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Biomedical subjects

E Mayr

Publications and source records attributed to E Mayr.

13 recordsLinked to original sources
PubMed1986

Transcranial Doppler CO2 test for the detection of hemodynamically critical carotid artery stenoses and occlusions.

Cerebral CO2-reactivity was tested by transcranial Doppler sonography (Doppler CO2 test) in 232 patients. Time averaged flow velocity in the middle cerebral artery at the 40 mm Hg blood pCO2 level was taken as a reference point, and the relative increase of flow in hypercapnia of 46.5 mm Hg pCO2 was defined as "Normalized Autoregulatory Response" (NAR). A total of 82 patients with no evidence of cerebrovascular disease gave "normal" values for NAR (23.2 +/- 5.2 SD). In 150 patients with 233 stenoses and occlusions of the internal carotid artery NAR was significantly decreased in higher-grade stenoses (P = 0.01 for 80% diameter reduction, P less than 10(-6) for 90% or more). In such stenoses, patients with NAR less than 14 had suffered more frequently (P less than 0.01) from ipsilateral transient ischemic attacks and/or stroke during the previous 6 months than patients with "normal" NAR. Preoperative NAR less than 14 always improved to "normal" values following carotid surgery, while preoperative NAR greater than 19 remained unchanged (60 cases). The transcranial Doppler CO2 test is thought to be a reliable noninvasive method to detect hemodynamically critical carotid stenoses and occlusions. This may be of interest in selecting patients for superficial temporal artery-middle cerebral artery bypass and carotid surgery. For practical use 4 categories of NAR are suggested.

Arterial Occlusive Diseases↗
PubMed1985

[Natural selection].

Much of the resistance against Darwin's theory of natural selection has been due to misunderstandings. It is shown that natural selection is not a tautology and that it is a two-step process. The first step, the production of variation, is under the control of chance; the second step, selection proper, is an anti-chance process, but subject to many constraints. The target of selection is the individual as a whole, and many neutral mutations can be retained as hitchhikers of successful genotypes. Sexual selection results from selection for pure reproductive success.

Animals↗
PubMed1979

[Dosage-problems in controlled sodium nitroprusside hypotension in oto-rhino-laryngological surgery (author's transl)].

During a study of 130 patients undergoing hypotensive anaesthesia for oto-rhino-laryngological surgery the most important dose problems with sodium nitroprusside (S.N.P.) were characterized. In 14% of the cases more than 15 mcg/kg body weight/min S.N.P. were required. Our data show, that the smallest S.N.P. consumption occurs during neuroleptanalgesia in combination with 0.3--0.8 Vol-% enflurane. On the other hand, during neuroleptanalgesia alone, in several cases toxic amounts of S.N.P. would have been necessary to produce adequate hypotension. In such cases about 0.5 mg/kg body weight dihydralazine must be employed as a supporting agent for hypotension. The influence of this drug on the manoeuvrability of the low pressure state and on the administration of S.N.P. was investigated. Although, the equivalent amount of sodium thiosulfate (S.T.) did not increase the S.N.P. sensibility, its routine use is reconviended, since the combination of S.Th, and even higher doses of S.N.P. were tolerated without metabolic acidosis. As an alternative substance after long-term use of S.N.P. nitroglycerine should be used.

Dihydralazine↗
PubMed1978

Evolution.

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Animals↗