PubMed Health⌕ Search

Biomedical subjects

A Juarez

Publications and source records attributed to A Juarez.

At least 19 recordsLinked to original sources
PubMed2003

Aggregation profile characterisation in dielectrophoretic structures using bacteria and submicron latex particles.

A novel quantitative characterisation method for the measurement of anomalous low frequency aggregation processes on dielectrophoresis electrodes has been developed. Experimental evidence is provided for the relationship between the aggregation effect and AC electro-osmotical fluid motion theory. The aggregation profile dependence for E.coli bacteria, as a function of frequency and applied field, has been quantitatively examined. Additional experimental observations of the aggregation profiles of latex particles with dimensions of hundreds of nanometres, also confirm the relationship between this aggregation effect and the mentioned fluid motion theory.

Journal Article↗
PubMed1998

Arthritogenicity of Yersinia enterocolitica O:8 in hamsters: analysis of the immune response.

An animal model, hamster, was used for the study of Yersinia-induced arthritis. The development of arthritis, estimated by measuring the inflammation on hind paws after infection, was correlated with the kinetics of the immune response. Histological and immunofluorescence (IFI) studies and serum antibody measurements were performed. Two inflammatory peaks were observed: an acute one on day 11 post-infection (p.i.) and a chronic one on days 26-35 p.i. Joint cultures were positive until day 14 p.i. IFI was used to demonstrate the deposit of bacterial antigens in the joint. A persistent response of cellular extract-specific IgG antibodies was observed until day 94. Lipopolysaccharide-specific IgG was statistically significant on day 26 p.i. Antibodies against bands 66 and 54 were observed by immunoblotting. Polyclonal activation was detected during reactive arthritis. It is shown that Y. enterocolitica is arthritogenic in hamsters, immune mechanisms participating in the development of this disease.

Animals↗
PubMed1996

The Hha protein as a modulator of expression of virulence factors in Escherichia coli.

We constructed hha derivatives from both a clinical uropathogenic Escherichia coli isolate (strain FVL4) and a wild E. coli strain causing bovine diarrhea (strain CCB21) and analyzed the effect of the hha allele on the expression of the different virulence factors exhibited by these strains. Expression of hemolysin and of the Vir antigen was altered in hha mutants. Whereas production of hemolysin by strain FVL4 was repressed both at a low temperature and at high osmolarity, the hha allele accounted for a significant increase of hemolysin production under these conditions. Also, the low temperature-sensitive expression of the Vir adhesin was modified in hha mutants, which were able to express this adhesin at a low temperature. Expression of other virulence factors, such as cytotoxic necrotizing factor type 1 and 2 toxins, remained unmodified in hha derivatives of strains FVL4 and CCB21.

Adhesins, Bacterial↗
PubMed1996

O serogroups, biotypes, and eae genes in Escherichia coli strains isolated from diarrheic and healthy rabbits.

A total of 305 Escherichia coli strains isolated from diarrheic and healthy rabbits in 10 industrial fattening farms from different areas of Spain were serotyped, biotyped, and tested for the presence of the eae gene and toxin production. The characteristics found in strains isolated from healthy rabbits were generally different from those observed in E. coli strains associated with disease. Thus, strains with the eae gene (74% versus 22%); strains belonging to serogroups O26, O49, O92, O103, and O128 (64% versus 12%); rhamnose-negative strains (51% versus 5%); and rhamnose-negative O103 strains with eae genes present (41% versus 1%) were significantly (P < 0.001 in all cases) more frequently detected in isolates from diarrheic animals than in those from healthy rabbits. Whereas a total of 35 serogroups and 17 biotypes were distinguished, the majority of the strains obtained from diarrheic rabbits belonged to only four serobiotypes, which in order of frequency were O103:B14 (72 strains), O103:B6 (16 strains), O26:B13 (12 strains), and O128:B30 (12 strains). These four serobiotypes accounted for 48% (112 of 231) and 5% (4 of 74) of the E. coli strains isolated from diarrheic and healthy rabbits, respectively. Only six strains were toxigenic (three CNF1+, two CNF2+, and one VT1+). We conclude that enteropathogenic E. coli strains that possess the eae gene are a common cause of diarrhea in Spanish rabbit farms and that the rhamnose-negative highly pathogenic strains of serotype O103:K-:H2 and biotype B14 are especially predominant. Detection of the eae gene is a useful method for the identification of enteropathogenic E. coli strains from rabbits. However, a combination of serogrouping and biotyping may be sufficient to accurately identify the highly pathogenic strains for rabbits.

