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Biomedical subjects

E Mayr

Publications and source records attributed to E Mayr.

At least 73 records · Page 4Linked 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↗
PubMed1984

Methicillin-resistant Staphylococcus aureus strains in New York City hospitals: inter-hospital spread of resistant strains of type 88.

A survey of methicillin-resistant strains of Staphylococcus aureus received for phage typing indicated a marked increase of resistant strains received in 1982 and 1983. Of 62 hospitals in New York City which sent strains for phage typing, 35 had methicillin-resistant isolates. A significant development was the presence of strains of the same phage type at several hospitals, indicating a possible inter-hospital spread of these strains. Among strains present at several hospitals, the largest group was of experimental phage type 88. Strains of type 88 were received from 23 hospitals, representing 56% of all methicillin-resistant strains received from New York City hospitals. Strains of type 88 were resistant to all antistaphylococcal antibiotics, with the exception of vancomycin, and represented a major source of nosocomial infections at 13 hospitals. As experimental phage 88 is not routinely used for typing in U.S. laboratories, the nationwide distribution of strains of type 88 is difficult to assess.

Anti-Bacterial Agents↗
PubMed1983

[Not Available].

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Biological Evolution↗
PubMed1981

Emergence of gentamicin- and methicillin-resistant Staphylococcus aureus strains in New York City hospitals.

Gentamicin- and methicillin-resistant strains of Staphylococcus aureus have been isolated from Spring 1979 to the present from many hospitals in New York City. A large proportion of the strains were resistant to the majority of antistaphylococcal antibiotics. The ratio of multiply resistant strains was highest among tetracycline-resistant strains. There were significant differences in phage susceptibility patterns and the resistance spectrum of strains isolated at different hospitals, whereas strains isolated at the same hospital often showed a marked degree of similarity. This suggests multiple origins of gentamicin- and methicillin-resistant strains isolated in New York City.

Bacteriophage Typing↗
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↗
PubMed1976

Species-area relation for birds of the Solomon Archipelago.

Accurate values of number of breeding bird species have been obtained for 50 islands of the Solomon Archipelago. From information about species altitudinal distributions on each island, the values are apportioned into number of montane species (S(mt)) and of species present at sea-level (S(low)). S(low) increases linearly with the logarithm of island area A over a million-fold range of areas (correlation coefficient 0.99) and with a comparatively low slope, while the log S-log A relation is markedly curved. With increasing isolation of an archipelago, the species-area relation decreases in slope and may shift in form from a power function to an exponential. Comparison of Pacific archipelagoes at different distances from the colonization source of New Guinea shows that the decrease in slope is due to increasing intra-archipelago immigration rates, arising from overrepresentation of the most vagile inter-archipelago immigrants in more distant archipelagoes. When colonists are sorted into sets correlated with their dispersal abilities, the slope of the species-area relation for the most vagile set is close to zero, but for the least vagile set is close to the value predicted by Preston for "isolated universes."

Journal Article↗
PubMed1976

Birds on islands in the sky: Origin of the montane avifauna of Northern Melanesia.

Biogeographers have long been fascinated by the disjunct distributions of species stranded on mountaintops. This paper analyzes, for the montane bird populations of Northern Melanesian islands, how many such populations there are, why they are restricted to mountains, and how they dispersed to mountains. The number of populations increases with island elevation and with montane area, and decreases with lowland area, exemplifying the problem of continental species diversity. Most species with montane populations on some island(s) have sea-level populations on some other island(s). These altitudinal niche shifts can be variously related to interisland differences either in altitudinal distribution of area or else in competitive pressure in the lowlands or mountains. Restriction of Northern Melanesian bird populations to mountains is more often due to lowland competitors than to inability to survive under the physical conditions of the lowlands. Of four possible mechanisms for the origin of a montane population (referred to as jumping, land-bridge crossing, trickling, and push-pull shifts), only the first and last have been significant for Northern Melanesian birds.

Journal Article↗
PubMed1976

Species-distance relation for birds of the Solomon Archipelago, and the paradox of the great speciators.

For scattered remote islands and for likely forms of immigration and extinction curves, the equilibrium theory of island biogeography leads to the prediction [unk](2) log S/[unk]A[unk]D > 0, where S is the number of species on an island, A island area, and D island distance from the colonization source. This prediction is confirmed for birds of the Solomon Archipelago. Bird species can be classified into three types according to how distance affects their distributions: non-water-crossers, which are stopped completely (usually for psychological reasons) by water gaps of even 1 mile; short-distance colonists, successful at colonizing close but not remote islands; and long-distance colonists, successful at colonizing remote as well as close islands. Almost all of the "great speciators", the species for whose inter-island geographic variation the Solomons are famous, prove to be short-distance colonists. Lack's interpretation of the decrease in S with D is shown to rest on incorrect assumptions.

Journal Article↗