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Biomedical subjects

S Drechsler

Publications and source records attributed to S Drechsler.

At least 19 recordsLinked to original sources
PubMed2001

Multiparametric microsensor chips for screening applications.

The identification of drug targets for pharmaceutical screening can be greatly accelerated by gene databases and expression studies. The identification of leading compounds from growing libraries is realized by high throughput screening platforms. Subsequently, for optimization and validation of identified leading compounds studies of their functionality have to be carried out, and just these functionality tests are a limiting factor. A rigorous preselection of identified compounds by in vitro cellular screening is necessary prior to using the drug candidates for the further time consuming and expensive stage, e.g. in animal models. Our efforts are focused to the parallel development, adaptation and integration of different microelectronic sensors into miniaturized biochips for a multiparametric, functional on-line analysis of living cells in physiologically environments. Parallel and on-line acquisition of data related to different cellular targets is required for advanced stages of drug screening and for economizing animal tests.

Biocompatible Materials↗
PubMed2001

Simultaneous measurement of cellular respiration and acidification with a single CMOS ISFET.

In vivo, the pH value and oxygen partial pressure are the most important physico-chemical parameters in the microenvironment of human tissues. In vitro, the extracellular acidification rate of cell cultures is an indicator of global cellular metabolism, while the rate of oxygen consumption is a measure of mitochondrial activity. Earlier approaches had the disadvantage that these two values had to be measured with two separate sensors at different loci within the tissue or cell culture. Furthermore, conventional Clark-type oxygen sensors are not very compatible for miniaturisation, making it impossible to measure at small cell volumes or even at the single cell level. We have, therefore, developed an ISFET based sensor structure which is able to measure both pH and oxygen partial pressure. This sensor structure was tested in vitro for simultaneous records of cellular acidification and respiration rates at the same site within the cell culture. This sensor is manufactured by a CMOS-process.

Biosensing Techniques↗
PubMed2001

Cyclosporine in severe psoriasis. Results of a meta-analysis in 579 patients.

OBJECTIVE: A meta-analysis of 3 major German studies conducted between 1989 and 1994 with cyclosporine in severe psoriasis was performed to allow an integrated evaluation of the efficacy and tolerability of cyclosporine in this indication. DESIGN AND SETTING: All 3 studies were prospective, randomized, parallel group studies. The studies were conducted in 61 dermatologic centers in Germany. PATIENTS AND INTERVENTIONS: The studies involved 597 patients with severe plaque type psoriasis. Treatment consisted of cyclosporine (at a dosage of 1.25, 2.5 or 5 mg/kg/day), etretinate (at a mean daily dose of 0.53 mg/kg/day) or placebo in a total of 756 treatment cycles with a maximum duration of 12 weeks. MAIN OUTCOME MEASURES: The main outcome measures were the psoriasis area and severity index (PASI) and serum creatinine level. RESULTS: The meta-analysis revealed that cyclosporine given in a dosage of 2.5 and 5 mg/kg/day was significantly superior to etretinate. In addition cyclosporine 1.25 mg/kg/day proved to be significantly more effective than placebo. An increase in serum creatinine level that required intervention occurred in 3.4% of cyclosporine treatment cycles. CONCLUSION: Cyclosporine is highly effective and well tolerated in the short term treatment of severe psoriasis.

Adolescent↗
PubMed1997

Comparison of three tropisetron-containing antiemetic regimens in the prophylaxis of acute and delayed chemotherapy-induced emesis and nausea.

There is still controversy as to what constitutes the optimal therapy for acute and delayed chemotherapy-induced emesis and nausea. We conducted a three-armed randomized multi-centre study in 193 chemotherapy-naive patients receiving highly emetogenic chemotherapy inducing both acute and delayed symptoms (cisplatin > or = 50 mg/m2, carboplatin > or = 300 mg/m2, cyclophosphamide > or = 750 mg/m2, ifosfamide > or = 1.5 g/m2 on day 1). Group A: 1 x 5 mg tropisetron i.v. on day 1 + 2, then 10 mg p.o. (oral dose now recommended: 5 mg); group B: tropisetron as for A+dexamethasone, 20 mg i.v., on days 1 + 2, then 4 mg i.v./p.o.; group C: tropisetron as for A+metoclopramide, 20 mg i.v. +2 x 10 mg p.o. on day 1, then 3 x 10 mg p.o. Treatment was continued for at least 2 days after the end of chemotherapy. Tropisetron+dexamethasone was significantly superior to tropisetron alone both for acute (P = 0.0064) and delayed (P = 0.0053) emesis. Complete control of acute and delayed emesis (nausea) was achieved in 80% (75%) and 53% (46%) in group A, 97% (90%) and 80% (58%) in group B, and 86% (80%) and 49% (45%) in group C. Patients completely asymptomatic during the whole cycle accounted for 26% of those in group A, 49% in group B and 28% in group C. The most frequent adverse events were constipation (16.6%), headache (7.3%) and tiredness (7.3%). Once-daily tropisetron+dexamethasone over several days is well tolerated and is a simple means of achieving further significant improvement in the efficacy of tropisetron against acute and delayed symptoms.

