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Biomedical subjects

J Pierre

Publications and source records attributed to J Pierre.

At least 91 records · Page 5Linked to original sources
PubMed1981

[A study of the transplacental passage of cefotaxime (author's transl)].

The authors have studied the transplacental transfer of cefotaxime in 19 women at the end of pregnancy, after injection of 1 g i.m. Amniotic fluid and cord blood samples were collected during cesarean section. The diffusion of the drug was rapid in cord blood and the concentrations were parallel to those measured in maternal blood; they decreased from 3.8 to 2.1 micrograms/ml between the first and the fourth hour following the injection. In amniotic fluid, diffusion was delayed; the peak reached 3.6 micrograms/ml at the third hour and a the fourth hour, the concentrations were still measurable (2.3 micrograms/ml). On the whole, cefotaxime concentrations measured in cord blood and amniotic fluid were superior to the MIC's of bacteria usually responsible for obstetrical infections; they may be efficient against most beta-lactamase producing enterobacteriaceae.

Amniotic Fluid↗
PubMed1981

Release of 7-methylguanine residues from alkylated DNA by extracts of Micrococcus luteus and Escherichia coli.

Cell extracts from Micrococcus luteus release both free 3-methyladenine and free 7-methylguanine from alkylated DNA. The glycosylase activity responsible for the liberation of 7-methylguanine is not 3-methyladenine-DNA glycosylase, which, when purified, does not liberate it. Furthermore, the heat inactivation rates of the two enzymatic activities are different. The release of 7-methylguanine by chemical depurination of ethanol-soluble oligonucleotides has been ruled out. A similar activity releasing 7-methylguanine is also found in Escherichia coli.

Animals↗
PubMed1980

Micrococcus luteus endonucleases for apurinic/apyrimidinic sites in deoxyribonucleic acid. 1. Purification and general properties.

Two chromatographically distinct endonucleases from Micrococcus luteus, specific for apurinic and apyrimidinic sites (AP-endonucleases A and B), have been extensively purified and characterized. Both are free from DNA glycosylase, unspecific endonuclease, and phosphatase activities. The two enzymes behave as monomeric proteins of approximately 35000 daltons. In addition to their different chromatographic properties on CM-cellulose, P-cellulose, hydroxylapatite, and DNA--Sepharose, both AP-endonucleases can be distinguished as follows: AP-endonuclease A has an isoelectric point of 4.8, shows a half-life of 4 min at 45 degrees C, reacts optimally at pH 7.5 and has a KM value of 2.3 X 10(-6) M. AP-endonuclease B has a pI of 8.8, is more stable at 45 degrees C (half-life of 10 min), and reacts optimally between pH 6.5 and pH 8.5; its KM value is 3.7 X 10(-6) M.

Chromatography, DEAE-Cellulose↗
PubMed1980

Micrococcus luteus endonucleases for apurinic/apyrimidinic sites in deoxyribonucleic acid. 2. Further studies on the substrate specificity and mechanism of action.

Two endonucleases specific for DNA-containing apurinic or apyrimidinic sites (AP-endonucleases A and B) have been isolated from Micrococcus luteus and highly purified. These enzymes have no exonuclease activity. Both AP-endonucleases hydrolyze DNA-containing apurinic or apyrimidinic sites at the 5' end of the lesion, thus generating 3'-hydroxyl and 5'-phosphoryl end groups. DNA-containing pyrimidine dimers, introduced at low doses of UV, are not hydrolyzed, whereas DNA-containing lesions, introduced at high doses of UV or by gamma irradiation are nicked by either AP-endonuclease. During hydrolysis of apurinic DNA, neither of the AP-endonucleases acts as a processive enzyme.

DNA, Viral↗
PubMed1980

Visible and ultraviolet spectral transitions of camphor-bound cytochrome P-450. A comprehensive study.

