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Biomedical subjects

W Niederer

Publications and source records attributed to W Niederer.

At least 19 recordsLinked to original sources
PubMed1992

Improved thrombolysis in acute myocardial infarction with front-loaded administration of alteplase: results of the rt-PA-APSAC patency study (TAPS)

Thrombolysis with recombinant tissue-type plasminogen activator (rt-PA) and anisoylated plasminogen streptokinase activator (APSAC) in myocardial infarction has been proved to reduce mortality. A new front-loaded infusion regimen of 100 mg of rt-PA with an initial bolus dose of 15 mg followed by an infusion of 50 mg over 30 min and 35 mg over 60 min has been reported to yield higher patency rates than those achieved with standard regimens of thrombolytic treatment. The effects of this front-loaded administration of rt-PA versus those obtained with APSAC on early patency and reocclusion of infarct-related coronary arteries were investigated in a randomized multicenter trial in 421 patients with acute myocardial infarction. Coronary angiography 90 min after the start of treatment revealed a patent infarct-related artery (Thrombolysis in Myocardial Infarction [TIMI] grade 2 or 3) in 84.4% of 199 patients given rt-PA versus 70.3% of 202 patients given APSAC (p = 0.0007). Early reocclusion within 24 to 48 h was documented in 10.3% of 174 patients given rt-PA versus 2.5% of 163 patients given APSAC. Late reocclusion within 21 days was observed in 2.6% of 152 patients given rt-PA versus 6.3% of 159 patients given APSAC. There were 5 in-hospital deaths (2.4%) in the rt-PA group and 17 deaths (8.1%) in the APSAC group (p = 0.0095). The reinfarction rate was 3.8% and 4.8%, respectively. Peak serum creatine kinase and left ventricular ejection fraction at follow-up angiography were essentially identical in both treatment groups. There were more bleeding complications after APSAC (45% vs. 31%, p = 0.0019).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Theoretical and practical vision quality with diffractive-multifocal lenses].

I investigated the discrimination of objects with diffractive bifocal contactlenses, when objects in different distances are presented simultaneously. Computer assisted considerations suggested an impairment of discrimination as compared to monofocal correction for far as well as for near. The theoretical loss of image information has been shown to occur also in a visual test with steric arrangement of object points. However, the experiments suggested, that this kinds of visual quality impairment does not play a dominant role in the qualification of diffractive bifocals, since a rather sophisticated procedure was needed to demonstrate the expected effect.

Computer Simulation↗
PubMed1989

Improved thrombolysis with a modified dose regimen of recombinant tissue-type plasminogen activator.

To improve further the patency rate of infarct-related coronary arteries, the following accelerated dosage regimen of recombinant tissue-type plasminogen activator (rt-PA) was administered to 80 patients with acute myocardial infarction of less than or equal to 6 h duration: 15 mg intravenous bolus, 50 mg infusion over 30 min and 35 mg infusion over the following 60 min. After coronary angiography at 90 min coronary angioplasty was performed in 16 patients and additional thrombolysis in 3 patients. Six patients were not included in the final angiographic analysis, mostly because of borderline ST segment elevations, in order to avoid overestimation of the efficacy of this dose regimen. Four of these had a patent infarct artery; no early angiogram was performed on two. Sixty minutes after the start of infusion, 54 (74%) of 73 patients had a patent infarct-related artery (Thrombolysis in Myocardial Infarction [TIMI] grade 2 or 3) as did 67 (91%) of 74 patients at 90 min. At 24 h, 61 (92.4%) of 66 patients showed a patent infarct artery. Recurrent myocardial ischemia was noted in 12 patients, 7 (9.4%) of whom experienced reinfarction during the hospital stay. Minor local bleeding complications were observed in 14 patients (17.5%). There were four in-hospital cardiac deaths; one patient who underwent additional thrombolysis for recurrent ischemia died from bleeding complications. These results show that a rapid infusion of 100 mg of rt-PA over 90 min yields a high early patency rate of the infarct-related artery without an increase in reocclusion rate and adverse reactions.

