PubMed Health⌕ Search

Biomedical subjects

M Lucas

Publications and source records attributed to M Lucas.

At least 163 records · Page 9Linked to original sources
PubMed1990

Suppression of blastogenic transformation of lymphocytes by Bacteroides fragilis in vitro and in vivo.

Bacteroides species and Enterobacteriaceae are known to cause synergistic infections. However, the mechanisms behind this synergy are not completely understood. Several authors have shown that Bacteroides species may inhibit the phagocytosis of Enterobacteriaceae by polymorphonuclear leukocytes as well as by macrophages. With the present study we have addressed the question of whether Bacteroides fragilis (BF) is also capable of suppressing specific immune functions. When incubated together with murine lymphocytes, BF significantly inhibited the blastogenic transformation of these cells stimulated by Escherichia coli-lipopolysaccharide (LPS) or concanavalin A. This effect was dose dependent and was not mediated by prostaglandins. Other bacteria such as E. coli or Listeria monocytogenes did not show such an extensive suppression, while Streptococcus pneumoniae was equally active. BF also inhibited the pokeweed mitogen induced blastogenic transformation of human lymphocytes. Moreover, lymphocytes from BF-injected animals obtained 3 to 12 hours after infection proved to be partly refractory for LPS-stimulation. Finally, BF injections also affected T-cell dependent immunity as judged from the aggravation of an experimental listeriosis in mice.

Animals↗
PubMed1990

Partial trisomy 4p resulting from a balanced intrachromosomal insertion, 4(q313p14p16).

Partial trisomy 4p was found in a child with dysmorphic features. Cytogenetic investigations in the parents revealed an intrachromosomal insertion in the mother, 46,XX,ins (4) (q313p14p16). The proband was trisomic for 4p(p14p16) as a result of a recombination event in the mother's chromosome 4 at meiosis. The clinical features of the proband are compared with those found in the literature.

Chromosome Aberrations↗
PubMed1990

Calcium movements mediated by proteolipid protein and nucleotides in liposomes prepared with the endogenous lipids from brain white matter.

A lipid extract with a composition similar to that of myelin was used to prepare liposomes and proteoliposomes containing the Folch-Lees proteolipid apoprotein. Freeze-fracture replicas of the proteoliposomes were prepared to demonstrate the presence of intramembrane protein particles in the fracture faces of the lipid bilayer. Experiments with 45CaCl2 showed that a steady calcium movement occurs across liposomal membranes, approaching equilibrium between intra- and extravesicular spaces. The most significant finding was that Mg-ATP, ATP analogues, and other nucleotides depressed significantly the calcium fluxes in proteoliposomes, having no effect on liposomes that lacked the proteolipid protein. It is suggested that this intrinsic protein, interacting with nucleotides and endogenous lipids, could be involved in the regulation of calcium levels in myelin by means of a conformational change mechanism. These observations could lead to implications concerning the pathophysiology of myelin.

Adenosine Triphosphate↗
PubMed1990

X linked hypophosphataemia: treatment, height gain, and nephrocalcinosis.

The clinical data of 18 patients with X linked hypophosphataemia were analysed retrospectively. The height data were expressed as SD scores. There was no difference in the final height of patients treated with vitamin D (or 1,25-dihydroxyvitamin D) and phosphate for at least two years (n = 12) and that of 16 hypophosphataemic family members who had never been treated. The mean final SD score (-2.07) of treated patients, however, was significantly higher than the value before treatment (-2.79), which indicated an average absolute height gain of 4-4.5 cm compared with the expected height values. Six of the treated patients developed ultrasonographically detectable nephrocalcinosis with normal renal function. The daily phosphate intake and excretion of patients with nephrocalcinosis was significantly higher than that of patients with normal renal morphology. There was no difference in the doses of vitamin D between the two groups. The average urinary calcium:creatinine ratio of the two groups was similar to and below the hypercalciuric 0.6 mmol:mmol limit. The group with nephrocalcinosis, however, had a higher incidence of hypercalciuric episodes than the group without nephrocalcinosis (12 in 130 observations compared with six in 334 observations, respectively). The benefits and risks of treatment of patients with X linked hypophosphataemia must be further evaluated. The high dose of phosphate seems to be an important factor in the development of nephrocalcinosis in this group of patients.

Adolescent↗
PubMed1990

Determination of the myeloperoxidase-hydrogen peroxide-halide system activity following the respiratory burst of human neutrophils.