Adhesins, Bacterial↗
PubMed1996

[Ureterosigmoidostomy detubularized with surgical staplers: C.F.C. (Original technique)].

Description of our modification of the detubulized ureterosigmoidostomy surgical technique (Castiñeiras-Ferragut-Camacho). In an attempt to shorten the surgery time, we used for these changes absorbable mechanical sutures (Poli Gia and T.A.). This paper analyzes the technical details of interest as well as the anatomicosurgical considerations that should be known prior to carry out this type of by-pass. The anatomicophysiological principles on which our developments are based are those referred by N.G. Kock15 and used by R. Hohenfellner and R. Fisch14, when they described the detubulized ureterosigmoidostomy performed manually. We believe that both surgical procedures, R. Hohenfellner & R. Fisch14 and ours (detubulized ureterosigmoidostomy, C.F.C.), are suitable alternatives to conventional ureterosigmoidostomy.

Colon, Sigmoid↗
PubMed1995

[Paratesticular neoplasms of mesenchymatous origin. Clinico-pathologic study].

There is a group of malignant intrascrotal tumours which represent a very small number when compared to testicular neoplasias and which are known as paratesticular neoplasias. More than 90% belong to the sarcomatous species. From a clinical point of view and based on the patient's age, two groups can be distinguished: sarcomas affecting children and adolescents (primarily rabdomiosarcomas) and those occurring in adulthood, the more frequent histopathological variants being fibrosarcoma, leiomiosarcoma and liposarcoma. This work contributes five paratesticular sarcomas (two rabdomiosarcomas, one liposarcoma, one leiomiosarcoma and one fibrosarcoma). The features related to histogenesis, diagnosis (revealing signs and clinical examination), natural history (dissemination routes based on histopathology) and treatment are reported. With regard to treatment, both the local surgery (total orchiectomy by inguinoscrotal approach with or without hemiscrotectomy), and indications for lymphadenectomy and radiotherapy in relation to staging are discussed though insisting on the chemotherapy approach.

Adolescent↗
PubMed1995

[Clinical features, diagnosis, and treatment of tumor lesions arising in the adrenal gland].

Between 1981 and 1993, 14 patients with tumoral adrenal disease were diagnosed and treated in the Urology Services of both Hospitals. Nature of the adrenal disease was functional in 8 patients (two carcinomas and six pheochromocytomas) and non-functional in the rest (three carcinomas, two adenomas and one myelolipoma). Reference is made to the clinical manifestations and laboratory tests related to hormonal activity, depending on whether the tumour is functional or non-functional, chromaffin or non-chromaffin. Patients with functional carcinomas had Cushing's syndrome, with very clear virtilization signs. Urine 17-hydroxycorticosteroid, 17-cetosteroides and cortisol were all increased, same as plasma cortisol. Patients with pheochromocytomas had hypertension and headaches (six patients), sweating (five patients), anxiety (four patients) and loss of weight (two patients). All of them had increased urine vainillylmandelic acid and catecholamines. Clinical signs and symptoms of non-functional tumours were related to bulk growth and size (in the three carcinomas), and sometimes was highly anodyne, or even absent (in the two adenomas and the myelolipoma), the cause of discovery being accidental during an ultrasound examination. An analysis is made of the different imaging diagnostic procedures performed, such as IVU (performed in 13 patients) with a 38.4% resolutory power; ultrasound (performed in 11 patients) with an 81.8% resolution; CAT (performed in 6 patients) with a 100% resolution capacity and arteriography (performed in 3 patients) with a 100% resolution power, although patients had previously undergone ultrasound and CAT.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Gland Neoplasms↗
PubMed1994

Environmental regulation of alpha-haemolysin expression in Escherichia coli.

The effect of osmolarity, temperature and anaerobiosis on the expression of Escherichia coli alpha-haemolysin was investigated. Low osmolarity of the culture medium, growth at high temperature (37 degrees C) and anaerobiosis increase haemolysin production in E. coli cells harbouring the haemolytic plasmid pHly152 as well as in haemolytic strains isolated from urinary-tract infections.

Anaerobiosis↗
PubMed1994

[Retropubic radical prostatectomy. I. Denonvilliers' aponeurosis, prostatic "pseudocapsule" and the external striated urethral sphincter].

