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P Martin

Publications and source records attributed to P Martin.

At least 415 records · Page 23Linked to original sources
PubMed1996

Transgenic expression of PML/RARalpha impairs myelopoiesis.

The translocation found in acute promyelocytic leukemia rearranges the promyelocytic leukemia gene (PML) on chromosome 15 with the retinoic acid receptor alpha (RARalpha) on chromosome 17. This yields a fusion transcript, PML/RARalpha, a transcription factor with reported dominant negative functions in the absence of hormone. Clinical remissions induced with all-trans retinoic acid (RA) treatment in acute promyelocytic leukemia are linked to PML/RARalpha expression in leukemic cells. To evaluate the PML/RARalpha role in myelopoiesis, transgenic mice expressing PML/RARalpha were engineered. A full-length PML/RARalpha cDNA driven by the CD11b promoter was expressed in transgenic mice. Expression was confirmed in the bone marrow with a reverse transcription PCR assay. Basal total white blood cell and granulocyte counts did not appreciably differ between PML/RARalpha transgenic and control mice. Cell sorter analysis of CD11b+ bone marrow cells revealed similar CD11b+ populations in transgenic and control mice. However, in vitro clonal growth assays performed on peripheral blood from transgenic versus control mice revealed a marked reduction of myeloid progenitors, especially in those responding to granulocyte/ macrophage colony-stimulating factor. Granulocyte/macrophage colony-stimulating factor and kit ligand cotreatment did not overcome this inhibition. Impaired myelopoiesis in vivo was shown by stressing these mice with sublethal irradiation. Following irradiation, PML/RARalpha transgenic mice, as compared with controls, more rapidly depressed peripheral white blood cell and granulocyte counts. As expected, nearly all control mice (94.4%) survived irradiation, yet this irradiation was lethal to 45.8% of PML/RARalpha transgenic mice. Lethality was associated with more severe leukopenia in transgenic versus control mice. Retinoic acid treatment of irradiated PML/RARalpha mice enhanced granulocyte recovery. These data suggest that abnormal myelopoiesis due to PML/RARalpha expression is an early event in oncogenic transformation.

Animals↗
PubMed1996

The catalysis of redox cycling by pyrroloquinoline quinone (PQQ), PQQ derivatives, and isomers and the specificity of inhibitors.

Pyrroloquinoline quinone (PQQ) is a widely distributed redox-active cofactor and essential nutrient. For its detection in protein-free ultrafiltrates or dialysates, a highly sensitive amplification assay was developed on the basis of PQQ's ability to catalyze redox cycling at pH 10 in the presence of excess glycine, oxygen, and nitro blue tetrazolium. Herein, we examine the propensities of PQQ, PQQ triester, and its various isomers, and certain PQQ triester derivatives, to catalyze glycine-fueled redox cycling and show that PQQ is the most capable of catalyzing redox cycling. Furthermore, PQQ has a unique pattern of inhibition induced by a series of PQQ antagonists of different potencies. The data indicate that putative PQQ from a biological sample, separated by HPLC and detected by the glycine-fueled redox-cycling assay, can be further identified as PQQ based on the profile of inhibition it displays with the antagonists such as those employed in this study. The methodology presented here should facilitate the specific detection of PQQ in biological samples.

Animals↗
PubMed1996

Characterization of a new melanocyte-specific gene (QNR-71) expressed in v-myc-transformed quail neuroretina.

Quail neuroretina cells (QNR) infected with the v-myc-expressing retrovirus MC29 become pigmented after several passages in vitro. After differential screening of a cDNA library constructed from these cells, we have isolated a cDNA clone (QNR-71) which identifies an RNA expressed only in the pigmented layer of the retina and in the epidermis. This gene can also be induced in other cell types transformed by MC29, suggesting that QNR-71 may be regulated by the v-myc protein. Sequence analysis showed that the QNR-71 cDNA exhibits stretches of homologies with melanosomal proteins encoding genes. From bacterially expressed QNR-71 peptides we obtained rabbit antisera able to specifically recognize two proteins of 95 and 100 kDa in pigmented retinal cells, but not in the neuroretina. To study the regulation of QNR-71, we used promoter fragments linked to the CAT reporter gene, in transient co-expression assay. We observed an increase in CAT expression with a c-MYC and microphtalmia (mi) expression vectors. Both MYC and mi activate the QNR-71 promoter through direct binding to a CATGTG site present in the promoter fragment.

