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P Melin

Publications and source records attributed to P Melin.

At least 37 records · Page 2Linked to original sources
PubMed1998

Typing of nosocomial strains of Serratia marcescens: comparison of pulsed-field gel electrophoresis of macrorestriction fragments with biotyping, esterase typing and ribotyping.

Fifty nosocomial isolates of Serratia marcescens, collected in six Belgian hospitals between 1986 and 1990, were characterized by using pulsed-field gel electrophoresis (PFGE) with XbaI. The results were compared with those previously obtained by three other methods: biotyping, esterase electrophoresis typing and ribotyping with EcoRI and HindIII. Macrorestriction analysis (42 PFGE groups) and esterase typing (42 zymotypes) proved to be the most discriminating, followed by ribotyping (28 ribotypes) and biotyping (10 biochemical profiles). Biotyping would serve as a screen to identify isolates, due to its accessibility. Esterase typing provided a reliable tool to make subdivisions within biotypes because of congruence between biochemical groups and esterase patterns. Additional discrimination was still achieved by ribotyping and PFGE. It is concluded that the combined results of these four markers were useful for distinguishing all epidemic and sporadic isolates.

Bacterial Typing Techniques↗
PubMed1997

Streptococcus difficile is a nonhemolytic group B, type Ib Streptococcus.

Whole-cell protein electrophoretic analysis of the type strain of Streptococcus difficile (LMG 15799) revealed that this organism was indistinguishable from Streptococcus agalactiae strains. Although LMG 15799T (T = type strain) was originally described as serologically untypeable, we found that this strain was a group B streptococcus belonging to the capsular polysaccharide antigen type Ib group. The biochemical reactivity of S. difficile, which differed from the biochemical reactivity of typical S. agalactiae strains mainly by being less versatile, is similar to the biochemical reactivity of other group B, type Ib streptococci isolated from poikilothermic animals, such as fish and frogs.

Aerobiosis↗
PubMed1997

Comparison of biotyping, ribotyping, and pulsed-field gel electrophoresis for investigation of a common-source outbreak of Burkholderia pickettii bacteremia.

Over a 3-month period, six immunocompromised patients developed one or more episodes of Burkholderia pickettii bacteremia and/or catheter infection. Vials of a commercially available, "sterile" saline for injection which had been used for flushing the patients' indwelling intravenous devices were implicated as the common source of the organisms. No further cases were diagnosed once the use of this saline was discontinued. Twenty-six isolates, including 9 outbreak-related strains from case patients and contaminated saline as well as 17 control strains, were tested comparatively by biotyping, ribotyping with EcoRI and HindIII, and pulsed-field gel electrophoresis (PFGE) with SpeI. Macrorestriction analysis revealed nine PFGE groups and was more discriminating than ribotyping (seven ribotypes) and biotyping (two biovars). Among the outbreak-related isolates, one B. pickettii type was found by the three typing methods. Furthermore, PFGE was useful for subdividing ribotypes and for distinguishing isolates involved in the outbreak from all epidemiologically unrelated strains.

Adult↗
PubMed1996

Bactericidal activity against Pseudomonas aeruginosa is acquired by cultured human monocyte-derived macrophages after uptake of myeloperoxidase.

Myeloperoxidase (MPO) is an enzyme located within polymorphonuclear neutrophils capable of producing cytotoxic oxidant species that are particularly active against bacteria with polysaccharide capsules. Pseudomonas aeruginosa (10(6) bacteria per 1ml) are killed within 1 h in vitro by a MPO/H2O2/C1- system (48mU=132ng of MPO). The question arose as to whether human macrophages would acquire cytotoxic activity when loaded with this enzyme. Monocytes were therefore isolated from human blood and cultured for up to ten days to induce maturation to macrophages. These cells lost endogenous MPO within five days while H2O2 production in response to stimulation by phorbol myristate acetate (10(-6)M) decreased to 23% within ten days. On the other hand, their capacity to take up exogenous MPO increased fourfold from day three to day ten. Human macrophages cultured from eight days (when both H2O2 production and MPO uptake were sufficient) were therefore used to study the effects of MPO uptake on cytocidal activity against Pseudomonas aeruginosa. After a 1 h MPO loading period, macrophages (5X10(5) cells per ml) were incubated in the presence of bacteria (0.5 to 2X10(6) bacteria per ml) for 2 h at 37 degrees C. At a bacteria/macrophage ratio of 1, only 34.8+/-7.0% of bacteria survived (compared to killing by non-loaded macrophages), while 74.4+/-9.3% survived at a ratio of 4. From these results, we conclude that loading macrophages with exogenous MPO could enhance their microbicidal activity, suggesting a potentially useful therapeutic application.