The present paper reviews the histological characteristics of the prostatic "pseudocapsule", Denonvilliers' aponeurosis and the external striated urethral sphincter. This morphological study has been conducted on pieces of prostate obtained through necropsies. We believe that the knowledge of the morphological characteristics of these structures as well as their relationships is necessary in order to perform the technique of radical retropubic prostatectomy.

Humans↗
PubMed1993

Loss of activity in the secreted form of Escherichia coli haemolysin caused by an rfaP lesion in core lipopolysaccharide assembly.

A transposon mutant of Escherichia coli 5K was isolated which reduced 10- to 50-fold the secreted extracellular haemolytic activity of cells carrying the complete hlyCABD operon while leaving unaffected the intracellular haemolytic activity and the levels of intracellular and extracellular haemolysin protein, HlyA. The transposon insertion was identified within the rfaP gene (required for attachment of phosphate-containing substituents to the lipopolysaccharide inner core), and extracellular haemolytic activity was restored in trans by the intact rfaP gene. The loss in cytolytic activity of the secreted HlyA protein was not related to the HlyC-directed acylation of the protoxin. Activity of the secreted toxin was restored by chaotropic agents and during rate-zonal centrifugation the mutant-secreted HlyA migrated as a larger species than the wild type. The results indicate that the rfaP mutation affects the aggregation behaviour of the active toxin during or following the signal peptide-independent secretion process.

Bacterial Proteins↗
PubMed1988

Characterization of a sequence (hlyR) which enhances synthesis and secretion of hemolysin in Escherichia coli.

A sequence (hlyR) of about 600 bp which enhances the expression of hemolysin (HlyA) more than 50-fold was identified in the plasmid pHly152-specific hemolysin (hly) determinant. Deletion of this entire hlyR sequence led to the same low level of hemolysin synthesis and excretion as that expressed by the recombinant plasmid pANN202-312. HlyR was active in cis but its activity was orientation-dependent. The enhancing sequence, hlyR, is separated from the promoter phlyI transcribing hlyC, hlyA and possibly hlyB by more than 1.5 kb including an IS2 element. Stepwise removal of the hlyR sequence from its 5' end by exonuclease III (ExoIII) digestion yielded several types of deletion mutants which expressed decreasing amounts of hemolysin. A similar observation was made when hlyR was shortened by ExoIII from its 3' end, which suggests that more than one functional region may be present in the hlyR sequence. A deletion of 717 bp within the adjacent IS2 element reduced the activity of hlyR only slightly, indicating that IS2 is not directly involved in the enhancement mechanism but that it may support an optimal positioning in hlyR relative to the hly promoter. The nucleotide sequence of hlyR is rich in A + T and does not contain an extended open reading frame, but exhibits several sequence motives that may represent sites for protein binding and DNA bending.

Base Sequence↗
PubMed1988

Role of lipopolysaccharide and complement in susceptibility of Escherichia coli and Salmonella typhimurium to non-immune serum.

The role of lipopolysaccharide (LPS) in the susceptibility of Escherichia coli and Salmonella typhimurium to non-immune human serum was investigated using serum-sensitive strains of both enterobacteria. LPS from serum-resistant strains of E. coli and S. typhimurium could activate and completely remove the serum bactericidal activity, and also showed dose-dependent anti-complement activity. These properties were mainly due to the high-molecular-mass LPS: the low-molecular-mass LPS from serum-resistant strains of E. coli and S. typhimurium had only a slight effect on the serum bactericidal activity, and showed only low anti-complement activity, even at high concentration. The results suggest that LPS composition, especially the O-antigen polysaccharide chains, contributes to the susceptibility of E. coli and S. typhimurium strains to complement-mediated serum bactericidal activity.

Blood Bactericidal Activity↗
PubMed1988

Improved lactose digestion during pregnancy: a case of physiologic adaptation?

Loss of intestinal lactase activity among adults could theoretically limit milk consumption and hence dietary availability of calcium during pregnancy. The present study sought to define, using breath hydrogen (H2) production as an index of incomplete carbohydrate absorption, the prevalence during pregnancy of lactose maldigestion of 360 mL of milk (18 g of lactose), and to determine whether lactose digestion improved as pregnancy advanced. The prevalence of lactose maldigestion among 114 pregnant women tested before the 15th week of gestation was 54%. By term, 44% of those originally classified as maldigesters had become digesters. There was a significant reduction in the four-hour sum of the changes in breath H2 concentration from the period before 15 weeks (116.6 +/- 9.6 ppm) to the time after 36 weeks (54.4 +/- 7.3 ppm; P less than .01). This apparent adaptive improvement in intestinal handling of milk lactose during gestation has implications for calcium intake and absorption.

