PubMed Health⌕ Search

Biomedical subjects

C M Ross

Publications and source records attributed to C M Ross.

At least 19 recordsLinked to original sources
PubMed1997

Arranging child care.

More than half of the children in families supported by welfare are under age six, and another third are in grade school. The mothers of these children cannot leave welfare for employment unless they can find and pay for child care. Yet, as this article points out, the child care needs of these families are not easily met: Many require care for infants and toddlers, care at odd hours, and care in poor neighborhoods-all of which are scarce. Evidence reviewed by the authors indicates that problems with child care affordability, availability, and quality impede mothers from participating in the labor force and in job training programs. Recent public finding for child care subsidies has helped families leaving welfare to afford the child care they need, although the demand for financial assistance outstrips available funding. This article urges that policymakers work to facilitate access to subsidies, increase the supply of care that can meet the needs of poor working families, and guard against exposure to poor-quality care that can jeopardize both children's well-being and parents' employment.

Aid to Families with Dependent Children↗
PubMed1993

Quality control of bacterial enumeration.

Standard bacterial suspensions can be used to assess test method performance, via control charts, and inhibition of recovery when analyzing water samples. Variability in standard suspensions prepared from different strains and species and the use of frozen environmental samples for quality control for spore and bacteriophage analyses are also discussed.

Bacteria↗
PubMed1990

An evolutionary comparison of Acinetobacter calcoaceticus trpF with trpF genes of several organisms.

The deduced amino acid sequence of Acinetobacter calcoaceticus N-(5'-phosphoribosyl) anthranilate isomerase (PRAI), which is coded by trpF, was compared with TrpF of Caulobacter crescentus, Escherichia coli, Bacillus subtilis, Saccharomyces cerevisiae, Neurospora crassa, and Aspergillus nidulans. Sixty percent of identical or similar amino acids were located in alpha/beta TIM (triose-phosphate isomerase) barrels and in residues important in substrate binding and catalysis. In addition, the analysis of trpF genes presented here supports a model by which fusion between separate trpC and trpF genes arose in some cases by in-frame deletions.

Acinetobacter↗
PubMed1988

Structure of the Caulobacter crescentus trpFBA operon.

The DNA sequences of the Caulobacter crescentus trpF, trpB, and trpA genes were determined, along with 500 base pairs (bp) of 5'-flanking sequence and 320 bp of 3'-flanking sequence. An open reading frame, designated usg, occurs upstream of trpF and encodes a polypeptide of 89 amino acids which seems to be expressed in a coupled transcription-translation system. Interestingly, the usg polypeptide is not homologous to any known tryptophan biosynthetic enzyme. S1 nuclease mapping of in vivo transcripts indicated that usg, trpF, trpB, and trpA are arranged into a single operon, with the transcription initiation site located 30 bp upstream from the start of usg. Sequences centered at -30 and -6 bp upstream from the transcription initiation site are somewhat homologous to the Escherichia coli promoter consensus sequence and are homologous to sequences found upstream of genes from several organisms which are evolutionarily related to C. crescentus. Furthermore, the trpFBA operon promoter sequence lacks homology to promoter sequences identified for certain developmentally regulated C. crescentus genes. The structures of the C. crescentus usg, trpF, trpB, and trpA genes were further analyzed in terms of codon usage, G+C content, and genetic signals and were related to genetic signals previously identified in C. crescentus and other bacteria. Taken together, these results are relevant to the analysis of gene expression in C. crescentus and the study of trp gene structure and regulation.

Amino Acid Sequence↗
PubMed1988

Regulation of tryptophan biosynthesis in Caulobacter crescentus.

