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Biomedical subjects

A Tu

Publications and source records attributed to A Tu.

12 recordsLinked to original sources
PubMed2000

Desferrioxamine (DFO) conjugated with starch decreases NAD redox potential of intact red blood cells (RBC): evidence for DFO as an extracellular inducer of oxidant stress in RBC.

Desferrioxamine (DFO) is an important iron-chelating agent. It has also been thought of as an agent with anti-oxidant potential as it chelates ferric iron in various parts of the body. However, there is evidence suggesting that it may paradoxically affect red blood cells (RBCs) by inducing intracellular oxidant stress. Recently we observed that incubation of RBCs with DFO decreases NAD redox potential in normal RBC. To further understand the mechanism of DFO's interaction with RBC, we conducted a study to determine the effect of extracellular DFO upon RBC's redox status. We examined NAD redox potential in intact RBC (N = 7) incubated with DFO conjugated to starch. RBCs were incubated with 4 mM DFO for 3(1/2) hr and with 6 mM DFO for 2 and 3(1/2) hr. Significant decreases in NAD redox potential were observed after the incubations. With 4 mM DFO at the 3 (1/2) hr time point the mean decrease was 12.37% +/- 9.96% (P < 0.0085). With 6 mM DFO, the mean decreases were 18.54% +/- 9.79% (P < 0.0013) and 19.16% +/- 8.78% (P < 0.0006) for the 2 and 3 (1/2) hr incubations, respectively. DFO by itself is very poorly permeable to RBC. Conjugation with starch further ensured impermeability of DFO. The data presented here confirm the oxidant effect of DFO on RBC. The data also demonstrate that the effect of DFO on RBC's NAD redox potential originates extracellularly.

Adult↗
PubMed1997

New spirostanol glycosides from Anemarrhena asphodeloides.

Two new spirostanol saponins, named anemarsaponin F (2b) and G (4b), along with six known spirostanol saponins were obtained from the rhizomes of Anemarrhena asphodeloides Bunge. On the basis of spectral analyses and chemical evidence, the structures of 2b and 4b were established as neogitogenin 3-O-beta-glucopyranosyl-(1-->2) [beta-xylopyranosyl-(1-->3)]-beta-glucopyranosyl (1-->4)-beta-galactopyranoside) and lilagenin 3-O-beta-glucopyranosyl-(1-->2)-[beta-xylopyranosyl-(1-->3)]-beta- glucopyranosyl-(1-->4)-beta-galactopyranoside, respectively.

Carbohydrate Conformation↗
PubMed1996

Expression of variants of the major surface glycoprotein of Pneumocystis carinii.

Previously, we have shown that a multicopy family of related but unique genes encodes the major surface glycoprotein (MSG) of Pneumocystis carinii. To examine whether different members of this gene family are expressed by P. carinii, antisera were prepared against peptides whose sequences were determined from the deduced amino acid sequences of variants of rat-derived MSG. Immunohistochemical staining of serial sections of rat lungs of infected animals showed that at least three variants of MSG were expressed in an individual lobe, that there was a focal expression of these variants within the lung, and that the relative numbers of these foci were different. Indirect immunofluorescent staining of purified P. carinii organisms using these antisera revealed that at least three variants of MSG were present in organisms isolated from an individual rat and that both cysts and trophozoites reacted with each antiserum. A substantial difference in the fraction of organisms reacting with a specific antipeptide antiserum was seen when comparing organisms isolated from rats raised in a single colony over a period of two years as well as organisms isolated at one time point from rats raised in different colonies. This demonstration of antigenic variation in P. carinii supports the hypothesis that P. carinii utilizes such variation for evading host defense mechanisms.

Amino Acid Sequence↗
PubMed1989

Relationship of histopathologic features to survival and relapse in nodular sclerosing Hodgkin's disease. A study of 1659 patients.

Nodular sclerosing (NS) Hodgkin's disease (HD) with extensive areas of lymphocyte depletion or with numerous anaplastic Hodgkin's cells, termed Grade II NS, is associated with a poor response to initial therapy, an increased relapse rate, and decreased survival when compared with other NS variants, termed Grade I NS. The histopathologic subdivision of NS HD into Grade I and Grade II is easy to perform and provides essential prognostic information that is independent of stage. Patients with Grade II NS HD may require more aggressive initial therapy if their survival is to be improved.

Adolescent↗
PubMed1986

An interlaboratory comparison of transformation in Syrian hamster embryo cells with model and coded chemicals.

Three independent laboratories tested eight "model" and five coded chemicals in the Syrian hamster embryo clonal transformation assay system to establish the intra- and interlaboratory reproducibility of the system and to identify sources of variability. When a common cell pool and the same lot of fetal calf serum were used, the three laboratories obtained consensus on the activity of eight model chemicals: five chemicals (benzo(a)pyrene, 7,12-dimethylbenz(a)anthracene, N-methyl-N'-nitro-N-nitrosoguanidine, nitroquinoline-N-oxide, and lead chromate) induced morphological transformation without exogenous metabolic activation and three (N-2-fluorenylacetamide, pyrene, and anthracene) produced no transformation response. Five coded chemicals (2,6-dichloro p-phenylenediamine, 4,4'-oxydianiline, cinnamyl anthranilate, dichlorvos, and reserpine), representative of environmental chemical classes, but not necessarily strong carcinogens, produced more equivocal responses in this interlaboratory study. Thus, while the assay can be used to distinguish between transforming and nontransforming chemicals in some cases, the intrinsic limitations in low transformation frequency and in achieving any dose-response results are major constraints to the use of this system in a routine testing program at the present time. Efforts to increase the transformation frequency or to amplify the expression of the transformed phenotype constitute some of the approaches which should be explored in order to overcome these limitations.

Animals↗
PubMed1986

Coagulant component in Cerastes cerastes (Egyptian sand viper) venom.

A coagulant component has been purified from Cerastes cerastes venom, using gel filtration on a Sephadex G 100 (fine) column followed by chromatography on a Bio-Rex 70 column. This compound had a proteolytic effect and could coagulate human plasma deficient in factor VIII or (VIII + IX) with the formation of a firm clot. It could also clot plasma deficient in factor X, but the clot formed was soft and not complete. The compound had no effect on platelet aggregation and was nontoxic. This compound is believed to be primarily a factor X activator, as it could replace factor VIII in hemophilic plasmas.

Animals↗
PubMed1985

[Not Available].

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Animal Population Groups↗
PubMed1979

Titin: major myofibrillar components of striated muscle.

Electrophoretic analyses of protein components of striated muscle myofibril purified from various vertebrate and invertebrate species revealed that proteins much larger than myosin heavy chain are present in significant amounts. To define possible roles of these heretofore unidentified proteins, we purified a combination of two uncommonly large proteins, designated as titin, from chicken breast myofibrils. Chemical and immunological studies indicated that titin is distinct from myosin, actin, and filamin. Specific titin anti body crossreacts with similar protein in both skeletal and cardiac myofibrils of many vertebrate and invertebrate species. Immunofluorescent staining of glycerinated chicken breast myofibrils indicated that titin is present in M lines, Z lines, the junctions of A and I bands, and perhaps throughout the entire A bands. Similar staining studies of myofibrils from other species suggest that titinlike proteins may be organized in all myofibrils according to a common architectural plan. We conclude that titin is a structurally conserved myofibrillar component of vertebrate and invertebrate striated muscles.

Animals↗