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Biomedical subjects

M A Costa

Publications and source records attributed to M A Costa.

At least 91 records · Page 5Linked to original sources
PubMed1992

Inhibition of Sucrose Enhancer Effect of the Potato Proteinase Inhibitor II Promoter by Salicylic Acid.

Effect of salicylic acid (SA) on the expression of the potato proteinase inhibitor (PI) II promoter was studied with transgenic tobacco plants (Nicotiana tabacum) carrying a gene fusion between the PI-II promoter and the chloramphenicol acetyltransferase (cat) reporter. As previously observed, the PI-II promoter was inducible by wounding and the promoter activity was further enhanced by sucrose. Addition of SA did not influence the wound induction of the PI-II promoter but significantly inhibited the sucrose response. The 5'-deletion mutant -573 was unable to respond to wounding but did respond to sucrose and SA. The 3'-deletion analysis indicated the presence of a sucrose-responsive element between -574 and -520. A study of the insertion mutants revealed the function of another sucrose-responsive element between -522 and -500. Enhancer effects of these sucrose-responsive elements were inhibited by SA. These studies suggest that SA inhibits PI-II promoter activity by decreasing the sucrose response. Analysis of SA-related chemicals revealed that only acetyl-SA showed a similar inhibitory effect, and other hydroxybenzoic acids had little or no effect on the sucrose enhancer activity. Therefore, it seems that the interaction between SA and the receptor molecule is specific.

Journal Article↗
PubMed1992

Identification of G-Box Sequence as an Essential Element for Methyl Jasmonate Response of Potato Proteinase Inhibitor II Promoter.

The potato proteinase inhibitor II promoter was studied to identify cis-acting regulatory sequences involved in methyl jasmonate (MJ) response using transgenic tobacco plants carrying various lengths of the promoter fused to a chloramphenicol acetyltransferase reporter gene. An internal fragment between -625 and -520 was sufficient to confer a response to MJ, wounding, or sucrose when it was placed upstream of the nos promoter -101, which contains the CAAT-TATA region. Deletion of the proteinase inhibitor II promoter sequence upstream of -611 did not affect the MJ response, but a further deletion to -573 eliminated the response. The 3'-deletion study showed that the DNA sequence downstream from -520 is dispensable. However, 3'-deletion mutant -574 did not respond to the MJ treatment. These results indicated that an element essential for the MJ response is located at the -574/-573 region where the G-box sequence (CACGTGG) is located. The G-box sequence was not required for the sucrose enhancer effect, suggesting that the MJ response mechanism is different from that of sucrose.

Journal Article↗
PubMed1992

Renal alteration and development of hypertension in diabetic rats.

UNLABELLED: There is a close association between diabetes and hypertension. Many studies have demonstrated an increased incidence of hypertension in the presence of diabetic nephropathy. The aim of the present work was to study the kallikrein-kinin system during the diabetic states with hypertension. In this study neonatal rats were injected with streptozotocin at two days of age. Plasma glucose, proteinuria, urinary kallikrein, blood pressure, creatinine clearance, diuresis and body weight were measured. RESULTS: control rats vs diabetic rats. Plasma glucose (mg/dl): 0 minutes 80.2 +/- 2.5 vs 105.5 +/- 4.5; 60 minutes 120.4 +/- 2.3 vs 220.0 +/- 4.6; 120 minutes 105.0 +/- 1.5 vs 140.0 +/- 3.6; p < 0.05. Proteinuria at 8 months of age (mg/24 hs): 12.5 +/- 1.6 vs 20.6 +/- 2.4; p < 0.05. Urinary kallikrein at 8 months of age (umol/min/24 hs)/(ml/min) x 10(3): 46.9 +/- 3.0 vs 28.5 +/- 2.5; p 0.005. Blood pressure at 8 months of age (mm Hg): 110.0 +/- 2.0 vs 132.0 +/- 4.0; p < 0.001. Creatinine clearance at 10 months of age (ml/min): 0.46 +/- 0.03 vs 0.70 +/- 0.14; p < 0.05. Diuresis at 8 months of age (ml/24 hs): 1.55 +/- 0.65 vs 10.30 +/- 1.44, p < 0.001. The early modifications of kallikrein-kinin system in the diabetes states may contribute to development hypertension with modifications in the hemodynamics renal function.