Blood Bactericidal Activity↗
PubMed1996

In vitro activity of amoxycillin/clavulanate and ticarcillin/clavulanate compared with that of other antibiotics against anaerobic bacteria: comparison with the results of the 1987 survey.

The activity of amoxycillin/clavulanate (Augmentin) and ticarcillin/ clavulanate (Timentin) was tested against 351 strict anaerobic clinical isolates collected from September 1993 to April 1994 in eight Belgian university hospitals and compared with that of 8 other antibiotics using the NCCLS reference agar dilution procedure. Production of beta-lactamase was detected by the nitrocefin test in 48% of the isolates. At NCCLS-recommended breakpoints, more than 90% of isolates were susceptible to amoxycillin/clavulanate, ticarcillin/clavulanate, piperacillin/tazobactam, imipenem, chloramphenicol and metronidazole but only 77%, 72% and 48% to cefoxitin, clindamycin and penicillin, respectively. In comparison with the results of a similar survey conducted in 1987 no major changes in susceptibility were observed except for the susceptibility to clindamycin that declined from 83% to 72% overall, and from 83% to 66% in the B. fragilis group. Furthermore one isolate of Clostridium clostridioforme was found produce beta-lactamase and few B. fragilis group isolates showed reduced susceptibility to metronidazole.

Amoxicillin↗
PubMed1996

[Traumatic and iatrogenic ocular infections: specimen handling and role of the laboratory].

Ocular inflammations may be due to a variety of diseases, and microorganisms play a major role in both acute and chronic eye diseases. Treatment of serious infections needs a good microbiological diagnostic. The indications and techniques for investigations are determined by the site of infection, severity of the process, and knowledge of the likely responsible organisms. Immediate inoculation of specimens on culture media in the examining room is often recommended. This article describes organisms associated with ocular infections, and is designed to assists ophthalmologists in the collection, processing and transport of specimens.

Bacteriological Techniques↗
PubMed1996

[Microbiological and serological verification of cornea donors].

A study was made during 1994 about microbiological contamination on the donor eyes before enucleation of whole globe. We studied the efficiency of the decontamination method by checking sterility of corneal storage medium after two days. We give results of serological tests on 252 donors.

Cornea↗
PubMed1995

Absorption of an oxytocin antagonist (antocin) and a vasopressin analogue (dDAVP) through a standardized skin erosion in volunteers.

PURPOSE: Transdermal administration of the peptides [Mpa1, D-Tyr (Ethyl)2, Thr4, Orn8]-oxytocin (antocin) and [Mpa1, D-Arg8]-vasopressin (dDAVP) was studied in healthy volunteers. METHODS: A standardized skin erosion was formed preliminary by suctioning. The peptides were administered in plastic reservoirs through a 5 mm erosion and the absorption was followed for a six-day period with plasma concentration determinations on days 1, 3 and 6 with refilling the reservoirs daily with 15 microns and 10 mM solutions of dDAVP and antocin, respectively. Fourteen healthy non-smoking volunteers divided equally between the sexes, participated in the study. Plasma concentrations were measured using specific radioimmunoassays. Reservoir concentrations and metabolic stability of the peptides were determined using reverse-phase HPLC. RESULTS: Both antocin and dDAVP were absorbed across the skin erosion. The absorption pattern was biphasic with a high initial absorption during days 1 and 2 followed by a lower absorption on days 3 and 6. The absorption on day 1, which was estimated at more than 50% for both peptides during a 24 h period, corresponded to a simultaneous decrease in peptide concentration in the reservoirs. The extent of absorption for antocin on days 3 and 6 was 1/3 to 1/6, respectively, of that observed on day 1. Antocin was minimally degraded in the skin reservoir while dDAVP was intact. However, accumulation of cellular material appeared in the antocin reservoirs. The absorption of antocin was reduced by exposure to intact skin surrounding the skin erosion. No pain was experienced and no scar formation was observed. CONCLUSIONS: The observed biphasic absorption may be a consequence of the mild inflammatory response occurring subsequent to eroding the skin. The standardized skin erosion may provide a route for the short-term delivery of otherwise poorly absorbable peptide and protein drugs.

Absorption↗
PubMed1995

Treatment of Clostridium difficile colitis. Summary of a round table held in Brussels on March, 3rd, 1994.

