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Biomedical subjects

V C Ferreira

Publications and source records attributed to V C Ferreira.

14 recordsLinked to original sources
PubMed2000

The genome sequence of the plant pathogen Xylella fastidiosa. The Xylella fastidiosa Consortium of the Organization for Nucleotide Sequencing and Analysis.

Xylella fastidiosa is a fastidious, xylem-limited bacterium that causes a range of economically important plant diseases. Here we report the complete genome sequence of X. fastidiosa clone 9a5c, which causes citrus variegated chlorosis--a serious disease of orange trees. The genome comprises a 52.7% GC-rich 2,679,305-base-pair (bp) circular chromosome and two plasmids of 51,158 bp and 1,285 bp. We can assign putative functions to 47% of the 2,904 predicted coding regions. Efficient metabolic functions are predicted, with sugars as the principal energy and carbon source, supporting existence in the nutrient-poor xylem sap. The mechanisms associated with pathogenicity and virulence involve toxins, antibiotics and ion sequestration systems, as well as bacterium-bacterium and bacterium-host interactions mediated by a range of proteins. Orthologues of some of these proteins have only been identified in animal and human pathogens; their presence in X. fastidiosa indicates that the molecular basis for bacterial pathogenicity is both conserved and independent of host. At least 83 genes are bacteriophage-derived and include virulence-associated genes from other bacteria, providing direct evidence of phage-mediated horizontal gene transfer.

Bacterial Adhesion↗
PubMed1990

The response to dietary treatment of patients with chronic post-infectious diarrhea and lactose intolerance.

The response to dietary treatment of patients with chronic post-infectious diarrhea and lactose intolerance was prospectively studied in 29 infants less than 1 year of age. All had gastroenteritis with diarrhea which persisted for more than 3 weeks. In the hospital, diarrhea continued and lactose intolerance was documented while being fed half-strength cow's milk formula. They were given dietary treatment with one of three formulas used for treatment of diarrhea in infancy. Improvement of diarrhea was more frequently achieved with Pregestimil when given as the initial therapy than with the other two formulas. With Pregestimil nine of 10 patients improved whereas only four of nine infants fed Portagen and one of 10 patients initially treated with soy formula improved. Pregestimil was also effective in three of five patients who initially failed to improve with Portagen and in four of eight patients tried with soy formula with or without carbohydrate. Additionally, in the patients who improved, recovery was more rapidly achieved with Pregestimil than with the other two formulas. Formula failures were due to intolerance to glucose polymers in three patients, possibly to protein in seven infants, and an intolerance to all nutrients in five patients. The improvement of the diarrhea was slower in patients who had evidence of colitis in rectal biopsies regardless of the dietary treatment given, but was not correlated with other variables, i.e., etiology of diarrhea, jejunal histology, or duration of diarrhea prior to treatment. However, as a group, the patients who failed to respond to Pregestimil were younger (less than 3 months of age), had more formula changes and associated infections, and were given more antibiotics; they also had more prolonged diarrhea before treatment and more severe jejunal mucosal lesions and jejunal bacterial overgrowth. The data suggests that Pregestimil seems to be the most effective formula for the treatment of infants with chronic post-infectious diarrhea and lactose intolerance.

Age Factors↗
PubMed1989

Rotavirus identification in jejunal juice and stools of acute and chronic forms of infantile gastroenteritis.

1. The present study investigates, by means of a combined enzyme immunoassay for rotaviruses and adenoviruses (EIARA), the occurrence of rotaviruses in stools and jejunal juices from 31 children with acute diarrhea and 18 with chronic diarrhea. 2. Stools from 8 acute cases contained rotaviruses (26%). In two of these cases rotaviruses were also detected in the jejunal juice. 3. In the chronic diarrhea group we identified rotaviruses in the stools of one patient and in the jejunal juice of another. 4. Some of the electropherotypes of the rotaviruses identified showed different patterns of RNA migration. 5. Abnormalities of the jejunal mucosa were characterized in 6 acute rotavirus-positive cases. No morphological or functional abnormalities of the intestinal mucosa were observed in the chronic diarrhea rotavirus-positive cases.

Diarrhea, Infantile↗
PubMed1988

Genetic regulation of multispecific antibody responsiveness: improvement of "high" and "low" characters.