Amino Acid Sequence↗
PubMed1996

Short-term crocidolite inhalation studies in mice: validation of an inhalation chamber.

A nose-only inhalation chamber is described: this chamber being computer automated has been particularly designed for mice on which it was validated using a crocidolite aerosol at a nominal concentration of 13.6 mg/m3, 6 h/day during 5 days. A month later the mice showed typical inflammatory bronchoalveolar liquids with many polynucleated or activated macrophages and asbestos bodies. The burden of crocidolite fibers ranged from 345,000 to 1,300,000 fibers per mg of dried lung. This study demonstrates that during the month that followed a short-term mice exposure to crocidolite fibers, the inflammatory response was still persistent. These toxicological endpoints validate the nose-only inhalation chamber to be useful for common or transgenic mice.

Administration, Inhalation↗
PubMed1996

Antagonism by benzodiazepines of the effects of serotonin-, but not norepinephrine-, uptake blockers in the learned helplessness paradigm in rats.

Benzodiazepines are routinely administered in combination with antidepressant drugs. Such combination can induce pharmacodynamic or pharmacokinetic interactions resulting in either a potentiation or a reduction of the effects of one of the drugs. The present study was undertaken to determine the effects of benzodiazepines alone and in combination with two classes of antidepressant drugs: "specific" norepinephrine uptake blockers (desipramine, maprotiline) and specific serotonin uptake blockers (indalpine, fluvoxamine) in the learned helplessness paradigm in rats. The present results show that daily injection of diazepam (0.2-2 mg/kg) and lorazepam (0.06-0.25 mg/kg) did not reverse the helpless behavior. The reversal of helpless behavior induced by indalpine (1 mg/kg/day) or fluvoxamine (4 mg/kg/day) was antagonized dose-dependently by daily coadministration of benzodiazepines. In contrast, the effects of desipramine (24 mg/kg/day) or maprotiline (48 mg/kg/day) were not modified.

Animals↗
PubMed1996

Impairment of protein kinase C activity in twitcher Schwann cells in vitro.

Twitcher (twi/twi) is a murine model of globoid cell leukodystrophy in humans caused by a genetic deficiency in activity of galactosylceramidase. Our previous study demonstrated that the rate of Schwann cell proliferation in twi/twi was considerably lower than that of the control (+/+) in vitro. We hypothesize that the lower mitotic rate in twi/twi results from the metabolic perturbation of Schawann cells caused by an accumulation of the toxic metabolite of galactosylceramidase, psychosine, a potent inhibitor of protein kinase C (PKC). Mouse Schwann cells are known to be stimulated to divide by growth factors in media containing fetal bovine serum. The stimulation by glial growth factor (GGF) or platelet-derived growth factor-BB (PDGF-BB) is though to be through the PKC pathway, but not by the basic fibroblast growth factor (bFGF) or transforming growth factor-beta (TGF-beta). Thus, we tested responses of twi/twi and +/+ Schwann cells to these growth factors. Schwann cells were isolated from the dorsal root ganglia at 30 days of age and the experiments were carried out at 21 days in vitro. In media containing PDGF-BB or bovine pituitary extract (BPE), the mitotic rate of twi/twi Schwann cells was 76% or 69% of the +/+ value, respectively, while significant differences were detected between twi/twi and +/+ in cultures containing TGF-beta or bFGF. When phorbol 12,13-dibutyrylate, a specific activator of PKC, was added to the media containing PDGF-BB or BPE, the mitotic rate of twi/twi Schwann cells improved up to 90% of +/+ cells. Staurosporine, an inhibitor of PKC. suppressed the proliferation of both twi/twi and +/+ Schwann cells. However, proliferation of twi/twi Schwann cells was suppressed by one-tenth of the concentration required for +/+ Schwann cells. These results are consistent with an accumulation of psychosine, an inhibitor of PKC, and suggest that the signal transduction system through PKC is impaired in the twi/twi Schwann cells.