Due to the growing incidence and the severity of infections due to vancomycin resistant enterococci, it is now recommended to treat mild to moderate cases of Clostridium difficile-associated diarrhoea with metronidazole while maintaining the use of oral vancomycin in serious or life-threatening colitis. Clostridium difficile is a common cause of diarrhoea after antibiotic therapy and induces a spectrum of diseases ranging from mild diarrhoea to pseudomembranous colitis (PMC). It is considered to be the first cause of diarrhoea occurring among hospitalized patients (1).

Clostridioides difficile↗
PubMed1995

Potential use of oxytocin and vasopressin V1a antagonists in the treatment of preterm labour and primary dysmenorrhoea.

In order to study the involvement of oxytocin (OT) and vasopressin (AVP) in mechanisms of uterine activation and to clarify the therapeutic potential of antagonists to these hormones in preterm labour and primary dysmenorrhoea, studies of human uterine contractility in vivo and in vitro as well as measurements of OT and AVP V1a receptors were performed. Good correlations between OT receptor concentrations and effects on contractility were observed in both the pregnant and non-pregnant states, which indicates that OT acts specifically on its own receptor in the uterus. For AVP there was lack of such correlation which may suggest that this hormone influences both the OT and AVP V1a receptor sites. At the onset of labour both preterm and at term no marked increase in the OT receptor concentration was observed, but OT may still be involved in the initiation of labour, being produced locally in the uterus and not detectable in plasma. We observed a reduced OT receptor concentration in advanced labour and after OT infusion, which suggests that OT influences its own receptor. The AVP V1a receptor concentration and the effect of AVP on the uterus were about equal to those for OT, and the concentration of AVP V1a receptors also tended to decrease in advanced labour, observations which support an involvement also of AVP in the mechanisms of labour. In non-pregnant women AVP receptors as well as uterine effects of AVP in vitro and in vivo were about five times higher than those for OT, and the effect of AVP was increased premenstrually. This firmly supports an aetiological role of this peptide in the uterine hyperactivity of primary dysmenorrhoea. We have also shown that the analogue 1-deamino-2-D-Tyr-(OEt)-4-Thr-8-Orn-OT, which blocks both the OT and AVP V1a receptor sites, given by intravenous infusion inhibits both preterm labour and dysmenorrhoea, and this is in agreement with our receptor and contractility findings.

Arginine Vasopressin↗
PubMed1994

Effect of oxytocin antagonists on the activation of human myometrium in vitro: atosiban prevents oxytocin-induced desensitization.

OBJECTIVE: Our purpose was to investigate whether the sensitivity of myometrial cells to oxytocin is affected by prolonged exposure to oxytocin antagonists. STUDY DESIGN: Tissue slices or cultured myometrial cells were exposed to peptides in vitro. Myometrial activation was studied by measuring the formation of inositol phosphates and the changes in intracellular calcium. Oxytocin binding was measured by saturation analysis. RESULTS: Atosiban and related peptides inhibited oxytocin-induced myometrial activation as pure antagonists (inhibition constant 10 nmol/L) but had no effect on prostaglandin E2-induced activation. Long-term (> or = 24 hours) exposure to atosiban had no residual effect on oxytocin sensitivity. However, long-term exposure to oxytocin resulted in homologous desensitization and loss of oxytocin receptors. Oxytocin-induced desensitization was prevented by coincubation with atosiban. CONCLUSIONS: Atosiban is a pure oxytocin antagonist and has a specific, reversible effect on myometrial cells in vitro. Its potential use for the management or even prevention of idiopathic preterm labor or to reverse uterine hypertony during oxytocin-induced labor should be tested in controlled clinical trials.

Calcium↗
PubMed1994

Receptors for and myometrial responses to oxytocin and vasopressin in preterm and term human pregnancy: effects of the oxytocin antagonist atosiban.

