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J Blanco

Publications and source records attributed to J Blanco.

At least 289 records · Page 16Linked to original sources
PubMed1987

Differential transcription of Xenopus oocyte and somatic-type 5 S genes in a Xenopus oocyte extract.

We have measured the transcription of Xenopus laevis oocyte and somatic-type 5 S RNA genes in S-150 extracts prepared from ovaries of mature X. laevis females (Glikin, G. C., Ruberti, I., and Worcel, A. (1984) Cell 37, 33-41). We find that somatic-type 5 S genes are transcribed at least 40-fold more efficiently than oocyte-type 5 S genes. Since adenovirus VA, Xenopus OAX, and Xenopus tRNAMet genes are all transcribed at levels similar to that of the somatic-type 5 S gene, this difference reflects a low level of oocyte-type 5 S gene transcription. Somatic-type 5 S transcription is a linear function of somatic-type 5 S DNA concentration and this, together with the efficient transcription of other class III genes, suggests that RNA polymerase III and the general class III transcription factors are not limiting under the conditions used here. Moreover, the 5 S gene-specific transcription factor TFIIIA does not limit transcription under these conditions as preincubation with purified TFIIIA does not alter transcription of either gene, and both genes exhibit characteristic TFIIIA footprints under transcription conditions in the S-150. Somatic-type 5 S DNA incubated in the S-150 and then injected into oocyte nuclei is actively transcribed whereas oocyte-type 5 S DNA treated in the same manner is inactive. We conclude that factors in the S-150 distinguish between somatic and oocyte-type 5 S genes, assembling active complexes preferentially on the former and inactive complexes preferentially on the latter. This process is not explained by binding properties of transcription factors for these genes as currently understood and represents a previously unrecognized mechanism of transcriptional regulation of the Xenopus 5 S genes.

Animals↗
PubMed1987

A method for detecting protein-DNA interactions at sites of chromatin replication.

Two versions of an approach to identify DNA-protein interactions at sites of DNA replication in HeLa cell nuclei are described. In this procedure, newly replicated DNA chains are first labeled and photosensitized in vitro by the incorporation of [alpha-32P] dCTP and bromodeoxyuridine triphosphate, respectively. Irradiation with ultraviolet light is then used to covalently crosslink the proteins that are adjacent to the photosensitized and isotopically labeled strands of newly replicated DNA. After the bulk of the DNA is digested with nucleases, the crosslinked proteins--marked by short covalently linked radioactive DNA tags--are fractionated by electrophoresis in sodium dodecyl sulfate-polyacrylamide gels and detected by autoradiography. With this technology, certain proteins have been shown to associate selectively with newly replicated DNA. The method appears adaptable for application to a variety of problems involving DNA-protein association.

Chromatin↗
PubMed1987

Epidural analgesia for post-caesarean pain relief: a comparison between morphine and fentanyl.

In 20 post-operative patients who had undergone caesarean section, morphine 2 mg or fentanyl 75 micrograms in 0.9% saline were given epidurally in a randomized study, to compare their effectiveness in providing post-operative pain relief and the incidence of untoward reaction. There was a faster onset of action (P less than 0.01) and the quality of pain relief was substantially better after epidural fentanyl (P less than 0.01). However, the duration of action was markedly longer after epidural morphine (P less than 0.01). There was a significantly greater incidence of urinary retention after morphine administration (P less than 0.05). It is suggested that fentanyl gives better relief of pain than morphine when given epidurally.

Analgesia↗
PubMed1987

Structure of the piriform cortex of the adult rat. A Golgi study.

The piriform cortex (PC) was studied in the adult rat with anilines, rapid Golgi and Golgi-Colonnier techniques. As in other animals in the PC of the adult rat three layers can be distinguished: layer I or plexiform layer, layer II or superficial cellular layer and layer III or deep cellular layer. Golgi impregnations allowed to describe seven different types of cells. Pyramidal cells, in which it is possible to distinguish three subtypes (superficial, middle and deep pyramidal cells) by virtue of their morphology and location. Bipolar cells, a very little and scarce type of cell restricted to layer I and that has not been previously described. Fusiform cells, similar to those found in other species. Semilunar cells, also like those described in other animals but which are only found in the posterior PC. These cells resemble other type of cell, the ovoid cells that neither have been described in other animals and, on the contrary, are only located in the anterior PC. Stellate cells, which are a very wide population of cells with variable sizes, dendritic patterns and locations. Horizontal cells, similar to pyramidal cells but oriented in horizontal direction and polymorphic cells, whose the most striking feature is their smooth and beaded prolongations. Morphological features of these cells are compared with those described in the cells of the PC of other animals.

Animals↗
PubMed1986

A procedure to increase the sensitivity of solid-phase immunoassays.

A strategy to increase the sensitivity of antibody detection is described. In this method, streptavidin is used as a cross-bridge between a biotin-conjugated second antibody and a DNA plasmid simultaneously labelled with biotin and 32P. With this simple approach antibodies can be detected with a significantly higher sensitivity as compared to the standard procedures using an 125I-labelled second antibody.