A systematic analysis of the low-spin to high-spin transition in the ultraviolet and visible absorption spectrum of camphor-bound cytochrome P-450 is presented. The equilibrium depends on the ionization of two groups, the deprotonation of the first one (pK1 = 5.4 at -17 degrees C) leading to an increased content of high-spin type of spectrum, that of the second one (pK2 > 6) to more low-spin type of spectrum. Both protonation processes and their thermodynamic terms are studied under various conditions of salt, solvent and temperature, including subzero temperatures. The basic mechanism of the transition is the same in aqueous and mixed organic solvent, i.e. the protonation of the first group triggers a conformational change of the whole protein. These phenomena are discussed with reference to functional conformational changes during the catalytic cycle of cytochrome P-450.

Camphor↗
PubMed1979

[The evolution of the thickness of rabbit corneas in hydratation, the influence of pH and composition of the solution (author's transl)].

The swelling of excised, de epitheliated, rabbit corneas has been measured every five minutes during their immersion in a hydrating medium. The following media have been used: distilled H2O, Krebs-bicarbonate Ringer solution, HCl 0,01 N and NaCl 1 M/l. The swelling is very moderate with Krebs and NaCl, much higher and practically proportional to the duration of immersion with HCl, still faster with H2O. On the other hand, the influence of pH has been studied using 13 different solutions buffered from pH 1 to pH 13. A pronounced minimum of the swelling was found for pH 4, along with 3 relative maxima: the first around pH 2, the second around pH 8 and the third around pH 12. The interpretation of those results on a biochemical basis is discussed. For all these media, the solvent was distilled H2O. At last, two statistical distributions, based on 131 corneas, have been determined: one concerning the initial thickness and the other concerning the difference between the initial thickness of the two corneas of the same rabbit.

Animals↗
PubMed1979

Cerebrospinal fluid penetration of mezlocillin.

The passage of 6-[(R)-2-[3-methylsulfonyl-2-oxo-imidazolidine-1-carboxamido]-2-phenyl-acetamido)-penicillanic acid sodium salt (mezlocillin, Baypen), into the CSF was studied in 9 patients with symptoms of acute meningitis, presumed to be of viral origin. The antibiotic was given as a single 5 g dose i.v. over 30 min. The CSF/serum concentration ratio of mezlocillin showed a variation from 0 to 10.7%. The antibiotic could be effective in the treatment of bacterial meningitis caused by ampicillin-resistant strains of Haemophilus influenzae and by most Enterobacteriaceae, provided these results will be confirmed by a study now in progress. In one patient suffering from meningococcal meningitis this concentration ratio varied between 72% (day 3) and 54% (day 12).

Adolescent↗
PubMed1978

[Pharmacokinetic study of antibiotics in human respiratory tract (author's transl)].

We report the results of the study of the bronchial concentrations of several antibiotics. The experiment included 280 patients and the concentrations achieved in bronchial secretions were measured for 11 antibiotics. The samples of bronchial secretions were taken in situ by fibroscopy or through the tracheostomy cannula. The results of the study show that the rate of penetration is variable according to the different drugs; even in the same antibiotic family such as beta-lactam antibiotics the rate of penetration is variable. The bronchial levels of aminoglycosides, macrolides and tetracyclines are worthwhile, and are often superior to the MIC of the infecting organisms; the penetration is also dependant of the inflammatory conditions of the bronchi. Otherwise the sampling conditions were the best possible since samples taken by fibroscopy or by tracheostomy are not contaminated by saliva which is a factor of dilutional error. The methodology used in this study is an approach of pharmacokinetics of antibiotics in respiratory tract.

Adult↗
PubMed1978

[An acquired B antigen in a subject of A2 group].

Almost all cases of acquired B antigen have been found in individuals. This report concerns a group A2 patient with acquired B antigen. The family was not available for genetic studies. Nevertheless two facts were in favour of A2 genotype: 10 after acetylation of the patient's red cells the A1 reactivity which usually reappears or is increased on acquired B cells, did not appear. 20 The study of the serum alpha-N acetyl galactosaminyl transferase showed an optimal activity at pH7, as it is usually found in A2. The respective roles of anti acquired B antibodies, group A specific structures and bacterial enzyme properties in the occurrence of acquired B antigen are discussed.