Adult↗
PubMed1988

Intravenous recombinant tissue plasminogen activator (rt-PA) and urokinase in acute myocardial infarction: results of the German Activator Urokinase Study (GAUS).

The effects of recombinant tissue plasminogen activator (rt-PA) and urokinase on patency and early reocclusion of infarct-related coronary arteries were investigated in a single blind, randomized multicenter trial in 246 patients with acute myocardial infarction of less than 6 h duration. Both 70 mg of single chain rt-PA with an initial bolus of 10 mg and 3 million units of urokinase with an initial bolus of 1.5 million units were given intravenously over 90 min. The first angiographic study at the end of the infusion revealed a patent infarct-related artery (Thrombolysis in Myocardial Infarction trial [TIMI] grade 2 or 3) in 69.4% of 121 patients given rt-PA versus 65.8% of 117 patients given urokinase (p = NS). Among patients treated within 3 h from symptom onset a patent infarct-related artery was found in 63.9% of 72 patients given rt-PA versus 70% of 70 patients given urokinase (p = NS). There were five cardiac deaths in each group and one fatal intracranial hemorrhage in the rt-PA group. The in-hospital reinfarction rate was 8.9% versus 13.2% for patients treated with rt-PA and urokinase, respectively. There was no difference in left ventricular function at baseline and follow-up catheterization studies. Both drugs were well tolerated and there was no significant difference in cardiovascular or bleeding complications between the two groups. It is concluded that rt-PA and urokinase in the dosages used provide similar efficacy and safety in the treatment of acute myocardial infarction. Reocclusion during the first 24 h may be less frequent after urokinase treatment.

Adult↗
PubMed1988

[Intravenous infusion of recombinant tissue-type plasminogen activator (rt-PA) and urokinase in acute myocardial infarct: intermediate results of the G.A.U.S. study (German Activator Urokinase Study)].

The effects of recombinant tissue plasminogen activator (rt-PA) and urokinase on patency and early reocclusion of infarct-related coronary arteries were investigated in a single blind, randomised multicenter trial in up to now 125 patients with acute myocardial infarction of less than six hours duration. Both, 70 mg of single-chain rt-PA with an initial bolus of 10 mg, and 3 million U of urokinase with an initial bolus of 1,5 million U were given intravenously over 90 minutes. The first angiogram at the end of the infusion revealed a patent infarct-related artery (TIMI grade 2 or 3) in 68% of 62 patients with rt-PA vs. 63% of 63 patients with urokinase (n.s.). Twenty-four hours later patent infarct-related arteries occurred in the same frequency in the rt-PA group and in the urokinase group (71.5% vs. 74.6%, n.s.), although additional recanalisation procedures in sequence with the first angiography were performed more frequent in the rt-PA group. There were two cardiac deaths in either group. In-hospital reinfarction rate was 9.7% vs. 17.5% for patients treated with rt-PA and urokinase, respectively. Both drugs were well tolerated, no significant difference of cardiovascular or bleeding complications could be observed between the two groups. It is concluded that rt-PA and urokinase in the dosages used provide similar efficiency and safety in the treatment of acute myocardial infarction.

Adult↗
PubMed1984

[Late complications following heart valve replacement].

Patients with cardiac valve replacement require regular follow-up examinations since complications are not infrequent with valve prostheses. All mechanical valves are thrombogenic, only bioprostheses implanted in patients with constant sinus rhythm do not require anticoagulation. One of the most important practical tasks is the exact adjustment of anticoagulant administration in order to achieve prothrombin values of between 15 and 25%. During check-ups the physician has to pay special attention to changes in symptoms and auscultation which might point to dysfunction of the valve. Of special importance is fever of unclear origin since endocarditis of the valve is a very serious complication. The patient must be admitted to hospital at the slightest suspicion of endocarditis.

