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Biomedical subjects

J Peter

Publications and source records attributed to J Peter.

At least 55 records · Page 3Linked to original sources
PubMed1996

Effect of histaminergic drugs on integumental melanophores of adult Bufo melanostictus.

Histamine and 2-methyl histamine caused dose-dependent aggregation of melanophores in toad B. melanostictus. The effects were effectively antagonised by mepyramine, a specific H1 histamine receptor antagonist, and metiamide a specific H2 receptor antagonist. On the other, hand 4-methyl histamine, a specific H2 receptor agonist dispersed the melanophores. The results suggest that adult Bufo melanophores have H1 histamine receptors which mediate melanophore aggregation, however, dispersion of melanophores may be controlled by undifferentiated histamine receptors of H2 type.

Animals↗
PubMed1995

Molecular neurobiology and pharmacology of the vasopressin/oxytocin receptor family.

1. VP and OT mediate their wealth of effects via 4 receptor subtypes V1a, V1b, V2, and OT receptors. 2. We here review recent insights in the pharmacological properties, structure activity relationships, species differences in ligand specificity, expression patterns, and signal transduction of VP/OT receptor. 3. Furthermore, the existence of additional VP/OT receptor subtypes is discussed.

Amino Acid Sequence↗
PubMed1995

A double chamber system for producing constant radon concentration.

An experimental arrangement of a radon chamber with an intrinsic constancy of the relative radon concentration is described. The system consists of a reference chamber and an auxiliary storage chamber. The only active device is a timer-controlled pump or valve which feeds radon gas from the storage into the reference chamber. The switching pattern of the timer is extracted from model calculations and theoretically performs an exact compensation of the radon loss by radioactive decay. If the calculations are done in real time and online, every known external event influencing the radon concentration can be compensated. This paper presents a simple timer circuit and a computer code which generates the timer program. The influence of the air flow stability and the leakage of the chambers are discussed. It is planned to apply this theoretical approach to provide a constant radon gas concentration for an actual chamber.

Calibration↗
PubMed1995

Comparative and collaborative evaluation of standardization of antifungal susceptibility testing for filamentous fungi.

The purpose of the study was to evaluate the interlaboratory agreement of broth dilution susceptibility methods for five species of conidium-forming (size range, 2 to 7 microns) filamentous fungi. The methods used included both macro- and microdilution methods that were adaptations of the proposed reference method of the National Committee for Clinical Laboratory Standards for yeasts (m27-P). The MICs of amphotericin B, fluconazole, itraconazole, miconazole, and ketoconazole were determined in six centers by both macro- and microdilution tests for 25 isolates of Aspergillus flavus, Aspergillus fumigatus, Pseudallescheria boydii, Rhizopus arrhizus, and Sporothrix schenckii. All isolates produced clearly detectable growth within 1 to 4 days at 35 degrees C in the RPMI 1640 medium. Colony counts of 0.4 x 10(6) to 3.3 x 10(6) CFU/ml (mean, 1.4 x 10(6) CFU/ml) were demonstrated in 90% of the 148 inoculum preparations. Overall, good intralaboratory agreement was demonstrated with amphotericin B, fluconazole, and ketoconazole MICs (90 to 97%). The agreement was lower with itraconazole MICs (59 to 79% median). Interlaboratory reproducibility demonstrated similar results: 90 to 100% agreement with amphotericin B, fluconazole, miconazole, and ketoconazole MICs and 59 to 91% with itraconazole MICs. Among the species tested, the MICs for S. schenckii showed the highest variability. The results of the study imply that it may be possible to develop a reference method for antifungal susceptibility testing of filamentous fungi.

Aspergillus↗
PubMed1995

Activities of amphotericin B and antifungal azoles alone and in combination against Pseudallescheria boydii.

In order to develop new approaches to treatment of infections due to Pseudallescheria boydii, the in vitro antifungal activity of amphotericin B alone and in combination with miconazole, itraconazole, and fluconazole was studied. Combinations of amphotericin B and antifungal azoles were synergistic, additive, or indifferent in their interaction against P. boydii. Antagonism was not observed.

Amphotericin B↗
PubMed1995

Effect of increasing inoculum sizes of pathogenic filamentous fungi on MICs of antifungal agents by broth microdilution method.

