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Biomedical subjects

C H Martin

Publications and source records attributed to C H Martin.

30 records · Page 2Linked to original sources
PubMed1990

[Pre-treatment serum levels of SCC antigen in epidermoid carcinoma of the upper respiratory and digestive tract].

Results from pre-treatment SCC antigen assay were assessed in 106 patients with epidermoid carcinoma of the upper aerodigestive ways. The control population consisted of healthy blood donors (N = 61). Blood antigen levels ranged 1.6 ng/ml to 21.5 ng/ml in the patient population. 35 patients in 106 (i.e., 33% of cases) had levels considered pathological (greater than 2.00 ng/ml). Antigen levels were higher with increasing tumor size and when adenopathy was more marked (N+, N+R+). However, no correlation could be found with the T (stage)--N (histological) classification of tumors or with the site of lesion. Tumor immunologic response was obviously not uniform. Although the SCC antigen presents no diagnostic value, it appears to bear some prognostic significance, regardless of the tumoral stage. Antigen levels below 2.00 ng/ml correlate with (p less than 0.001) good immediate therapeutical results. On the other hand, serum levels greater than 2.00 ng/ml correlate either with non-sterilization, or with locoregional recurrence and/or rapid development of metastases. Other studies are required to confirm these data, and to demonstrate the value of long-term SCC antigen monitoring in these patients.

Adult↗
PubMed1988

Evolution and expression of the Sgs-3 glue gene of Drosophila.

A cluster of three glue genes is present at chromosomal site 68C in the Drosophila melanogaster genome. In this study, we have used a comparative approach to investigate both the regulation and the evolution of the largest of these three genes, Sgs-3. The homologous genes from two related Drosophila species (D. erecta and D. yakuba) have been introduced into the D. melanogaster genome by P-factor-mediated transformation. When the resulting transformant lines were assayed for expression of the introduced genes, near-normal patterns of expression were seen. This demonstrates that the cis-acting regulatory sequences of the introduced Sgs-3-homologous glue genes are capable of interacting effectively with the transcriptional machinery of D. melanogaster. We have also determined the sequences of the Sgs-3-homologous glue genes from D. simulans, D. erecta and D. yakuba. These sequences were compared and used in two ways. The first was to locate conserved sequence elements in regions known to be involved in regulation of the gene. Several such elements were found; they represent potential sites of cis-acting regulatory sequences. Second, we looked at the evolution of the glue gene protein-coding regions. A very rapidly evolving central region of the protein-coding sequences was found; this region contains a striking series of tandem repeats of a five amino acid residue sequence in all four species. Also a number of conserved aspects of the Sgs-3-homologous proteins were found; these features may be essential to their function as a glue.

Amino Acid Sequence↗
PubMed1986

Characterization of the boundaries between adjacent rapidly and slowly evolving genomic regions in Drosophila.

The site of a dramatic change in the rate of DNA sequence evolution exists near the 68C glue gene clusters of several Drosophila species. We have previously determined the approximate location of this transition site by comparison of restriction maps of the regions flanking the 68C-like glue gene cluster of five members of the melanogaster species subgroup. In the present work we report the sequence of the transition region in three of these Drosophila species: D. melanogaster, D. yakuba, and D. erecta. Using a best-fit alignment of these sequences, we find that the site of transition from slowly to rapidly evolving sequences occurs abruptly within a region less than 50 nucleotides in length. Although frequency of nucleotide substitutions changes as much as 10-fold across this boundary, frequency of small insertion/deletion events stays nearly constant.

Animals↗
PubMed1984

Adjacent chromosomal regions can evolve at very different rates: evolution of the Drosophila 68C glue gene cluster.

The 68C puff is a highly transcribed region of the Drosophila melanogaster salivary gland polytene chromosomes. Three different classes of messenger RNA originate in a 5000-bp region in the puff; each class is translated to one of the salivary gland glue proteins sgs-3, sgs-7, or sgs-8. These messenger RNA classes are coordinately controlled, with each RNA appearing in the third larval instar and disappearing at the time of puparium formation. Their disappearance is initiated by the action of the steroid hormone ecdysterone. In the work reported here, we studied evolution of this hormone-regulated gene cluster in the melanogaster species subgroup of Drosophila. Genome blot hybridization experiments showed that five other species of this subgroup have DNA sequences that hybridize to D. melanogaster 68C sequences, and that these sequences are divided into a highly conserved region, which does not contain the glue genes, and an extraordinarily diverged region, which does. Molecular cloning of this DNA from D. simulans, D. erecta, D. yakuba, and D. teissieri confirmed the division of the region into a slowly and a rapidly evolving portion, and also showed that the rapidly evolving region of each species codes for third instar larval salivary gland RNAs homologous to the D. melanogaster glue mRNAs. The highly conserved region is at least 13,000 bp long, and is not known to code for any RNAs.

Animals↗
PubMed1968

Hemolysin and peroxide activity of Mycoplasma species.

Various methods for the detection of hemolysin production by Mycoplasma species were compared. Inoculation of blood-agar by the push-block method and by use of concentrated mycoplasma cell suspensions was compared with the agar-overlay technique. The preferred method was direct surface inoculation of concentrated suspensions onto the blood-agar. Among the conditions tested, refrigeration of 48-hr cultures gave the best results. A wide variety of mycoplasma species were tested for hemolytic activity towards rabbit, sheep, guinea pig, duck, and chicken bloods. Guinea pig erythrocytes were found to be the most susceptible to lysis by mycoplasma, and rabbit erythrocytes were found to be the least susceptible. A sensitive technique for the detection of peroxide production by mycoplasma strains, employing agar containing benzidine and sheep blood, was used. With this method, peroxide production could be correlated with hemolysis on blood-agar. Peroxidase and catalase inhibited both the benzidine reaction and hemolysis. It was concluded that the major hemolysin of the Mycoplasma species examined is a peroxide.

Bacteriological Techniques↗