Pharmacokinetic study of meropenem in healthy beagle dogs receiving intermittent hemodialysis

Meropenem, a second carbapenem antimicrobial agent with a broad spectrum of activity, is used to treat sepsis and resistant-bacterial infections in veterinary medicine. The objective of this study was to identify the pharmacokinetics of meropenem in dogs receiving intermittent hemodialysis (IHD) and to determine the proper dosing in renal failure patients receiving IHD. Five healthy beagle dogs were given a single i.v. dose of 24 mg/kg of meropenem and received IHD. The blood flow rate, dialysate flow, and ultrafiltration rate were maintained at 40 mL/min, 300 mL/min, and 40 mL/h, respectively. Blood samples were collected for 24 h from the jugular vein and from the extracorporeal arterial and venous line. Urine samples and dialysate were also collected. The concentrations of meropenem were assayed using HPLC/MS/MS determination. The peak plasma concentration was 116 ± 37 μg/mL at 15 min. The systemic clearance was 347 ± 117 mL/h/kg, and the steady-state volume of distribution was 223 ± 67 mL/kg. Dialysis clearance was 71.1 ± 34.3 mL/h/kg, and the extraction ratio by hemodialysis was 0.455 ± 0.150. The half-life (T_1/2 ) in dogs with IHD decreased compared with those without IHD, and the reduction in T_1/2 was greater in renal failure patients than in normal patients. Sixty-nine percent and 21% of the administered drug were recovered by urine and dialysate in the unchanged form, respectively. In conclusion, additional dosing of 24 mg/kg of meropenem after dialysis could be necessary according to the residual renal function of the patient based on the simulated data.

Netrin-1 protects hypoxia-induced mitochondrial apoptosis through HSP27 expression via DCC- and integrin α6β4-dependent Akt, GSK-3β, and HSF-1 in mesenchymal stem cells

Netrin (Ntn) has the potential to be successfully applied as an anti-apoptotic agent with a high affinity for tissue, for therapeutic strategies of umbilical cord blood-derived mesenchymal stem cells (UCB-MSC), although the mechanism by which Ntn-1 protects hypoxic injury has yet to be identified. Therefore, the present study examined the effect of Ntn-1 on hypoxia-induced UCB-MSC apoptosis, as well as the potential underlying mechanisms of its protective effect. Hypoxia (72 h) reduced cell viability (MTT reduction, and [³H]-thymidine incorporation) and cell number, and induced apoptosis (annexin and/or PI positive), which were reversed by Ntn-1 (10 ng/ml). Moreover, Ntn-1 decreased the increase of hypoxia-induced Bax, cleaved caspase-9, and -3, but blocked the decrease of hypoxia-reduced Bcl-2. Next, in order to examine the Ntn-1-related signaling cascade in the protection of hypoxic injury, we analyzed six Ntn receptors in UCB-MSC. We identified deleted in colorectal cancer (DCC) and integrin (IN) α6β4, except uncoordinated family member (UNC) 5A–C, and neogenin. Among them, IN α6β4 only was detected in lipid raft fractions. In addition, Ntn-1 induced the dissociation of DCC and APPL-1 complex, thereby stimulating the formation of APPL-1 and Akt2 complex. Ntn-1 also reversed the hypoxia-induced decrease of Akt and glycogen synthase kinase 3β (GSK-3β) phosphorylation, which is involved in heat shock factor-1 (HSF-1) expression. Ntn-1-induced phospho-Akt and -GSK-3β were inhibited by DCC function-blocking antibody, IN a6b4 function-blocking antibody, and the Akt inhibitor. Hypoxia and/or Ntn-1 stimulated heat shock protein (HSP)27 expression, which was blocked by HSF-1-specific small interfering RNA (siRNA). Furthermore, HSP27-specific siRNA reversed the Ntn-1-induced increase of phospho-Akt. Additionally, HSP27-specific siRNA attenuated the Ntn-1-reduced loss of mitochondrial membrane injury via the inhibition of cytochrome c (cyt c) release and formation of cyt c and HSP27 complex. Moreover, the inhibition of each signaling protein attenuated Ntn-1-induced blockage of apoptosis. In conclusion, Ntn-1-induced HSP27 protected hypoxic injury-related UCB-MSC apoptosis through DCC- and IN α6β4-dependent Akt, GSK-3β, and HSF-1 signaling pathways.

