Determination of the electrophoretic order of 26 nucleotides by isotachophoresis.
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Electrophoresis↗
Biomedical subjects
H Rink
Publications and source records attributed to H Rink.
Heavy ion effects on cellular DNA: strand break induction and repair in cultured diploid lens epithelial cells.
The relative biological effectiveness (RBE) for the induction of DNA strand breaks and the efficiency of repair of these breaks in cultured diploid bovine lens epithelial cells was measured, using accelerated heavy ions in the linear energy transfer (LET)-range up to 16,200 keV/micron. At LET values above 800 keV/micron, the number of DNA strand breaks induced per particle increases both with the atomic number of the projectile and with its kinetic energy. About 90 per cent or more of the strand breaks induced by ions with an LET of less than 10,000 keV/micron are repaired within 24 h. Repair kinetics show a dependence on the particle fluence (irradiation dose). At higher particle fluences a higher proportion of non-rejoined breaks is found, even after prolonged periods of incubation. At any LET value, repair is much slower after heavy-ion exposure than after X-irradiation. This is especially true for low energetic particles with a very high local density of energy deposition within the particle track. At the highest LET value (16,200 keV/micron), no significant repair is observed.
Animals↗
Cataractogenic risk factors.
It was the intention of this study to provide a review on cataractogenic risk factors which are already known from the early and recent literature. Additional causative or mutual causative factors have been derived from recent studies [Bloemendal et al., 1984; Hockwin et al., 1984; Rink and Hockwin, 1985b; Eckerskorn et al., 1986]. Under this view it seems necessary to classify the cataractogenic risk factors into 3 subgroups: (a) factors from which we definitely know their cataractogenic potential and their mode of action (e.g. diabetes); (b) factors from which we certainly know that they are closely related to cataractogenesis, without knowing the mechanism of action, and (c) factors that are only assumed to be involved in the development of cataractogenesis; however, neither origin nor mode of action has been explained (e.g. nicotine or alcohol intake). For further epidemiological research it would be important to introduce many of the known factors into the corresponding questionnaires. As we may assume that different risk factors with differing mechanisms of action are responsible for the variety of cataract types, it is a prerequisite for future studies to improve the cataract classification systems possibly by using the Scheimpflug camera method [Eckerskorn et al., 1986] which results in hard, reliable and highly reproducible data.
Adolescent↗
Radiation induced formation of giant cells in Saccharomyces uvarum. III: Effect of X-rays on nuclear division.
Spindle formation and nuclear division of budding and irradiated yeast cells (Saccharomyces uvarum) was investigated by fluorescence microscopy of protoplasted cells. Protoplasts were treated with antitubulin antibodies and DAPI, a fluorescent dye staining DNA. In budding yeast cells, duplication of spindle pole bodies as well as formation of complete 1-micron spindles and elongated 8-micron spindles were documented. In X-irradiated cells, spindle pole bodies were duplicated as well, forming the complete 1-micron spindle. Nuclei of giant cells have lost the elongation ability and remain in a "normal" G2-phase state, thus preventing nuclear as well as cellular division.
Cell Cycle↗
Radiation induced formation of giant cells in Saccharomyces uvarum. IV. Macromolecular synthesis and protein patterns.
X-irradiated (1.0 kGy) yeast cells (Saccharomyces uvarum, ATCC 9080), grown in liquid medium stop their mitotic activities and form giant cells by development of several buds which do not separate from mother cells. Depending on the time in culture, wet and dry weights per cell, protein-RNA- and DNA- contents per cell as well as incorporation rates of 14C-leucine per cell and per hour and patterns (isoelectric focussing) of water soluble proteins were studied. Weights per cell, RNA and protein contents per cell and 14C-leucine incorporation rates increase markedly in giant cells, whereas DNA content per cell is only duplicated. Protein patterns in isoelectric focusing show one interesting difference. In samples from giant cells one protein band (IP = 6.63) decreases after 8 h in culture and later on disappears completely. This finding is not due to primary damage in X-irradiated DNA but seems to be related to the control of cell cycle events.
DNA, Fungal↗
Calcium-induced opacification and loss of protein in the organ-cultured bovine lens.
