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At least 73 records · Page 4Linked to original sources
PubMed1991

Stability of classification of filamentous fungi under changes in character coding strategy.

The characteristics of a number of filamentous fungal cultures were obtained from two previously published numerical taxonomic studies on Penicillium and Phoma. The coding strategies for some of the physiological and morphological properties employed in the original studies were re-examined and the data was re-coded by combining sets of characters into single ordered multistate characters. The different coding procedures were compared by generating average linkage (UPGMA) dendrograms which were in turn compared by calculating correlation coefficients between the final similarity matrices implied by these dendrograms. The character conversions had no significant effect on the final outcome of the clustering.

Mitosporic Fungi↗
PubMed1979

Coding of incremental changes in skin temperature by single warm fibers in the monkey.

1. Experiments were designed to answer the question: how well does a single warm fiber innervating the glabrous skin of the monkey's hand resolve incremental changes in the intensity of near-rectangular warming pulses applied to the fiber's receptive field? 2. In these experiments the measure of the warm fiber's capacity to resolve incremental changes in the intensity of successive warming pulses was termed the discriminable stimulus increment (DSI). The DSI is defined as that incremental difference in the intensity of a pair of warming pulses that could be resolved correctly, with a probability of 0.75, by comparing the fiber's responses to these two stimuli. In the specified conditions of the experiment, DSI = 0.67 sigma delta tau/(dR/dI) where sigma delta tau is the standard deviation of the difference in responses of the fiber to pairs of stimuli, and dr/dI is the fiber's sensitivity to incremental stimulus change. (dr/dI) was experimentally determined as the mean rate of change of the fiber's responses to incremental changes in the intensity of the warming pulse. 3. The DSI, as defined above, assumes that the basis for differentiating the stimuli in each pair was that the larger response in the fiber was in each instance generated by the more intense stimulus. A more general form of the DSI was also developed and used to examine the effects on intensity resolution of different discrimination rules that the brain might use. 4. In the experimental analysis the response measure of each warm fiber was the cumulative impulse count over successively longer segments of the stimulus period. With short integration intervals the DSI was high (i.e., intensity resolution was poor), but typically the DSI fell to a plateau level within 2.0--2.5 s of the onset of the warming stimulus. 5. The DSI was measured on 23 warm fibers in Macaca nemestrina for warming pulses with intensities of 0, 2, 4, 6, and 8 degrees C, at T-base levels of 29, 34 (near normal temperature of palmar skin), and 39 degrees C. For most observations the intensity resolution possible from the responses of single warm fibers, measured over this wide variety of stimulus conditions, was less than is achieved by the human observer trained to differentiate comparable warming pulses applied to the skin of the thenar eminence.

Adaptation, Physiological↗
PubMed1992

Dipeptidyl peptidase IV (CD 26) gene expression in enterocyte-like colon cancer cell lines HT-29 and Caco-2. Cloning of the complete human coding sequence and changes of dipeptidyl peptidase IV mRNA levels during cell differentiation.

A cDNA (DPCR1) specific for human intestinal dipeptidyl peptidase IV (DPP IV) has been isolated. This 1.7-kilobase cDNA, together with a previously published partial sequence, covers the entire open reading frame of human DPP IV plus 67 base pairs of the 3'-untranslated end. Human DPP IV is a 766-amino acid polypeptide with a high degree of homology with the rat liver protein. The characterization of this molecular probe allowed us to definitively confirm the identity of DPP IV with CD 26, a mouse thymocyte activation antigen, a conclusion strengthened by the fact that we observed identical patterns on Southern blot of human genomic DNA hybridized either with human DPP IV or mouse CD 26 cDNA probe. Using this new tool, we have investigated the expression of DPP IV during the onset of enterocytic differentiation of two cultured human colon cancer cell lines, HT-29 and Caco-2. Whatever the cell line and the culture conditions, DPP IV expression strictly correlates with the presence of a differentiated phenotype, as shown by enzyme activity and the steady state amount of the protein measured by indirect immunofluorescence and Western blot. Accordingly, DPP IV biosynthesis exclusively increases in cells that display an enterocytic differentiation. Neither the glycosylation nor the stability of the protein appear to be dependent on the state of enterocytic differentiation. The DPP IV mRNA level remains very low in undifferentiated cell populations and specifically increases in cells that undergo an enterocytic differentiation. These results strongly suggest that DPP IV gene expression is controlled at the transcriptional or posttranscriptional level during intestinal differentiation.

Amino Acid Sequence↗
PubMed1989

Twenty-year trends in mortality from chronic obstructive pulmonary disease: the Honolulu Heart Program.