Cloning of canine GM-CSF and SCF genes

Cytokines have pleiotropic regulatory effects on hematopoietic cells and many other cell types that participate in host defence and repair processes. Granulocyte-macrophage colony-stimulating factor (GM-CSF) mediates the growth and differentiation of granulocytes and macrophages and regulates the biological functions expressed by mature cells of these lineages. Stem cell factor (SCF) is a multifunctional cytokine involved in hematopoiesis, melanogenesis and gametogenesis. In order to determine the complementary DNA (cDNA) of canine GM-CSF and canine SCF, cDNA clones were generated from lipopolysaccharide (LPS) stimulated peripheral blood mononuclear cells (PBMCs) and bone marrow cells by reverse transcription PCR amplification. The canine GM-CSF cDNA obtained in this study contains an open reading frame encoding 144 amino acid residues and has 53-75% homology with those of human, cat, sheep, pig, cow and mouse, Canine SCF cDNA consist of an open reading frame encoding 274 amino acid residues and shares 81-92% homology with those of human, cat, pig, cow and mouse.

Studies of cocktail therapy with multiple cytokines for neoplasia or infectious disease of the dog I. cDNA cloning of canine IL-3 and IL-6

This paper describes the cloning and sequence analysis of the cDNAs encoding the canine homologues of interleukin-3 (IL-3) and interleukin-6 (IL-6). The coding sequences for canine IL-3 and IL-6 were obtained by using the reverse transcription polymerase chain reaction (RT-PCR) with RNA harvested from canine peripheral blood mononuclear cells (PBMCs). Canine IL-3 cDNA includes a single open reading frame of 432 nucleotides, which encodes a 143 amino acid polypeptide and has 44.7, 42.4, 37 and 23.7% homology with the cow, sheep, human and rat IL-3 sequences, respectively. Canine IL-6 cDNA (GenBank accession number; AF275796) encodes a putative 20-amino acid signal peptide followed by a 187-amino acid mature protein. The predicted amino acid sequence of canine IL-6 shares 60.4, 77.2, 71.0, 55.8 and 42.0% sequence identity with those of human, feline, porcine, sheep and rat IL-6, respectively.

Detection of canine distemper virus (CDV) through one step RT-PCR combined with nested PCR

A one step reverse transcription PCR (RT-PCR) combined nested PCR was set up to increase efficiency in the diagnosis of canine distemper virus (CDV) infection after developement of nested PCR. Two PCR primer sets were designed based on the sequence of nucleocapsid gene of CDV Onderstepoort strain. One-step RT-PCR with the outer primer pair was revealed to detect 10(2) PFU/ml. The sensitivity was increased hundredfold using the one-step RT-PCR combined with the nested PCR. Specificity of the PCR was also confirmed using other related canine virus and peripheral blood mononuclear cells (PBMC) and body secretes of healthy dogs. Of the 51 blood samples from dogs clinically suspected of CD, 45 samples were revealed as positive by one-step RT-PCR combined with nested PCR. However, only 15 samples were identified as positive with a single one step RT-PCR. Therefore approximately 60% increase in the efficiency of the diagnosis was observed by the combined method. These results suggested that one step RT-PCR combined with nested PCR could be a sensitive, specific, and practical method for diagnosis of CDV infection.

