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Biomedical subjects

E Hubert

Publications and source records attributed to E Hubert.

At least 19 recordsLinked to original sources
PubMed2001

Production of antimicrobial substances, by hospital bacteria, active against other micro-organisms.

Fifty-nine clinical strains of bacteria, isolated from patients in the Regional Hospital of Talca, were studied. Seventy-four percent of these strains produced antibacterial substances, in comparison with 18% of the same bacterial species obtained from patients from a non-hospital habitat. Almost all the bacteria isolated from hospitalized patients demonstrated in vitro resistance to different antimicrobial agents. Pseudomonas aeruginosa was the most frequent species producing antibacterial substances and its products were of high potency, with a wide spectrum of antimicrobial activity. Cure of plasmid DNA, in most of the antibacterial-producer strains, resulted in the loss of their lethal activity and they also became susceptible in vitro to anti-microbials. These results indicated that such properties are encoded in extrachromosomal DNA. We believe that the knowledge of the antimicrobial activity and resistance to antimicrobials of bacteria from a hospital habitat can help explain the selection and persistence of such strains in this particular ecological niche.

Anti-Bacterial Agents↗
PubMed2000

Echocardiographic follow-up after Ross procedure in 100 patients.

The Ross procedure could provide an ideal aortic valve replacement method in children and young adults. We evaluated midterm echocardiographic results to assess pulmonary homograft function as well as pulmonary autograft dimensions and function. In all, 105 patients (26 women and 79 men) underwent the Ross procedure; median age at implant was 29 years. All patients underwent free root replacement. Transvalvular gradients and autograft dimensions were measured at 3 levels (annulus, sinuses of Valsalva, and proximal aorta) at discharge, at 6 months, and annually thereafter. Perioperative mortality was 4.7%. The mean period for echocardiographic follow-up in 100 patients was 32.7 months (range 0.5 to 7 years), during which 4 noncardiac-related deaths occurred. Two patients underwent late reintervention. No moderate or severe regurgitation was recorded. There was 1 case of mild homograft regurgitation and 4 of mild autograft regurgitation at late follow-up. Autograft peak gradients were low and reproducible (5 +/- 2.8 mm Hg at discharge vs 5.5 +/- 3.5 mm Hg at last follow-up, p = NS). Homograft peak gradients increased significantly without severe obstruction (7.8 +/- 5.7 mm Hg at discharge vs 15.8 +/- 9.2 mm Hg at last follow-up). The diameter of the autograft annulus was stable during follow-up, whereas autograft dimensions at sinuses and proximal aorta increased significantly. One group of patients was identified with sinus diameter increases >20% (group A). The 90 remaining patients were classified into group B. The only parameter significantly different between the 2 groups was the sinus diameters measured at discharge (1.74 cm/m2 (group A) vs 1.92 cm/m2 (group B); p = 0.036). In 100 patients and with echocardiographic follow-up for up to 7 years, the Ross procedure showed excellent results. For 10% of patients, we observed a 20% dilation of sinus diameters, but in only 3 patients (3%) was this beyond the upper normal limit.

Adolescent↗
PubMed1999

Suppression of kinetic AMP cooperativity of fructose-1,6-bisphosphatase by carbamoylation of lysine 50.

Selective treatment of pig kidney fructose 1,6-bisphosphatase with cyanate leads to the formation of an active carbamoylated derivative that shows no cooperative interaction between the AMP-binding sites, but completely retains the sensitivity to the inhibitor. By an exhaustive carbamoylation of the enzyme a derivative is formed that has a complete loss of cooperativity and a decrease of sensitivity to AMP. It was proposed that the observed changes of allosteric properties were due to the chemical modification of two lysine residues per enzyme subunit [Slebe et al. (1983), J. Protein Chem. 2, 437-443]. Studies of the temperature dependence of AMP sensitivity and the interaction with Cibacron Blue Sepharose of carbamoylated fructose 1,6-bisphosphatase derivatives indicate that the lysine residue involved in AMP sensitivity is located at the allosteric AMP site, while the lysine residue involved in AMP cooperativity is at a distinct location. Using [14C]cyanate, we identified both lysine residues in the primary structure of the enzyme; Lys50 is essential for AMP cooperativity and Lys112 appears to be the reactive residue involved in the AMP sensitivity. According to the fructose 1,6-bisphosphatase crystal structure, Lys50 is strategically positioned at the C1-C2 interface, near the molecular center of the tetramer, and Lys112 is in the AMP-binding site. The results reported here, combined with the structural data of the enzyme, strongly suggest that the C1-C2 interface is critical for the propagation of the allosteric signal among the AMP sites on different subunits.