ABO Blood-Group System↗
PubMedDate not supplied

The serotoninergic system of the brain of the viper, Vipera aspis. An immunohistochemical study.

Serotoninergic cell bodies and fibers in the brain of the viper, Vipera aspis, were visualized by immunohistochemistry. Immunoreactive cell bodies were observed in the diencephalic hypothalamic periventricular organ and in the dorsal wall of the infundibular recess, in the nuclei raphe superior and inferior of the midbrain and hindbrain, and to a lesser extent in the nuclei reticularis superior, reticularis inferior and reticularis lateralis. In contrast to other reptilian species, serotoninergic cells were also observed in the central gray matter of the midbrain in the neighbourhood of the nucleus of the trochlear nerve. Immunoreactive fibers are widely distributed throughout the brain of the viper. In the olfactory bulb, fibers were observed in the internal plexiform layer and mitral cell layer. The cerebral cortex contains the highest density of fibers in the dorsal region. The distribution of immunoreactive fibers in the dorsal ventricular ridge is extremely heterogeneous, and five subcomponents of this structure can be distinguished. The majority of diencephalic and mesencephalic structures that contain immunoreactive fibers are also primary visual centres: the nuclei geniculatus lateralis pars dorsalis, the n. posterodorsalis and n. opticus tegmenti, and the optic tectum. Serotoninergic fibers in the nuclei of the oculomotor and motor cranial nerves (III, IV, V, VII, X) are disposed in a tightly woven basket around the non-immunoreactive cell bodies of the motoneurons. These findings, together with the available literature, suggest that the serotoninergic system in snakes is comparable to that in lizards, with a massive ascending projection of fibers from the n. raphe superior to mesencephalic and prosencephalic structures, and a descending projection from the n. raphe inferior to the spinal cord.

Animals↗
PubMedDate not supplied

The serotoninergic system of the brain of the lamprey, Lampetra fluviatilis: an evolutionary perspective.

The distribution of serotonin(5HT)-immunoreactive cell bodies, nerve fibers and terminals was investigated by light microscopy in the lamprey Lampetra fluviatilis. Twenty-three distinct groups of 5HT neuronal somata were identified from diencephalic to rhombencephalic levels in the brain. The diencephalon contained a subependymal population of immunoreactive cells in contact with the cerebrospinal fluid (CSF), which could be subdivided into five separate groups situated in the hypothalamus and ventral thalamus; five additional groups of immunoreactive diencephalic neurons, situated in the dorsal thalamus and thalamo-pretectum, which were not in contact with the CSF, were also identified. In the midbrain, in addition to a few labelled neurons in the optic tectum, two structures containing immunoreactive cells were identified in the tegmentum mesencephali. None of these 5HT cells corresponded to the retinopetal neurons which are situated in the same region. A very large number of 5HT neurons were observed in the hindbrain which could be divided into seven groups in the isthmus rhombencephali and a further three in the rhombencephalon proper. Immunoreactive fibers and terminals were widely distributed throughout the neuraxis. In the telencephalon two 5HT fibers assemblies, lateral and medial, could be identified which terminated in both pallial and subpallial structures. The richest serotoninergic innervation in the telencephalon was found in the lateral portion of the primordium hippocampi and the medial part of the corpus striatum. In the diencephalon, the distribution of immunoreactive fibers and terminals was heterogeneous, being most pronounced in the lateral hypothalamic area and in the infundibulum. The densest arborization of fibers in the mesencephalon was found in the stratum fibrosum et cellulare externum of the optic tectum, a major site of retinal projection, and in the nucleus interpeduncularis mesencephali as well as in the oculomotor nuclei. The rhombencephalon is richly endowed with serotoninergic fibers and terminals, many labelled arborizations being found in the nuclei isthmi rhombencephali and around the nucleus motorius nervi trigemini. Comparative analysis of the serotoninergic systems of petromyzontiforms and gnathostomes indicates that the evolution of this system involves a progressive elimination of the rostral immunoreactive cells and an increasing complexity of the caudal population of serotoninergic neurons.

