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Biomedical subjects

L Evans

Publications and source records attributed to L Evans.

At least 199 records · Page 11Linked to original sources
PubMed1976

Quantitative microchromatographic determination of hemoglobin F in patients with hemoglobins S and/or C.

The improved microchromatographic procedure for the detection of Hb-S and/or Hb-C in cord blood at birth (Schroeder et al.: J. Lab Clin Med 86:528-532, 1975) as well as a modification thereof may also be used for the quantitative determination of Hb-F in the presence of Hb-S and/or Hb-C. However, Hb-A interferes and must be absent. The methods use 0.5 X 6 cm columns of CM-cellulose with Tirs or Bis-tris developers and require 2-4 hr to complete. At low percentages of Hb-F, the sharper zone of the Tris method is more easily visible than that of the Bis-tris method, but the latter is a somewhat more rapid procedure. About 300 cases with Hb-S and/or Hb-C have been examined by the microchromatographic procedure. Most of these results (Fmicro) have been compared with data from the determination of Hb-F by one or more of the following methods: alkali denaturation (FAD), conventional DEAE-Sephadex chromatography (FDES), or isoleucine analyses of zones from DEAE-Sephadex chromatography (FIle). The accuracy and precision of the microchromatographic method is estimated to be 5-10%. The microchromatographic methods require much less time than conventional chromatography but more time than alkali denaturation procedures. Compared to the latter, the new methods use whole blood and less blood and permit the physical separation of Hb-F.

Chromatography↗
PubMed1976

Characterization and tissue distribution of N-acetyl hexosaminidase C: suggestive evidence for a separate hexosaminidase locus.

1. An electrophoretic system in which N-acetyl hexosaminidase C (HEX(C)) MIGRATES LESS ANODALLY THAN N-acetyl hexosaminidase A (HEX(A)) is described. 2. HEX(C) is shown to differ from HEX(A) and HEX(B) in substrate specificity, molecular size and affinity for Concanavalin-A. 3. HEX(C) is present in a wide range of adult and foetal tissues and in tissues from patients with Tay-Sachs and Sandhoff's diseases. It is particularly prominent in brain, testis, thymus and lymphoblastoid cell extracts and in several foetal tissues. 4. It is suggested that HEX(C) is coded at a separate gene locus from HEX(A) and HEX(B).

Acetylglucosaminidase↗
PubMed1975

Microchromatography of hemoglobins. IV. An improved procedure for the detection of hemoglobins S and C at birth.

Substitution of CM-cellulose for CM-Sephadex had yielded a superior microchromatographic method for distinguishing the AS, AC, SS, SC, and CC conditions at birth. On the translucent columns of CM-Sephadex, the hemoglobin zones are somewhat diffuse. However, the compact, well-defined zones on the CM-cellulose column facilitate the interpretation of the results even though the amount of sample is only 20 per cent as great. The CM-cellulose method is as simple and rapid as the original CM-Sephadex procedure.

Chromatography↗
PubMed1969

Studies on the cathepsins in elastic cartilage.

1. The presence of several enzymes in rabbit ear cartilage was examined by a quantitative method that permits the incubation of a fixed weight of cartilage sections (18mum.) with an appropriate exogeneous substrate. 2. As the presence of cathepsins B and D in cartilage has already been established, evidence is now provided to show that cathepsins A and C are also present and are maximally active at pH5. 3. Cathepsin A was recognized by its hydrolysis of benzyloxycarbonyl-glutamyl-tyrosine and cathepsin C by its hydrolysis of glycyl-tyrosine amide; the cartilage also hydrolysed benzyloxycarbonyl-glutamyl-phenylalanine and benzoyl-dl-phenylalanine 2-naphthyl ester at pH5. 4. The acid phosphatase activity and the DNA content of cartilage have also been measured to provide a basis for comparison with the cathepsin activity of cartilage obtained from other sites and species.

Acid Phosphatase↗
PubMed1968

Purification of rabbit kidney cytokinase and a comparison of its properties with human urokinase.

1. The cytokinase (tissue activator of plasminogen) content of several mammalian tissues was evaluated by a quantitative casein hydrolysis method. 2. An alkaline (pH10.5) extraction of cytokinase from rabbit kidney lysosome-microsome fraction, followed by chromatography on DEAE-cellulose at pH7.6 with stepwise or linear increase in concentration of phosphate buffer, gave an 86-fold purification of the enzyme. The purified material was non-proteolytic against casein and heated fibrin and was freeze-dried without significant loss of activity or solubility. 3. Cytokinase is a protein with E(0.1%) (1cm.)=0.87 at 280mmu, and does not possess sufficient hexose or sialic acid to be classified as a glycoprotein. It has S(20,w) 2.9-3.1s and molecular weight 50000 when measured on a calibrated Sephadex G-100 column. It has an isoelectric point between pH8 and pH9, and is maximally active and stable at pH8.5. It is inactivated by heat at 78 degrees . 4. Cytokinase and human urokinase have the same K(m) value and are inhibited in a partially competitive manner by in-aminohexanoic acid and aminomethylcyclohexanecarboxylic acid. They are also inhibited by cysteine and arginine, but are unaffected by iodoacetamide and p-chloromercuribenzoate. 5. On the basis of this and other evidence it is suggested that rabbit kidney cytokinase and human urokinase are similar, if not identical, enzymes.

