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N Baird

Publications and source records attributed to N Baird.

8 recordsLinked to original sources
PubMed1998

NHE-1 is the sodium-hydrogen exchanger isoform present in erythroid cells.

Erythrocyte sodium hydrogen exchanger (NHE) represents one of a limited number of sodium entry pathway in erythrocytes. At least five NHE isoforms have been identified, differing in tissue specificity, regulatory characteristics, and pharmacological sensitivities. Although physiological characteristics of erythrocyte NHE suggest that the widely expressed NHE-1 isoform may be present, evidence is not conclusive and does not exclude the existence of other isoforms. In this study, Northern blot and reverse transcription-polymerase chain reaction (RT-PCR) analyses were used to test for five NHE isoforms in erythroid cells. Blood from patients with sickle cell disease was depleted of white blood cells (WBC) by passage through leukocyte filters and cellulose column. RT-PCR performed on WBC depleted reticulocyte RNA using a NHE-1 primer set yielded product a of expected size, the sequence of which was identical to the published human NHE-1 sequence. Northern blot analysis of the reticulocyte RNA using a 1.6 kb probe revealed a message of approximately 5.0 kb in size. RT-PCR analysis of rat kidney RNA using primers specific for NHE isoforms -2, -3, -4 and rat brain RNA using primer specific for NHE-5 isoform yielded products of expected size, whereas WBC depleted RNA under identical conditions yielded no products. These results identify the erythroid isoform of the sodium hydrogen exchanger as NHE-1.

Animals↗
PubMed1997

Potassium depletion and acid-base transporters in rat kidney: differential effect of hypophysectomy.

Potassium depletion is involved in the pathophysiology of metabolic alkalosis. In the present study, the expression of renal acid-base transporters that are involved in HCO3- reabsorption was studied in potassium depletion. Rats fed potassium-deficient (KD) diet developed significant hypokalemia at 14 days (serum K+ 1.9 +/- 0.2 in KD vs. 4.2 +/- 0.2 meq/l in control, P < 0.01) but not at 6 days (3.8 +/- 0.3 in KD vs. 4.1 +/- 0.3 meq/l in control, P > 0.05). Kidney mRNA for colonic H(+)-K(+)-adenosinetriphosphatase (H(+)-K(+)-ATPase, cHKA) increased by approximately 3- and 11-fold at 6 and 14 days of KD diet, respectively, indicating that increased expression preceded the onset of hypokalemia. The expression of Na+/H+ exchanger 3 (NHE-3) mRNA and its cognate protein remained unchanged at 6 and 14 days of KD diet. The mRNA levels for NHE-1, NHE-2, and NHE-4 also remained unchanged at 6 and 14 days of KD diet. Hypophysectomized (HPX) rats fed KD diet for 14 days developed similar hypokalemia. However, the expression of cHKA mRNA in the kidney was decreased by approximately 80% in potassium-depleted (HPX+KD) rats (P < 0.01 vs. KD only). Hypophysectomy did not affect the mRNA levels for either gastric H(+)-K(+)-ATPase (gHKA) or NHE isoforms in KD animals. Thus potassium depletion increases expression of cHKA in the kidney but not that of gHKA or NHE isoforms. The signal for this increase appears to precede hypokalemia. Furthermore, the data suggest that pituitary hormone(s) plays an important and novel role in the regulation of cHKA.

Acids↗
PubMed1995

Molecular cloning and physical and genetic mapping of a novel human Na+/H+ exchanger (NHE5/SLC9A5) to chromosome 16q22.1.

