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Biomedical subjects

C Siebert

Publications and source records attributed to C Siebert.

24 records · Page 2Linked to original sources
PubMed1991

Effects of submergence on development and gravitropism in the coleoptile of Oryza sativa L.

Caryopses of rice (Oryza sativa L. cv. Sasanishiki) were germinated in air or under water. In submerged seedlings a twofold increase in coleoptile growth rate and an inhibition of root growth was observed. The amount of starch in the amyloplasts of submerged coleoptiles was substantially reduced compared to the air-grown control plants and plastids had a proplastidic character. During the rapid elongation of coleoptiles under water, the osmotic concentration of the press sap remained constant, whereas in air-grown coleoptiles a decrease was measured. Determination of curvature of gravistimulated air-grown and submerged shoots was carried out by placing the coleoptiles horizontally in air of 98% relative humidity. Air-grown coleoptiles reached a vertical orientation within 5 h after onset of gravistimulation. In coleoptiles germinated under water the first signs of consistent negative gravitropic bending occurred after 4-5 h and curvature was complete after 24 h. During the first 5 h of gravistimulation the water-grown coleoptiles grew at an average rate of 0.39 mm h-1, whereas in air-grown coleoptiles a rate of 0.27 mm h-1 was measured. Concomitant with the delayed onset of gravitropic bending of the water-grown coleoptiles, a change in plastid ultrastructure and an increase in starch content was observed. We conclude that the gravitropic responsiveness of the rice coleoptile depends on the presence of starch-filled amyloplasts.

Cotyledon↗
PubMed1990

[Undesirable side effects of contrast media during i.v. DSA--a comparison of 2 nonionic contrast media].

For the first time a controlled double-blind study was performed to compare side effects and complications of i.v. DSA with central venous application of iopamidol and iopromide. 200 consecutive patients 15-85 years of age were studied. The randomisation brought up two homogeneously structured groups of 100 patients each. Using a given protocol, 66% of the patients were classified as high-risk patients. Side-effects and complications were registered by an extensive, standardised protocol. In 71 (35.5%) of 200 patients contrast-media related side effects and complications were noted. 37 reactions in 24 patients (9 iopamidol, 15 iopromide group) were classified as clinically relevant. In four patients (4%) of each group a drug therapy was initiated. Contrast-media related reactions occurred with delay in 5.5% of initially symptom-free patients. In no case intensive care or hospital admission became necessary. There were no significant differences between the two non-ionic contrast media in the incidence of side effects and complications. Both substances were well tolerated in i.v. DSA. In the total population patients with diseases known as auto-immune diseases and prior drug reactions demonstrated clinically relevant reactions significantly more often.

Adolescent↗
PubMed1986

Rapid cation-exchange chromatography of hemoglobins and other proteins.

A new, weak cation exchanger (MA7C) is useful for the very rapid resolution of protein mixtures. MA7C columns (30 X 4.6 mm I.D.) are packed with non-porous spherical particles (7-micron in diameter) having carboxylic acid ion-exchange groups. These columns can readily separate human hemoglobin A1c from other hemoglobin species in 7 min. Quantitative results agree well with those of accepted techniques. Other separations are possible with flow-rates up to 5 ml/min. Chromatography on MA7C columns is characterized by very narrow bandwidths, even at high flow-rates.

Buffers↗
PubMed1978

Extreme insulin resistance in ataxia telangiectasia: defect in affinity of insulin receptors.

The syndrome of ataxia telangiectasia is associated with glucose intolerance and insulin resistance. We examined the status of insulin receptors on circulating monocytes and on cultured fibroblasts from two siblings with ataxia telangiectasia and severe insulin resistance. 125I-insulin binding to monocytes of the two patients consistently demonstrated an 80 to 85 per cent decrease in receptor affinity. In contrast, the defect in receptor affinity was not expressed on the patients' cultured fibroblasts or on monocytes or fibroblasts obtained from unaffected family members. Whole plasma and immunoglobulin-enriched fractions of plasma from the patients inhibited the normal binding of insulin to its receptors on cultured human lymphocytes (IM -9 line) and on human placental membranes. We conclude that the insulin resistance in the two siblings with ataxia telangiectasia was associated with defects in the affinity of the receptors for insulin, probably caused by circulating inhibitors of insulin binding.

Acanthosis Nigricans↗
PubMedDate not supplied

[Kyphoplasty - a new minimally invasive treatment for repositioning and stabilising vertebral bodies].

AIM OF THE STUDY: Osteoporotic vertebral fractures are an ailment of the aging population of increasing incidence and high socioeconomic impact. Intractable pain causing significant morbidity leads to long-term hospitalisation. Kyphoplasty offers a new minimal invasive operative stabilisation procedure for these vertebral compression fractures. This study is conducted to investigate whether this procedure significantly reduces both pain and the duration of hospital stay in comparison to conservative treatment modalities. METHOD: From January until July 2002 a total of 22 patients had undergone kyphoplasty in 37 vertebral bodies. Osteoporotic vertebral fractures were treated in 18 cases, while in another 4 cases prophylactic stabilisation for osteolytic lesions was performed. Both the duration of hospital stay and the reduction of pain symptoms were determined and compared to a conservatively treated control group of 20 patients suffering from 35 fractured vertebral bodies. Pre- and postoperative endplate angles were measured to assess the restoration of the sagittal alignment. The effects on pain symptoms were measured on a self-reported Visual Analogue Score Scale. RESULTS: The mean pain relief for the patients undergoing kyphoplasty was 82 %, which was significantly higher (p < 0.0001) compared to the group of the conservatively treated patients (42 %). Reduction of the kyphotic deformity was achieved in 4 cases (average 8.5 degrees ). The average in-patient treatment duration for the surgical treated patients was 10 days as opposed to a significantly longer mean hospitalisation of 20 days (p = 0.003). Cement extravasation was observed in 5 out of 37 treated vertebral bodies without clinical sequelae. CONCLUSION: Kyphoplasty is a safe minimal invasive procedure for the stabilisation of osteoporotic vertebral fractures leading to a statistically significant reduction both of pain status and duration of hospitalisation.

Aged↗