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Biomedical subjects

D Rohrbach

Publications and source records attributed to D Rohrbach.

8 recordsLinked to original sources
PubMed2001

Improving nitrogen efficiency: lessons from Malawi and Michigan.

Two case studies are presented here of nitrogen (N) dynamics in potato/maize systems. Contrasting systems were investigated from (1) the highland tropics of Dedza, Malawi in southern Africa and (2) the northern temperate Great Lakes region of Michigan. Formal surveys were conducted to document grower perceptions and N management strategies. Survey data were linked with N budgets conducted by reviewing on-farm data from representative farms in the targeted agroecosystems and simulation modeling to estimate N losses. Potential N-loss junctures were identified. Interventions that farmers might accept are discussed. The Malawi system uses targeted application of very small amounts of fertilizer (average 18 kg N ha(-1)) to growing plants. This low rate is on the steep part of plant response to N curve and should serve to enhance efficiency; plant growth, however, is generally stunted in Malawi due to degraded soils and weed competition. Very limited crop yields reduce N efficiency from a simulated 60 kg grain per kg N to an actual of approximately 20 kg grain per kg N (at 40 kg N ha(-1) applied). Legume-intensified systems could improve growth potential and restore N use efficiency through amelioration of soil quality and transfer functions and from biological fixation N inputs. In the Michigan system, N efficiency is enhanced currently through multiple, split applications of N fertilizer tailored to plant growth rate and demand. Fertilizer N rates used by growers, however, averaged 32% higher than recommended rates and 40% higher than N removed in crop product. Application of 50 kg N ha(-1) to cover crops in the fall may contribute to the apparent high potential for N leaching losses. Careful consideration of N credits from legumes and residual soil N would improve N efficiency. Overall, N budgets indicated 0 to 20 kg N ha(-1) loss potential from the Malawi systems and tenfold higher loss potential from current practice in Michigan maize/potato rotations. Best management practices, with or without integration of legumes, could potentially reduce N losses in Michigan to a more acceptable level of about 40 kg N ha(-1).

Agriculture↗
PubMed1993

Quantitative EEG before and after open heart surgery in children. A significant decrease in the beta and alpha 2 bands postoperatively.

Quantitative EEGs of 30 patients undergoing open heart surgery were investigated before, 6 days, 11 days and 44 days after operation. The study was conducted in order to investigate whether quantitative EEGs can show postoperative changes in children after open heart surgery. In 28 children, no new neurological signs of cerebral involvement were seen postoperatively. The most striking feature in these children was a significant decrease in the beta and the alpha 2 bands 6 and 11 days postoperatively. The pattern in the delta band was dominated by an increase 6 days postoperatively. Except for a slight decrease in alpha 2 waves, all variables were restored to preoperative values at 44 days after the operation. We found a significant decrease in plasma sodium and chloride after surgery but children with no or slight declines (1-3 mmol/l) also showed increased slow activity postoperatively. Therefore we conclude that an organic brain syndrome, although usually mild and transient, is a general phenomenon after open heart surgery.

Adolescent↗
PubMed1989

[BRL 43694A--a 5-hydroxytryptamine receptor blocker as an antiemetic in cytostatic therapy].

An open study of the new antiemetic BRL 43694A, a 5-hydroxytryptamine-3-receptor antagonist, was performed in 29 patients undergoing highly emetogenic cancer chemotherapy (25 patients received cisplatin in a dose greater than or equal to 50 mg/m2). Patients received BRL 43694A as a 30-minute infusion one hour after the administration of chemotherapy. 7 patients were treated with 40 micrograms/kg and 13 patients with 100 micrograms/kg BRL 43694A; the last 9 patients received an initial dose of 40 micrograms/kg with a provision for two additional interventional doses over 24 hours in the event of prolonged nausea or vomiting. 14 patients experienced no vomiting (48%) and 13 patients (45%) had 1-5 vomiting episodes over 24 hours following administration of the cytostatic agents. BRL 43694A did not cause major side effects. Based on our preliminary experience the new 5-HT3-receptor antagonist BRL 43694A is a potent antiemetic drug for the treatment of chemotherapy-induced nausea and vomiting.

Adult↗
PubMed1987

[Metoclopramide, methylprednisolone and flunitrazepam in cytostatic-induced vomiting].

The antiemetic efficacy of a combination of high-dose metoclopramide, methylprednisolone and flunitrazepam was tested in an open pilot study in 30 tumor patients undergoing strongly emetic chemotherapy. 26 of 30 patients (87%) were partially or completely protected from nausea and vomiting. In 11 of 12 patients receiving the strongly emetogenic cytostatic agent cisplatin in a dose of greater than or equal to 50 mg/m2, the gastrointestinal side effects were partially or completely abolished. The antiemetic efficacy of the combination was maintained during subsequent courses of chemotherapy. All patients experienced somnolence after administration of flunitrazepam. Only 2 of 30 patients had a shortlived extrapyramidal reaction. The combination of high-dose metoclopramide, methylprednisolone and flunitrazepam is an effective antiemetic treatment and should be considered as first-line antiemetic treatment in patients receiving strongly emetic cancer chemotherapy.

Adolescent↗
PubMed1980

The effects of laminin on the growth and differentiation of embryonal carcinoma cells in defined media.

In this paper we have examined the growth and differentiation of the embryonal carcinoma cell line, F9, in the defined medium EM-3 at low density. We show that the growth of F9 and their differentiated cells (F9-diff) in EM-3 is strongly density dependent. At low cell densities the growth of both cell types is severely limited and most of the cells do not survive. Although this poses a problem for working with F9 and F9-diff in EM-3, it provides a convenient assay for identifying molecules that support their growth at low density. Using this assay, we have determined that laminin, a newly isolated glycoprotein of basement membranes, significantly improves the growth and short-term survival of both F9 and F9-diff. However, addition of laminin to EM-3 is insufficient to promote the clonal growth of these cell types. Our findings also indicate that laminin promotes the attachment of F9 and F9-diff in defined media. On the basis of our results, we propose an attachment function for laminin during the early stages of mammalian development.

Animals↗