Animals↗
PubMed1996

Report on the third EDNAP collaborative STR exercise. European DNA Profiling Group.

This report describes an inter-laboratory exercise completed on behalf of the European DNA Profiling (EDNAP) group. The exercise is one in a series designated to identify STR loci which could be used for harmonisation between participating European forensic science laboratories. Participants were asked to identify the alleles present in five bloodstains at the STR loci HUMTHO1 and HUMVWFA31/A. Two of the stains were prepared from mixtures of two different blood samples. There were no special instructions and each laboratory was requested to use the methodology normally employed for crime case investigations. All participating laboratories achieved the same results for both loci. In addition, the laboratories were also requested to report the results obtained from any other loci which would normally be used in crime case investigations. A comparison of these results showed some inter-laboratory variation.

Alleles↗
PubMed1996

Perfect wound healing in the keratin 8 deficient mouse embryo.

It is generally believed that the strength and structural integrity of both adult and embryonic epithelia comes, at least in part, from their internal cytoskeletal network of keratin filaments and associated cell:cell junctions. Indeed, recent keratin depletion experiments in Xenopus suggest that the capacity of embryonic epithelia to undergo natural morphogenetic movements such as gastrulation, or artificially triggered epithelial movements such as wound closure, are severely compromised in the absence of the predominant embryonic keratin, K8 [Torpey et al., 1992: Nature 357:413-415; Klymkowsky et al., 1992: Proc. Natl. Acad. Sci. USA 89:8736-8740]. These experiments contrast with studies of genetically K8 deficient mouse embryos which undergo gastrulation quite normally and, dependent upon background strain, can survive until beyond birth [Baribault et al., 1993: Genes Dev. 7:1191-1202; Baribault et al., 1994: Genes Dev. 8:2964-2973], but to date no wound healing investigations have been carried out on mK8-mice. In this article, we report our studies of healing in embryonic day 11.5 mouse embryos, wounded by amputation of the hindlimb bud and then cultured in roller bottles. In wild-type embryos, wound closure puts severe strain on the embryonic epidermis since it is under tension and gapes immediately upon wounding; subsequently, epithelial cells tug on one another by means of an actin purse-string in order to close the defect. Even given these extremely challenging conditions, we show here that the mK8- epidermis performs no differently from wild-type epidermis, assembling an actin purse-string in the wound marginal cells and closing the wound with identical timecourse to its wild-type counterpart.

Actins↗
PubMed1996

Rapid detection of sequence polymorphisms in the human mitochondrial DNA control region by polymerase chain reaction and single-strand conformation analysis in mutation detection enhancement gels.

The article describes a rapid approach for the detection of sequence polymorphisms in the mitochondrial (mt)DNA control region that involves enzymatic amplification of each entire mtDNA control region (HV1 and HV2) and the subsequent analysis of the PCR products by single-strand conformation analysis (SSCA) in mutation detection enhancement (MDE) gels, followed by silver stain detection. HV1 and HV2 SSC reference ladders were developed to standardize the classification of the different mtDNA types. Twenty-five mtDNA types were observed among the 45 Spanish individuals analyzed: 11 types were observed in the HV1 region as compared with 10 types in the HV2 region. This mutation scanning strategy could be a promising method of potential use not only in forensic genetics but also in population and evolutionary studies.

DNA, Mitochondrial↗
PubMed1996

Orthotopic liver transplantation for bone-marrow transplant-associated veno-occlusive disease and graft-versus-host disease of the liver.