Acidosis, Respiratory↗
PubMed1987

Microbial coagulation of alfalfa green juice.

Of the different bacterial strains isolated from alfalfa raw material, nine were able to coagulate the protein fraction of alfalfa green juice. The two strains showing the highest efficiency were further used for coagulation experiments. They were classified as Erwinia carotovora and Escherichia coli. Juice samples inoculated (1:10 to 1:100) with stationary-phase cultures were efficiently coagulated. The amount of protein recovered was equivalent to that obtained when the juice was heat treated. A minimal incubation temperature of 30 degrees C was required. The protein coagulum appeared after 8 to 10 h of incubation. During this period no bacterial growth was apparent, but glucose was actively fermented. For both strains no extracellular enzymatic activity could be shown in the culture supernatants. The fermentative metabolism during the incubation period seems to be responsible for protein coagulation.

Erwinia↗
PubMed1984

Expression and regulation of the plasmid-encoded hemolysin determinant of Escherichia coli.

As a first approach towards studying the regulation of hemolysin synthesis in Escherichia coli, we have fused lacZ into the four hly genes (hlyC, hlyA, hlyBa and hlyBb) using the Mud-1 (Mu::lacZ, Y, Apr) phage. The sites of insertion of Mud-1 within the various hly genes of the Hly plasmid pHly152 were determined by the hemolytic phenotype of the Hly- mutants (Hly-ex/Hly-in or Hly-ex/Hly+in) and by complementation of these Hly- mutants with recombinant plasmids carrying cloned hly genes. It was found that hlyC, hlyA and hlyBa are transcribed from a relatively weak promoter (hlypL) located in front of hlyC. The activity of beta-galactosidase is considerably lower when Mud-1 is integrated in hlyBa than when it is inserted in hlyC, suggesting a considerable decline in hly gene expression from hlyC to hlyBa. The DNA sequence upstream of the coding region of hlyC was found to promote galK gene expression when a fragment covering this region was inserted into the promoter-probe vector pKO-11. A putative promoter sequence, which could correspond to hlypL, was identified in this sequence. The hlyBb gene appears to be transcribed from a different promoter and the direction of transcription seems to be opposite to that of the hlyC, A, Ba operon. The strength of this promoter (hlypR), based on the level of beta-galactosidase activity of Mud-1 insertion mutants in hlyBb, is considerably higher than that of hlypL.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1984

Chromosomal mutation that affects excretion of hemolysin in Escherichia coli.

Two types of mutants unable to excrete hemolysin were obtained when E. coli 5K carrying the multicopy hemolytic recombinant plasmid pANN202-312 was mutagenized with Mu d1. One type is altered in the plasmid hly-specific gene, hlyBb, but the other is caused by an insertion of Mu d1 into a chromosomal locus.

Aminocoumarins↗
PubMed1984

Study of regulation and transport of hemolysin by using fusion of the beta-galactosidase gene (lacZ) to hemolysin genes.

Operon and gene fusions between lacZ and the hemolysin genes, hlyC and hlyA, were performed. These two genes are essential for the synthesis of active hemolysin and are transcribed from a common promoter (p1). Whereas the amount of hemolysin produced in Escherichia coli is not changed by altering the hly gene dose, beta-galactosidase activity follows the gene dosage in both types of fusions when lacZ comes under the control of p1. This indicates that hemolysin is not negatively regulated on the transcription or translation level. The products of the gene fusions hlyC::lacZ and hlyA::lacZ were identified in maxicells as stable proteins of 146,000 and 220,000 daltons, respectively. Both fusion proteins possess beta-galactosidase activity indicating that the performed fusions of lacZ to the hly genes do not destroy the reading frame of hlyC and hlyA. The fusion proteins HlyC-beta-gal and HlyA-beta-gal were predominantly detected in the cytoplasm, confirming previous data which suggested that the primary gene products of hlyC and hlyA are not transported across the cytoplasmic membrane.

Bacterial Proteins↗