Acute Disease↗
PubMed1997

Treatment of prolonged chemotherapy induced severe thrombocytopenia with recombinant human interleukin-3--a report on four cases.

Interleukin-3 (IL-3) is a multipotent hematopoietic growth factor, which exhibits stimulatory effects on leucocytes, reticulocytes and platelets. Due to its pronounced induction of megakaryopoiesis, IL-3 is thought to be a cytokine with the potential to prevent and to overcome chemotherapy-induced thrombocytopenia. We report on four cases (two of metastatic breast cancer, one of metastatic ovarian cancer and one of Hodgkin's disease) with prolonged chemotherapy-induced thrombocytopenia in whom rhIL-3 in combination with either recombinant human (rh) granulocyte macrophage colony stimulating factor (GM-CSF) or rh granulocyte colony stimulating factor (G-CSF) was administered. In all cases, a steady and clinically significant increase in platelet counts could be observed. No major side effects, neither due to the application of rhIL-3 nor due to rhGM-CSF or rhG-CSF, occurred; only flu-like symptoms were seen, which could effectively be treated with paracetamol. This report highlights the efficacy of combined treatment with rhIL-3 plus rhGM-CSF or rhG-CSF in chemotherapy-induced thrombocytopenia, where megakaryopoiesis could be stimulated efficiently by rhIL-3. Based on this experience, the authors conclude that established thrombocytopenia as a major side effect of myelosuppressive chemotherapy should be considered as an indication for the use of rhIL-3 in interventional treatment. Further investigations in this area are encouraged.

Adult↗
PubMed1994

Atrial natriuretic peptide inhibits cyclosporin A-induced endothelin production and calcium accumulation in rat vascular smooth muscle cells.

1. As we have previously shown, cyclosporin A enhances the vasoconstrictor-induced rise in intracellular free calcium in vascular smooth muscle cells. This effect may contribute to important side-effects in cyclosporin therapy, such as hypertension and nephrotoxicity. Atrial natriuretic peptide has been shown to inhibit this effect as well as the cyclosporin-stimulated transmembrane calcium influx in smooth muscle cells. 2. The present study, therefore, was designed to examine the effect of cyclosporin and atrial natriuretic peptide on total cellular calcium content in the rat. Furthermore, since cyclosporin was recently shown to induce endothelin production in smooth muscle cells, we investigated the effect of atrial natriuretic peptide on this potentially adverse cellular effect of cyclosporin therapy. 3. Total cell calcium was measured by atomic absorption, and cellular endothelin production was estimated by radioimmunoassay. 4. Preincubation of the cells with cyclosporin (10 micrograms/ml) for 30 min increased total cell calcium from 2.6 +/- 0.5 to 6.9 +/- 0.3 nmol/mg of protein (P < 0.01). Within 24 h endothelin production was significantly enhanced in the presence of cyclosporin (52.2 +/- 2.5 versus 65.9 +/- 2.7 fmol/mg of protein, P < 0.05). Therefore, the cyclosporin-induced rise in total cell calcium in smooth muscle cells is associated with enhanced production of endothelin. Thus, it is tempting to speculate that the cyclosporin-induced changes in calcium kinetics may be mediated by endothelin. 5. In the presence of atrial natriuretic peptide (10(-8) mol/l), the cyclosporin-induced rise in total cell calcium was significantly reduced (6.9 +/- 0.3 versus 5.1 +/- 0.2 nmol/mg of protein, P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Interleukin-6 stimulates the hypothalamus-pituitary-adrenocortical axis in man.