Bone marrow transplantation (BMT) is a highly successful and curative therapy for many primary hematologic malignancies. However, hepatic dysfunction and failure are important causes of morbidity and mortality in this patient group after BMT. Hepatic failure can occur as a result of involvement by graft-versus-host disease (GVHD) or as a result of veno-occlusive disease (VOD). Therapies for these complications are often ineffective, especially for VOD, as approximately one fourth of patients develop irreversible liver disease and die of multiorgan failure. Accordingly, we have reviewed our center's experience with orthotopic liver transplantation (OLT) to manage the hepatic complications of BMT. We describe two patients who were treated with OLT after developing hepatic failure post-BMT. One patient had VOD with mild cutaneous and gastrointestinal GVHD; in the other patient, the pathophysiologic process affecting the liver was severe GVHD. Based on our center's experience and review of the literature, we believe OLT should be considered in patients with severe hepatic dysfunction post-BMT.

Adult↗
PubMed1996

Failure of ganciclovir prophylaxis to prevent allograft reinfection following orthotopic liver transplantation for chronic hepatitis B infection.

The effect of ganciclovir prophylaxis on reinfection of hepatic allografts by hepatitis B virus (HBV) was studied in 26 patients undergoing orthotopic liver transplantation (OLT) for decompensated cirrhosis due to HBV. Patients were randomized to receive either ganciclovir (6 mg/kg/day intravenously for a total of 100 days) or acyclovir (10 mg/kg every 8 hours intravenously until discharged and then 800 mg orally every 6 hours) for a total of 100 days after OLT as part of a study of prophylaxis against cytomegalovirus infection. All patients received hepatitis B immunoglobulin (HBIG), 10,000 units intravenously, during the anhepatic phase, daily for the first 7 days, after OLT, and then every 4 weeks for 6 months, Seven of 12 (58%) patients in the ganciclovir group developed recurrent HBV, compared with 6/14 (46%) of the acyclovir group (nonsignificant). No significant difference was observed in time to recurrent HBV in the ganciclovir group (mean 13.2 months) compared to the acyclovir group (mean 11 months). Our results suggest that ganciclovir administered prophylactically for 100 days after OLT does not prevent or delay graft reinfection by HBV.

Acyclovir↗
PubMed1996

Production of recombinant insulin-like growth factor-II in the development of a radioimmunoassay in rainbow trout (Oncorhynchus mykiss).

Rainbow trout (Oncorhynchus mykiss) insulin-like growth factor-II (IGF-II) cDNA was amplified by reverse transcription-polymerase chain reaction and cloned into an expression vector (parHS3) for production by Escherichia coli. Recombinant rainbow trout IGF-II (rtIGF-II) was recovered from bacterial inclusion bodies, solubilized, and purified by gel filtration chromatography under reducing conditions. After refolding of the peptide by dialysis at basic pH, we obtained a final yield of 820 micrograms/liter culture medium. The rtIGF-II appeared as a single band estimated at 80% and with molecular mass of 7.5 kDa. A homologous radioimmunoassay (RIA) for the measurement of IGF-II in trout plasma has been developed using rtIGF-II as antigen, radiolabeled tracer, and standard. RIA sensitivity was 0.1 ng/ml and the ED50 was 0.75 +/- 0.06 ng/ml. Intra- and interassay coefficients of variation were 4.04% (n = 6) and 4.56% (n = 9), respectively, at ED50 levels. Cross-reactivities of 1 and 0.1% were found for recombinant coho salmon (Oncorhynchus kisutch) IGF-I and coho salmon insulin, respectively. No cross-reactivities were found for recombinant human IGF-I and IGF-II, porcine insulin, or a variety of salmonid pituitary hormones. The interference of IGF binding proteins (IGFBP) in the RIA has been tested with and without extraction (acid/ethanol extraction or C-25 acid chromatography) of fed and fasted trout plasma samples. Parallel displacement curves were obtained for unextracted and C-25-extracted plasma but not for acid/ethanol-extracted plasma. Comparison of IGF-II levels from these samples showed a possible interference of IGFBP in the RIA in fed (19.6 +/- 1.56 ng/ml unextracted and 25.25 +/- 1.21 ng/ml extracted) and fasted (21.58 +/- 1.02 ng/ml unextracted and 9.86 +/- 1.68 ng/ml extracted) trout plasma. Finally, the displacement curves for unextracted plasma from rainbow trout, Couch's sea bream (Pagrus pagrus), and carp (Cyprinus carpio) were parallel to that of the rtIGF-II standard and not strictly parallel for tilapia (Oreochromis niloticus) and catfish (Silurus glanis) plasma. No significant cross-reaction occurred with eel (Anguilla anguilla) plasma. The rainbow trout IGF-II RIA reported in this study has low variability and is highly sensitive. Therefore it is a reliable method for measuring IGF-II levels in salmonids and some nonsalmonid fish species.

