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Biomedical subjects

R Rieger

Publications and source records attributed to R Rieger.

At least 19 recordsLinked to original sources
PubMed1992

Drosophila retinal degeneration C (rdgC) encodes a novel serine/threonine protein phosphatase.

The Drosophila retinal degeneration C (rdgC) gene is required to prevent light-induced retinal degeneration. Molecular analysis shows that the rdgC transcription unit encodes a novel serine/threonine protein phosphatase. Amino acids 153-393 define a domain that has 30% identity with the catalytic domains of types 1, 2A, and 2B serine/threonine protein phosphatases. A putative regulatory domain is appended that contains multiple potential Ca(2+)-binding sites or "EF hand motifs." Thus, the analysis suggests that the rdgC protein is a novel type of serine/threonine protein phosphatase that is directly regulated by Ca2+. rdgC is expressed in the visual systems of the fly, as well as in the mushroom bodies of the central brain.

Amino Acid Sequence↗
PubMed1992

Low temperature between conditioning and challenge treatment prevents the 'adaptive response' of Vicia faba root tip meristem cells.

When the temperature during intertreatment time (2 h) between conditioning and challenge treatment of Vicia faba root tip meristems with either triethylenemelamine or maleic hydrazide was reduced from 24 degrees C to 12 degrees C no adaptive response occurred any more. The yield of metaphases with chromatid aberrations under these circumstances was similar to that observed after challenge treatment alone, i.e., no reduction occurred. This indicates that the metabolic state of the cells is of critical importance for the presence or absence of adaptive responses.

Adaptation, Physiological↗
PubMed1992

[Laparoscopic surgery--the revolution in gallstone treatment].

The treatment of gallbladder disease is revolutionized by laparoscopic cholecystectomy (LCHE). Less pain postoperatively, earlier mobilization and a fascinating cosmetic result as well as a definitive cure of the disease have led to a fast acceptance by patients and doctors. From March 1990 to March 1991 we have performed 250 LCHE. Only 5 times we had to switch to the conventional procedure. 5 complications (1 lesion of the common bile duct, 2 biliary effusion, 1 abscess formation, 1 bleeding) were treated by laparotomy without further morbidity or lethality. Our rate of gallbladders operated by laparoscopy has increased from 35% in 1990 to 75% in 1991.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1992

[Technique of recurrent laryngeal nerve exposure within the scope of interventions of the thyroid gland].

In anatomical preparations performed during autopsy we developed a well-defined approach for the identification of the recurrent laryngeal nerve during surgery on the thyroid gland. The principle of this concept is to visualize the nerve near the branching of the inferior thyroid artery, where it shows a 30 degree angle to the trachea in a direction running from caudal lateral to cranial medial and lies in front of, behind, or between the branches of the artery. This preparation mode has been prospectively performed in 100 patients undergoing thyroid surgery. In 159 (= 97.6%) sides of the neck out of 163 we identified the nerve at the typical site. The topographical relation of the recurrent nerve to the inferior thyroid artery revealed the following differences for the right and left side of the neck: On the right side the nerve was found to be behind in 48%, in front in 33% and between the branches of the artery in 15% of cases. In contrast, on the left side the nerve was found to be dorsal in 53%, ventral in 23% and between the branches in 23%. Of 163 nerves at risk we observed primary nerve palsy in 2 cases (1.2%), and a definitive palsy rate of 0.6% at the 3-month follow-up. In conclusion, we recommend the described approach for the identification of the recurrent laryngeal nerve during thyroid surgery whenever complete mobilisation of the thyroid lobe (e.g. thyroidectomy, lobectomy, resection of retrotracheal adenomas) is necessary.

Female↗
PubMed1991

Determination of glycyrrhetinic acid in human plasma by high-performance liquid chromatography.