Adenosine Monophosphate↗
PubMed1999

[Turner syndrome in a girl with marker chromosome in karyotype].

OBJECTIVES: There are suggestion, that Turner syndrome (TS) patients with mosaic karyotype for a Y-DNA-containing cell line are at risk of Y-induced gonadoblastoma. The TS patients in whom some or all cells contain a marker chromosome of unknown origin and those in whom there is clitoromegaly or other evident virillisation should be tested by FISH or PCR techniques. DESIGN: The aim of our study to present a TS girl with mosaic karyotype and marker chromosome, which origin from X chromosome was detected by FISH method. MATERIAL AND METHODS: 5-years old girl in whom TS was established. Clinical analysis included the full dysmorphic and clinical phenotype of TS. Chromosome analysis was performed on peripheral blood samples using routine cytogenetic methods and FISH technique. RESULTS: Clinical examination of girl showed many typical signs of TS besides of normal weight and length at birth and not typical for TS patients heart defect. First routine chromosome analysis, at age of 6 month, showed only 45,X cell line, Second study revealed mosaic karyotype with marker chromosome. FISH analysis for interphase nuclei and metaphase chromosomes using X centromere probe explained origin of marker from X chromosome. The karyotype was 45,X[155]/46,X,+mar[8].fish mar(X)(DXZ1+). CONCLUSION: Presence of marker chromosome in karyotype of patient with TS may modify their phenotype and it is a indication for molecular examination by FISH technique.

Adolescent↗
PubMed1998

Predictors of restenosis after coronary stent implantation.

OBJECTIVES: We sought to determine predictors of restenosis after coronary stenting (CS) in a consecutive series of patients. BACKGROUND: Although stenting in highly selected patient groups reduces restenosis, the results of stenting in a heterogeneous patient group and the effects of clinical and procedural factors on stent restenosis are currently unclear. METHODS: We analyzed the 6-month angiographic outcome of 500 lesions in 463 consecutive patients undergoing successful CS. Clinical, qualitative and quantitative angiographic variables were correlated with restenosis assessed as both a binary and a continuous variable. RESULTS: Restenosis, defined as the presence of >50% diameter stenosis in the dilated segment, was present in 105 (26%) of the 405 lesions with angiographic follow-up. The mean late lumen loss during the follow-up period was 0.79+/-0.64 mm. Implantation of multiple stents (p < 0.0001) and a high acute gain (p < 0.0002) were independently associated with a higher late lumen loss. In contrast, the use of high inflation pressure (p < 0.02) and Palmaz-Schatz stents (p < 0.005) was independently associated with a lower late lumen loss. When restenosis was defined as a qualitative variable, implantation of multiple stents (p < 0.001), stenosis length (p < 0.01), small reference diameter (p < 0.02) and stent type other than Palmaz-Schatz (p < 0.01) were independent predictors of restenosis. None of the clinical variables tested was associated with restenosis. CONCLUSIONS: Coronary stenting in an unselected patient group is associated with an acceptable restenosis rate. Although some risk factors were identified, the risk of restenosis was not related to most of the variables tested. This suggests that the superiority of CS over balloon angioplasty, in terms of restenosis, might also apply to subgroups of patients that were not included in the recent randomized studies.

Aged↗
PubMed1998

Note: purification and characterization of the bacteriocin PsVP-10 produced by Pseudomonas sp.