A sensitive assay was developed for the determination of the activity of cell derived myeloperoxidase-hydrogen peroxide-halide system associated with the respiratory burst of human neutrophils. The methodological approach relies on the oxidation of 2-nitro-5-thiobenzoic acid (TNB) which could be continuously monitored by means of a chart recorder attached to a photometer. The oxidation of TNB by neutrophils stimulated with either phorbol myristate acetate or N-formyl-Met-Leu-Phe showed the following features: a) Superoxide dismutase failed to modify the rate of TNB oxidation; b) it was strongly inhibited by catalase but not by boiled catalase; c) azide and cyanide inhibited the reaction; d) it required a halide cofactor, namely chloride, and e) the onset of TNB oxidation was strongly potentiated by the calcium ionophore A23187. These results support the involvement of the myeloperoxidase system in the oxidation of TNB. Therefore, the procedure described here seems to be a suitable method for the above indicated purpose.

Azides↗
PubMed1989

Sugar modified oligonucleotides. I. Carbo-oligodeoxynucleotides as potential antisense agents.

For the first time, carbo-oligodeoxynucleotides, namely c-dT4 and c-dT12, have been synthesized. As compared to the natural oligomers these carbo-oligodeoxynucleotides are at least 5 times more stable toward enzymatic degradation and bind more strongly to complementary DNA. These preliminary data indicate that such oligomers fulfill the requirements to be considered as potential antisense agents.

Base Composition↗
PubMed1989

Murine muscle-specific enolase: cDNA cloning, sequence, and developmental expression.

In vertebrates, the glycolytic enzyme enolase (EC 4.2.1.11) is present as homodimers and heterodimers formed from three distinct subunits of identical molecular weight, alpha, beta, and gamma. We report the cloning and sequencing of a cDNA encoding the beta subunit of murine muscle-specific enolase. The corresponding amino acid sequence shows greater than 80% homology with the beta subunit from chicken obtained by protein sequencing and with alpha and gamma subunits from rat and mouse deduced from cloned cDNAs. In contrast, there is no homology between the 3' untranslated regions of mouse alpha, beta, and gamma enolase mRNAs, which also differ greatly in length. The short 3' untranslated region of beta enolase mRNA accounts for its distinct length, 1600 bases. It is known that a progressive transition from alpha alpha to beta beta enolase occurs in developing skeletal muscle. We show that this transition mainly results from a differential regulation of alpha and beta mRNA levels. Analysis of myogenic cell lines shows that beta enolase gene is expressed at the myoblast stage. Moreover, transfection of premyogenic C3H10T1/2 cells with MyoD1 cDNA shows that the initial expression of beta transcripts occurs during the very first steps of the myogenic pathway, suggesting that it could be a marker event of myogenic lineage determination.

Actins↗
PubMed1988

Comparison of the active calcium extrusion, calcium buffering capacity and ATPase activity in rabbit reticulocytes and mature red cells.

The purpose of the present work was to study the changes in the pattern of calcium homeostasis following the loss of intracellular organella during red cell maturation. Reticulocytes and mature red cells were prepared from anaemic rabbits blood after daily bleeding. Experimental protocols were designed to study the calcium buffering capacity in intact and digitonin-disrupted cells, the calcium pumping rate and, the Ca2+-translocating ATPase activity in the aforementioned red cells subpopulations. In digitonin-disrupted cells, a vesicular calcium pool, sharing the properties of mitochondria, could be detected in reticulocytes but no in mature red cells. Calcium content and calcium buffering capacity were significantly lower in reticulocytes than in mature red cells. The pattern of active calcium extrusion was quite similar in the two cell subpopulations, although reticulocytes had somewhat higher calcium affinity. Besides, an estimation of the calcium pumping rate gave higher values in reticulocytes than in mature erythrocytes. These values were 21 and 9 mmol/l cells per h, respectively. Maximal activities of the high-affinity (Ca2+ + Mg2+)-ATPase and basal Mg2+-ATPase were significantly higher in reticulocytes than in mature red cells, but no differences were observed regarding calcium affinity. The results show that changes in the properties of the Ca2+-translocating ATPase and intracellular calcium buffering systems are mechanisms involved in the process of red cell maturation.

Adenosine Triphosphatases↗
PubMed1988

Riluzole, a glutamate antagonist, enhances slow wave and REM sleep in rats.