Animals↗
PubMed1986

Antral gastrin-producing G-cells and somatostatin-producing D-cells in peptic ulcer.

The number of G cells and D cells per area unit and the G cell/D cell ratio was studied in control subjects and patients with duodenal or gastric ulcer. A great inter-individual variation in the population density of both types of cells was observed in the three groups studied. G cell density was significantly decreased in both duodenal and gastric ulcer patients, when compared with controls; whereas no difference in G cell density was seen between duodenal ulcer patients and gastric ulcer patients. However, D cell density was significantly decreased in duodenal ulcer patients when compared with control subjects and gastric ulcer patients. In this latter group, D cell density was also lower than in control subjects. A significant positive linear correlation between G cell number and D cell number was found in the three groups studied. The G cell/D cell ratio was significantly increased in duodenal and gastric ulcer patients when compared with controls. This was mainly due to a decrease in D cell numbers. It is concluded that a local deficit in antral D cells in patients with peptic ulcer may favor the pathogenesis of ulcer disease.

Adult↗
PubMed1986

Colonization antigens, antibiotic resistance and plasmid content of enterotoxigenic Escherichia coli isolated from piglets with diarrhoea in Galicia (north-western Spain).

Escherichia coli colonies isolated from 50 diarrhoeic and 29 healthy piglets were investigated for several properties related to pathogenicity, such as production of heat-labile (LT) and heat-stable (STa) enterotoxins, presence of K88 and K99 colonization antigens, mannose-resistant haemagglutinating activity (MRHA), beta-haemolysis and antibiotic resistance. The objective was to establish the toxic and adhesive abilities of E. coli strains that cause porcine diarrhoea in Galician farms. Fifty-seven colonies from 14 diarrhoeic piglets formed STa, while no STa+ colony was detected from healthy piglets. Thirty-four of the 57 STa+ colonies were resistant to gentamicin. Sixteen representative STa+ strains isolated from the 14 infected piglets were serotyped, investigated for plasmid content and examined by electron microscopy. Of these STa+ strains, 15 belonged to serotype 0141:K85ab and carried on their surface the fimbrial antigen P987. The remaining representative STa+ strain belonged to serotype 0101:K30 and was K99+, being the only STa+ strain with MRHA activity. All 15 STa+ P987+ strains possessed a similar plasmid pattern, with three plasmids ranging in molecular weight from 33 X 10(6) to 74 X 10(6); nine of the gentamicin-resistant strains possessed an additional plasmid of molecular weight 16 X 10(6), which was absent in the six gentamicin-sensitive strains. Strains producing LT or K88 antigen were not detected. Forty-one MRHA+ colonies were isolated at similar rates from both diarrhoeic and healthy piglets. Twelve of the 19 non-enterotoxigenic MRHA+ strains of which the O-group was established, belonged to serogroups (01, 02, 07, 08, 09 and 075) typical of the human E. coli strains that cause extraintestinal infections. Finally, a statistically significant association between haemolytic and MRHA activities in porcine E. coli was found. In conclusion, it was found that STa+ E. coli strains belonging to serotype 0141:K85ab:P987 are associated with porcine diarrhoea in Galicia. Additionally, no correlation between the isolation of non-ETEC MRHA+ strains and diarrhoea was observed.

Animals↗
PubMed1985

General method for isolation of DNA sequences that interact with specific nuclear proteins in chromosomes: binding of the high mobility group protein HMG-T to a subset of the protamine gene family.

A general method is described for the isolation of the DNA with which specific nuclear proteins interact in chromosomes. This method is based on the covalent photo-cross-linking of nuclear proteins to the DNA sequences, to which they normally bind, by means of irradiation with UV light and the selective retrieval of specific subsets of protein-DNA adducts by using specific antibodies. The application of this procedure to isolate the DNA sequences with which the trout high mobility group protein (HMG-T) interacts has shown that in trout liver this protein associates specifically with DNA sequences in proximity to a subset of the family of protamine genes but not with the histone or vitellogenin genes. From these observations, it appears that the HMG-T protein may be associated with inactive gene sequences.

Animals↗
PubMed1985

Colonization antigens and haemagglutination patterns of human Escherichia coli.

The haemagglutinating properties of 223 (35 enterotoxigenic and 188 non-enterotoxigenic) Escherichia coli strains with nine erythrocyte types were investigated; 153 strains were also tested for beta-haemolysis and colicin production and for the presence of CFA/I, CFA/II, K88 and K99 antigens. A selected group of strains was also examined by electron microscopy to determine the presence of fimbriae or fibrils and to establish the relationship between these, the haemagglutinating properties and the presence of colonization antigens. Generally, the haemagglutinating patterns yielded by the same strains grown in Mueller Hinton broth and on CFA agar differed considerably. Mannose-sensitive haemagglutinating (MSHA) patterns were more homogeneous than mannose-resistant haemagglutinating (MRHA) patterns. Forty-seven percent of the non-enterotoxigenic MRHA+ strains were haemolytic while only 6% of the remaining strains were (chi2 correction = 34.01; p less than 0.001). CFA/I was only detected in the four enterotoxigenic MRHA+ strains which were positive only with human and calf erythrocytes when grown on CFA agar. CFA/II was detected in three of a total of six enterotoxigenic strains which were MRHA+ only with calf erythrocytes when grown on CFA agar. K88 and K99 antigens were not detected. All strains in which bacteria with fimbriae or fibrils were observed showed haemagglutinating activity. Thus, 18 (66.7%) of the 27 haemagglutinating strains grown on CFA agar showed fimbriae or fibrils while none of the 19 non-haemagglutinating strains did (chi2 correction = 18.10; p less than 0.001).

