Biomedical subjects

E R Fischer

Publications and source records attributed to E R Fischer.

21 records · Page 2Linked to original sources

PubMed1993

Comparison of intermittent oral and intravenous calcitriol in hemodialysis patients with secondary hyperparathyroidism.

Both intermittent intravenous and intermittent oral calcitriol have been shown to be effective in the treatment of secondary hyperparathyroidism in hemodialysis patients and it has been claimed that intravenous calcitriol causes less hypercalcemia. However, there has been no published systematic comparison of the two routes of administration of intermittent calcitriol. Therefore in a prospective crossover study 11 (9 male) patients on maintenance hemodialysis were randomized to receive intravenous followed by oral calcitriol for 4 months each, or oral followed by intravenous calcitriol, commencing at 2 micrograms postdialysis three times per week. Initial serum immunoreactive parathyroid hormone (PTH) was 446 +/- 111 (normal < 65) pg/ml. Calcium-containing phosphate binders were not used. Calcitriol was ceased if hypercalcemia developed and restarted at 2 micrograms or 1 microgram when calcium returned to normal. Hypercalcemia was frequent (11 episodes in 8 patients on intravenous calcitriol and 10 episodes in 7 patients on oral calcitriol) and dose reduction to 1 microgram was necessary in 7 patients on intravenous and on 6 patients on oral. Serum PTH fell during both treatments. Parathyroid enlargement was seen in 10 glands from 4 patients, but no size reduction was demonstrated with treatment. There was no reduction in activity on quantitative metabolic bone scan. In summary, intermittent oral calcitriol and intermittent intravenous calcitriol were equally effective in reducing serum parathyroid hormone levels and at a dose of 2 micrograms postdialysis caused hypercalcemia with equal frequency.

Administration, Oral↗

PubMed1993

Interpatient variation in response to subcutaneous versus intravenous low dose erythropoietin.

Subcutaneous (SC) recombinant human erythropoietin (EPO) has been reported to correct anemia in hemodialysis patients at lower doses than intravenous (IV) EPO. Those trials involved relatively high doses of EPO or did not control adequately for time-related falls in dose requirements. Therefore, on open-label double-crossover study was performed to compare the hemoglobin (Hb) response to low dose SC versus IV EPO. Ten (4 male) maintenance hemodialysis patients previously stabilised on low dose EPO for 18 +/- 3 months (mean +/- SEM) were given EPO IV for 12 weeks (IV#1), then SC for 24 weeks and then IV for a further 20 weeks (IV#2). Iron status and other factors known to modify response to EPO were kept constant. EPO dose was not changed unless Hb rose above 100 g/l, when the dose was reduced to keep Hb between 90 and 100 g/l. Initial EPO dose was 64 +/- 10 u/kg/week. Mean Hb, measured monthly, was not different during the 3 treatment periods. There was wide interpatient variation in the relative response to IV versus SC EPO. Mean Hb was higher on IV EPO in 5 patients (by 6.1 +/- 2.0 g/l) and higher on SC EPO in 5 patients (by 12.1 +/- 4.1 g/l). The difference in mean Hb during IV versus SC administration was more than 5 g/l in 6 patients, being higher in 3 patients during IV administration (by 8.7 +/- 4.6 g/l) and in 3 during SC (by 17.4 +/- 4.6 g/l). In conclusion, the more efficient route of administration of EPO is not predictable for individual patients, and should be sought to allow possible dose reduction.

Anemia↗

PubMedDate not supplied

Adhesion of Plasmodium gallinaceum ookinetes to the Aedes aegypti midgut: sites of parasite attachment and morphological changes in the ookinete.

Plasmodium gallinaceum ookinetes adhered to Aedes aegypti midgut epithelia when purified ookinetes and isolated midguts were combined in vitro. Ookinetes preferentially bound to the microvillated luminal surface of the midgut, and they seemed to interact with three types of structures on the midgut surface. First, they adhered to and migrated through a network-like matrix, which we have termed microvilli-associated network, that covers the surface of the microvilli. This network forms on the luminal midgut surface in response to blood or protein meals. Second, the ookinetes bound directly to the microvilli on the surface of the midgut and were occasionally found immersed in the thick microvillar layer. Third, the ookinetes associated with accumulations of vesicular structures found interspersed between the microvillated cells of the midgut. The origin of these vesicular structures is unknown, but they correlated with the surface of midgut cells invaded by ookinetes as observed by TEM. After binding to the midgut, ookinetes underwent extensive morphological changes: they frequently developed one or more annular constrictions, and their surface roughened considerably, suggesting that midgut components remain bound to the parasite surface. Our observations suggest that, in a natural infection, the ookinete interacts in a sequential manner with specific components of the midgut surface. Initial binding to the midgut surface may activate the ookinete and cause morphological changes in preparation for invasion of the midgut cells.

Aedes↗