Riluzole is a drug that interferes with glutamate neurotransmitters. We studied the sleep pattern of rats treated orally with riluzole at doses ranging from 0.5 to 8 mg/kg. Duration of slow wave sleep and rapid eye movement sleep was found to increase in a dose-dependent manner from 1 mg/kg, at the expense of awakeness. These data suggest that glutamate neurotransmission may be involved in the regulation of sleep. Riluzole can be of interest as sleep modulator, in particular in psychiatric disorders.

Animals↗
PubMed1988

Topically applied furazolidone or parenterally administered oxytetracycline for the treatment of infectious bovine keratoconjunctivitis.

The effectiveness of topically applied furazolidone (FZ) or parenterally administered oxytetracycline (OTC) for treatment of infectious bovine keratoconjunctivitis was determined in a field study. Between June 13 and Aug 6, 1985, a study was conducted on a ranch in northern California. Eyes of Hereford calves (n = 103) were examined 3 times each week for 7 weeks. After daily examinations on June 13 and 14, calves were allotted randomly to 3 groups. On June 17, calves (that had corneal ulcers) of groups 1 (n = 35) and 2 (n = 35) were treated with OTC and FZ, respectively. Treatments were administered again only if new ulcers were observed, if an existing ulcer worsened, or if a healed ulcer recurred. Calves of group 3 remained untreated (controls). Corneal ulcers developed in 35 of the FZ-treated calves, in 33 of the OTC-treated calves, and in 33 of the untreated calves. Corneal perforations were observed in 3 untreated and 2 FZ-treated calves but were not observed in any OTC-treated calves. Panophthalmitis developed in one eye of an untreated calf. Corneal ulcers in the OTC-treated calves were smaller and healed more rapidly than did corneal ulcers in calves of the other groups. By the 22nd day of the study (July 3), the number of OTC-treated calves with corneal ulcers was less than that of the other 2 groups. Calves of the OTC treatment group had the fewest multiple corneal ulcer recurrences, but calves of all 3 groups had a similar number of single corneal ulcer recurrences.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗
PubMed1988

DNA-nitrosourea interactions. High-performance liquid chromatography of cross-linked dinucleosides and substituted deoxynucleosides.

A reconstituted mixture of five cross-linked dinucleosides possibly involved in DNA-nitrosourea interactions, and of their degradation products (nucleobases, deoxynucleosides and mono- or disubstituted deoxynucleosides), was analysed by reversed-phase high-performance liquid chromatography using C18 columns and an diode-array detector. The chromatographic conditions for separating the twenty-one investigated compounds were optimized, and the compounds were identified by both their retention times and their UV spectra. A structure-retention time relationship was observed under suitable conditions and is discussed. Its validity was confirmed by the prediction of the retention time of a new cross-linked dinucleoside synthesized for this purpose.

Chromatography, High Pressure Liquid↗
PubMed1988

Experience with the Brindley anterior sacral root stimulator.

Brindley anterior sacral root stimulators have been implanted into 22 spinal cord injured patients from the spinal injury units in Cardiff and Sheffield. The group comprised 20 men and 2 women (15 paraplegics and 7 tetraplegics); 16 patients are using the implant, of whom 11 (68%) are continent. Of the remaining 5, 4, who empty completely, are incontinent because of inability to use the implant with sufficient frequency; 6 patients are not using their implant, though 4 are continent. Of 11 patients with detrusor/sphincter dyssynergia, sphincterotomy was necessary in 3 patients before implantation and in a further 3 after implantation. Of 4 patients with abnormal upper tracts prior to implantation, 2 resolved and 2 deteriorated, in the presence of dyssynergia; 1 patient developed hydronephrosis after implantation, having previously had normal upper tracts. Although erectile function with the stimulator was clinically adequate in 6 patients, in no patient has intercourse been achieved because of concurrent lower limb spasm.

Adult↗
PubMed1988

Developmental expression of alpha- and gamma-enolase subunits and mRNA sequences in the mouse brain.

Nonneuronal alpha alpha- and neuron-specific alpha gamma- and gamma gamma-enolase activities were measured in the mouse brain during development. The corresponding mRNA sequences were quantified directly by hybridization with cDNA probes. The variations in alpha- and gamma-monomer levels inferred from the enzymatic activities were very similar to those of their respective mRNAs. We conclude that monomer levels are primarily controlled by the amounts of their mRNAs during mouse brain development.

Animals↗