A high-performance liquid chromatographic (HPLC) method has been developed for measuring 18 beta-glycyrrhetinic acid (GRA) in human plasma in the range of 0.1-3 micrograms/ml. The acetate ester of GRA is added to the plasma as an internal standard, plasma proteins are denatured with urea to release GRA, and the GRA and the internal standard are extracted in an ion-pairing solid-phase extraction process. An isocratic, reversed-phase HPLC separation is used, followed by ultraviolet absorbance detection at 248 nm. The results from the analysis of five GRA-fortified plasma pools show a mean relative standard deviation of 7% and are accurate to within 10%. With evaporative concentration of the extract, the limit of detection for GRA in plasma is approximately 10 ng/ml.

Chromatography, High Pressure Liquid↗
PubMed1991

Isolation of mutants defective in early steps of meiotic recombination in the yeast Saccharomyces cerevisiae.

Using a selection based upon the ability of early Rec- mutations (e.g., rad50) to rescue the meiotic lethality of a rad52 spo13 strain, we have isolated 177 mutants. Analysis of 56 of these has generated alleles of the known Rec genes SPO11, ME14 and MER1, as well as defining five new genes: REC102, REC104, REC107, REC113 and REC114. Mutations in all of the new genes appear to specifically affect meiosis; they do not have any detectable mitotic phenotype. Mutations in REC102, REC104 and REC107 reduce meiotic recombination several hundred fold. No alleles of RED1 or HOP1 were isolated, consistent with the proposal that these genes may be primarily involved with chromosome pairing and not exchange.

Alleles↗
PubMed1990

[Value of preoperative fine needle puncture cytology in the diagnosis of highly malignant thyroid tumors].

Highly malignant thyroid tumours are frequently diagnosed only at an advanced stage where radical resection is no longer feasible. By the wide application of fine needle aspiration biopsy as a diagnostic tool in nodular thyroid diseases occasionally early stages of these tumours can be diagnosed. Despite early detection in 23% of our patients with anaplastic carcinomas and sarcomas of the thyroid gland and subsequent radical resection an improvement in the long-term outcome was not achieved. In contrast, thyroidectomy and appropriate oncologial therapy may result in long-term survival of patients with early stages of thyroid lymphomas.

Adult↗
PubMed1990

Involvement of phytochelatins in NiCl2-triggered protection against induction of chromatid aberrations by TEM and MH in Vicia faba root tip meristems?

Conditioning treatment of Vicia faba root tip meristem cells with NiCl2 prior to challenge treatment with triethylenemelamine (TEM) or maleic hydrazide (MH) triggered protective functions against both these clastogens, i.e., resulted in a significantly reduced yield of metaphases with chromatid aberrations. Protection was prevented by pretreatment with buthionine sulfoximine (BSI), an inhibitor of the synthesis of plant phytochelatins (PCs), indicating that the NiCl2-triggered PC synthesis may be involved in the protective functions induced by NiCl2 conditioning treatment. BSI (instead of NiCl2) conditioning treatment triggered protection against MH but not against TEM.

Buthionine Sulfoximine↗
PubMed1989

Repair of bleomycin-induced DNA double-strand breaks in Vicia faba.

As detected by neutral DNA elution, bleomycin induced at the concentrations tested (5, 10 and 50 micrograms/ml) DNA double-strand breaks (dsbs) in in vitro cultured embryos of V. faba. Most of these breaks were repaired during a 4-h incubation period after treatment. Dsbs also occurred after treatment with 2.5 and 5 mM of N-methyl-N-nitrosourea (MNU) but in contrast to those induced by bleomycin, these dsbs remained unrepaired during the 4-h incubation period following the treatment.

Bleomycin↗
PubMed1989

Hyperthyroidism and concurrent thyroid malignancies.