We present an analysis of the expression of the trpE gene and the trpFBA operon in the dimorphic bacterium Caulobacter crescentus. The catalytic activity of component I of anthranilate synthase, the product of the trpE gene, was efficiently inhibited by tryptophan, the end product of the pathway, which suggests that tryptophan biosynthesis is likely controlled at the pathway level in C. crescentus. However, trpFBA mRNA levels and trpE enzyme levels did not vary significantly in wild-type C. crescentus in response to the presence of tryptophan in the growth medium or to growth in minimal versus rich medium. This lack of regulation of the trpE, trpF, trpB, and trpA genes is consistent with the idea that oligotrophic bacteria, such as C. crescentus, do not utilize regulatory mechanisms that greatly alter the biosynthetic capabilities in exponentially growing cells. In contrast, mRNA levels from the 5'-untranslated region and the upstream gene (usg) coding region increased dramatically in C. crescentus trpD or hisB auxotrophs starved for tryptophan or histidine, respectively. Surprisingly, concomitant increases in mRNA levels were not detected from the trpF, trpB, or trpA coding regions downstream in the operon. Thus, severe starvation of C. crescentus for amino acids appears to elicit a strong, general transcriptional response that is not observed in bacteria growing exponentially in medium lacking amino acids.

Culture Media↗
PubMed1986

Revivon reaction.

Explore the source record for details and available documents.

Accidents, Occupational↗
PubMed1984

Genetic and physical analyses of Caulobacter crescentus trp genes.

Caulobacter crescentus trp mutants were identified from a collection of auxotrophs. Precursor feeding experiments, accumulation studies, and complementation experiments resulted in the identification of six genes corresponding to trpA, trpB, trpC, trpD, trpE, and trpF. Genetic mapping experiments demonstrated that the trp genes were in two clusters, trpCDE and trpFBA, and a 5.4-kilobase restriction fragment from the C. crescentus chromosome was isolated that contained the trpFBA gene cluster. Complementation experiments with clones containing the 5.4-kilobase fragment indicated that trpF was expressed in Escherichia coli and that all three genes were expressed in Pseudomonas putida. This expression was lost in both organisms when the pBR322 tet gene promoter was inactivated, indicating that all three genes were transcribed in the same orientation from the tet promoter. Thus, the C. crescentus promoters do not seem to be expressed in E. coli or P. putida. Complementation of the C. crescentus trp mutants indicated that the tet promoter was not necessary for expression in C. crescentus and suggested that at least two native promoters were present for expression of the trpF, trpB, and trpA genes. Taken together, these results indicate that C. crescentus promoters may have structures that are significantly different from the promoters of other gram-negative species.

Bacteria↗
PubMed1983

Non-Hodgkin's lymphoma in Sheffield 1971-1980.

Data from a study of 342 patients with histologically proven non-Hodgkin's lymphoma treated in Sheffield between 1970-1979 is presented. The Working Formulation for Clinical Usage (National Cancer Institute, 1982) has been applied to histology reviews. The overall 5 year survival was 34.2%. Analysis of data by two factor contingency table analysis of possible prognostic indices showed the favourable effects of low grade histology, localized extranodal staging, asymptomatic (A) status, complete response to initial therapy, high haemoglobin and normal ESR. Unfavourable markers were stage IV disease, histology other than low grade, older age, low haemoglobin and elevated ESR. One hundred and ten cases initially referred to our centre as non-Hodgkin's lymphoma were not histologically acceptable as such, one third of these showed reactive hyperplasia only. A broad spectrum of extra nodal lymphoma was seen in the series (78 patients, 23%); the commonest sites being Waldeyer's ring, gastrointestinal tract, thyroid and skin. Necropsy (50 patients) confirmed that infection, usually bronchopneumonia, in association with persistent lymphoma was the commonest cause of death.

Adult↗
PubMed1977

Blue naevi of lymph node capsule.

Blue naevi are reported for what is believed to be the first time in the capsule and fibrous trabeculae of lymph nodes. In one of the two cases that nodal blue naevus was accompanied by an ordinary blue naevus in the regional skin. These blue naevi are compared with the 'naevus-cell aggregates' in nodal capsule, the histogenesis of which is currently disputed. A developmental migratory arrest of melanocytes is thought to be the histogenetic mechanism involved in the production of these blue naevi in lymph nodes.

Adult↗