Biomedical subjects

S Kidd

Publications and source records attributed to S Kidd.

26 records · Page 2Linked to original sources

PubMed1988

Forgetting falls. The limited accuracy of recall of falls in the elderly.

To determine how accurately elderly subjects recall recent falls, we studied 304 ambulatory men and women over the age of 60 years who completed a 12-month prospective study of risk factors for falling. We developed a system of weekly follow-up and home visits to record and confirm all falls. During the study, 179 participants suffered at least one fall that was confirmed by home visit. At the end of the study, all subjects were interviewed by telephone about whether they had suffered a fall during the preceding 3, 6, or 12 months. Depending on the time period of recall, 13% to 32% of those with confirmed falls did not recall falling during the specific period of time. Recall was better for the preceding 12 months than for 3 or 6 months. There were only weak correlations (r = 0.28 to 0.59) between the number of falls that were documented and the number that the subjects recalled during each of these periods. Those with lower scores on the Mini-Mental State Examination were more likely to forget falls. We conclude that elderly subjects often do not recall falls that occurred during specific periods of time over the preceding 3 to 12 months. Researchers and clinicians should consider using methods besides long-term recall for ascertaining and counting falls over specific periods of time.

Accidental Falls↗

PubMed1987

Mutations altering the structure of epidermal growth factor-like coding sequences at the Drosophila Notch locus.

The Drosophila neurogenic protein Notch is largely composed of tandemly repeated copies of an epidermal growth factor-like sequence. Notch protein contains 36 EGF-like elements, but no two are identical. In the present study, eight mutations are correlated with single amino acid substitutions in EGF-homologous elements of this protein. Genetic analyses of the mutations and comparisons of DNA from mutant and wild-type flies indicate that differentiation of function exists among the tandemly repeated EGF-like sequences and that the total number of repeats and minor variations from the consensus repeat sequence are important for wild-type Notch protein function. One group of EGF-like repeats may be involved in the formation of functional Notch dimers or multimeric proteins. EGF-like elements in a second region of the Notch protein appear to govern its interaction with the product of Enhancer of split, another neurogenic locus of D. melanogaster.

Alleles↗

PubMed1987

Restriction of P-element insertions at the Notch locus of Drosophila melanogaster.

P elements move about the Drosophila melanogaster genome in a nonrandom fashion, preferring some chromosomal targets for insertion over others (J. C. J. Eeken, F. H. Sobels, V. Hyland, and A. P. Schalet, Mutat. Res. 150:261-275, 1985; W. R. Engels, Annu. Rev. Genet. 17:315-344, 1983; M. D. Golubovsky, Y. N. Ivanov, and M. M. Green, Proc. Natl. Acad. Sci. USA 74:2973-2975, 1977; M. J. Simmons and J. K. Lim, Proc. Natl. Acad. Sci. USA 77:6042-6046, 1980). Some of this specificity may be due to recognition of a particular DNA sequence in the target DNA; derivatives of an 8-base-pair consensus sequence are occupied by these transposable elements at many different chromosomal locations (K. O'Hare and G. M. Rubin, Cell 34:25-36, 1983). An additional level of specificity of P-element insertions is described in this paper. Of 14 mutations induced in the complex locus Notch by hybrid dysgenesis, 13 involved P-element insertions at or near the transcription start site of the gene. This clustering was not seen in other transposable element-induced mutations of Notch. DNA sequences homologous to the previously described consensus target for P-element insertion are not preferentially located in this region of the locus. The choice of a chromosomal site for integration appears to be based on more subtle variations in chromosome structure that are probably associated with activation or expression of the target gene.

Animals↗

PubMed1986

An improved filamentous helper phage for generating single-stranded plasmid DNA.

Gene cloning in plasmid vectors that contain a filamentous phage intergenic region presents several advantages. However, technical difficulties have been a problem, primarily low yields of packaged single stranded (ss) plasmid DNA from the rapid, small scale procedures usually employed, and ambiguities in sequencing reactions attributed to the contamination by helper phage ss DNA. We report here the construction and some properties of a new f1 helper phage. Using this phage, R408, plasmid ss DNA is packaged and exported preferentially over phage ss DNA, and the absolute yield of plasmid ss DNA is usually increased.