Animals↗
PubMed1991

A method for eluting DNA in a wide range of molecular weights from agarose gels.

We have developed a simple and rapid method for recovering DNAs of a wide range of molecular weights from agarose gels. A DNA-containing gel slice is placed on a Parafilm sheet in the center of a circular (positive) electrode and covered with a drop of buffer, while a linear (negative) electrode is placed on the top of the gel and driven about 1 mm into the gel itself. When a continuous current is applied, the DNA migrates into the buffer toward the circular electrode. We have obtained almost total recovery of DNAs up to 10 kb in size. Our method may also be used, under appropriate conditions, for higher molecular weight DNAs. The yield and all the biological assays performed on the DNAs obtained by our method recommend it for routine laboratory use.

DNA↗
PubMed1991

Sugar response element enhances wound response of potato proteinase inhibitor II promoter in transgenic tobacco.

The promoter region of the potato proteinase inhibitor II (PI-II) gene was studied to identify cis-acting regulatory sequences involved in sugar response using transgenic tobacco plants. The 5' control region covering an 892 nucleotide sequence upstream from the cap site and a 32 nucleotide untranslated region of the PI-II promoter was able to activate a reporter chloramphenicol acetyltransferase (cat) gene by wounding or by incubating in a sugar-free medium. This wound response was further enhanced by sugar. Hexoses, disaccharides, and some trisaccharides were strong inducers whereas pentoses, deoxy sugars, sugar acids, TCA cycle intermediates, amino acids, and other carbohydrates had little effect on the promoter activity. Deletion of the sequence between -892 and -573 abolished the wound response but not the sugar response. An additional 5' deletion to -453 removed the sugar inducibility. Locations of the cis-acting regulatory elements were further elucidated by 3' deletion analysis. Deletion of the downstream region from -520 did not affect the wound or sugar response of the promoter. However, 3' deletion mutant -574 was unable to respond to sugar but did respond weakly to wounding. Further deletion to -624 abolished both responses. Therefore, it can be concluded that a wound response element is located in between -624 and -574 and that the response is further enhanced by a sugar response element located in the sequence between -573 and -520.

Agrobacterium tumefaciens↗
PubMed1991

[Urinary acidification by furosemide test].

The aim of this study was to investigate the effect of furosemide on urinary acidification in 7 healthy children (aged 7 to 9 years) 5 patients with normokalemic distal renal tubular acidosis (RTA) (aged 4 to 13 years) and in 1 patient with proximal RTA (aged 20 months). Furosemide was given (2 mg/kg orally) as a tool to stimulate H+ and K+ secretion by enhancing Na delivery and transport in distal tubular segments. Patients with distal RTA were diagnosed by means of the ammonium chloride test and the alkaline overload and the one with proximal RTA by the ammonium chloride test only. Urinary acidification was evaluated 1 hour before and until 4 hours after furosemide administration. Healthy children (Fig. 1) showed a significant fall in urinary pH, 5.8 +/- 0.27 to 4.88 +/- 0.18 (p less than 0.02) and increase of NH3 excretion from 38.58 +/- 10.33 to 79.09 +/- 10.38 microEq/min/1.73 m2 (p less than 0.05). There was a direct correlation between urinary pH and urinary flow: r = 0.62 p less than 0.01 (Fig. 3). In patients with distal RTA (Fig. 5) furosemide failed to lower urine pH below 6 and net acid excretion persisted low: 47.9 +/- 6.1 microEq/min/1.73 m2. In the patient with proximal RTA (Fig. 4) furosemide produced the same effect as in healthy children with a fall in urine pH to 4.4 and an increase in net acid excretion to 118 microEq/min/1.73 m2. Furosemide proved to be effective to differentiate the type of RTA.(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis, Renal Tubular↗
PubMed1990

Readthrough transcription occurs at the rho dependent signal F1 TIV in suppressor cells.

Suppressor cells infected with bacteriophage f1 yield phage encoded gene IV transcripts longer than those present in the supo host and identical to those found in a rho- host. However, such longer transcripts do not appear in the suppressor-infected cell when, by changing the translation frame of gene IV, the ribosome is not allowed to proceed to the end of the gene IV message and thus to reach the rho dependent transcription terminator f1 TIV. This suggests that ribosome movement beyond the natural gene IV stop codon disturbs the activity of that termination signal. In contrast to the rho- behaviour, the suppressor does not accumulate high levels of gene IV messages indicating that the accumulation occurring in the rho- mutant may not be a primary effect of the readthrough per se.