A long-term system of organ culture for bovine lenses was used to investigate the effect of osmotic stress on lens opacification and crystallin loss. Lenses were pre-incubated in control medium containing L-[U-14C]tyrosine so that labelled crystallins were produced. The fate of these crystallins was studied in relation to two forms of osmotic stress. The addition of either ouabain or EGTA to the medium induced severe osmotic swelling and disturbance of the lens monovalent cation balance, but only the former treatment was followed by an increase in lens calcium. The changes due to osmotic stress were accompanied by loss of transparency and protein only in the lenses with increased calcium. Both opacification and increased calcium were found largely to be confined to the outer cortical fibres. Protein loss increased with time as lens calcium continued to increase. The protein recovered from the incubation medium was characterized by gel filtration and immunological techniques. The first protein detected was beta L-crystallin, and this formed the major part of the lost protein throughout, although alpha- and gamma-crystallins were detected at a later stage. Increased calcium also resulted in a change in the susceptibility of the crystallins to aggregation, since there was an increase in [14C]tyrosine incorporated into the lens high-molecular-weight (HM) fraction after exposure to ouabain, but not after exposure to EGTA. The relevance of these findings to human cataract is discussed.
Animals↗
Developmental changes in membrane protein expression by chick lens cells in vivo and in vitro and the detection of main intrinsic polypeptide (MIP).
We have compared the long-term developmental changes in water-insoluble protein expression by chick lens cells in vitro and in vivo. Crude membrane fractions were prepared by alkali treatment of the urea-insoluble protein fraction, and the proteins analysed by sodium dodecyl sulphate-polyacrylamide (SDS-PAGE) gel electrophoresis. The major component present in the urea-insoluble fraction of chick lens fibres, a 25,000 MW polypeptide (MIP-25K) was more abundant in adult (8 weeks) than day-old post-hatch chick lens fibre masses. MIP-25K was detected in differentiated but not predifferentiated lens cell cultures, and indirect immunofluorescence using anti-bovine MIP antiserum indicated that MIP-25K was localized in the lentoid bodies. Our findings indicate that the urea-insoluble protein profiles of long-term well-differentiated chick lens cell cultures are qualitatively very similar to the profiles of the lens fibres. The data also confirm that the expression of MIP-25K, rather than the expression of water-soluble crystallin protein, is a marker for lens cell differentiation, and confirm earlier reports, which have been disputed, that delta-crystallin (but not alpha-or beta-crystallin) is specifically associated with chick lens fibre membranes.
Aging↗
Radiation induced formation of giant cells in Saccharomyces uvarum. II. Effect of X-rays on septum formation.
Thin sections of budding yeast cells and giant gells grown after X-irradiation have been examined by electron microscopy. The different steps of cross-wall formation during budding were documented with unirradiated cells. With X-ray induced giant cells cytokinesis was shown to be absent. Neither primary nor secondary septae appeared thus cell separation did not occur. Despite this fact both macromolecular synthesis and bud growth continued, giving rise to the formation of giant cells.
Cell Wall↗
Content and distribution of calcium in bovine lenses of different ages.
Calcium content was measured in five different parts of clear bovine lenses obtained from animals throughout the bovine life span of 0.3-24 years. In lenses of animals older than 6 years there is a moderate increase in calcium content with the most significant increase measured in lens nuclei. Differences in calcium content between age groups are discussed.
Age Factors↗
A large fragment approach to DNA synthesis: total synthesis of a gene for the protease inhibitor eglin c from the leech Hirudo medicinalis and its expression in E. coli.
A DNA containing the coding sequence for the proteinase inhibitor protein, eglin c, from the leech Hirudo medicinalis has been obtained by enzymatic assembly of chemically synthesized DNA fragments. The synthetic gene consists of a 232 base-pair fragment containing initiation and termination codon signals with restriction enzyme recognition sites conveniently placed for cloning into a plasmid vector. Only six oligonucleotides from 34 to 61 bases in length, sharing pairwise stretches of complementary regions at their 3'-termini, were prepared by phosphotriester solid-phase synthesis. The oligomers were annealed pairwise and converted into double stranded DNA fragments by DNA polymerase I mediated repair synthesis. The fragments were assembled by ligation, and the synthetic gene was expressed in high yield in E. coli under the transcriptional control of the E. coli tryptophan promoter. The expression product was purified to homogeneity and was shown to have similar physicochemical and identical biological properties as the authentic protein isolated from the leech.
Amino Acid Sequence↗
Radiation induced formation of giant cells (Saccharomyces uvarum). I. Budding process and chitin ring formation.
