Phytochrome A (phyA) is responsible for the very low fluence response (VLFR) under inductive light conditions and for the high irradiance response (HIR) under continuous far-red light. We have recently shown that nuclear import of rice phyA:GFP is regulated by VLFR in transgenic tobacco. The import is preceded by very fast, light-induced formation of sequestered areas of phyA:GFP in the cytosol. Here we report that expression of the Arabidopsis phyA:GFP fusion protein in phyA-deficient Arabidopsis plants complements the mutant phenotype. In these transgenic Arabidopsis lines, both light-dependent cytosolic formation of sequestered areas of the phyA:GFP as well as VLFR or HIR-mediated nuclear import of the fusion protein was observed. By contrast, light-dependent nuclear import of the same fusion protein was induced only by continuous far-red light (HIR) but not by pulses of far-red light (VLFR) in transgenic tobacco. These results demonstrate that photoregulation of intracellular partitioning of the Arabidopsis phyA:GFP differs significantly in different genetic backgrounds.

Arabidopsis↗
PubMed1984

Cardiac muscle development in mice exposed to ethanol in utero.

The purpose of the present research was to determine the effect of in utero ethanol exposure on cardiac muscle development. Pregnant albino mice (Swiss strain) at 8 days of gestation were divided into three groups: a normal group fed Purina lab chow for rodents and water ad libitum; an ethanol group fed the liquid diet ENSURE with 20% of the calories derived from ethanol (12.6 +/- 1.2 gm/kg body weight per day); and an isocaloric group pairfed ENSURE with 20% of the calories derived from sucrose. These diets were continued until birth, at which time the litter size, crown to rump length, and weight were recorded. Randomly selected neonatal pups from each litter were decapitated and their hearts immediately processed for transmission electron microscopy. Litter size, crown to rump length, and body weight of the ethanol-treated mice at birth were significantly less than normal but not less than pairfed controls. Ultrastructural evaluation of cardiac muscle from mice treated in utero with ethanol in comparison to that from both normal and pair-fed control animals revealed various degrees of morphological alterations. The most pronounced alterations were in mitochondrial structure and included an increase in mitochondrial volume per cytoplasmic volume and a marked decrease in the amount of inner mitochondrial membrane. Myofibrillar abnormalities were also evident in the ethanol group but not in either control group. These abnormalities included a decrease in the myofibril volume per cytoplasmic volume and a disruption in myofibril organization particularly the Z-bands. The ultrastructural alterations in the cardiac muscle from the ethanol treated group were not a result of malnutrition or dehydration as the pairfed group did not exhibit these changes. It is apparent from this study that exposure of mice in utero to ethanol can cause ultrastructural abnormalities in cardiac muscle cells. Whether these changes result in heart pathophysiology and persist to adulthood are not known.

Animals↗
PubMed1984

Total and free plasma neuroleptic levels in schizophrenic patients.

Nineteen male patients, under 35 years of age, newly admitted with a diagnosis of schizophrenia, were treated with either chlorpromazine or haloperidol at a fixed dosage for 25 days. Both total and free plasma neuroleptic levels were measured using a radioreceptor assay. Clinical response was measured by the Brief Psychiatric Rating Scale (BPRS). On day 25, nonresponders (those with a decrease of less than 8 points on the BPRS) had both total and free plasma neuroleptic levels within the range observed in responders. It is therefore concluded that lack of therapeutic response is generally not due to inadequate plasma drug levels.

Adult↗
PubMedDate not supplied

Detection of acquired immunodeficiency syndrome (AIDS) retrovirus antibody by lymphadenopathy-associated virus (LAV) enzyme immunoassay in low- and high-risk populations.

Antibody to the acquired immunodeficiency syndrome (AIDS) retrovirus was evaluated by an lymphadenopathy-associated (LAV) enzyme immunosorbent assay (EIA) and compared with the standard human T-cell lymphotropic virus, Type III (HTLV-III) screening test in two groups of people. The first group consisted of those at low risk for AIDS, including 1352 random volunteer donors, 1140 of whom were prospective donors and 212 of whom were retrospective donors, repeatedly reactive by HTLV-III EIA. The second group was composed of those at high risk for AIDS, including 54 hemophiliacs, one of whom had AIDS, seven AIDS-related complex (ARC), and one immune thrombocytopenia (ITP). Of the 1140 prospective donors, one was repeatedly reactive by LAV EIA and four by HTLV-III EIA; none was positive by Western blot. Of the 212 retrospective donors, six were repeatedly reactive by LAV EIA and 212 by HTLV-III EIA; only six (the six LAV EIA positive) were positive by Western blot. Of the 54 hemophiliacs, 46 were repeatedly reactive by both LAV EIA and HTLV-III EIA, and all 46 were positive by Western blot. Both LAV EIA and HTLV-III EIA were positive in all hemophiliacs with AIDS, ARC, and ITP. The marked reduction in HTLV-III EIA repeatedly reactive, Western blot nonreactive samples by the LAV EIA system suggests that this assay may be as sensitive but more specific than the standard HTLV-III EIA in low-risk populations. The strong correlation between the LAV EIA and the Western blot assay further suggests that this assay may provide an efficient screening test for AIDS antibody in the donor population.

Acquired Immunodeficiency Syndrome↗