A human genomic clone for a novel fifth member of the Na+/H+ exchanger (NHE) family, NHE5 (gene symbol SLC9A5), has been isolated and partially sequenced. The deduced amino acid sequence of two exons, containing 154 codons, exhibits 59-73% identity to the other members of the NHE family, with closest similarity to NHE3. Northern blot analysis demonstrated that the NHE5 gene is expressed in brain, testis, spleen, and skeletal muscle. Fluorescence in situ hybridization analysis of a cosmid containing NHE5 to human metaphase chromosomes localized the NHE5 gene to the cytogenetic interval 16q21-q22. A panel of somatic cell hybrids containing various portions of chromosome 16 was used to refine further the placement of NHE5 within band 16q22.1. A polymorphic dinucleotide (GT/CA)n repeat contained in the NHE5 cosmid was identified and developed into a microsatellite PCR marker. This was typed in a subset of the CEPH (Centre d'Etude du Polymorphisme Humain) families to place it on a genetic map of the human genome. Pairwise linkage analysis of this marker showed that it was linked to marker D16S421 with a maximal lod score of 35.21 at a recombination fraction (theta) of 0.000, in complete concordance with its chromosomal localization by physical mapping. Multipoint linkage analysis placed NHE5 between the flanking markers D16S421 and D16S512. The cloning of this new member of the sodium hydrogen exchanger family, its chromosomal localization, and the discovery of a polymorphic marker for it now make it feasible to study the possible involvement of this gene in disorders of Na+/H+ transport.

Amino Acid Sequence↗
PubMed1994

Regulation of prostaglandin endoperoxide synthase gene expression in rat mesangial cells by interleukin-1 beta.

In primary cultures of rat mesangial cells from passage 3 to 6, interleukin-1 beta (IL-1) induced a time-dependent increase in prostaglandin E2 (PGE2) formation and release into the extracellular medium. This increase was associated with a dramatic upregulation of the steady-state levels of mRNA for the prostaglandin endoperoxide synthetase (PES)-2 gene transcript as demonstrated by Northern analysis. In contrast, there did not appear to be a significant increase in the mRNA levels for a 2.8-kb transcript for the PES-1 gene. At 18 h of exposure to IL-1, the steady-state level of message for PES-2 remained elevated at 50% of the 2-h time point. Culturing the cells in the presence of cycloheximide and IL-1 demonstrated a superinduction of the PES-2 message without any change in PES-1 message. The tumor-promoting phorbol ester, phorbol myristate acetate (PMA), was also associated with an upregulation of the message for the PES-2 gene and did not influence the levels of the message for the PES-1 gene as demonstrated by Northern analysis. Dexamethasone (Dex) inhibited to control levels the induction by PMA, but the induction of the message by IL-1 was only inhibited 30%. Despite 70% of the message being present by 2 h of induction, Dex was capable of totally inhibiting the inductive effect of IL-1 with respect to PGE2 biosynthesis. Immunocytochemical studies demonstrated a dramatic induction of PES-2 protein by IL-1, which was inhibited by Dex. The data suggest that Dex inhibits the translation of the PES-2 protein.

Animals↗
PubMed1988

Characterization of a human hematopoietic progenitor cell capable of forming blast cell containing colonies in vitro.

A hematopoietic cell (CFU-B1) capable of producing blast cell containing colonies in vitro was detected using a semisolid culture system. The CFU-B1 has the capacity for self-renewal and commitment to a number of hematopoietic lineages. Monoclonal antibody to the human progenitor cell antigen-1 (HPCA-1) and a monoclonal antibody against the major histocompatibility class II antigen (HLA-DR) were used with fluorescence activated cell sorting to phenotype the CFU-B1. The CFU-B1 was found to express My10 but not HLA-DR antigen; experiments using complement-dependent cytotoxicity to eliminate DR positive cells confirmed this finding. Pretreatment of marrow cells with two chemotherapeutic agents, 5-fluorouracil and 4-hydroperoxycyclophosphamide facilitated detection of CFU-B1 derived colonies, while diminishing or totally inhibiting colony formation by other hematopoietic progenitor cells. CFU-B1-derived colony formation was dependent upon the addition of exogenous hematopoietic growth factors. Media conditioned either by the human bladder carcinoma cell line 5637 or lectin stimulated leukocytes, as well as recombinant granulocyte-macrophage colony stimulating factor, interleukin 3 or interleukin 1 alpha promoted blast cell colony formation. By contrast, neither recombinant erythropoietin, recombinant interleukin 4, purified macrophage colony stimulating factor or recombinant granulocyte colony-stimulating factor alone promoted blast cell colony formation.

Bone Marrow↗