There is evidence of a rising trend in COPD mortality. Whether this is due to changes in coding or diagnostic practices, increase in disease incidence or severity, or other causes is unknown. The Honolulu Heart Program (HHP) has followed a cohort of 11,136 Japanese-American men, 45 to 65 yr of age at onset, from 1965 to 1984. Following a fixed protocol, study physicians assigned cause of death after review of hospital records, pathology and autopsy reports, the death certificate, and, in doubtful cases, after interview with family and personal physician. The eighth revision of the international Classification of Diseases was used throughout. During 20 yr of follow-up, 2,624 men died, 113 from COPD by HHP coding and 105 from COPD by State Health Department (HD) coding. There was no change in age-adjusted or age-specific COPD mortality rates from 1965 to 1984 by HHP coding (tests for trend, p greater than 0.05). In contrast, when HD coding was used there was a significant decline in COPD mortality over the same time period. The frequency with which COPD was found on the death certificate decreased significantly for diagnoses listed in Section 1 and increased for those in Section 2. Current smokers showed increasing trends and past smokers decreasing trends in COPD mortality. When HHP and HD codings were compared, there was agreement in only 46% (69 of 149) of the cases. Agreement was greater in 1965-1974 than in 1975-1984. This study found no evidence of increasing mortality rates from 1965 to 1984 in this cohort of Japanese-American men.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1992

Mutagenesis induced by bacterial UmuDC proteins and their plasmid homologues.

The popular image of a world full of pollutants mutating DNA is only partly true since there are relatively few agents which can subtly and directly change base coding; for example, some alkylating agents alter guanine so that it pairs like adenine. Many more mutagens are less subtle and simply destroy coding altogether rather than changing it. Such mutagens include ultraviolet light, X-rays, DNA cross-linkers and other agents which make DNA breaks or large adducts. In Escherichia coli, mutagenesis by these agents occurs during a DNA repair process which increases cell survival but with an inherent possibility of changing the original sequence. Such mutagenic DNA repair is, in part, encoded by the E. coli umuDC operon. This article reviews the structure, function, regulation and evolution of the umuDC operon and similar genes found both in other species and on naturally occurring plasmids.

Amino Acid Sequence↗
PubMed1991

Issues in neural plasticity as related to cochlear implants in children.

There is compelling evidence across species for a changing place code during development. This change in frequency organization may provide a mechanism for all elements within the central auditory pathways to receive the necessary stimulation to promote normal growth and development. We must take these normal developmental processes into consideration when deciding on the appropriate stimulation, training, and success procedures in cochlear implants in children.

Animals↗
PubMed1984

Strategy choices by young Braille readers.

The hypotheses that in Braille learning coding strategies change with reading level, and coding differs between normal and retarded readers were tested with oddity judgments by blind children. Experiment 1 showed that strategy choices varied with reading level only in association with mental age. By contrast, shape neglect and preference for phonological strategies were shown by retarded readers rather than by matched normal readers. Experiment 2 showed that under instructions to use given coding strategies the retarded were as accurate as normal readers. Accuracy for all forms of coding increased with reading level, but coding word shape was significantly less accurate than other forms of coding, and even correct coding of shape was no faster than semantic or phonological coding. It is concluded that coding the shape of Braille words is unlikely to be a major factor in producing faster Braille reading, and retarded Braille readers differ from normal readers in their spontaneous choice of strategy rather than in the ability to use the relevant codes.

Blindness↗
PubMed1985

A change in the genetic code in Mycoplasma capricolum.

Mycoplasma capricolum was previously found to use UGA instead of UGG as its codon for tryptophan and to contain 75% A + T in its DNA. The codon change could have been due to mutational pressure to replace C + G by A + T, resulting in the replacement of UGA stop codons by UAA, change of the anticodon in tryptophan tRNA from CCA to UCA, and replacement of UGG tryptophan codons by UGA. None of these changes should have been deleterious.

Anticodon↗
PubMed1979

Evolutionary nucleotide replacements in DNA.

With the increasing availability of analytical information on mRNA molecules, it is now possible to compare homologous nucleotide sequences from different organisms and to draw conclusions about their evolution. Such comparisons have shown that silent changes in codons occur more frequently than nucleotide replacements that produce changes in amino acid sequences (code-altering changes). Furthermore, there is an important difference between amino acid sequence comparisons and nucleotide sequence comparisons. The former show only differences in amino acid residues, but the latter show several types of differences when corresponding codons are compared. Single-base replacements may be degenerate (silent) or expressed as amino acid replacements. Two-base codon changes may be degenerate, single-base changes, or be visible as such. Three-base codon changes may be degenerate (involving serine), simulate either single-base or two-base changes or be visible as such. All nine types of change are found in comparisons of genes from the viruses phi X174 and G4. The relative numbers of these nine types as based on all possible interchanges between all 61 amino acid codons were listed by Holmquist et al. and are shown in Table 1. We discuss these results in the light of the significance of nucleotide changes in molecular evolution.

Base Sequence↗