Base Sequence↗
PubMed1990

Wound-inducible nuclear protein binds DNA fragments that regulate a proteinase inhibitor II gene from potato.

Deletion analysis from the 3' to the 5' end of the promoter region of the wound-inducible potato proteinase inhibitor IIK gene has identified a 421-base sequence at -136 to -557 that is necessary for expression. Utilizing DNA band-shift assays, a 10-base sequence within the 421-base region was found to bind a nuclear protein from wounded tomato leaves. This 10-base sequence is adjacent to an 8-base consensus sequence at -147 to -155 that is present in the promoter region of several elicitor-inducible genes from various other plants. The evidence suggests that a complex set of cis- and trans-acting elements within the -136 to -165 region of the potato IIK gene may be involved with the signaling mechanisms that regulate the inducibility of this gene in response to pest and pathogen attacks.

Base Sequence↗
PubMed1990

Nopaline synthase promoter is wound inducible and auxin inducible.

The activity of the nopaline synthase (nos) promoter is differentially regulated in several plant organs. In this article we demonstrate that the nos promoter is wound inducible in both vegetative and reproductive organs. The induction of the nos promoter was observed in leaves, stems, cotyledons, and various reproductive organs, suggesting that the response is not organ specific. The wound response was further enhanced by addition of auxins. Other growth substances had no effect on the wound-inducible nos promoter activity. Deletion analysis of the nos promoter indicated that the 10-base pair (GCACATACGT) Z element located between -123 and -114 or an element overlapping with this sequence is essential for the wound and auxin responses.

Amino Acid Oxidoreductases↗
PubMed1990

[Clinical picture of Hartnup disease. Without urine amino acids or any other identified metabolic disorder (a new entity)].

Harthnup disease clinical picture without aminoaciduria or other identified metabolic disturb (New entity?). The authors present a patient with clinical picture superposed to the Hartnup disease's, a rare, autosomic and recessive metabolic disturbance, characterized by typical aminoaciduria consequent to tryptophan and other neutral aminoacids defective transport by jejunal mucous membrane and renal tubules, clinically expressed by photosensitive pellagra-like dermatitis, mental retardation and intermittent cerebellar ataxia. The laboratorial results did not confirm Hartnup aminoaciduria nor other identified metabolic change that justify his clinical manifestations.

Child↗
PubMed1989

Effects of dietary cellulose and psyllium husk on monkey colonic microbial metabolism in continuous culture.

The effects of inoculating an in vitro continuous culture system with primate colon contents compared to fecal material, and the effect of feeding these cultures psyllium husk, a fermentable, or cellulose, a less fermentable, dietary fiber were tested. Modified 500-ml Bellco culture chambers were continuously infused with buffered medium containing vitamin mix, deoxycholate, urea, hemin, casein and mucin. Cultures were fed a mixture of minerals, sucrose, starch and either psyllium husk or cellulose twice daily. Chambers were inoculated with fecal or colonic samples obtained from adult male African green monkeys fed the respective fiber source in a purified diet for more than 3 yr. After a 5-d stabilization period, samples were collected for total viable anaerobe and aerobe counts, microbial beta-glucuronidase (EC 3.2.1.31) activity, volatile fatty acid (VFA) and ammonia nitrogen concentrations, dry matter, pH and oxidation-reduction potential. Inoculation with fecal material or colon contents produced similar results for the above mentioned characteristics; major differences were found due to the fiber treatments. Psyllium-fed cultures had lower pH (P less than 0.01) and higher VFA concentration (P less than 0.01) and beta-glucuronidase activity (P less than 0.10) than cellulose-fed cultures. The ratio of anaerobes to aerobes was lower (P less than 0.01) in psyllium-fed than in cellulose-fed cultures. These results indicate that feces can be used as an inoculum source for in vitro studies of changes in colonic microbial metabolism due to diet, and that dietary fiber source affects the colonic microbial population and metabolism.

Animals↗
PubMed1989

Effects of dietary cellulose, psyllium husk and cholesterol level on fecal and colonic microbial metabolism in monkeys.