X-irradiated yeast cells (Saccharomyces uvarum) grown in liquid media stop mitosis and form giant cells. Chitin ring formation, being a prerequisite for cell separation, was studied by fluorescence microscopy using calcofluor white, a chitin specific dye. Experiments with inhibitors of DNA synthesis (hydroxyurea) and chitin synthesis (polyoxin D) demonstrate chitin ring formation to be dependent on DNA synthesis, whereas bud formation is independent of DNA synthesis and chitin ring formation respectively. Basing on these results the formation of X-ray induced giant cells implies one DNA replication which in turn induces the formation of only one chitin ring between mother cell and giant bud. Obviously no septum can be formed. Thus cell separation does not occur, but the bud already formed, produces another bud demonstrating that bud formation itself is independent of DNA synthesis.
Cells, Cultured↗
Growth potential, repair capacity and protein synthesis in lens epithelial cells during aging in vitro.
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Animals↗
Monitoring yeast spindles in the fluorescence microscope.
Formation of the complete spindles during the budding process of Saccharomyces uvarum was investigated by fluorescence microscopy of protoplasted cells. Protoplasts were treated with anti-tubulin antibodies and DAPI, a fluorescent dye staining DNA. Thus, both chromatin and spindles could be visualized. Duplication as well as formation of separated spindle pole bodies during the different stages of budding are documented, demonstrating the occurrence and behaviour of microtubules during yeast cell cycle.
Antibodies↗
Immunological properties of rat lens gamma-crystallins. III. Changes during development and ageing.
The rat lens contains three immunologically different gamma-crystallins, gamma 1-, gamma 2-, and gamma 3-crystallins. With the aid of specific antisera, it could be established that partial identity exists between gamma 1- and gamma 2-crystallins, and non-identity between gamma 1- and gamma 3-, and between gamma 2- and gamma 3-crystallins. The occurrence of these three crystallins has been investigated in rat lenses, aged 5-1,162 days, by isoelectric focusing, immunofocusing and immunodiffusion. The gamma 1- and gamma 2-crystallins are already present in 5-day-old lenses, but diminish during ageing and finally disappear. In contrast, gamma 3-crystallin develops first in 10-day-old lenses, it remains present during progressed ageing.
Aging↗
Large scale microbial production of human interferon.
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Base Sequence↗
High-field 1H NMR studies of synthetic analogs of somatostatin. Structural features involving aromatic residues in an active eight-membered ring analog.
360 MHz 1H-NMR data are presented for somatostatin and an analog whose primary structure is cyclo(-Gaba-Asn5-Phe6-Phe7-DTrp8-Lys9-Thr10-Phe11-). This report focuses on the aromatic portion of the spectrum, and this region for the analog is unambiguously assigned, using two experimental approaches: selective deuteration and photo-induced CIDNP. The most prominent feature of the analog aromatic spectrum is a two-proton resonance which exhibits a pronounced upfield shift. Significantly, this feature is also present for somatostatin and other active analogs (unpublished data). Assignments show that this resonance derives from the ortho hydrogens of the Phe6 and that aromatic resonances of Phe6 shift markedly upfield as temperature is decreased. In contrast, the aromatic resonances of Phe7,11 and DTrp8 reveal generally much smaller temperature coefficients and shift primarily downfield as temperature is decreased. Ring-current analysis shows that simple pair-wise parallel pi-stacking alone cannot give rise to the observed data. However, a simple hypothesis involving only two phenylalanine residues is totally consistent with the data if they maintain a time-averaged co-perpendicular orientation. Indirect evidence is offered which implicates only one phenylalanine stacking partner for Phe6, which we tentatively identify as Phe11.
Amino Acid Sequence↗
The major polypeptide (MIP) of lens fiber junctions and its synthesis in cultured differentiating lens epithelial cells.
Lens and liver contain many gap junctions, which for a long time have been considered to be very similar. Recent results, however, point to differences on morphological and biochemical levels, especially when the liver gap junction polypeptide (26,000 Daltons) is compared with the main intrinsic polypeptide (MIP) from lens junctions. The lens fiber specific MIP, which represents a marker molecule for lens cell differentiation could be detected by indirect immunofluorescence as well as by immunodiffusion in lens epithelial cells, which differentiated in vitro under distinct culture conditions. The fine structure of these differentiated cells is presented.
Animals↗
[X-ray-induced cataract as a model for investigating cataractogenesis (author's transl)].
X-rays are known to be a true cataractogenic agent. Since they can be accurately dosed and directed they are particularly suitable for inducing experimental cataracts. By means of ionizing rays, lesions are induced in various lens segments. Both the extent of the damage as well as the latency period until it becomes manifest are highly age-dependent. Since lens changes effected by ionizing rays are in many respects, similar to age-related changes, experimental cataracts induced by X-rays provide suitable models for investigating processes involved in the multifactorial genesis of senile cataract.
Animals↗