A proposed nomenclature of the domestic cat karyotype

High-resolution G- and Q-band patterns of cat (Felis catus) prometaphase chromosomes with more than 450 numbered bands are presented. This number represents approximately twice the number of bands per haploid set exhibited by feline chromosomes at mid-metaphase. A diagrammatic representation of G-banded cat chromosomes has already been described (O'Brien and Nash, 1982); however, precise numbering of bands and landmarks, as in the human karyotype and in the karyotypes of other domestic and laboratory animals, has not yet been available for the domestic cat karyotype, except for the RBG-banded ideograms constructed by Shibasaki et al. (1987) and Rønne and Storm (1995). In this report, we propose a numbering system for the G-banded ideogram reported previously (O'Brien and Nash, 1982) and an extended ideogram at the high-resolution level (473 numbered bands) as a contribution to the future standardization of the feline karyotype.

Cloning and mapping of cat (Felis catus) immunoglobulin and T-cell receptor genes

Molecular cloning and chromosomal mapping of the cat immunoglobulin (Ig) and T-cell receptor (TcR) genes were carried out to provide basic information for genetic analysis of immunologic diseases including leukemias and lymphomas in cats. We cloned two Ig constant genes, IGHM and IGHG and three TcR constant genes, TRAC, TRGC, and TRDC, by polymerase chain reaction (PCR) amplification of cDNA from cat peripheral blood mononuclear cells. For chromosomal mapping of the Ig and TcR loci including the IGK, IGL, and TRB on the cat genome, we performed PCR screening of DNAs from 37 cat x rodent somatic cell hybrids by using specific primers for the given genes. Consequently, three loci for IGH, TRA, and TRD, and two loci for TRB and TRG were found to be syntenic and assigned to cat chromosomes (FCA) B3 and A2, respectively. Further, IGK and IGL loci were mapped on FCA A3 and D3, respectively. These findings support the notion that the genetic linkages between the Ig and TcR genes are extensively conserved between humans and cats.

Genomic structure of the bovine mb-1 gene encoding the Ig-alpha subunit of the B cell antigen receptor complex

The B cell antigen receptor, (BCR) comprises surface immunoglobulin and disulfide-bonded heterodimer of Ig-alpha and Ig-beta chains, which are the products of the mb-1 and B29 genes, respectively. In this study, we describe the isolation and analysis of a 6.2-kb genomic DNA clone containing bovine mb-1 gene encoding Ig-alpha. Sequence data revealed that the bovine mb-1 gene is composed of five exons and four introns, and that its overall structure is very similar to those of murine and human genes. The 5' upstream region of the bovine mb-1 gene contained potential protein binding motifs of transcription factors including EBF, Sp1, NF-kappa B, MUF/Ets-1 and AP 2. As with the murine and human mb-1 genes, the 5' region of the bovine mb-1 gene lacked a TATA box. The present study will be useful for understanding the regulated expression of the bovine mb-1 gene at different stages of development and activation as well as in bovine leukemia virus infection.

Identification of an alternatively spliced transcript of equine interleukin-1 beta

Using lipopolysaccharide (LPS)-stimulated equine peripheral blood mononuclear cell (PBMC) cDNA as a template, we performed polymerase chain reaction (PCR) amplification with equine interleukin-1 beta (IL-1 beta) specific primers. Electrophoresis of the PCR product on agarose gel revealed an additional smaller fragment that hybridized with an equine IL-1 beta cDNA probe. Sequencing of this fragment demonstrated that it was shorter than normal equine IL-1 beta cDNA by 162 nucleotides, which corresponded to exon 5 of the human and murine IL-1 beta genes. The deletion of 162 nucleotides did not result in a frame shift but spliced out the putative exon 5 of the IL-1 beta gene which includes the cleavage site for the IL-1 beta converting enzyme (ICE) in human and murine IL-1 beta. Expression of the alternatively spliced IL-1 beta transcript in PBMC was also detected after stimulation with other compounds. These results clearly indicate the existence of an alternatively spliced IL-1 beta transcript in equine PBMC.