A recent study in humans, animal studies, and in vitro data have suggested that interleukin-6 (IL-6) stimulates the secretory activity of the hypothalamus-pituitary-adrenocortical (HPA) axis. In a phase II study, one female and six male patients with metastatic renal cell carcinoma received IL-6 to evaluate a possible antitumor effect of IL-6. This offered the possibility of investigating the influence of IL-6 on the HPA axis in man. The subjects were studied 1 day before, on day 1, and on day 21 of IL-6 therapy (150 micrograms administered sc every day at 0900 h). Blood samples were taken at 0900, 1100, 1300, 1600, and 2000 h the day before, on day 1 of IL-6 therapy, 24 h after the first IL-6 injection, and on day 21 of IL-6 treatment. Plasma ACTH and cortisol levels promptly followed the rise of IL-6, which peaked 4 h after administration. They were significantly (P < 0.05) higher at 1100 and 1300 h on day 1 of IL-6 therapy compared with the corresponding plasma levels the day before IL-6 treatment. Cortisol concentrations remained significantly increased at 1600 and 2000 h after IL-6 administration. Twenty-four hours after the first IL-6 administration, IL-6, ACTH, and cortisol levels had reached preinjection values. Although plasma cortisol levels were similar on days 1 and 21, ACTH levels were lower on day 21 (than on day 1), but significantly elevated at 1100 h compared with levels on the day before the first IL-6 injection. Results confirming the very recent data of another study demonstrate a stimulating effect of IL-6 on the HPA axis in man. They support the notion that IL-6 is one of the cytokines involved in the interaction between the immune system and the HPA axis.

Adrenal Cortex↗
PubMed1994

Prevention of chemotherapy-induced nausea and vomiting by tropisetron (Navoban) alone or in combination with other antiemetic agents.

We report an open, three-armed, multicenter study being carried out to assess the optimum treatment for acute and delayed emesis and nausea in patients undergoing highly emetogenic chemotherapy. Eighty-seven patients were randomized to receive tropisetron (Navoban; Sandoz Pharma Ltd, Basel, Switzerland), tropisetron plus dexamethasone, or tropisetron plus metoclopramide during chemotherapy. Tropisetron in combination with dexamethasone produced the best control of both acute and delayed emesis. Acute vomiting was prevented in 69% of patients by tropisetron monotherapy, and the addition of dexamethasone significantly increased the total control of vomiting to 92% (P < .01). Similarly for delayed vomiting, total control of emesis was seen in approximately 70% of patients on tropisetron alone during days 2 and 3; this control rate increased to almost 90% with combined tropisetron/ dexamethasone treatment. In all patients receiving cisplatin, the tropisetron/dexamethasone combination produced total control of acute emesis. The tropisetron and dexamethasone combination also provided the best control of acute and delayed nausea. Tropisetron produced total control of acute nausea in 69% of patients. The addition of dexamethasone increased this control rate to 81%. Similarly for delayed nausea, on days 2 and 3 of treatment, dexamethasone plus tropisetron provided total control of nausea in more than 80% of patients compared with a control rate of more than 60% achieved using tropisetron. The combination of tropisetron and metoclopramide did not improve significantly on the control of nausea and vomiting achieved using tropisetron alone. Evaluation of quality of life events by patients indicated no appreciable change in their mental or physical condition during chemotherapy, irrespective of antiemetic therapy. In the tropisetron and tropisetron plus metoclopramide treatment groups, a decreased food intake was observed due to delayed nausea while the addition of dexamethasone prevented loss of appetite. The antiemetic treatments were similarly well tolerated. The most common adverse events were constipation (15%) and tiredness (7%).

Adult↗
PubMed1994

Dose comparison of tropisetron (Navoban) 5 mg and 10 mg orally in the prophylaxis of dacarbazine-induced nausea and emesis.

In this double-blind, randomized trial performed at five study centers, the prophylactic, antiemetic effect of two different dosages of tropisetron (Navoban; Sandoz Pharma Ltd, Basel, Switzerland) was investigated in dacarbazine-treated patients with melanoma. Patients received tropisetron 5 mg or 10 mg orally (as one capsule) once daily (minimum 3 days) on each day of chemotherapy. No significant differences were found in the effects of tropisetron 5 mg and 10 mg. During the first 24 hours, total control of vomiting was seen in 93% and 98% of patients receiving tropisetron 5 mg and 10 mg, respectively. Total control of nausea was achieved in 84% and 80% of patients receiving tropisetron at these dosages. Over days 2 to 7 of chemotherapy, total control of vomiting and nausea remained high. Patients reported that quality of life remained good throughout chemotherapy, as did mood; only a small decrease in food intake occurred. Tropisetron was well tolerated. Constipation was the most common adverse event, occurring in 13% of patients. Headache (4%), diarrhea (4%), and anorexia (2%) also were observed.

Administration, Oral↗
PubMed1993

Cellular signaling by cyclosporine A in contractile cells: interactions with atrial natriuretic peptide.

