[Study on the expression and roles of nucleolin in cardiac injury in septic mice].

Objective: To explore the expression and roles of nucleolin in cardiac injury in septic mice. Methods: C57BL/6 mice (WT mice) and myocardium-specific expression of nucleolin transgenic mice (TG mice) were randomly divided into sham group (n=10, sham-operated) and sepsis group (n=15, animal model). Cecal ligation and puncture (CLP) was adopted to produce animal models of sepsis. The expression of nucleolin was detected by Western blotting analysis at 0, 12, 24, 48 hours after the operation. The 7-day survival rate, haemodynamic measurement, levels of isoenzyme of creatinekinase-MB (CK-MB) and cardiac troponin I (cTnI) in serum and levels of reactive oxygen species (ROS) and malondlaldehyde (MDA) in myocardium were evaluated 24 hours after the operation. The data were compared between groups with t test. Results: The expression of nucleolin in myocardium up-regulated significantly in WT+CLP group when compared with that in the WT+Sham group(2.57±0.34 vs 1.00±0.15, t=7.468, P<0.01). Compared with those in the WT+Sham group, the survival rate decreased (33.3% vs 100%, χ(2)=13.375, P<0.01), maximal rate of pressure development (+dp/dtmax) declined (t=4.993, P<0.01), but the serum levels of CK-MB and cTnI and the levels of ROS and MDA in myocardium increased in the WT+CLP group(t=5.031, 4.335, 3.365, 2.375, all P<0.05). Compared with that in WT+CLP group, the 7-day survival rate of mice increased in TG+CLP group (60.0% vs 33.3%, χ(2)=8.227, P=0.004), and the cardiac function improved (t=2.337, P=0.019), but the serum levels of CK-MB and cTnI and the levels of ROS and MDA in myocardium in TG+CLP group reduced significantly (t=2.127, 3.347, 2.115, 2.224,P<0.05). Conclusion: The expression of nucleolin is up-regulated in the myocardium of septic mice, and the overexpression of nucleolin can inhibit oxidative stress injury, attenuate the cardiac injury and dysfunction, and reduce mortality in septic mice.

Effect of antibiotics on clinical, pathologic and immunologic responses in murine Potomac horse fever: protective effects of doxycycline.

Effects of three antibiotics on clinical, pathologic and immunologic responses in murine Potomac horse fever caused by Ehrlichia risticii infection were examined. When antibiotics were given after the development of clinical signs, antibiotics ranked in the order of reducing clinical signs and in preventing body weight loss and an intestinal enlargement were doxycycline, demeclocycline and rifampin. Infected mice treated with doxycycline and demeclocycline developed greater splenomegaly than rifampin-treated or untreated infected mice. All antibiotics used prevented thymic atrophy due to E. risticii infection. Indirect fluorescent antibody titers were highest with doxycycline treatment. Mice treated with demeclocycline and rifampin produced higher antibody titer than those without treatment. Ehrlichia risticii was reisolated from the spleens of both untreated and rifampin-treated infected mice. The effects of administering single doses of doxycycline at different times after infection were examined. Body weight loss was prevented by the drug given at every treatment day examined, i.e. Days 3, 5 and 7 post-infection (PI). Thymic atrophy was minimum in mice treated at Day 5 PI, while splenomegaly was found on every treatment day. Splenocyte proliferative response to concanavalin A and lipopolysaccharide, and specific antibody development against E. risticii was best in mice treated at Day 5 PI followed by those treated at Day 3 and Day 7 PI.

[Use of double McAb sandwich ELISA to detect circulating antigen of Toxoplasma in infected rabbits].

This paper reports on the cumulative positive frequencies of circulating antigen (CAg) detected in the sera of rabbits infected with Toxoplasma by using double-McAb sandwich ELISA. The positive frequencies of rabbits with heavy and medium infection in the incubation period are 30.8% and 11.1%. Those with medium infection in acute, subacute and early chronic period are 86.1% and 76.7%, 43.3% and 32.0% with light infection. The positive rates of CAg in rabbits of medium and light infection rose progressively in acute period, but declined in subacute and early chronic period. Cross reaction with schistosomiasis and coccidiosis was all negative. This method of high specificity, sensitivity and duplication possesses certain value in the diagnosis of acute or active Toxoplasma infection and may be useful for the diagnosis in the early period.

In vitro susceptibilities of Ehrlichia risticii to eight antibiotics.

