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Biomedical subjects

S Somma

Publications and source records attributed to S Somma.

9 recordsLinked to original sources
PubMed2004

PCR identification of durum wheat BAC clones containing genes coding for carotenoid biosynthesis enzymes and their chromosome localization.

Carotenoids are essential components in all plants. Their accumulation in wheat seed determines the endosperm colour, which is an important quality trait in wheat. In this study, we report the isolation of BAC clones containing genes coding for three different enzymes of the carotenoid biosynthesis pathway: phytoene synthase (PSY), phytoene desaturase (PDS), and zeta-carotene desaturase (ZDS). Primers were designed on the basis of wheat ESTs similar to the sequences of these three genes in other species, and used to screen a BAC library from Triticum turgidum var. durum (2n = 28, genomes AABB). Eight, six, and nine 384-well plates containing at least one positive clone were found for PSY, PDS, and ZDS, respectively. BACs selected for each of these genes were then divided in two groups corresponding to the A and B genomes of tetraploid wheat, based on differences in the length of the PCR amplification products, conformation-sensitive gel electrophoresis (CSGE), or cleavage amplification polymorphisms. Positive clones were then assigned to chromosomes using a set of D genome substitution lines in T. turgidum var. durum 'Langdon'. PSY clones were localized on chromosomes 5A and 5B, PDS on chromosomes 4A and 4B, and ZDS on chromosomes 2A and 2B. The strategies used for the PCR screening of large BAC libraries and for the differentiation of BAC clones from different genomes in a polyploid species are discussed.

Alkyl and Aryl Transferases↗
PubMed1991

Malignant melanoma.

The incidence of malignant melanoma is increasing faster than that of any other cancer except lung cancer in women. Understanding malignant melanoma and recognizing suspicious lesions is critical in curtailing the spread of this potentially fatal disease.

Female↗
PubMed1984

Teicoplanin, a new antibiotic from Actinoplanes teichomyceticus nov. sp.

Teicoplanin, a new glycopeptide antibiotic belonging to the same family as vancomycin, inhibits cell wall synthesis in Bacillus subtilis; the inhibition is accompanied by an intracellular accumulation of UDP-N-acetyl-muramyl-pentapeptide. A cell-free system from Bacillus stearothermophilus, capable of synthesizing peptidoglycan, is 50% inhibited by teicoplanin at 40 micrograms/ml and 100% inhibited at 100 micrograms/ml; suppression of peptidoglycan synthesis is accompanied by parallel accumulation of the lipid intermediate. Teicoplanin binds to cell walls and forms a complex with N,N'-diacetyl-L-lysyl-D-alanyl-D-alanine. The association constant of this complex is 2.56 X 10(6) liters mol-1, calculated by spectrophotometric titration. The mechanism of action of teicoplanin is discussed in comparison with those of other inhibitors of cell wall biosynthesis, namely, vancomycin, ristocetin, and gardimycin.

Acetylglucosamine↗
PubMed1984

7-(D,L-alpha-fluoro-2-thienylacetamido)cephalosporanic acid (L 14655), a new semisynthetic cephalosporin. Synthesis and preliminary biological evaluation.

We describe the synthesis and some preliminary antimicrobial and enzymatic properties of 7-(D,L-alpha-fluoro-2-thienylacetamido)cephalosporanic acid (L 14655), a fluorinated derivative of cephalothin. L 14655 had antimicrobial activity similar to that of cephalothin. Cell-free studies demonstrated that L 14655 was very stable to hydrolysis by type Ia beta-lactamase (325 times more than cephalothin) but not to TEM enzyme. In addition, L 14655 was 480 times more active than cephalothin in preventing the hydrolysis of nitrocephin by type Ia enzyme. Preliminary studies in intact beta-lactamase-producing cells did not however produce evidence of enhanced activity of L 14655 relative to cephalothin.

Anti-Bacterial Agents↗
PubMed1984

Inhibitory activity and resistance to hydrolysis by beta-lactamases of some (D,L)-7-(alpha-fluoroacylamino)cephalosporins.

The synthesis of a series of (D,L)-7-(alpha-fluoroacylamino)-cephalosporanic acids are described. In vitro antimicrobial activity was determined in comparison with the corresponding non-fluorinated compounds. None of them were found to be better than clinically used cephalosporins. Resistance to and inhibition of beta-lactamases from gram-negative organisms were also determined. All the fluorinated derivatives were found to be as resistant to hydrolysis by Escherichia coli R+TEM beta-lactamase as the corresponding non-fluorinated compounds, but resulted more resistant (from 2.3 to 61.2 times) to Enterobacter cloacae 214 beta-lactamase. Title compounds were also found to be better inhibitors of E. cloacae 53 and E. cloacae 214 beta-lactamases than the related non-fluorinated cephalosporins.

Bacteria↗
PubMed1977

Gardimycin, a new antibiotic inhibiting peptidoglycan synthesis.

Gardimycin, a new antibiotic, at 100 mug/ml, specifically inhibited cell wall synthesis and induced accumulation of uridine 5'-diphosphate-N-acetylmur-amylpentapeptide in whole cells of Bacillus subtilis. The antibiotic was active in a particulate enzyme preparation from Bacillus stearothermophilus: 60 mug/ml caused 50%, and 200mug/ml caused 100%, inhibition of peptidoglycan synthesis. Suppression of peptidoglycan synthesis was accompanied by parallel accumulation of the lipid intermediate. This mechanism of action is discussed in comparison with those of other antibiotics that are known to inhibit bacterial cell wall biosynthesis.

Anti-Bacterial Agents↗
PubMed1970

Quantitive autoradiographic study of competence and deoxyribonucleic acid incorporation in Bacillus subtilis.

The relationships among deoxyribonucleic acid (DNA) uptake, transformation, and autoradiographic labeling were investigated. It is shown that: (i) autoradiography is a good method for measuring the total fraction of competent cells able to incorporate transforming DNA; in our best experiment that fraction was 11.5%. (ii) Computation of the fraction of competent cells in a culture of Bacillus subtilis, by comparing the frequencies of single and double transformants for two unlinked markers, gives values which are somewhat different from those obtained by auto-radiography. (iii) On the average, a competent cell of B. subtilis irreversibly takes up from 0.9 x 10(-10) to 1.4 x 10(-10) mug of DNA; this amount represents about 1/55 to 1/35 of the bacterial chromosome weighing 5 x 10(-9) mug, and corresponds to three to six DNA molecules having a molecular weight of 1.6 x 10(7).

Autoradiography↗
PubMedDate not supplied

Analysis of Q fever in Uruguay.

The first outbreak of Q fever in Uruguay occurred in 1956. The infection, which is caused by Coxiella burnetti, occurs in sheep, cattle, swine, and horses, but not in fowl or guinea pig. Most of the cases studied have been traced to cattle. Fourteen outbreaks of this disease were studied between 1975 and 1985. All of the 1,358 clinically suspected cases (814 serologically confirmed) reported in Uruguay occurred in workers at meat-processing plants. Diagnoses of cases and serologic surveys were made by use of complement fixation, capillary agglutination, and layer microagglutination techniques.

Agglutination Tests↗