Animals↗
PubMed1967

Characterization of cathepsins in cartilage.

The presence of a cathepsin B-like enzyme in rabbit ear cartilage was established by the use of the synthetic substrates benzoyl-l-arginine amide and benzoyl-dl-arginine 2-naphthylamide. This was facilitated by using a technique that permits the incubation of a fixed weight of thin (18mu) cartilage sections with an appropriate exogenous substrate. The enzymic properties of cathepsin B in cartilage have been compared with an endogenous enzyme that liberates chondromucopeptide by degrading the cartilage matrix autocatalytically at pH5. Besides being maximally active at pH4.7, these cartilage enzymes are enhanced in activity by cysteine and inhibited by arginine analogues, iodoacetamide, chloroquine and mercuric chloride. They are not inhibited by EDTA, di-isopropyl phosphorofluoridate and diethyl p-nitrophenyl phosphate. When inhibiting the release of chondromucopeptide from cartilage at pH5, the arginine-containing synthetic substrates are hydrolysed simultaneously. These enzymes also share the same heat-inactivation characteristics at various pH values, being stable at acid pH and unstable at neutral and alkaline pH. The experimental evidence indicates that a cathepsin B-like enzyme may be partly responsible for the autolytic degradation of cartilage matrix at pH5.

Amines↗
PubMedDate not supplied

Motorized two-point safety belt effectiveness in preventing fatalities.

The effectiveness of two-point motorized restraint systems in preventing fatalities to outboard front-seat car occupants is estimated using published fatality data for one model car equipped with a motorized two-point-belt system, together with a number of assumptions. Effectiveness estimates are obtained for the motorized belt system as used in the field, which reflects the mix of occupants who do and do not fasten the manual lap belt, and for effectiveness when the lap belt is not used. This latter estimate is, therefore, an estimate of the effectiveness of shoulder belts in preventing fatalities. In the data for the one car model, 18% of the fatally injured occupants were ejected. By assuming that three-point belt systems prevent ejection, these data are used to compute the difference in effectiveness between two-point and three-point systems. The result applies to the two-point belt system used in conjunction with whatever manual belt-use rates occurred in traffic. From published observations of lap-belt-use rates for this same vehicle, the effectiveness of the shoulder belt only is estimated. It is found that effectiveness of the two-point restraint system in conjunction with the lap-belt use that occurred in traffic is (32 +/- 5)%. The effectiveness of the shoulder belt only is estimated as (29 +/- 8)%.

Accidents, Traffic↗
PubMedDate not supplied

Personality and treatment response in agoraphobia with panic attacks.

The present study investigated the association of specific personality characteristics with agoraphobia, and whether they predicted long-term outcome following a group cognitive behavior therapy program. Thirty-three patients with agoraphobia with panic attacks, 18 with social phobia, and 26 "normals" were used in the study. Personality factors were measured with the Maudsley Personality Inventory (MPI), the Hostility and Direction of Hostility Questionnaire (HDHQ), and the Fundamental Interpersonal Relations Orientation-Behavior Scale (FIRO-B). The results showed that (1) agoraphobics are more extroverted and more likely to include others in their activities than are social phobics; however, they are less extroverted, more neurotic, more hostile and intropunitive, and less likely to include others in their activities than are normals; (2) social phobics are similarly less extroverted, more neurotic, and more hostile and intropunitive than normals, but, in addition, are less likely to exert control over others, more likely to want to be controlled, and less expressive of affection than normals; and (3) personality characteristics did not predict treatment outcome.

Adult↗
PubMedDate not supplied

An exploration of the relationship between expression of hostility and the anxiety disorders.

The purpose of the present study was to investigate differences between four anxiety disorder groups with respect to their levels of hostility. Patients with diagnoses of panic disorder, agoraphobia with panic, generalized anxiety disorder and social phobia were compared as regards their performance on the Hostility and Direction of Hostility Questionnaire (HDHQ). Results showed that while the groups did not differ on their extrapunitiveness, there were significant differences on intropunitive scores, with social phobics showing the most self criticism and guilt, followed in order by the agoraphobics with panic, generalized anxiety disorder and panic disorder subjects. Scores on the Anxiety Symptoms and Consequences Scale were used to predict intropunitiveness and extrapunitiveness for each diagnostic group. Results showed that intropunitiveness was related to anxiety symptoms differently for each diagnostic group. Overall, the study indicates that intropunitive hostility may be an important feature of anxiety disorders, especially panic with and without agoraphobia, and that the finding is worth further exploration with longitudinal studies.

Adult↗
PubMedDate not supplied

Premature rupture of the membranes with routine cervical exams.

Premature rupture of the membranes at term occurs frequently in otherwise uncomplicated pregnancies. Several theories have been postulated as to the cause of this complication, including the practice of routine prenatal cervical examinations. A randomized prospective study was done to determine if prenatal cervical exams did increase the risk of premature rupture of the membranes. Fifty-six women were examined intracervically every week from 37 weeks' gestation until delivery, and 45 women received no cervical examinations until labor began. Premature rupture of the membranes occurred in ten women (18%) who were examined and in six women (13%) who were not. There was no statistically significant difference between the two groups of women, leading to the conclusion that prenatal cervical examinations do not cause an increase in the frequency of premature rupture of the membranes.

Adult↗