Molecular characterization of feline immunodeficiency virus genome obtained directly from organs of a naturally infected cat with marked neurological symptoms and encephalitis

Feline immunodeficiency virus (FIV) was first isolated from cats with immunodeficiency syndrome. Recently, neurological abnormalities and brain lesions were shown in cats infected with FIV. To investigate the FIV genome associated with central nervous system (CNS) lesions, proviral DNA sequences from the V3-V6 region of the FIV env gene were directly amplified from uncultured necropsy tissues of a 2-year-old naturally FIV-infected cat with marked neurological symptoms and encephalitis. By in situ hybridization, FIV RNA was detected mainly in the astrocytes. Fifteen clones isolated from cerebrum, bone marrow and lymph node samples showed only a small number of mutations or deletions in this region. A representative clone, JN-BR1, was distantly related to the previous Japanese strain (TM2) belonging to the subtype B. However, it was relatively close to the Petaluma strain which is known to infect feline brain-derived culture cells and induce brain lesions in inoculated cats. By phylogenetic analysis, the JN-BR1 strain was placed in subtype A that included Petaluma strain and several other American and European strains. The JN-BR1 strain derived from brain with encephalitis in this study and the Petaluma strain may share a common genetic structure that is related to their neuropathogenicity.

Molecular cloning of bovine mb-1 cDNA

Ig-alpha of the B-cell antigen receptor complex forms a heterodimeric structure with Ig-beta on the plasma membrane of B-lymphocytes and is apparently involved in signal transduction during the activation of B-cells. Bovine leukemia virus (BLV) is predominantly a B-cell tropic retrovirus, which induces persistent lymphocytosis and leukemia/lymphoma of B-cell lineage in cattle. To understand the mechanisms of proliferation and tumorigenesis of bovine B-cells that are associated with BLV infection, we investigated the B-cell antigen receptor complex, especially bovine mb-1 encoding the bovine Ig-alpha protein. We isolated a full-length bovine mb-1 cDNA clone encoding 223 amino acid residues. The deduced amino acid sequence of the bovine mb-1 showed extensive homology with those of human and murine mb-1. The cytoplasmic tail of the bovine mb-1 also contained a consensus motif (D/E-X7-D/E-X2-L/I-X7-Y-X2-L/I) that may interact with the SH2 domain of src-type kinase. Interestingly, a similar consensus sequence motif was found in the BLV gp30env, although the overall sequence similarity between bovine mb-1 and BLVgp30 was not significant. Furthermore, elevated levels of mb-1 transcript were detected in various bovine leukemia/lymphoma cell lines. These results indicated that the proliferation of B-cells associated with BLV-infection may be related to abnormal signal transduction through the B-cell antigen receptor complex.

Elevation of serum G-CSF level in horses with transportation-induced fever

Levels of granulocyte-colony stimulating factor (G-CSF) in the blood of horses were measured before and after a long-distance transportation to clarify the pathogenesis of transportation-induced fever. The serum G-CSF level was measured by its ability to stimulate growth in a mouse myeloblastic cell line, NFS-60. Of 26 horses transported for a long distance, 9 had fever more than 39.0 degrees C during or after transportation. After transportation, the serum G-CSF level significantly increased in horses with transportation-induced fever but not in those without fever, and the serum G-CSF level correlated positively with the peak body temperature and with an increase in peripheral white blood cell count. These data indicate that microbial infection, which is closely related to the elevation of the serum G-CSF levels, is the causative factor of transportation-induced fever.

Gammopathy with two M-components in a dog with IgA-type multiple myeloma

A 12-year neutered male mixed-breed dog was referred to hospital for evaluation of chronic diarrhea. Cellulose acetate electrophoresis of its serum revealed two monoclonal peaks in the gamma-globulin fraction. On immunoelectrophoretic analysis, the two monoclonal peaks in the gamma-globulin region were strongly precipitated with anti-dog IgA serum. On sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis, the fractions corresponding to these two peaks were shown to be dimer and trimer or tetramer of immunoglobulin consisting of heavy and light chains. These results indicated that the studied dog had gammopathy with two M-components with dimer and trimer or tetramer of IgA. Accumulations of large amounts of these immunoglobulins with very high molecular weight in the serum were concluded to induce the hyperviscosity syndrome in this dog in the terminal stage.