A bacteriocin (bacteriocin PsVP-10) produced by Pseudomonas sp. R-10 was purified by a simple method that included an extraction of the bacteriocin with chloroform, followed by cation exchange chromatography. The purity of the bacteriocin was verified by RP-HPLC. It is a peptide of 2.4 kDa, very stable to heat, to proteolytic enzymes and to pH. It presents a very broad spectrum of antimicrobial activity against Gram-positive and Gram-negative bacteria.

Amino Acids↗
PubMed1997

Restenosis rates in diabetic patients: a comparison of coronary stenting and balloon angioplasty in native coronary vessels.

BACKGROUND: Diabetes is a major risk factor for restenosis after coronary balloon angioplasty. Recent studies have shown that coronary stenting significantly reduces restenosis compared with balloon angioplasty alone. However, limited information is available on the effect of coronary stenting in diabetic patients. METHODS AND RESULTS: We designed this study to analyze the effect of diabetes on restenosis in patients treated with either balloon angioplasty or coronary stenting who were enrolled in a 6-month angiographic follow-up program. Three hundred consecutive patients, 19% of whom were diabetics, who underwent coronary stent implantation during a single-vessel procedure on native coronary vessels and who had 6-month angiographic follow-up constituted the study group (stent group). Three hundred consecutive patients who underwent 6-month angiographic follow-up after single-vessel conventional balloon angioplasty served as control patients (balloon group). Preprocedural, postprocedural, and follow-up angiograms were analyzed with quantitative angiography. In the balloon group, the restenosis rate was almost twofold higher in diabetic than in nondiabetic patients (63% versus 36%; P=.0002) owing to both a greater late loss (0.79+/-0.70 versus 0.41+/-0.61 mm, respectively; P<.0001) and a higher rate of late vessel occlusion (14% versus 3%, respectively; P<.001). In the stent group, restenosis rates were similar in diabetics and nondiabetics (25% versus 27%, respectively). Furthermore, in the stent group, late loss (0.77+/-0.65 versus 0.79+/-0.57 mm, respectively) and the rate of late vessel occlusion (2% versus 1%, respectively) did not differ significantly between diabetic and nondiabetic patients. CONCLUSIONS: Although diabetics have increased rates of restenosis and late vessel occlusion after simple balloon angioplasty, they have the same improved outcome with coronary stenting that has been documented in nondiabetic patients.

Aged↗
PubMed1997

Prospective evaluation of high-dose or low-dose isoproterenol upright tilt protocol for unexplained syncope in young adults.

The sensitivity of the passive head-up tilt test (HUT) in the evaluation of unexplained short-lasting syncope in young adults remains insufficient. The infusion of isoproterenol was proposed to improve the benefit. To evaluate the sensitivity-specificity relationship during isoproterenol dosing, we studied 76 young adults (aged 20.9 +/- 1.7 years) (group S) with recurrent (mean 3.8 +/- 1.6) losses of consciousness that remained unexplained after clinical and noninvasive assessment and 35 young healthy volunteers (aged 22.6 +/- 2.7 years) (group V). Subjects underwent either passive HUT (45 min, 60 degrees without drug dosing for 48 subjects in group S (S1) and 17 in group V (V1), or HUT with isoproterenol infusion at progressive doses (2 then 5 micrograms/min) after 30 minutes of passive tilting for 28 patients in group S (S2) and 18 in group V (V2). During passive HUT, the test was positive (asystole, bradycardia, or fall in systolic blood pressure) in 2 of 17 (11.8%) patients in group V1 and in 7 of 48 (14.6%) in group S1 before 30 minutes, and in 3 of 17 (17.6%) in group V1 compared with 10 of 48 (20.8%) in group S1 at the end of the 45-minute infusion, with no difference in delay before the appearance of a positive result. During HUT with isoproterenol dosing, the test was positive in 2 of 18 (11.1%) patients in group V2 and in 18 of 28 (64.2%) in group S2 before 45 minutes (2 micrograms/min; p < 0.01) in 7 of 18 (38.8%) in group V2 compared with 24 of 28 (85.7%) in group S2 before 60 min (5 micrograms/min; p < 0.01). In both cases the mean delay in evoking a positive response was significantly shorter. No asystolic response was observed in the volunteers regardless of the protocol used. The most characteristic response to isoproterenol injection was the appearance of a junctional escape rate with a fall in systolic blood pressure (61.5% of subjects in group S2). The infusion of isoproterenol considerably improves the sensitivity of the HUT with satisfactory specificity if low doses are used (< 3 micrograms/min). These results support the use of HUT with isoproterenol in the evaluation of unexplained syncope in young adults.

