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D Galli

Publications and source records attributed to D Galli.

30 records · Page 2Linked to original sources
PubMed1992

Transcriptional control of sex-pheromone-inducible genes on plasmid pAD1 of Enterococcus faecalis and sequence analysis of a third structural gene for (pPD1-encoded) aggregation substance.

The expression of several neighbouring genes on plasmid pAD1 that are necessary for conjugation depend on induction with sex pheromone cAD1. Analyses of transcripts by Northern blot hybridization demonstrated that the genes sea1 (encoding surface exclusion protein) and asa1 (encoding aggregation substance) are transcribed independently. Both genes are organized in different operons together with neighbouring open reading frames of unknown function. Several transcripts could be identified for sea1 and asa1. Their transcriptional start sites were determined by primer extension experiments, confirming the results of the Northern blot experiments. We also could identify sea1- and iad- (encoding an inhibitory peptide counteracting sex pheromone cAD1) specific transcripts which are expressed constitutively, but to a lower extent relative to induced conditions. In addition, we localized the asp1 gene coding for aggregation substance of sex pheromone plasmid pPD1 and determined its DNA sequence, which was found to be highly homologous to asa1 (aggregation substance gene of pAD1) and prgB (aggregation substance gene of pCF10). The structural genes were found to be organized more or less identically on the three sex-pheromone plasmids pAD1, pCF10, and pPD1, and to be highly conserved. Regions supposed to be of crucial importance for regulatory functions, however, were found to differ. We also could identify some conserved DNA motifs which might be potential target sites for transcriptional regulators. In combination these data allowed us to formulate a model for the regulation of sex-pheromone-inducible genes of plasmid pAD1. Its main statement is that only in the presence of cAD1 can the gene traE1 be transcribed. The positive regulatory factor TraE1 then can trigger expression of the structural genes sea1 and asa1.

Amino Acid Sequence↗
PubMed1992

[Intestinal volvulus in pregnancy].

Intestinal occlusion is a rare pathologic event during pregnancy occurring mostly in the second and third trimenon when increased volume of the uterus and the consequent displacement of abdominal organs cause complications of pathologies which would otherwise escape notice, such as intestinal adhesions, to become manifest. Diagnosis is difficult for a number of reasons. Vomiting during the first trimenon and mild abdominal pain during the third are often neglected or considered to be part of the normal course of pregnancy; pain is sometimes referred to atypical sites due to the displacement of abdominal organs; in other cases, the high endorphin tonus is apt to reduce the customary defence reaction. All this should not cause time to be lost, and whenever intestinal occlusion is suspected all the necessary diagnostic procedures must at once be carried out and appropriate therapy must speedily be started so as to reduce the risk of mortality and morbidity for mother and fetus. Management of ileus in pregnancy is identical to that for the non pregnant woman, except for the need to empty the uterus in cases in which it prevents treatment or if the fetus has reached a sufficient degree of pulmonary maturity. The paper describes a case of ileal volvulus and revisits the literature analyzing the diagnostic and therapeutic options suggested.

Adult↗
PubMed1991

Comparative analysis of Enterococcus faecalis sex pheromone plasmids identifies a single homologous DNA region which codes for aggregation substance.

An analysis of the 11 known sex pheromone plasmids of Enterococcus faecalis was performed by DNA-DNA hybridization. Plasmids pAD1, pJH2, and pBEM10 turned out to be closely related, whereas pAM373 showed only weak homology with pAD1. A comparison of the hemolysin/bacteriocin determinants of pAD1, pJH2, and pOB1 revealed strong similarities at the DNA level. Our main finding was that one DNA region is conserved among all sex pheromone plasmids, with pAM373 again being an exception; for pAD1 this region was shown earlier to code for aggreagation substance. Detailed hybridization studies of the genes for this plasmid-coded adhesin, which is responsible for cell-cell contact during conjugative transfer via the so-called sex pheromone system of E. faecalis, support the idea of their common origin.

Adhesins, Escherichia coli↗
PubMed1990

Sequence analysis of Enterococcus faecalis aggregation substance encoded by the sex pheromone plasmid pAD1.