Amino Acid Sequence↗
PubMed1996

Effect of carbamazepine, oxcarbazepine and lamotrigine on the increase in extracellular glutamate elicited by veratridine in rat cortex and striatum.

Lamotrigine, carbamazepine and oxcarbazepine inhibit veratrine-induced neurotransmitter release from rat brain slices in concentrations corresponding to those reached in plasma or brain in experimental animals or humans after anticonvulsant doses, presumably due to their sodium channel blocking properties. Microdialysis measurements of extracellular glutamate and aspartate were carried out in conscious rats in order to investigate whether corresponding effects occur in vivo Veratridine (10 microM) was applied via the perfusion medium to the cortex and the corpus striatum in the presence of the glutamate uptake inhibitor L-trans-pyrrolidine-2,4-dicarboxylic acid (1 mM in perfusion medium). Maximally effective anticonvulsant doses of carbamazepine (30 mg/kg), oxcarbazepine (60 mg/kg) and lamotrigine (15 mg/kg) were given orally. The uptake inhibitor increased extracellular glutamate and aspartate about 2-fold in striatum and about 7-fold and 3-fold, respectively, in cortex. Veratridine caused a further 2-3-fold increase in extracellular glutamate in striatum and cortex, respectively, but its effect on extracellular aspartate was less marked in both areas. None of the anticonvulsant compounds affected the veratridine-induced increases in extracellular glutamate or aspartate in the striatum which were, however, markedly inhibited by tetrodotoxin (1 microM) and thus are sensitive to sodium channel blockade. In the cortex the same drugs at the same doses did cause about 50% inhibition of the veratridine-induced increase in extracellular glutamate. Carbamazepine and to a lesser extent lamotrigine, but not oxcarbazepine, also inhibited the veratridine-induced increase in extracellular aspartate in the cortex. Although our results might seem to support the view that inhibition of glutamate and aspartate release is responsible for the anticonvulsant effects of lamotrigine, carbamazepine and oxcarbazepine, two complementary findings argue against this interpretation. First, as previously shown, inhibition of electrically induced released of glutamate requires 5 to 7 times higher concentrations of these compounds than release elicited by veratrine. Second, the present study indicates that doses totally suppressing convulsions caused no inhibition in the striatum and at best a 50% inhibition in the brain cortex. From this we conclude that the doses used here, although to some extent effective against veratridine, did not suppress the release of GLU and ASP elicited by the normal ongoing electrical activity of the glutamatergic and aspartatergic neurons and that the mechanism of the suppression of convulsions must be sought elsewhere.

Animals↗
PubMed1996

The role of macrophages in clearing programmed cell death in the developing kidney.