Adrenergic beta-Agonists↗
PubMed1997

Floating Harbor syndrome. Case report and further syndrome delineation.

Floating Harbor syndrome was diagnosed in a 9 years old girl on the basis of short stature, delayed bone age, mild mental retardation, speech problems and specific craniofacial features. A detailed phenotype description is given and evaluated together with 18 other published case reports according to the concept of the Munich Dysmorphology Database (Stengel-Rutkowski et al., 1996) with the aim to delineate the spectrum of clinical and anthropological features.

Abnormalities, Multiple↗
PubMed1997

[Recanalization of complete coronary occlusions followed by STENT implantation. An angiographic study after 6 months].

The restenosis and reocclusion rate after coronary recanalization by conventional angioplasty are high. The role of stent implantation in this context is unknown. The authors assessed a group of 49 patients who underwent implantation of one or more stent after a recanalization procedure by angiography at 6 months. The restenosis rate assessed by quantitative angiography was 24%; no cases of reocclusion were observed. These angiographic results were accompanied with a significant improvement of the anginal symptoms (p < 0.01). These results suggest that stent implantation following recanalization of a coronary occlusion may be beneficial on the restenosis and reocclusion rates and anginal symptoms. However, they should be confirmed by randomised study. It would also be important to analyse the impact of this procedure on the outcome of left ventricular function.

Aged↗
PubMed1995

In vitro toxicity assays for dye ligands used in affinity chromatography.

Some reactive textile dyes have been used for years as biomimetic ligands in protein purification. There has been reluctance, however, to use these dyes on a large scale for therapeutically applicable proteins for fear of possible dye leakage and consequent contamination. Therefore, toxicological data are necessary to quantify the level of this hazard. This study deals with a series of in vitro toxicity investigations with eukaryotic cells (growth, polyploidy, etc.) and with prokaryotic cells (Escherichia coli) for genotoxic studies. Both approaches demonstrated a lack of or slight toxicity for Reactive Blue 2 and Reactive Red 120 and their derivatives over the range 10-62.5 micrograms/ml in several assays.

Chromatography, Affinity↗
PubMed1995

[Floating-Harbor syndrome in a girl with somatic asymmetry].

Floating-Harbor syndrome, a genetic disorder of unknown etiology, was diagnosed in a 9-year-old girl with delayed morphologic, bone and dental age, lateral asymmetry of the body, triangular face, hypotelorism, broad palpepral fissures, long eye-lashes, narrow jaw, retrogenia, a defect of phonemic audition and speech delay with poor articulation. Similarity between Floating-Harbor syndrome and Silver-Russel syndrome is discussed.

Abnormalities, Multiple↗
PubMed1993

[Adenoid cystic carcinoma in the head and neck: clinical and pathologic review].

19 patients with adenoid cystic carcinoma of the minor and major salivary glands were analysed clinicopathologically. Majority (8) of the tumours originated in the parotid gland. The palate was the most common location among the tumour of the minor salivary glands. The tumours were classified by their histology patterns into three groups: I tubular and cribriform pattern, II cribriform with less than 30% of solid pattern, III solid forms. A positive correlation between increasing grade and aggressive behavior was not observed in our study. All patients were treated with surgery. Eight of them received postsurgical radiation therapy. Recurrence of disease at the primary site occurred in 5 of 19 patients. Distant metastases developed in 3 patients. An adequate surgical excision of the tumour yields optimal local control and survival rates.