Inoculum size is a critical variable in development of methods for antifungal susceptibility testing for filamentous fungi. In order to investigate the influence of different inoculum sizes on MICs of amphotericin B, 5-fluorocytosine, itraconazole, and miconazole, 32 clinical isolates (8 Aspergillus fumigatus, 8 Aspergillus flavus, 5 Rhizopus arrhizus, 8 Pseudallescheria boydii, and 3 Fusarium solani isolates) were studied by the broth microdilution method. Four inoculum sizes were studied: 1 x 10(2) to 5 x 10(2), 1 x 10(3) to 5 x 10(3), 1 x 10(4) to 5 x 10(4), and 1 x 10(5) to 5 x 10(5) CFU/ml. The National Committee for Clinical Laboratory Standards reference method for antifungal susceptibility testing in yeasts was modified and applied to filamentous fungi. The inoculum was spectrophotometrically adjusted, and all tests were performed in buffered medium (RPMI 1640) at pH 7.0 with incubation at 35 degrees C for 72 h. MICs were read at 24, 48, and 72 h. Amphotericin B showed a minimum effect of inoculum size on MICs for all species with the exception of P. boydii (P < 0.05). A significant effect of inoculum size on MICs was observed with 5-fluorocytosine, for which there was an increase of more than 10-fold in MICs against all Aspergillus spp. between inoculum concentrations of 10(2) and 10(4) CFU/ml (P < 0.001). For itraconazole, the results showed a more species-dependent increase of MICs, most strikingly for R. arrhizus and P. boydii. Miconazole, which was tested only with P. boydii, did not demonstrate a significant effect of inoculum size on MICs. In summary, the effect of inoculum size on MICs for filamentous fungi was dependent upon the organism and antifungal compound tested. Thus, among antifungal compounds, itraconazole and 5-fluorocytosine demonstrated significant inoculum effects, while amphotericin B and miconazole showed comparatively minimum inoculum effects against pathogenic filamentous fungi. Moreover, among filamentous fungi, P. boydii and R. arrhizus exhibited the greatest inoculum effect.

Amphotericin B↗
PubMed1995

Role of cholinergic receptors in melanophore responses of amphibians.

Responses of isolated skin melanophores of Rana tigerina and Bufo melanostictus to cholinergic drugs were studied using the Mean Melanophore Size Index assay to explore the nature and role of cellular receptors in melanophore regulation activity. Acetylcholine (Ach) in a concentration of 10(-7) to 6.4 x 10(-6) g/ml caused dispersion of the skin melanophores of R. tigerina and B. melanostictus. These effects were blocked by both atropine and hyoscine in a concentration of 8 x 10(-6) g/ml each. Eserine augmented the melanophore dispersal effects of Ach. This potentiation of the dispersal effect of Ach by eserine was also antagonised by hyoscine. Carbachol another specific cholinergic agonist significantly caused dispersion of the melanophores of both the amphibian species. The effects were also blocked by atropine and hyoscine. These data indicate that cholinergic receptors of muscarinic type are present on the melanophores of R. tigerina and B. melanostictus which mediate dispersion of integumental melanophores leading to darkening of the skin.

Acetylcholine↗
PubMed1994

Emergency intubation of the pediatric medical patient: use of anesthetic agents in the emergency department.

STUDY OBJECTIVES: To delineate the diagnoses of children who required emergency intubation, to ascertain which medications were used, and to describe the complications of intubation and their association with the choice of medications. DESIGN, SETTING, AND TYPE OF PARTICIPANTS: Three-year retrospective study of 60 intubations of critically ill pediatric patients by pediatric emergency physicians in the emergency department setting. MEASUREMENTS AND MAIN RESULTS: Clinical complications were noted for intubations with neuromuscular paralysis and intubations initially attempted without a paralyzing agent. Intubations attempted without neuromuscular paralysis resulted in a higher rate of complications (53% versus 26%) and a greater risk of more than one complication per intubation. This finding appeared to be independent of physicians' clinical experience. CONCLUSION: Rapid-sequence protocols with paralysis facilitate intubations in the complex pediatric patient in the ED setting.

Adolescent↗
PubMed1994

Efficacy of unilamellar liposomal amphotericin B in treatment of pulmonary aspergillosis in persistently granulocytopenic rabbits: the potential role of bronchoalveolar D-mannitol and serum galactomannan as markers of infection.

A model of primary pulmonary aspergillosis in rabbits was developed to reproduce the persistent levels of profound granulocytopenia and the histopathologic features of bronchopneumonia, vascular invasion, and hemorrhagic infarction encountered in humans. D-mannitol was detectable in bronchoalveolar lavage fluid by gas-liquid chromatography/mass spectroscopy, and galactomannan was measurable in serum by latex agglutination immunoassay. A pharmacokinetically distinctive unilamellar vesicle formulation of liposomal amphotericin B, 5 mg/kg/day intravenously, compared with high-dose conventional desoxycholate amphotericin B, 1 mg/kg/day intravenously, was more effective in preventing nephrotoxicity, increasing survival, reducing the number of viable organisms, and decreasing tissue injury due to Aspergillus organisms. Thus, D-mannitol in lavage fluid and galactomannan in serum may be useful markers of pulmonary aspergillosis, and liposomal amphotericin B was significantly more effective and safer than desoxycholate amphotericin B for treatment of pulmonary aspergillosis in profoundly granulocytopenic rabbits.

Agranulocytosis↗
PubMed1993

Two-step binding mechanism of fibrinogen to alpha IIb beta 3 integrin reconstituted into planar lipid bilayers.