The effect of long-term feeding of dietary fiber and two levels of cholesterol on monkey colonic microbial metabolism was studied. Three groups of African green monkeys were fed for 3.5 yr purified diets containing 9.7% cellulose or psyllium husk and 0.8 mg cholesterol per kcal or 9.7% cellulose and 0.1 mg cholesterol per kcal. Total viable anaerobe and aerobe counts, microbial beta-glucuronidase activity, volatile fatty acid and ammonia nitrogen concentrations, dry matter and pH were determined in fecal and colonic samples. Compared to cellulose, psyllium husk feeding decreased (P less than 0.05) percentage dry matter, beta-glucuronidase (EC 3.2.1.31) activity and pH, and increased (P less than 0.05) ammonia nitrogen and volatile fatty acid output in feces and in colon contents. In all groups, colonic beta-glucuronidase activity was greater (P less than 0.05) than in fecal samples. Microbial beta-glucuronidase activity, pH or percentage dry matter in the ascending colon was not different from that in the transcending or descending segments. The ratio of anaerobic to aerobic bacteria was lower in colon contents from monkeys fed psyllium husk compared to those fed cellulose. Total viable bacterial counts were lower in monkeys fed low cholesterol compared to high cholesterol diets. The results suggest that chronic intake of dietary psyllium husk resulted in greater colonic microbial metabolism compared to cellulose feeding.

Animals↗
PubMed1989

Functional analysis of the 3' control region of the potato wound-inducible proteinase inhibitor II gene.

Proteinase inhibitor genes are expressed strongly in specific plant tissues under both developmental and environmental regulation. We have studied the role of the 3' control region of the potato proteinase inhibitor II gene (PI-II) that is inducible in leaves in response to herbivore attacks or other severe wounding. Comparison of the terminator from the PI-II gene with two different terminators from the 6b and 7 genes, driven by a common PI-II promoter-cat fusion molecule, indicated that the PI-II terminator provided the most efficient expression of cat. The PI-II terminator also caused a significantly elevated cat gene expression driven by the cauliflower mosaic virus 35S promoter. The increase in the level of expression is probably not due to the presence of an enhancer element in the PI-II terminator region, but to cis-acting elements involved in mRNA processing or stability. Both transient and stable transformation analyses of the deletion mutants in the 3'-flanking sequence indicated that about a 100-base pair DNA fragment surrounding the polyadenylation site is essential for the efficient gene expression. This region seems to consist of several regulatory elements, including the conserved sequence, CGTGTCTT, which is located 9 bases downstream from the polyadenylation site. The elements appear to contribute to the increased stability of mRNAs containing the PI-II terminator.

Amino Acid Sequence↗
PubMed1988

Organ-specific and developmental regulation of the nopaline synthase promoter in transgenic tobacco plants.

Control regions of the nopaline synthase (nos) gene have been widely used to express foreign genes in plants since the promoter is active in a wide variety of plant tissues. We report here the characteristics of the nos promoter activity in transgenic tobacco (Nicotiana tabacum) plants at various developmental stages. The promoter was highly active in the lower parts of a plant and gradually decreased in the upper parts. This vertical gradient was maintained throughout plant growth until the flowering stage when the overall promoter strength decreased significantly in the vegetative organs. However, in various flower organs, the nos promoter activities increased dramatically. Higher activity was observed in calyx, corolla, and stamens although the maximum promoter activity in each organ was found at different stages of flower development. The promoter activity in pistils was low and gradually increased in the ovaries after anthesis. In developing fruits, the nos promoter activity was strongly induced during the mid-stage of embryogenesis. These results indicate that the expression of the nos promoter is developmentally regulated and organ specific in transgenic tobacco plants.

Journal Article↗
PubMed1988

Recovery of Leishmania (Viannia) braziliensis from inoculated hamsters.

Leishmania (Viannia) braziliensis has never been isolated from wild animals although it is apparently capable of inducing infections in man, dogs, and donkeys. An analysis of the standard hamster culture system for analyzing infectivity of Leishmania sp. was undertaken. Results indicate that for L. (V.) braziliensis, routine cultivation of aspirates taken from the inoculation sites of 1-mo-infected hamsters should be undertaken. Moreover, in at least 1 of the 3 strains examined, isolation of the parasite was only achieved after 84 days of cultivation.

Animals↗