Agglutination Tests↗
PubMed1985

Relation between antibiotic resistance and number of plasmids in enterotoxigenic and non-enterotoxigenic Escherichia coli strains.

We have investigated the relation between antibiotic resistance and the number of plasmids contained in 44 enterotoxigenic (ETEC) and 69 non-enterotoxigenic (non-ETEC) Escherichia coli strains. Both ETEC and non-ETEC strains were resistant to one or more antibiotics at a similar rate, but multiple resistance in resistant non-ETEC strains was higher than in resistant ETEC strains, showing a significant difference (P less than 0.001) when subjected to Student's t test. Among the ETEC strains, those producing both LT and STa enterotoxins were more sensitive to antibiotics than strains producing only a single toxin type. On the other hand, resistant ETEC strains possessed a higher number of plasmids per strain than the resistant non-ETEC strains (P less than 0.05 by Student's t test). Consequently, resistance to antibiotics could not be related to the possession of a higher number of plasmids. Furthermore, our results support the hypothesis that there is a generalized incompatibility process between plasmids which code for antibiotic resistance and plasmids which code for enterotoxin production in ETEC strains, at least in those strains producing both LT and STa enterotoxins.

Ampicillin↗
PubMed1985

Comparison between enterotoxic activity and methanol solubility in heat-stable enterotoxins (STa and STb) from Escherichia coli of human, porcine and bovine origins.

We have investigated the enterotoxic activity of culture filtrates and their methanol extracted fractions from 10 ST (STa or STb) producing Escherichia coli strains from human, porcine and bovine origin, in the infant mouse test (IMT) as well as in the rabbit intestinal loop test (RILT). Unconcentrated culture filtrates and methanol-soluble fractions from the eight STa-producing strains were positive in the IMT while methanol-insoluble fractions obtained from these STa-positive strains, like methanol-soluble and -insoluble fractions from the two strains producing only STb, lacked activity in the IMT. Unconcentrated culture filtrates from all ST-producing strains were unable to cause fluid accumulation in the rabbit ligated intestinal loops after 6 h incubation. When this material, concentrated 5-fold, was tested again, the culture filtrates and methanol-soluble fractions from all STa-producing strains yielded strongly positive fluid accumulation in the RILT, whereas culture filtrates and their methanol extracted fractions from the strains producing only STb, like methanol-insoluble fractions from four STa-producing strains, caused slight fluid secretion in the rabbit intestinal loops.

Animals↗
PubMed1983

Enterotoxigenic and enteropathogenic Escherichia coli in Galicia (north-west Spain).

We have studied the incidence of enterotoxigenic and enteropathogenic Escherichia coli strains associated with infant diarrhoeal disease in Galicia (North-west Spain). During a period of 9 months we isolated heat-labile enterotoxin-positive strains in 2.1% of children with diarrhoea examined, whereas the production of heat-stable enterotoxin was detected in 1.1% of them. Enteropathogenic strains were isolated from 5.3% of the children with diarrhoea, but none of these strains released heat-labile or heat-stable enterotoxins.

Animals↗
PubMed1983

Long-term maintenance of reduced intraocular pressure by daily or twice daily topical application of prostaglandins to cat or rhesus monkey eyes.

Substantial evidence indicates that a single topical application of prostaglandins (PGs) can reduce intraocular pressure (IOP) in the eyes of several species. However, earlier literature, dealing with ocular hypertensive and inflammatory responses, shows the development of tachyphylaxis to subsequent doses of PGs. If similar tolerance developed to the ocular hypotensive effects of PGs, it would preclude the use of these agents in the treatment of chronic glaucoma. The present study shows, however, that although tachyphylaxis to the ocular hypotensive effects of PGs develops in rabbits, this is not a typical response among mammals. Significant IOP reduction was maintained in cats for up to 9 months by topical application of PGE2 at 12-, 24-, or 48-hr intervals. The IOP reduction was jeopardized seriously only when the PG was applied every other day for several days or when, on a few occasions, 3 days were allowed to elapse between PGE2 applications. Ocular hypotension was also maintained during the course of topical treatment of rhesus monkey eyes with PGF2 alpha. Short periods of pupillary constriction followed the application of each dose of PGF2 alpha to cat eyes, but the miotic response of rhesus monkeys to PGF2 alpha and cats to PGF2 was negligible. Other apparent side effects were noted, but none of these were severe or progressive. These results clearly demonstrate that tachyphylaxis, or tolerance, is not expected to present an obstacle to the development of eicosanoids and/or their derivatives as therapeutic agents for the long-term treatment of ocular hypertension and chronic glaucoma.

Administration, Topical↗