Animals↗
PubMedDate not supplied

Template properties of ultraviolet-irradiated poly(dC) replicated by E. coli DNA polymerase I: indication for a role of apyrimidinic-sites in UV-induced mutagenesis.

Ultraviolet irradiation alters the template properties of poly(dC) when replicated by Escherichia coli DNA polymerase I. These effects are due to base modifications. Some of them are identified as apurinic/apyrimidinic sites (AP-sites) by their sensitivity to AP-endonuclease B purified from Micrococcus luteus, and their template properties. The rate of formation of AP-sites in poly(dC) is estimated at 3 X 10(-7) site per nucleotide per J.m-2. Exposure of supercoiled or relaxed pBR322 DNA to UV light results also in the formation of sites sensitive to AP-endonuclease B. In this case, the rate of formation of AP-sites is the same in relaxed or supercoiled DNA: 0.3 X 10(-7) site per nucleotide per J.m-2. The apyrimidinic sites are generated through the processing of an ultraviolet induced primary lesion. We suggest that this lesion is cytosine hydrate by its rate of decay and preferential formation in single stranded DNA. Our results suggest that AP-sites might be a minor pathway leading to UV-induced mutagenesis.

Cytosine↗
PubMedDate not supplied

Penetration of cefotaxime into bronchial secretions.

The penetration into bronchial secretions of cefotaxime, a new, highly active cephalosporin, was studied in 45 patients with respiratory infections. Ten patients received 0.75 g and 25 received 1 g of cefotaxime intramuscularly; 10 patients received a 30-min intravenous infusion of 2 g of cefotaxime. Samples of bronchial secretions were obtained by means of fiber-optic bronchoscopy after a single dose in all patients and after three and seven days of treatment in 30 and 15 patients, respectively. Simultaneous serum samples were collected for determination of the relationship between the levels of drug in bronchial secretions and those in serum. Assays were performed by microbiologic agar diffusion. In 30 cases bacteriologic analysis determined the minimal inhibitory concentrations of cefotaxime for the bacteria isolated from sputum. Mean peaks in bronchial secretions reached 1.5-2.5 microgram/ml (according to the groups) after 3 hr; individual concentrations varied according to the dose, the route of administration, and the duration of the treatment. Ratios between the levels in bronchial secretions and the corresponding levels in serum were approximately 8%-25% after 3 hr, as is usual for other cephalosporins. Cefotaxime reached significant concentrations in bronchial secretions, exceeding the minimal inhibitory concentrations for microorganisms responsible for respiratory infections.

Bronchi↗
PubMedDate not supplied

[GABA immunoreactivity in the main olfactory bulb of the frog Rana temporaria].

Immunoreactivity for gamma-aminobutyric acid (GABA) was localized at the light microscopic level in the main olfactory bulb (MOB) of the frog, Rana temporaria. By means of free-floating peroxidase-antiperoxidase immunocytochemical technique, GABA was found in a large number of neurons in the granular cell layer, in a few small somata in the mitral cell layer and in two different types of cell somata in the glomerular layer. Individual GABA-immunopositive cells were found in the olfactory nerve layer. GABA immunostaining was also localized in cell processes and fiber fragments. There were many immunoreactive puncta in all layers of the MOB. GABA-positive punctate structures often outlined immunonegative cells in the mitral cell and glomerular layers. Rounded tightly packed groups of immunoreactive puncta were found only along ventral border of the glomerular layer. The results are discussed in comparison with data obtained on mammalian MOB in terms of MOB functional organization.

Animals↗