The platelet integrin alpha IIb beta 3 binds to fibrinogen and thus mediates platelet aggregation after stimulation. This integrin was isolated from human platelets and reconstituted into lipid vesicles. As judged by electron microscopy the integrin incorporated adequately only into 1,2-dimyristoylglycero-3-phosphocholine/1,2-dimyristoylphosphatidy lglycerol vesicles after removal of the detergent by adsorption to Bio-Beads. These vesicles were then used to generate planar lipid bilayers. The binding of fluorochrome labeled fibrinogen or the peptide ligand Gly-Arg-Gly-Asp-Ser-Pro-Cys (GRGDSPC) was monitored by total internal reflection fluorescence microscopy and a solid phase binding assay. Analysis of the kinetics revealed fast reversible formation of a fibrinogen/integrin precomplex (KD = 50 nM) followed by formation of a stable irreversible complex. This transition was monitored by measuring the fraction of precomplex which could be dissociated by addition of excess Gly-Arg-Gly-Asp-Ser (GRGDS). For the peptide, the KD was 1200 nM, and the rates of association and dissociation were faster than the time resolution of the method. Similar KD values were found by inhibition of fibrinogen binding to alpha IIb beta 3 in the immobilized receptor assay. Since the binding of fibrinogen was irreversible, KD values were dependent on the time period between fibrinogen incubation and peptide addition. These and results by other authors point to the biological importance of the biphasic binding process of fibrinogen to its receptor on platelets.

Amino Acid Sequence↗
PubMed1992

The gene for proliferating cell nuclear antigen (Pcna) maps to mouse chromosome 2.

The structural gene for proliferating cell nuclear antigen (Pcna) has been mapped to mouse Chromosome (Chr) 2 by use of a PCR-based assay. With somatic cell hybrids, Pcna was mapped between the T(2;4)13H and T(2;4)1Sn breakpoints. An interspecific backcross was employed to map Pcna 1.9 +/- 1.3 cM distal to Il-lb. This was confirmed by mapping Pcna in the BXH recombinant inbred (RI) strains; no recombinants were seen between Il-la and Pcna. In addition, a PCNA-related sequence (Pcna-rsl) was mapped to Chr 19 in the BXH RI strains.

Animals↗
PubMed1991

[Computer programming for delivery. Evaluation of 5 years of activity and 1,752 inductions of labor].

3,300 women were delivered between January 1986 and July 1990 inclusive. 1,267 of them had no pathology and 341 were induced for a pathological reason. Our attitude is to suggest systematically to every pregnant woman that her labour can be programmed to the time that she reaches the middle of the 39th week of amenorrhea providing she is sure of her dates and that the cervix is favourable. Labour is induced by using the electric pump to administer Syntocinon and by rupturing the membranes early. If an epidural anaesthetic is anticipated this is carried out during the first hour after induction. This policy does not bring about premature labours (the mean duration of amenorrhoea was 39.73 weeks) and it does not involve long labours (the mean total duration of labour was 5.68 hours and 7 hours for primipara) 1 UI Oxytocin was delivered per hour. In the group where labours were induced the Caesarean section rate at 6.35% was lower than those who went into labour spontaneously. There were fewer Cesareans for acute fetal distress. Five children had to be transferred to the Paediatric unit and one died after major fetal distress at 9 cms, 48 hours after delivery. The series shows that it is possible to have a policy for programming labour and increasing the comfort of the parturient and controlling her labour. Furthermore, the work of the staff in the labour ward and its staff are helped.

Amnion↗
PubMed1990

SCH-39304 in prevention and treatment of disseminated candidiasis in persistently granulocytopenic rabbits.

To investigate the potential use of SCH-39304 for the prevention and treatment of disseminated candidiasis in granulocytopenic patients, we studied its in vivo antifungal activity as preventive, early, and late treatments in three models (acute, subacute, and chronic) of disseminated candidiasis in persistently granulocytopenic rabbits. SCH-39304 was an effective as amphotericin B alone and fluconazole alone for the prevention of disseminated candidiasis. SCH-39304 alone and fluconazole alone were as effective as amphotericin B plus flucytosine for early treatment of subacute disseminated candidiasis. When treatment was delayed for 5 days to establish chronic disseminated candidiasis, SCH-39304 was less effective than amphotericin B plus flucytosine. In comparison with different treatment regimens, SCH-39304 was more effective in early and preventive treatment. Thus, SCH-39304 was comparable to treatment control regimens in prevention and early treatment of subacute disseminated candidiasis. SCH-39304 also was most effective in granulocytopenic rabbits with disseminated candidiasis when used for prevention or early treatment.

Agranulocytosis↗
PubMed1990

[Results of a policy of labor induction].

In 1986 and 1987, among 1,323 patients who came in labour to the "Clinic Saint-Anne", 672 (50.8 p. cent) were induced without any pathological reason as part of a labour protocol. The technique used consisted in the combination of oxytocics and rupture of the membranes. 85 p. cent received a peridural anesthesia. Comparison between scheduled deliveries and spontaneous labour inductions show no significant difference concerning terms and birth weights. The labour is longer by an average of one hour in the group of scheduled deliveries. In this group, the percentage of caesarean sections is 8.2 p. cent versus 9.12 p. cent (NS). No child born following a scheduled delivery required resuscitation and only one was transferred to pediatrics (because of infection).

Apgar Score↗