Search PubMed⌕ Search

Biomedical subjects

E Yamada

Publications and source records attributed to E Yamada.

241 records · Page 14Linked to original sources
PubMedDate not supplied

Point mutation of alanine (31) to valine prohibits the folding of reduced lysozyme by sulfhydryl-disulfide interchange.

In the preceding paper in this issue, we described the overproduction of one mutant chicken lysozyme in Escherichia coli. Since this lysozyme contained two amino acid substitutions (Ala31----Val and Asn106----Ser) in addition to an extra methionine residue at the NH2-terminus, the substituted amino acid residues were converted back to the original ones by means of oligonucleotide-directed site-specific mutagenesis and in vitro recombination. Thus, four kinds of chicken lysozyme [Met-1Val31Ser106-, Met-1Ser106-, Met-1Val31- and Met-1 (wild type)] were expressed in E. coli. From the results of folding experiments of the reduced lysozymes by sulfhydryl-disulfide interchange at pH 8.0 and 38 degrees C, followed by the specific activity measurements of the folded enzymes, the following conclusions can be drawn: (i) an extra methionine residue at the NH2-terminus reduces the folding rate but does not affect the lysozyme activity of the folded enzyme; (ii) the substitution of Asn106 by Ser decreases the activity to 58% of that of intact native lysozyme without changing the folding rate; and (iii) the substitution of Ala31 Val prohibits the correct folding of lysozyme. Since the wild type enzyme (Met-1-lysozyme) was activated in vitro without loss of specific activity, the systems described in this study (mutagenesis, overproduction, purification and folding of inactive mutant lysozymes) may be useful in the study of folding pathways, expression of biological activity and stability of lysozyme.

Alanine↗
PubMedDate not supplied

Infants of depressed mothers exhibit atypical frontal electrical brain activity during interactions with mother and with a familiar, nondepressed adult.

Previous studies have shown that infants of depressed mothers exhibit atypical frontal brain electrical activity when they are interacting with their mothers. Whereas typically developing infants exhibit greater left versus right frontal brain activity, infants of depressed mothers have been found to exhibit reduced relative left frontal activity. The left frontal brain region has been associated with the expression of positive emotions. In the present study, the question of whether the atypical pattern of brain activity found in infants of depressed mothers generalizes to situations not involving mother was addressed. Brain electrical activity was recorded from 13- to 15-month-old infants of depressed (N = 59) versus nondepressed (N = 40) mothers during a baseline condition, and during several social conditions that included a playful social interaction with a familiar experiments. Infants of depressed mothers exhibited reduced left relative to right frontal activity during the baseline condition, and during interactions with their mothers and with the familiar experimenter. The present results suggest that the atypical pattern of electrical brain activity found in infants of depressed mothers generalizes to a variety of situations, including positive interactions with nondepressed adults.

Adult↗
PubMedDate not supplied

Changes of 5'-nucleotidase activity in cultured glioma cells.

Changes of 5'-nucleotidase (5'-N) activity during subcultivation of C6 clonal rat glioma cells were studied histochemically, cytochemically and biochemically. Two different cell populations were seeded with high or low cell density respectively. 5'-N activity in cultured cells increased continuously in both populations. The enzyme activity was always higher in the cells growing in high density than in those growing in low density, and this difference became statistically significant after 6 days of subcultivation. It seemed likely that the increase in 5'-N activity depended on cell density, not on the frequency of mitosis. Cytochemically, enzyme activity was detected on the outer surface of the plasma membrane of cell bodies or cell processes. Strong activity was found on the processes and cell membranes where cells touched each other. In the regions where cells had intimate cell-to-cell contact, marked elevation of the enzyme activity was seen. Increased 5'-N activity, which appeared to depend on cell density, was considered to be related with this cell-to-cell contact.

5'-Nucleotidase↗
PubMedDate not supplied

International Study of Asthma and Allergies in Childhood (ISAAC) written questionnaire: validation of the asthma component among Brazilian children.

Written questionnaires have been widely used in epidemiological studies of asthma. However, when translated to another language, they must be validated. The International Study of Asthma and Allergies in Childhood (ISAAC) written questionnaire had been previously validated by a comprehensive study, but this had not been done in Brazil. Our objective was to validate the asthma component of the ISAAC self-applicable written questionnaire following its translation to Portuguese. A group of 10 pediatricians and 10 pediatric allergists graded the questions from 0 to 2, and established a maximum score for each question. The questionnaire was answered by parents or guardians of asthmatic children, aged 6 to 7 years old (n = 26) and of nonasthmatic control children of the same age (n = 26); and by asthmatic (n = 33) and nonasthmatic (n = 33) adolescents, aged 13 to 14 years. Half of these individuals responded to the same questionnaire after 2 to 4 weeks. This second response allowed the evaluation of the reproducibility of the ISAAC questionnaire. The maximum global score possible was 14, and cut-off levels of 5 and 6 were found for the groups of 6 to 7 and 13 to 14 year olds, respectively. There was significant agreement between the adolescents' responses to the questionnaire and those from their parents or guardians (74.3%); however, significant discordance was observed for individual questions including "wheezing with exercise." In both age periods the questionnaire was significantly reproducible (Kappa test) (6 to 7 year olds Kw = 1; 13 to 14 year olds Kw = 0.89). In conclusion, the asthma component of the ISAAC written questionnaire was proven to be reproducible, adequate and able to differentiate between asthmatics and controls. Adolescents answered the questionnaire appropriately, however the results suggest that adolescents' parents or guardians underestimate asthma symptoms which interfere little with the adolescent's daily activities.

Adolescent↗
PubMedDate not supplied

The surgical treatment of cancer of the stomach.

From 1965 to 1977, 2421 patients with gastric cancer underwent operation in our hospital. 66% were males (mean age 55.9 years) and 34% females (mean age 52.2 years); 31% had a mucosal (m) and submucosal cancer (sm); 16.8% had intramuscular cancer (pm); a curative operation was performed in 62.0% of cases. The five and ten year survival rates of the advanced cancer group are 52.5% and 42.3%, whereas in the early cancer cases they are 95.0% and 85.4% respectively. These five and ten-year survival rates are significantly lower in patients with lymph node metastasis (43.3% and 35.4%). Thirty five per cent of the patients who underwent resection from 1957 to 1963 required an enlarged total gastrectomy, compared with 15% in the present series.

Adult↗