Two forms of the mb-1 gene transcript in cattle

We have isolated two forms of bovine mb-1 cDNA clones from a cDNA library of a bovine leukemia virus-infected B-lymphoblastoid cell line. The nucleotide sequence analysis of these cDNA clones indicated that the shorter form of cDNA had a 119-bp deletion that precisely corresponded to the exon III domain of the human and murine mb-1 genes. This deletion would result in a frame shift, producing a premature translation termination leading to the lack of the entire transmembrane and cytoplasmic domains of the normal mb-1 molecule. The existence of two species of mRNA transcripts corresponding to the isolated cDNA clones were confirmed in all of the bovine leukemia cell lines examined by PCR with the use of the primers flanking the deletion site. Furthermore, the shorter mb-1 transcript was induced in normal PBMC by stimulation with mitogens or culture supernatants of bovine leukemia virus-infected cell lines. These findings indicate the presence of the truncated mb-1 gene product which may have some function different from that of the normal mb-1 gene product.

Two forms of the mb-1 gene transcript in cattle

We have isolated two forms of bovine mb-1 cDNA clones from a cDNA library of a bovine leukemia virus-infected B-lymphoblastoid cell line. The nucleotide sequence analysis of these cDNA clones indicated that the shorter form of cDNA had a 119-bp deletion that precisely corresponded to the exon III domain of the human and murine mb-1 genes. This deletion would result in a frame shift, producing a premature translation termination leading to the lack of the entire transmembrane and cytoplasmic domains of the normal mb-1 molecule. The existence of two species of mRNA transcripts corresponding to the isolated cDNA clones were confirmed in all of the bovine leukemia cell lines examined by PCR with the use of the primers flanking the deletion site. Furthermore, the shorter mb-1 transcript was induced in normal PBMC by stimulation with mitogens or culture supernatants of bovine leukemia virus-infected cell lines. These findings indicate the presence of the truncated mb-1 gene product which may have some function different from that of the normal mb-1 gene product.

Apoptotic changes in the thymus of mice infected with mouse hepatitis virus, MHV-2

In mice infected with MHV-2, histopathological changes of the thymus was studied. Extensive cell lysis with pyknotic nuclear debris appeared at 48 hr postinfection, and cortico-medullary border was indistinguishable. Electron microscopy revealed vacuolation and shrinkage of the cytoplasm of lymphoid cells, margination of nuclear chromatin, and fragmentation of nuclei. Virus particles were detectable in the lymphoid and reticular epithelial cells, being immunohistochemically positive for viral antigen. By DNA electrophoresis thymocytes showed DNA fragmentation with a laddering pattern characteristic of apoptosis.

Cloning of feline p53 tumor-suppressor gene and its aberration in hematopoietic tumors

Alterations of the p53 tumor-suppressor gene have been observed in a variety of human and mouse tumors. For investigation of the role of this gene in tumors of cats, feline p53 cDNA was molecularly cloned from a feline lymph-node cDNA library. The cloned cDNA (FF53) contained the whole open reading frame of p53 gene encoding 386 amino acids. The amino-acid sequence of the feline p53 gene showed 82.1% and 74.9% similarities with those of the human and mouse counterparts, respectively, and had structural characteristics in common with the p53 genes of several other species. Aberrations of the p53 gene were investigated by RT-PCR and single-strand conformation polymorphism analyses. Of 10 primary hematopoietic tumors and 3 lymphoma cell lines examined, one lymphoma and one lymphoma cell line had a point mutation of the p53 gene, resulting in single amino-acid substitutions.