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Biomedical subjects

E Schenk

Publications and source records attributed to E Schenk.

At least 37 records · Page 2Linked to original sources
PubMed1985

Primary structure of copper-zinc superoxide dismutase from Neurospora crassa.

The complete amino acid sequence of copper-zinc superoxide dismutase from Neurospora crassa is reported. The subunit consists of 153 amino acids and has a Mr of 15,850. The primary structure was determined by automated and manual sequence analysis of peptides obtained by digestions of the carboxymethylated and aminoethylated enzyme with trypsin and thermolysin. The protein is devoid of tryptophan and methionine and displays a free amino terminus. Comparison of the amino acid sequence with those from human erythrocyte, bovine erythrocyte, horse liver, swordfish liver, and yeast copper-zinc superoxide dismutases reveals a high degree of sequence homology among the six enzymes. Most prominently, the regions containing the amino acid residues participating in the metal-binding and the half-cystine residues forming the intramolecular disulfide bridge are highly conserved. The invariant amino acids Pro 74 and Asp 76 of the four vertebrate and yeast superoxide dismutases were found to be substituted by arginine and alanine, respectively, in the Neurospora enzyme. These radical substitutions occurring in the zinc ligand region, known to form a characteristic loop structure in bovine erythrocyte copper-zinc superoxide dismutase (Tainer, J. A., Getzoff, E. D., Beem, K. M., Richardson, J. S., and Richardson, D. C. (1982) J. Mol. Biol. 160, 181-217), however, do not affect the catalytic properties of the Neurospora enzyme.

Amino Acid Sequence↗
PubMed1984

Is routine angiography necessary prior to carotid endarterectomy?

The records of 111 consecutive patients undergoing evaluation for possible carotid endarterectomy at the University of Rochester were reviewed. All patients had noninvasive evaluation (oculoplethysmography-Gee and direct, continuous-wave Doppler ultrasonography) as well as selective carotid angiography. Patients were grouped by clinical presentation to ascertain the relative importance of angiography in determining the need for surgery. Arteriography added nothing to clinical and noninvasive evaluation in over two thirds of patients with hemispheric cerebral symptoms or asymptomatic carotid bruits. In contrast, we found that almost all patients with nonhemispheric symptoms required angiography for adequate evaluation prior to surgery. The implication of these findings on preoperative evaluation of patients with carotid surgery is discussed.

Angiography↗
PubMed1982

Sub-threshold near-UV radiation effects on aphakic guinea pig retinas.

Monocularly aphakic guinea pigs (Cavia porcellis), prepared by removing the lens by phacoemulsification, were maintained under near-UV lighting conditions for several months. Exposure to near-UV energy was at much lower irradiance levels than that of sunlight, and was at lower than the threshold level for near-UV damage to the aphakic monkey retina as reported by Ham, et al (1). In some aphakic eyes, regenerated lens-like structures formed which scattered light appreciably. After increasing light exposure periods, the eyes of control and irradiated animals were studied histologically. Other animals were periodically examined by electroretinographic (ERG) techniques. While there was no observable histopathological damage, aphakic-UV irradiated eyes with little or no lens regrowth exhibited depressed b-waves, late time constants and altered wave forms when compared with control eyes. The results demonstrate that ambient near-UV light exposure can adversely influence retinal electrical activity in aphakic eyes at irradiance levels below threshold for morphological damage. The protective function of the lens is also supported by these findings.

Animals↗
PubMed1981

Lack of photosensitization of ocular tissues by allopurinol.

Based on careful double-blind studies using albino mouse ocular tissues, we conclude that allopurinol does not act as a photosensitizer for ocular tissue damage in mice relative to exposure to environmental near ultraviolet (UV) light. Damage to lens epithelial cells and retinal photoreceptors was equivalent in UV light-exposed mice that were either fed or not fed a dose of allopurinol equivalent to that used by humans in the treatment of gout. There was also no direct in vitro photosensitizing interaction between allopurinol and protein or nucleic acids. We conclude that patients in whom cataracts developed after using allopurinol and exposure to high irradiances of near UV light were most likely affected by the UV light itself.

Allopurinol↗
PubMed1980

The predictive value of myocardial radioisotope scanning in animals treated with doxorubicin.

Thirty-four New Zealand white rabbits were treated with doxorubicin and imaged weekly with Tc-99m pyrophosphate to define the value of abnormal myocardial images in predicting doxorubicin-induced cardiac toxicity. Increased myocardial uptake was detected in most animals on sustained treatment with doxorubicin. A greater proportion of the heart was involved with doxorubicin-related histologic changes in animals with strongly positive myocardial images than in treated animals with moderately positive or normal scans. The myocardial images returned to normal levels 2--6 wk after doxorubicin was discontinued. Five of seven rabbits that received doxorubicin after they had three moderately positive myocardial scans, died from congestive heart failure. Three rabbits whose doxorubicin was discontinued because of scan findings, survived for 6 wk or more before dying from renal failure. The three rabbits who received the highest total dose of doxorubicin died of renal failure without developing abnormal myocardial scans.

Animals↗
PubMed1980

[Fatal hyperthermic crisis after premedication. Human stress syndrome or trigger effect of promethacine (author's transl)].

A case report of a fatal hyperthermic crisis after premedication and before introduction of anaesthesia is given. Based on the typical clinical course, CK isoenzyme patterns and preliminary results of familial investigation the diagnosis of malignant hyperthermia could be established. According to literature reports, psychic stress and/or phenothiazine medication may be assumed as triggering factors. Until a potential causality between malignant hyperthermia and phenothiazine medication can definitely be ruled out, their use in suspicious cases of susceptibility to malignant hyperthermia should be avoided.

Adolescent↗