OBJECTIVE: Our purpose was to study myometrial oxytocin and type V1 vasopressin receptors, the in vitro contractile effects of these hormones, and the influence of an oxytocin antagonist. STUDY DESIGN: Women delivered by cesarean section preterm (n = 51) and at term (n = 71), with and without labor contractions, gave myometrium for the estimation of oxytocin and V1 vasopressin receptors. The in vitro myometrial effects of the peptides and the influence on these of the competitive oxytocin receptor blocking agent 1-deamino-2-D-Tyr(OEt)-4-Thr-8-Orn-oxytocin were also tested. RESULTS: The median concentration of oxytocin receptors was 116 fmol/mg protein (range 15 to 372 fmol/mg protein) in patients delivered preterm not in labor, 134 fmol/mg protein (27 to 1421 fmol/mg protein) in the beginning of labor, and 46 fmol/mg protein (9 to 140 fmol/mg protein) in advanced labor. At term the corresponding concentrations were 172 (25 to 629), 223 (24 to 414), and 70 (21 to 92) fmol/mg protein. The concentration of V1 vasopressin receptors also decreased in advanced labor. In advanced labor after oxytocin infusion a reduction in the concentration of the receptor for this hormone was observed, which appeared to be related to the duration and dose of treatment. Oxytocin receptors did not vary between women with different indications for cesarean section. The oxytocin effects in vitro and the degree of inhibition by the antagonist of oxytocin responses correlated with the concentration of oxytocin receptors but not with that of V1 vasopressin receptors. No correlation was seen between the response to vasopressin and concentrations of oxytocin or V1 vasopressin receptors. CONCLUSIONS: The effect of oxytocin on the myometrium in pregnancy is mediated by an oxytocin receptor, whereas vasopressin acts on both oxytocin and vasopressin receptors. The initiation of labor both preterm and at term may be primarily related to increased release of oxytocin, which is locally produced in the uterus and not detectable in the plasma, but oxytocin and vasopressin receptors may play a role in the regulation of labor. The analog 1-deamino-2-D-Tyr(OEt)-4-Thr-8-Orn-oxytocin, which blocks both the oxytocin and the V1 vasopressin receptor, should inhibit labor both preterm and at term, the former confirming results of recent clinical studies in Sweden and the United States.

Cesarean Section↗
PubMed1994

Antagonists for the human oxytocin receptor: an in vitro study.

The oxytocin antagonist [Mpa1, D-Tyr(Et)2, Thr4, Orn8]-oxytocin has been successfully used for treating premature labour. The interactions of this antagonist with neurohypophysialhormone receptors in the human myometrium were investigated. Competition curves among [3H]oxytocin, [3H]arginine vasopressin, [3H][1-(beta-mercapto-beta,beta-cyclopentamethylenepropionic acid)2-(O-methyl)-tyrosine, 8-arginine] vasopressin, the corresponding unlabelled peptides and a series of oxytocin antagonists including [Mpa1,D-Tyr(Et)2,Thr4,Orn8]-oxytocin were constructed from results taken from the myometrium of pregnant women and rabbits, and were analysed simultaneously using the computer program LIGAND. The biological activity of [Mpa1,D-Tyr(Et)2,Thr4,Orn8]-oxytocin in the human uterus was investigated by studying its effect on oxytocin-induced intracellular Ca2+ mobilization in human myometrial cells in culture that were expressing high concentrations of oxytocin receptors. The results indicate that [Mpa1,D-Tyr(Et)2,Thr4,Orn8]-oxytocin and related antagonists are selective for the oxytocin receptor in the myometrium of pregnant rabbits but not of pregnant women. In women, they bind with high affinity to the V1 vasopressin receptor. In myometrial cells [Mpa1,D-Tyr(Et)2,Thr4,Orn8]- oxytocin inhibits the oxytocin-induced increase in intracellular Ca2+ concentration in a dose-dependent fashion, with an IC50 value of 5 nmol l-1. The uterine relaxant effect of this antagonist might result not only from the block of the oxytocin receptor, but also from interaction with the V1 vasopressin receptor.

Animals↗
PubMed1994

[A case of keratitis due to Mycobacterium chelonae].

The authors presents one case of primitive corneal mycobacterium keratitis after corneal graft. This rare form of keratitis is analysed in the field of mycobacterial infections who's nowadays more developed in our industrialised countries. The description of the case point out the multiresistance of this mycobacterium and describe the different treatments.

Aged↗
PubMed1993

Antidiuretic activity and release of factor VIII by vasopressin analogues.

Vasopressin and in particular its structural analogue dDAVP (1-deamino-8-D-arginine vasopressin) can increase plasma concentrations of Factor VIII and tissue plasminogen activator (tPA) in some species of animals and in humans. For this reason dDAVP is used therapeutically in the treatment of bleeding episodes in patients suffering from haemophilia A and Von Willebrand's disease. However, the high antidiuretic activity of dDAVP constitutes and unwanted effect in this context. In the present study, a large number of analogues of vasopressin were designed, synthesized and tested in monkeys with the aim of producing compounds in which the Factor VIII-releasing activity was selectively isolated from the vasopressor and antidiuretic actions of the peptide. The results indicate that it is possible to separate these biological activities; however, none of the analogues tested so far possessed Factor VIII potencies comparable to that of dDAVP.

Amino Acid Sequence↗