The location of the structural gene for aggregation substance on the sex pheromone plasmid pAD1 of Enterococcus faecalis was determined using an oligonucleotide deduced from the N-terminal amino acid sequence of the purified protein. The nucleotide sequence was determined for the corresponding region and two open reading frames (ORFs) could be identified. ORF1 codes for a small (Mr 13,160) acidic protein of unknown function. The gene for aggregation substance (named asa1) was found to code for a protein of 1296 amino acids (Mr 142,248). The protein has a signal peptide of 43 amino acids (the resulting Mr for mature aggregation substance is 137,429) and contains in its C-terminal region a proline-rich sequence, previously characterized as being involved in cell wall association, which is followed by a membrane anchor. The membrane anchor showed significant similarity to that of other Gram-positive organisms, but no other similarities to surface proteins from Gram-positive bacteria were found. In particular, no repeats on the DNA or protein level could be detected for pAD1-specific aggregation substance. The protein contains the amino acid motifs Arg-Gly-Asp-Ser and Arg-Gly-Asp-Val (once each), which, it is proposed, play a crucial role in adherence to eukaryotic cells.

Amino Acid Sequence↗
PubMed1989

Identification of aggregation substances of Enterococcus faecalis cells after induction by sex pheromones. An immunological and ultrastructural investigation.

The sex pheromone system of Enterococcus faecalis is responsible for the clumping response of a plasmid carrying donor strain with a corresponding plasmid free recipient strain due to the production of sex pheromones by the recipient strain. The clumping response is mediated by a surface material (called aggregation substance) which is synthesized upon addition of sex pheromones to the cultures. Here we show that after induction a dense layer of "hairlike" structures is formed on the cell wall of the bacteria. These hairlike structures are responsible for the cell-cell contact which leads to the aggregation of cells. Formation of these structures was specific, only occurring after the addition of homologous sex pheromone.

Biological Factors↗
PubMed1989

Localization of aggregation substances of Enterococcus faecalis after induction by sex pheromones. An ultrastructural comparison using immuno labelling, transmission and high resolution scanning electron microscopic techniques.

The distribution of sex pheromone induced aggregation substance was studied on the cell surface of various Enterococcus faecalis strains. In the accompanying paper we have shown that the aggregation substance appears as a layer of hairlike structures. Using direct and indirect immunogold technique, transmission electron microscopy and high resolution scanning electron microscopy we investigated the appearance and distribution of the aggregation substance. The "hairs" increase in number with increasing exposure to sex pheromones (maximum density: 1300/microns2). We show that these structures are unequally distributed over the cell surface, even if the cells were induced by sex pheromones for a long period of time. Statistical analysis of the unequal distribution indicates that aggregation substance is incorporated into pre-existing "old" cell-walls and that this incorporation shows a saturation ca. 40 min after addition of sex pheromones.

Biological Factors↗
PubMed1987

Fecal neutral steroids in normal conditions and in patients with polyps or cancer of the large bowel.

There is evidence suggesting that the excretion and conversion of neutral sterols in the human large bowel might be somewhat related to the development of colorectal cancer. Therefore, our objectives were: to characterize the excretion and the major pattern of sterol degradation in normal conditions, both in children and in adults; and to investigate if abnormalities of these parameters are frequent in patients with colorectal cancer or polyps. The study has been carried out in: 38 adult volunteers; 29 children divided into 4 age groups; 22 patients with colorectal cancer; 16 members of 6 families with adenomatosis coli; 15 members of 2 families with a high prevalence of multiple polyps or cancer of the large bowel; 12 subjects with colorectal polyps without familiality. With the subjects kept under metabolic control, fecal samples were collected for at least 3 days and analyzed by thin layer chromatography and gas-liquid chromatography. Total neutral steroid excretion was lower in children than in adult volunteers; in contrast, there was no significant difference between the latter and the other investigated group of patients with cancer or polyps, with values ranging between 230 and 680 mg/day. All the adult volunteers were "high converters" of cholesterol to its intestinal metabolites coprostanol and coprostanone [89 +/- 10% (SE) of degradation]. Children less than 1 year old degraded little or no cholesterol (10.4 +/- 6% of total neutral sterols), whereas with increasing age the fraction of conversion became more similar to that of adults. In patients with colorectal tumors 2 populations could be defined, one characterized by a large degradation of cholesterol and the other by little or no conversion. Low degradation of cholesterol was found in 3 of 6 families with adenomatosis coli. In conclusion, we did not find any significant difference in total neutral sterol excretion among controls, colorectal cancer patients, or subjects at risk. In adult volunteers the normal pattern of cholesterol degradation is characterized by a large conversion of cholesterol to its intestinal metabolites. In children this process changes with increasing age from an absolute "nonconverter" state (after birth) to the pattern typical of adults. Finally, in a minority of patients with either polyps or cancer of the large bowel and of their first-degree relatives, cholesterol is poorly degraded and represents the most abundant fecal sterol.