The five selections carried out in the mouse for high or low antibody responsiveness to various multideterminant immunogens were successful. In all cases the large interline difference was shown to result from the additive effects of several independently segregating loci (polygenic regulation). However, important peculiarities were demonstrated in these original selections concerning either the cellular mechanisms operating or the effect of the selected genes on antibody responses to antigens unrelated with those used for the selection (multi-specific effect). In an attempt to improve and generalize the effect of selection, the 5 high and the 5 low lines were inter-crossed to obtain populations with a balanced proportion of the 5 genomes. These two populations were then submitted to selective breedings in which the phenotypic character was the weighted responses to pluri-antigen immunization. The data obtained in 16 consecutive generations of two selective breedings (general-primary, GP and general-secondary, GS, responses) carried out from these populations are reported. The genetic parameters of the response to GP and GS selections are compared with those obtained in the original selections. The final result of both GP and GS selections demonstrate a marked improvement of the high and low antibody production traits, both quantitatively (interline divergence) and qualitatively (multi-specific effect). The success of GP and GS selections agrees with the concept that distinct groups of genes are preferentially affected by selection according to the nature of the selection antigen and the immunization procedure.

Analysis of Variance↗
PubMed1986

Genetics of antibody responsiveness to bovine serum albumin and rabbit gamma-globulin. I. Genetic analysis of high and low responder lines of mice produced by selective breeding.

The selective breeding for antibody production against bovine serum albumin (BSA) and rabbit gamma-globulin (RGG) induced a large modification in responsiveness in the high (Hv) and low (Lv) responder lines at selection limit. The total response to selection (RT) was 9.0 log2 for BSA and 8.4 log2 for RGG. This gives an interline difference of 500-fold and 337-fold respectively in terms of passive agglutinin titres. For BSA responsiveness, there is, in F1 interline hybrids, an incomplete dominance effect of the low character (-0.41) and a marked maternal effect. Complete dominance effect of high character (1.08) without any maternal effect is observed for responses to RGG. The phenotypical variability of BSA responses in F2 segregants is due 60% to genetic factors and 40% to environmental effects. Such a distribution cannot be achieved for RGG responsiveness. Both responses to BSA and RGG are controlled by the additive effect of several independent loci (polygenic regulation). One of these genes is linked with the H-2 locus. The H-2 linked gene accounts for 29% of the total interline difference for response to BSA and only 11% for response to RGG. Experiments carried out to measure the reciprocal nonspecific effect of BSA and RGG responses failed to give clear-cut results. This important phenomenon will be the subject of the companion article.

Animals↗
PubMed1986

Genetics of antibody responsiveness to bovine serum albumin and rabbit gamma-globulin. II. Evidence for a partially common genetic regulation of response to bovine serum albumin and rabbit gamma-globulin.

In order to measure the reciprocal nonspecific effect of the genetic regulation of antibody responsiveness to bovine serum albumin (BSA) and rabbit gamma-globulin (RGG), two independent bidirectional selective breedings for responses to these two antigens were carried out: selection V/BSA and selection V/RGG respectively. The total interline separation at selection limit (RT) was 5.3 log2 for selection V/BSA and 2.6 log2 for selection V/RGG. The sum of these two values (7.9 log2) is similar to the RT in selection V carried out by alternating these two antigens in consecutive generations. In selection V/BSA, the nonspecific effect for responsiveness to RGG was 72%. In selection V/RGG, the nonspecific effect for BSA responsiveness was 135%. The F1 hybrids between homologous lines of selection V/BSA and selection V/RGG presented a larger difference in antibody response to both antigens than their parental lines. This demonstrates an additive effect of the loci controlling the two responses.

Animals↗
PubMed1985

Effect of genetic modification of antibody responsiveness on resistance to Toxoplasma gondii infection.

Resistance to Toxoplasma gondii infection was studied in the high (H/f) and low (L/f) antibody responder lines of mice that were selected on the basis of quantitative antibody responsiveness to the flagellar antigen of Salmonella (selection III). No interline difference was observed in resistance to a highly virulent strain of T. gondii. In contrast, H/f mice were much more resistant than L/f mice to a moderately virulent strain of T. gondii: a 5000-fold difference in terms of the 50% lethal dose was found. The degree of resistance in (H/f X L/f)F1 hybrids was intermediate compared with that in parental lines for both mortality and survival time. The antibody titers to Toxoplasma antigens measured during the course of the infection were significantly higher in H/f than in L/f mice. This interline difference was underestimated because parasite multiplication occurs faster in L/f mice, which increases antigenic stimulation. The stronger resistance of H/f mice is probably due to their higher capacity of antibody production in the course of infection.

Animals↗
PubMed1983

Inverse modification of antibody responsiveness to RGG in lines of mice selected for high or low responses to somatic antigen of Salmonella.