Immunosuppressive therapy with cyclosporine A (CyA) may be associated with severe side effects such as nephrotoxicity and arterial hypertension. The partial reversibility of these effects suggests that they are at least in part functional. The present study examined the effects of CyA on cellular signaling in vascular smooth muscle cells and in glomerular mesangial cells and the interactions with the endogenous vasodilator atrial natriuretic peptide (ANP). Intracellular free calcium concentrations ([Ca2+]i) were measured using Fura-2. 45Ca2+ was used to measure Ca2+ efflux and cellular Ca2+ influx. In the presence of cyclosporine (10 micrograms/ml), the Ca(2+)-mobilizing effects of angiotensin II (10(-8)M) in smooth muscle cells and of arginine vasopressin (AVP) in mesangial cells were significantly enhanced. CyA significantly stimulated cellular Ca2+ uptake in both cell types. ANP blocked the Ca2+ mobilization by angiotensin II and AVP and also completely inhibited the potentiating effect of CyA on angiotensin II- and AVP-induced Ca2+ mobilization. ANP also completely blocked the CyA-stimulated Ca2+ uptake. These findings suggest that CyA stimulates transmembrane Ca2+ influx, thereby increasing vasopressor-sensitive intracellular Ca2+ stores and augmenting vasopressor-induced Ca2+ mobilization. This cellular effect of CyA in vitro was markedly diminished by ANP. The effects of CyA on intracellular signaling may directly enhance the contractile response of smooth muscle and the glomerular mesangium to vasopressor stimuli and may also contribute to other disturbances of cell metabolism associated with CyA.

Angiotensin II↗
PubMed1993

Influence of oral calcium medication on nasal resistance in the nasal allergen provocation test.

Although calcium has been used for several decades to treat allergic diseases of the skin and respiratory tract, controlled studies demonstrating the action of oral preparations in allergic rhinitis are lacking. This placebo-controlled, double-blind, crossover study shows that 1000 mg calcium administered orally significantly inhibits the allergen-induced swelling of the nasal mucosa in the allergen provocation test. Sneezing and secretion, which are allergic symptoms, were not reduced. This study is the first to confirm the positive effect of oral calcium on a symptom of allergic rhinitis.

Administration, Oral↗
PubMed1993

Tropisetron in the prevention of chemotherapy-induced nausea and vomiting in patients responding poorly to previous conventional antiemetic therapy.

An open, two-armed, multicentre trial was conducted in 231 patients with malignant disease who had previously failed to respond to conventional antiemetic treatment for the prevention of chemotherapy-induced nausea and vomiting. Patients were randomized to receive either tropisetron (5 mg/day; n = 115) or a standard antiemetic therapy, which was considered optimal for each individual but did not include a 5-HT3 receptor antagonist (n = 116). Acute vomiting on Day 1 was controlled in 60 (52%) tropisetron patients, compared with only 29 (25%) patients receiving optimal standard therapy (p < 0.001). Acute nausea was completely inhibited in 37 (32%) tropisetron patients, compared with 22 (19%) patients on optimal standard therapy (p < 0.05). On Day 1, delayed vomiting was also significantly better prevented by tropisetron (p < 0.001). Side effects from tropisetron (headache and constipation) were mild, and no extrapyramidal symptoms were observed in any tropisetron patients, in contrast, to 14 (13%) patients in the 'optimal standard' group. In conclusion, in cases of acute nausea and vomiting it is more effective to switch refractory patients to tropisetron rather than attempt to optimize the dose of standard antiemetic therapy. For delayed nausea and vomiting, combination antiemetic therapy, with differing types of receptor antagonism and corticosteroids may provide the best way forward. Such studies are in progress.

Antiemetics↗
PubMed1992

Calcium regulating hormones after oral and intravenous calcium administration.