Adolescent↗
PubMedDate not supplied

Biological monitoring of human exposure to acephate.

Acephate is a water-soluble organophosphate insecticide whose action on insects has been related to its conversion to methamidophos, a very potent anticholinesterase agent which has caused delayed neuropathy in man. Inhalation and skin exposure to acephate was evaluated in four workers engaged in 8-day campaigns with the formulation of the 97%-pure technical product. Before, during, and after exposure, the workers were monitored for the urine content of acephate and methamidophos, and for erythrocyte (AChE) and plasma (PChE) cholinesterase levels. Median air concentrations (8-hr TWA) ranged from 0.278 to 2.170 mg/m3; median total-body skin deposition ranged from 26.1 to 41.9 mg/day. Based on these values, daily workers' absorption of acephate was estimated to be in the order of 10-20 mg. Urinary excretion of unchanged acephate followed a pattern consistent with exposure, showing peak values of excretion during the workshift or in the eight hr after the end of the workshift. The urine levels of unchanged acephate were found to vary from 1 to 10 mg/L. Methamidophos was not detected in any urine sample (detection limit: 30 micrograms/L). High correlation (r = 0.78) was found between skin exposure level and urine acephate elimination. No changes in AChE or PChE were observed for the workers whose urinary concentrations of acephate were 1 or 2 mg/L. One subject who had urinary acephate excretion between 3 and 8 mg/L, showed slightly decreased values of PChE during exposure and of AChE after exposure.

Agricultural Workers' Diseases↗
PubMedDate not supplied

[Validity of the H2 breath test and limits of blood xylose in the evaluation of malabsorption in children].

Many authors have recently discussed the real value of the xylose test in the evaluation of intestinal malabsorption, especially its correlation with the morphological damage of the duodenal-jejunal mucosa. In our study we have performed in 48 pediatric patients one-hour blood xylose test and breath H2 test, method used for the diagnosis of sugar malabsorption, in order to value small bowel function and to know indirectly small intestinal mucosal structure. We have compared the values of the xylose test with those of the breath H2 test and both with hystological findings. The D-xylose absorption test was performed using the technique described by Roe and Rice. A serum concentration of more than 25 mg/dl was considered normal. For the breath H2 test the technique described by Douwes was used. A hydrogen concentration lower than 20 p.p.m. in expired air was considered normal. All of the patients in whose breath hydrogen was not detected after lactose oral load (2g/Kg body-weight, maximum 50 g), underwent a second test with lactulose (0,8 - 1 g/Kg body-weight), is not absorbed. We performed this test to rule out a false negative result (2% of the normal population). On histologic criteria, the patients were assigned to one of three study groups. Group I: normal duodenal-jejunal mucosal structure (11 patients). Group II: structural abnormalities not diagnostic of celiac diseases (7 patients). Group III: mucosal structural abnormalities typical of celiac disease (30 patients). In the first group the one-hour blood xylose test was normal in 9 patients (81.81%), whilst the breath H2 test was normal in 11 patients (100%).(ABSTRACT TRUNCATED AT 250 WORDS)

Breath Tests↗