Base Sequence↗

PubMed1986

Sequence of the notch locus of Drosophila melanogaster: relationship of the encoded protein to mammalian clotting and growth factors.

The Notch locus is essential for proper differentiation of the ectoderm in Drosophila melanogaster. Notch corresponds to a 37-kilobase transcription unit that codes for a major 10.4-kilobase polyadenylated RNA. The DNA sequence of this transcription unit is presented, except for portions of the two largest intervening sequences. DNA sequences also were obtained from three Notch cDNA clones, allowing the 5' and 3' ends of the gene to be mapped, and the structures and locations of nine RNA coding regions to be determined. The major Notch transcript encodes a protein of 2,703 amino acids. The protein is probably associated with cell surfaces and carries an extracellular domain composed of 36 cysteine-rich repeating units, each of about 38 amino acids. The gene appears to have evolved by repeated tandem duplications of the DNA coding for the 38-amino-acid-long protein segments, followed by insertion of intervening sequences. These repeating protein segments are quite homologous to portions of mammalian clotting factors IX and X and to the product of the Caenorhabditis elegans developmental gene lin-12. They are also similar to mammalian growth hormones, typified by epidermal growth factor.

Amino Acid Sequence↗

PubMed1983

The Notch locus of Drosophila melanogaster.

The Notch locus appears to correspond to a 37 kb transcription unit. Homologous poly(A)+ RNA is about 11.7 kb. Nine RNA coding regions have been detected and localized within the transcription unit by S1 nuclease analyses. These range in size from 130 to 7250 bp. Sequences within the 3' coding region are variably used. Twenty-four Notch locus "point" mutations have been examined. Seven are associated with DNA insertions. Four insertions are associated with dominant mutations and are located within or very near RNA coding sequences of the 37 kb transcription unit. Three insertions are associated with recessive mutations and fall within intervening sequences. The positions of all insertions agree with the genetic map. It is estimated that, in the Notch region, one map unit corresponds to approximately 275 kb. On this basis, most of the 17 mutations that were not associated with DNA insertions can be placed within coding sequences of the 37 kb transcription unit.

Animals↗

PubMedDate not supplied

Transposon-dependent mutant phenotypes at the Notch locus of Drosophila.

Many mutations at complex genetic loci in the fruitfly Drosophila melanogaster are associated with insertions of transposable elements. At the Notch locus, members of one class of insertion-associated mutations, termed glossy-like, produce a recessive viable, smooth-eye phenotype with mottled pigmentation. Members of a second class, facet, produce a recessive viable, rough-eye phenotype with homogeneous pigmentation. Both classes of mutations fail to complement Notch lethal mutations, so they behave as Notch alleles. Here we report that each glossy-like mutation is associated with an insertion of the same transposable element (flea). Each flea insertion occurs in the same orientation, but at different locations within intervening sequences of the Notch locus. In contrast, each facet mutation is associated with insertion of a unique, non-flea, transposable element. Insertions producing a facet phenotype and insertions causing a glossy-like phenotype can break Notch intervening sequences at precisely the same location. This suggests that the type of insertion element rather than its position within an affected gene is the primary determinant of the phenotype observed.

Animals↗

PubMedDate not supplied

Antimutagenicity of phenothiazine-metal co-ordination complexes in chemically induced mutagenesis.

Phenothiazines are heterocyclic organic compounds in which nitrogen and sulfur are incorporated in the tricyclic system, and are known to have antimutagenic activity by shielding DNA-base pairs. Inorganic metals have also been intensively studied for DNA-adduct formation as potential anticancer agents. Phenothiazine, promethazine, promazine and chlorpromazine were complexed either with copper, palladium or gold. The antimutagenicity of twelve phenothiazine-metal complexes, four phenothiazines and three inorganic metals was examined on Salmonella typhimurium TA98 strain treated with a strain-specific, direct-acting mutagen, 4-nitro-o-phenylene-diamine, and the ligand-DNA interaction was analyzed by ultraviolet (UV) spectrophotometry. Phenothiazine-metal co-ordination complexes generally increased their antimutagenic activity, compared to their parent compounds, and the enhanced antimutagenicity was attributed to their interaction with DNA as evidenced by the UV spectra.

Anticarcinogenic Agents↗