In a 17-year period 1848 patients with hyperthyroidism were operated on. Fourteen (0.76%) had a coexisting thyroid malignancy. Preoperative scintiscan and pathologic diagnoses were compared: 10 malignancies were in cold nodules, two were unidentifiable preoperatively due to small size, and two were in hot areas. Five patients had papillary cancer, four follicular, three anaplastic, and two medullary. Patients with uninodular toxic goiter had a low rate of associated malignancy (0.27%, 3/1108). In contrast, patients with multinodular toxic goiter had an incidence of 1.63% (11/676). No patient with Graves' disease (n = 64) had a carcinoma. Extensive use of fine-needle aspiration biopsy enabled preoperative diagnosis in a majority of the cases (9/14, 64%). We conclude that the incidence of coexisting thyroid malignancy and hyperthyroidism is rare in our endemic iodine-deficiency goiter area.

Adult↗
PubMed1989

[Current aspects of prevention of struma recurrence].

Prevention of struma recurrence is a major aspect in postoperative management, following struma surgery. Prophylaxis is based on substitution of L-thyroxine, depending on TSH levels. The latter should be somewhere between 0.5 and 2.0 microU/ml. The rate of struma recurrence was below two per cent.

Adenoma↗
PubMed1988

Promutagen activation by Vicia faba: an assay based on the induction of sister-chromatid exchanges in Chinese hamster ovary cells.

Plant activation of promutagens was studied using Vicia faba S10 (in vitro activation) and the extracts prepared from promutagen-treated roots of Vicia faba (in vivo activation). The induction of sister-chromatid exchanges in Chinese hamster ovary cells was used as an endpoint to evaluate the cytogenetic effects of promutagens activated by Vicia faba. Cyclophosphamide and ethyl alcohol were activated both by Vicia S10 and by the Vicia extracts, and their activation resulted in an increase in SCEs. Benzo[a]pyrene, 2-aminofluorene, and maleic hydrazide were not activated. Aniline was activated, but without effect on the induction of SCEs. The activation capacity in vitro and in vivo of Vicia faba was not very pronounced, except for the activation of ethyl alcohol, when compared with that of rat-liver S9, and showed differences in activation for the 6 chemical agents tested.

Animals↗
PubMed1988

Effects of novobiocin on heat shock protection against chromatid aberration induction by triethylenemelamine (TEM) and maleic hydrazide (MH) in Vicia faba.

Heat shock (10 min 40 degrees C) prior to challenge treatment with triethylenemelamine (TEM) or maleic hydrazide (MH) significantly reduced the frequency of induced chromatid aberrations in Vicia faba main root meristems. Novobiocin treatment before heat shock did not prevent heat shock protection against both clastogens; novobiocin application after heat shock prevented protective effects. These results and those obtained earlier for heat shock protection against X-ray challenge are used to discuss possible causes underlying the protective effects triggered by heat shock.

Chromosome Aberrations↗
PubMed1988

Effects of ethidium bromide and nalidixic acid pretreatment on the induction of chromatid aberrations by TEM and maleic hydrazide in Vicia faba main root meristems.

Pretreatment of Vicia faba main root meristems with ethidium bromide (EB) or nalidixic acid (NA) significantly reduced the yield of metaphases with chromatid aberrations induced by maleic hydrazide (MH), i.e., triggered clastogenic adaptation to MH. No such protection occurred when the alkylating agent triethylenemelamine (TEM) was used for challenge treatment. The differential response of pretreated cells to MH on the one hand (protection) and to TEM (no protection) on the other supports the conclusion that clastogenic adaptation is due to different inducible (repair?) functions, which eventually exert protection against clastogenic impacts.

Chromatids↗
PubMed1988

Induction of chromatid aberrations by TEM and maleic hydrazide is differently affected by pretreatment of Vicia faba root-tip meristems with methyl iodide.

Treatment of Vicia faba main root meristems with methyl iodide (MeI) 2 h before challenge treatment with triethylene melamine (TEM) significantly reduced the yield of metaphases with chromatid aberrations, i.e., resulted in clastogenic adaptation. Combined treatment with MeI and TEM increased the aberration yield; MeI treatment alone (10(-3) M, 0.5 h) was without clastogenic effect. No protective effects were observed after MeI pretreatment and challenge treatment by maleic hydrazide (MH). The data obtained in V. faba are compared to those previously reported for E. coli.

Chromatids↗