High (H/s) and low (L/s) antibody responder lines of mice selected according to their response to the somatic (s) antigen of Salmonella (Selection IV) have unexpected inverse capacity for antibody production to rabbit gamma globulin (RGG): H/s mice are low or even nonresponders to this antigen, whereas L/s mice are high responders. It was shown that the phenotypic variability within each line is due to environmental factors. RGG was a selection antigen in Selection V; the high (H/p) and low (L/p) responder mice are therefore considered as homozygous for the RGG genes. Responsiveness to RGG was investigated in F1 and F2 hybrids obtained by crossing the phenotypically similar RGG responder or nonresponder mice of Selections IV and V. The results support the hypothesis that the same genes control the response to RGG in L/s and H/p lines as well as in H/s and L/p lines. This means that the genes specific for RGG responsiveness were independent from those regulating responses to the s antigen. Unaffected by the selective breeding in Selection IV, they have been fixed by chance in an inverse way in H/s and L/s lines.

Animals↗
PubMed1982

Genetic parameters of the polygenic regulation of antibody responsiveness to flagellar and somatic antigens of salmonellae.

Selective breedings of mice were carried out for quantitative antibody responsiveness to flagellar Ag., f (Selection III) or somatic Ag., s (Selection IV) of two non cross-reacting Salmonellae (Salm. tm., Salm. or.) alternated for immunization of consecutive generations. At the selection limit, these selections produced homozygous high (H) and low (L) responder lines for the character investigated: peak agglutinin response to optimal secondary immunization. The responsiveness to both f and s Ags. is submitted to polygenic regulation. The heritability (h2) realized during the selective breeding was 0.37 +/- 0.07 for the response to fAg. and 0.40 +/- 0.1 for the response to s Ag. The respective part of genetic and environmental variance in F2 hybrids was 64% and 36% in selection III and 61% and 39% in selection IV. In the two selections, the dominance variance is negligible (less than 1%), therefore the genetic variance is essentially additive. The additive variance calculated as the heritable fraction of the F2 hybrid variance is somewhat lower, the reason for this difference is discussed. The quantitative antibody response to f Ag. in selection III is controlled by about seven independent loci. The antibody response to s Ag. in selection IV is controlled by about four independent loci. A possible association of relevant genes with the H-2 locus was investigated. In selection III, no significant participation if H-2 linked genes, in the regulation of responses to f and s Ags. of Salm. tm and Salm. or. could be demonstrated. In selection IV a partial contribution of H-2 linked genes was observed concerning responsiveness to both f and s Ags. of Salm. tm. but not Salm. or. Ags. The H-2 effect accounts for 25% of the total interline difference.

Agglutinins↗
PubMedDate not supplied

Effect of silica on the genetic regulation of antibody responsiveness.

The high (H) and low (L) antibody responder lines of mice produced by selective breeding are characterized by different modifications in immunocompetent cell potentialities, according to the immunization procedure used for the selection process. In selections I and II, the difference in antibody responsiveness between H and L lines was clearly shown to depend mainly on macrophage function: the more rapid catabolism of antigens in L mice was the main cause of the low antibody production. In contrast, up to now, no difference has been observed between H and L mice of selections III and IV in terms of the macrophage accessory role. The administration of silica particles has a well known impairment effect on macrophage activity. Therefore, the effect of silica injection on the kinetics of antibody responses to selection antigens was compared in H and L mice of the four selections. Silica was given either intravenously or locally in one hind footpad 6 or 24 h before immunization by the same route. Silica treatment consistently improved antibody responsiveness in the L mice of selections I and II, but had no effect in the L mice of selections III and IV. The antibody responses of the H lines of the four selections were not substantially modified by silica injections. Therefore, the silica treatment reduced the interline difference in antibody responses in selections I and II only, by interfering with the expression of the genetic modification of macrophage activity. However, a similar effect was not obtained with other substances known to affect macrophages, including dextran sulphate or carrageenan. The results reported here are in agreement with the above-mentioned statement that the genetic modification of macrophage function plays a major role in the interline difference in selections I and II and is not involved in selections III and IV.

Animals↗
PubMedDate not supplied

[Actinic lesions: computed tomography features].

The authors emphasize the importance of knowing, understanding and identifying the radiation-induced changes in various body organs by radiologists in order to distinguish them from residual or recurrent malignancies. Computed tomography enables the evaluation of the effects and complications of the radiation therapy, besides other image modalities, and its findings are outlined. The clinical correlation, mainly with the time elapsed between the treatment and the examination is very important to establish the diagnosis.

Child↗