Adult↗
PubMed1993

TAR syndrome with orofacial clefting.

A case of TAR syndrome with bilateral cleft lip and palate is presented. Bilateral symmetric focomelia, normal thumbs among five fingers of hands, synostosis of IVth and Vth metacarpal bones and some defects of lower limbs with associated thrombocytopenia were noted. Dysmorphic facial features included hypertelorism, epicanthus, blue sclerae, broad nasal root, micrognathia, low-set ears, sparse blond hair. To our knowledge this patient represents an unusual association of TAR syndrome with orofacial clefting. A common background of TAR and Roberts/SC syndrome is suggested.

Abnormalities, Multiple↗
PubMed1988

Site-specific methylation of a strategic lysyl residue in aspartate aminotransferase.

Conditions for reductive methylation of amine groups in proteins using formaldehyde and cyanoborohydride can be chosen to modify selectively the active site lysyl residue of aspartate aminotransferase among the 19 lysyl residues in each subunit of this protein. Apoenzyme must be treated, under mildly acidic conditions (pH = 6), at a relatively low molar ratio of formaldehyde to protein (40:1); and, upon reduction with sodium cyanoborohydride, 85% of the formaldehyde is incorporated at Lysine 258 and 15% at the amino-terminal alanyl residue. The modified protein, characterized after tryptic hydrolysis, separation of the peptides by high performance liquid chromatography procedures and subsequent amino acid analysis, shows that lysine 258 is preferentially modified as a dimethylated derivative. Modified apoenzyme can accept and tightly bind added coenzyme pyridoxal phosphate, as measured by circular dichroism procedures. The methylated enzyme is essentially catalytically inactive when measured by standard enzymatic assays. On the other hand, addition of the substrate, glutamate, produces the characteristic absorption spectral shifts for conversion of the active site-bound pyridoxal form of the coenzyme (absorbance at 400 nm) to its pyridoxamine form (absorbance at 330 nm). Such a half-transamination-like process occurs as in native enzyme, albeit at several orders of magnitude lower rate. This event takes place even though the characteristic internal holoenzyme Schiff's base between Lys-258 and aldehyde of bound pyridoxal phosphate does not exist in methylated, reconstituted holoenzyme. It is concluded that this chemically transformed enzyme can undergo a half-transamination reaction with conversion of active site-bound coenzyme from a pyridoxal to a pyridoxamine form, even when overall catalytic turnover transamination cannot be detected.

Amino Acid Sequence↗
PubMed1987

Selective thiol group modification renders fructose-1,6-bisphosphatase insensitive to fructose 2,6-bisphosphate inhibition.

Limited treatment of native pig kidney fructose-1,6-bisphosphatase (50 microM enzyme subunit) with [14C]N-ethylmaleimide (100 microM) at 30 degrees C, pH 7.5, in the presence of AMP (200 microM) results in the modification of 1 reactive cysteine residue/enzyme subunit. The N-ethylmaleimide-modified fructose-1,6-bisphosphatase has a functional catalytic site but is no longer inhibited by fructose 2,6-bisphosphate. The enzyme derivative also exhibits decreased affinity toward Mg2+. The presence of fructose 2,6-bisphosphate during the modification protects the enzyme against the loss of fructose 2,6-bisphosphate inhibition. Moreover, the modified enzyme is inhibited by monovalent cations, as previously reported (Reyes, A., Hubert, E., and Slebe, J.C. (1985) Biochem. Biophys. Res. Commun. 127, 373-379), and does not show inhibition by high substrate concentrations. A comparison of the kinetic properties of native and N-ethylmaleimide-modified fructose-1,6-bisphosphatase reveals differences in some properties but none is so striking as the complete loss of fructose 2,6-bisphosphate sensitivity. The results demonstrate that fructose 2,6-bisphosphate interacts with a specific allosteric site on fructose-1,6-bisphosphatase, and they also indicate that high levels of fructose 1,6-bisphosphate inhibit the enzyme by binding to this fructose 2,6-bisphosphate allosteric site.

Animals↗