Endocarditis, Bacterial↗
PubMed1978

Glucagon, insulin, cortisol, and growth hormone levels following major surgery: their relationship to glucose and free fatty acid elevations.

Circulating hormone and substrate levels were measured in 7 patients at regular intervals before, during and after pulmonary surgery. During surgery, cortisol and growth hormone were significantly elevated, pancreatic glucagon was unchanged and insulin was depressed. One and two days after surgery, growth hormone had almost returned to preoperative fasting values, but cortisol, insulin and glucagon levels were significantly increased. The mean insulin:glucagon molar ratio declined from a preoperative fasting value of 3.2 +/- 0.5 (+/- SEM) to 1.7 +/- 0.4 during operation but was within normal limits 1 and 2 days after surgery due to a parallel rise and fall in plasma insulin and glucagon. Plasma glucose was elevated both during operation and for several days thereafter, whereas free fatty acid levels were increased only during operation. Thus, there was no consistent relation between insulin:glucagon ratio or any of the hormone levels and the observed elevations in plasma glucose and free fatty acids. It is concluded that neither any of the hormones assayed nor the insulin:glucagon ratio was the primary determinant of plasma glucose and free fatty acid responses to surgery. Rather, fuel homeostasis appeared to result from the combined effects of glucagon, insulin, growth hormone, cortisol and adrenergic activity.

Adult↗
PubMed1978

Failure of inhibiting corneal graft rejection in rabbits by 5 alpha-androstane-3,17-dione.

Corneal transplantations were performed on both eyes of 19 albino rabbits. For each animal both grafts were taken from one pigmented donor rabbit. In all animals one eye was treated with a 2% 5alpha-androstane-3,17-dione ointment (alphaA) and the other eye with an ointment containing no steroid (6 rabbits) or 2% cortisol (13 rabbits). Our experiments showed that alphaA cannot inhibit the efferent limb of corneal graft rejection as effectively as cortisol. we discuss some histological features of corneal graft rejection and our technique of corneal grafting in rabbits.

Androstanes↗
PubMed1977

[Trabeculectomy: surgical technique, results, indications (author's transl)].

In this teaching-course special emphasis is given on surgical techniques and postoperative care of trabeculectomy. The follow-up of 114 eyes of 103 patients is reported. High tension in the early postoperative phase allowed no prediction of the later results. After 3 months 11%, and after one year 39% of the operated eyes with simple glaucoma had a tension higher than 22 mm Hg, even if drugs were given. Different sites of the excision in regard to the trabecular meshwork and Schlemm's canal gave no statistically different results. The filtering blebs have the tendency to develop in two directions, either scarring or becoming cystic. The cystic filtering blebs give better functional results. The development of the filtering bleb was inversely proportional to the height of the tension but went parallel to the facility of outflow. The visual acuity diminished in 35%, mostly due to cataract-formation and improved in 3%. Different complications happened in 6%. The authors consider the trabeculectomy to be the operation of choice for almost all forms of glaucoma.

Follow-Up Studies↗
PubMed1976

Pharmacokinetic study with synthetic salmon calcitonin (Sandoz).

18 patients randomly divided into 3 groups of six each received 35 mug (140 M.R.C. Units) of synthetic salmon calcitonin intravenously, intramuscularly or subcutaneously. Plasma and urin concentrations were determined using the radioimmunoassay method. There was a rapid distribution phase of ca. 12 minutes after intravenous injection then an elimination half-life of 1.1 hours. The volume of distribution was 11 litres. The invasion half-life after intramuscular and subcutaneous administration was 12 and 11 minutes respectively and the elimination half-lives 1 and 1.5 hours, respectively. The bioavailability of the intramuscular and subcutaneous forms was found to be 66 and 71% respectively when areas under their plasma concentration/time curves were compared with the intravenous area.

Adolescent↗