The metanephric kidney develops from two tissue sources, the metanephric mesenchymal blastema and the ureteric bud epithelium. Following a complex interplay of inductive signals between these two tissues, small groups of metanephric mesenchymal cells aggregate and epithelialise to form young nephrons. As this is happening, significant numbers of cells in close proximity to the forming nephrons undergo programmed cell death or apoptosis. In this paper we investigate the clearance of developmental cell death in the mouse kidney between embryonic days 11.5 and 16.5; specifically, we address the issue of whether specialist macrophages or non-specialist neighbouring mesenchymal cells are responsible for phagocytosis and removal of dying cells. We show, using a monoclonal antibody F4/80 that specifically recognizes murine macrophages, that whenever and wherever there is cell death in the developing mesonephric or metanephric kidney there are also haemopoietically derived specialist macrophages. Moreover, in the mesonephros and from E14.5 in the metanephric kidney, we see large numbers of macrophages clearly swollen with phagocytosed apoptotic bodies. Double-labelling experiments using the DNA dye 7AAD to reveal condensed apoptotic nuclei and F4/80 to reveal macrophage plasma membranes show definitively that the majority of dying cells in the developing kidney are engulfed by macrophages.

Animals↗
PubMed1996

A survey of the goat genome transcribed in the lactating mammary gland.

To fulfill its primary function, which is to synthesize milk during the course of lactation, the mammary gland requires efficient transcriptional, translational, and secretory machineries involving multiple genes among which promising candidates underlying the genetic variation of milk production have to be found. With the aim of providing a first transcriptional profile of lactating mammary tissue, a non-normalized cDNA library has been constructed from the udder of a lactating goat. After having discarded cDNA clones encoding the major milk proteins the rapid characterization of genes expressed in this tissue, by automated partial cDNA sequencing, was used to analyze a total of 435 cDNA clones. Examination of the Expressed Sequence Tags (ESTs) for similarities with sequence databases identified 234 cDNAs corresponding to 140 unique genes or proteins. Eighty-three clones, not similar to any current database entries, representing 77 novel sequences unrelated to previously described genes, were thus identified. Tissue specificity and relative abundance of 18 of these 77 unidentified clones were examined by dot blot and RT-PCR experiments. Sequence data were subsequently used to assign six genes of unknown localization in the bovine genome, to synteny groups by use of bovine-hamster cell hybrids and PCR.

Animals↗
PubMed1996

Kinetics of local immune responses in mouse Peyer's patches after respiratory exposure to flour.

Peyer's patches play a major role in the initiation of mucosal immune responses since most environmental antigens gain access to the digestive tract and are therefore liable to achieve contact with their specialized dome epithelium. We investigated kinetics of immunophenotypic modifications induced in the cells from murine Peyer's patches in a model of intensive controlled exposure to flour dust. Three groups of mice were placed in an atmosphere enriched in wheat flour for 3, 6 or 10 consecutive days. Although Ig bearing B cell numbers did not vary, the numbers of IgA-containing plasma-cells increased significantly during the course of exposure. A significant and increasing imbalance of the CD4/CD8 ratio was noted, as early as after 3 days of exposure related both to increasing numbers of CD4+ and decreasing numbers of CD8+ cells. These data indicate a rapid kinetics of immune responses in Peyer's patches in an original model of controlled respiratory challenge.

Animals↗
PubMed1996

An investigation of the properties of a "shielded" phase for the solid phase extraction of acidic and basic compounds.

The extraction properties of Hisep, a novel bonded phase for solid phase extraction, have been investigated using a number of acidic and basic analytes and compared with those of a conventional ODS bonded material. Marked differences in extraction properties for the test analytes propranolol, anisic acid and ICI 128436 from aqueous buffer were noted between the two materials. Thus, extraction onto the ODS material was by both ionic and reversed-phase mechanisms whilst retention on the Hisep phase appeared to be mediated predominantly by reversed-phase hydrophobic interactions. The presence of dog plasma had no effect on the extraction of propranolol but did reduce the extraction efficiencies observed for anisic acid and ICI 128436 in a pH dependent manner.

Adrenergic beta-Antagonists↗