The aim of this study was to determine the changes in serum calcium concentration and in the concentrations of calcium regulating hormones after a single oral or intravenous calcium administration. Standard dosages of calcium, as used in routine patient care, were employed. Intact parathyrin, calcitonin, calcitriol, calcidiol, total calcium, ionized calcium, total protein and phosphate were determined in 12 healthy young men before and up to 8 h after oral and intravenous administration of calcium. During a fortnight there were four study days with 1000 mg calcium orally (p.o.), 2000 mg orally, 180 mg calcium intravenous (i.v.) and a control day without calcium. During the study the men were on a low calcium diet. We observed a sharp increase in the calcium concentration after i.v. administration (15 min: total Ca: + 0.48 +/- 0.32 mmol/l; ionized Ca: + 0.25 +/- 0.15 mmol/l; p < 0.01). The concentration increase after the two oral loads was nearly identical. The maximal concentration of total calcium was reached after 120 min (1000 mg: + 0.1 +/- 0.04 mmol/l; p < 0.001; 2000 mg: + 0.12 +/- 0.04 mmol/l; p < 0.001). There was a significant increase in urinary calcium after all modes of calcium administration. Calcitonin increased significantly only after i.v. injection of calcium (+ 9.2 +/- 3.4 pmol/l; p < 0.001) while parathyrin decreased significantly after all modes of calcium administration (i.v.: 15 min: -1.9 +/- 0.88 pmol/l; p < 0.01; 1000 mg: 90 min: -0.78 +/- 0.75 pmol/l; p < 0.001; 2000 mg: 90 min: -1.02 +/- 0.57 pmol/l; p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1992

Prevention of chemotherapy-induced nausea and emesis in patients responding poorly to previous antiemetic therapy. Comparing tropisetron with optimised standard antiemetic therapy.

In a multicentre trial, 78 patients with a variety of malignancies, who had experienced insufficient control of emesis (greater than or equal to 3 episodes within 24 hours) while receiving standard antiemetics during previous chemotherapy, were randomly assigned to receive tropisetron 5mg once daily for 5 days or conventional antiemetic drugs. No attempt was made to standardise the conventional antiemetic treatment, which was given according to the usual practice of the participating institutions. Emesis was evaluated by counting emetic episodes and nausea by asking the patients to record on a diary chart the duration and severity of the nausea. Emesis was much better controlled with tropisetron than with standard drugs, complete control during the first 24 hours being achieved in 42% and 8% of patients, respectively, (p less than 0.001). Nausea was of significantly shorter duration (6.9 vs 10.3 hours; p less than 0.01) and was less severe (p less than 0.005) in the tropisetron group. The patients' overall assessment of treatment outcome was markedly better for tropisetron than for the standard antiemetic therapy. The superior efficacy of tropisetron was especially marked during the first 24 hours. For delayed nausea, no significant difference between treatments was seen. No serious adverse effects were observed.

Adult↗
PubMed1990

[Reduction of reactivity to allergic rhinitis with intravenous administration of calcium. Clinical-experimental study on the effect of changes of local airway resistance after nasal allergen provocation].

The antiallergic activity of calcium was investigated in 25 patients with allergic rhinitis by nasal provocation with increasing doses of phleum pratense during a symptom free interval. Prior to that provocation, the patients received 9 mmol calcium (Calcium-Sandoz) i.v. or placebo respectively (double blind cross-over design). The concentration of serum calcium increased after calcium injection by 0.45 +/- 0.055 mmol/l. Calcium exerted a significant protective effect as compared to placebo: higher allergen doses, (p = 0.021) i.e. 20433 biological units/ml vs. 7494 biological units/ml, were required in order to induce a defined allergic reaction (50% decrease of nasal air flow). The data thus furnish evidence that intravenous calcium reduces the allergic response in type I allergy.

Adult↗
PubMedDate not supplied

Pharmacokinetics of the 5HT3 receptor antagonist tropisetron in children.

A pharmacokinetic study in children was performed to assess whether the pharmacokinetic profile of tropisetron in pediatric patients in similar to that in adults. In three pediatric centers, three dosages were tested in two age groups during chemotherapy (Group A, 3-6 years, 2, 5, or 20 mg/m2; group B, 7-15 years, 2, 5, or 20 mg). Children received tropisetron intravenously (course 1) or orally (course 2) before the start of chemotherapy. Blood samples were drawn over 24 hours. Tropisetron treatment continued for up to 6 days at the same daily dose, administered orally. Data were available for 45 patients after intravenous and for 38 patients after oral administration. 82% of course 1 patients and 72% of course 2 patients had no emesis on day 1. Headache occurred in eight patients and abdominal symptoms in three patients. Terminal half-life (5.3-6.6 hours), tmax (1.4-1.5 hours), and absolute bioavailability (41-42%) were identical in both age groups and comparable to those in adults. Because of a smaller volume of distribution, group A children showed a higher Cmax/dose (P < .001) and a higher area under curve (AUC) dose (P < .05) than adults. All parameters were independent of the dose administered. In conclusion, the elimination and absolute bioavailability of tropisetron in children are similar to those in adults. Because of its age-dependent volume of distribution, tropisetron should be administered once a day according to the body surface area in children below 10 years of age.

Administration, Oral↗