Inhibition of the proliferation of Ehrlichia risticii cultured in murine macrophage P388D1 cells by eight antibiotics was evaluated by indirect fluorescent-antibody staining with an antiserum specific to E. risticii. There was a negative correlation between the percentage of infected cells and the log10 of the concentrations of all antibiotics examined. The ranks of the antibiotics in the order of 50% inhibitory concentrations (on a microgram-per-milliliter basis) after 48 h of exposure were as follows: demeclocycline, doxycycline, and oxytetracycline less than minocycline less than rifampin less than tetracycline less than erythromycin and nalidixic acid. When the antibiotics were removed after 48 h of incubation, continuous inhibition of proliferation was evident at 72 h. At 96 h regrowth of the organisms occurred in most of the cultures. The rate of regrowth was the highest with nalidixic acid, followed by erythromycin, at all concentrations of the antibiotic tested. Regrowth was observed with less than 0.1 microgram of minocycline per ml and less than 0.01 microgram of oxytetracycline, tetracycline, and doxycycline per ml. With more than 0.01 microgram of demeclocycline per ml, however, the inhibition persisted for up to 72 h after removal of the antibiotic. These results indicate that demeclocycline was slightly more effective than doxycycline, oxytetracycline, and minocycline in eliminating E. risticii in macrophages in vitro, whereas tetracycline and rifampin were less effective. Nalidixic acid and erythromycin were ineffective.

In vitro transcription and translation of genomic RNA from a porcine group C rotavirus.

Eleven segments of ssRNA were synthesized from dsRNAs of a porcine group (Gp) C rotavirus (Cowden strain) using an in vitro transcription system. In vitro translation of unfractionated ssRNAs revealed at least nine viral proteins, ranging from 22 kDa to 93 kDa. The 37 kDa and 25 kDa proteins were glycosylated as demonstrated by the endoglycosidase H assay. In vitro translated products analyzed by SDS-polyacrylamide gel electrophoresis and partial protease peptide mapping were comparable to those synthesized in vivo (MA 104 cells).

Biochemical characterization of the structural and nonstructural polypeptides of a porcine group C rotavirus.

Purified virions or radiolabeled lysates of infected MA104 cells were used to characterize the structural and nonstructural polypeptides of a porcine group C rotavirus. At least six structural proteins were identified from purified group C rotavirus by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Of these, two (37,000- and 33,000-molecular-weight polypeptides) were associated with the outer shell, as demonstrated by the ability of EDTA to remove them from the purified virion. The other four polypeptides (molecular weights, 125,000, 93,000, 74,000, and 41,000) were located in the inner shell. The structural or nonstructural nature of a 25,000-molecular-weight protein identified in our studies was unclear. Glycosylation inhibition studies with tunicamycin in infected cells demonstrated that the 37,000- and 25,000-molecular-weight proteins were glycosylated and contained mannose-rich oligosaccharides identified by radiolabeling of the infected cells with [3H]mannose. The 37,000-molecular-weight outer shell glycoprotein was shown by pulse-chase experiments to be posttranslationally processed. The kinetics of viral polypeptide synthesis in infected cells were also studied, and maximal synthesis occurred at 6 to 9 h postinfection. The 41,000-molecular-weight inner capsid polypeptide was the most abundant and was the subunit structure of a 165,000-molecular-weight protein aggregate. Two polypeptides (molecular weights, 39,000 and 35,000) appeared to be nonstructural, as determined by comparison of the protein pattern of radiolabeled infected cell lysates with that of purified virions. Radioimmunoprecipitation was used to examine the serologic cross-reactions between the viral polypeptides of a group C rotavirus with those of a group A rotavirus. No serologic cross-reactivities were detected. The polypeptides of group A and C rotaviruses are compared and discussed.

Analysis of the gene encoding the outer capsid glycoprotein (VP7) of group C rotaviruses by northern and dot blot hybridization.

The genetic diversity of gene 8 (encoding the outer capsid glycoprotein VP7) among group (Gp) C rotaviruses was examined by Northern and dot blot hybridization. A cDNA clone of the porcine Gp C Cowden strain gene 8 was labeled with 32P by nick translation and used as a probe. The gene 8 probe hybridized with the corresponding gene of one human (88-196) and four porcine (Cowden, NB, WH, and Wi) strains of Gp C rotaviruses under both moderate (50% formamide, 5X SSC, and 42 degrees) and high (50% formamide, 5X SSC, and 52 degrees) stringency conditions. However, under high stringency conditions little or no hybridization was detected with the corresponding gene of one bovine (Shintoku) and three other porcine (Ah, HF, and KH) strains of Gp C rotaviruses. In control experiments, the Cowden gene 8 probe did not hybridize with Gp A (Gottfried strain) or Gp B (Ohio strain) rotaviruses. These data demonstrate that the Cowden gene 8 probe is Gp C rotavirus-specific and that genetic diversity exists among Gp C rotaviruses in the gene encoding the outer capsid glycoprotein VP7. Our gene 8 probe may be useful in hybridization assays for serotyping Gp C rotaviruses, analogous to the use of VP7 probes for serotyping Gp A rotaviruses. However, final confirmation of our genetic approach to serotype Gp C rotaviruses awaits the serologic analysis of these viruses.

Analysis of the genetic diversity of genes 5 and 6 among group C rotaviruses using cDNA probes.

Two partial cDNA clones of genes 5 (encoding the major inner capsid protein VP 6) and 6 (encoding a nonstructural protein) of the porcine group (Gp) C rotavirus (Cowden strain) were radiolabeled with 32P and used individually as probes in Northern and dot blot hybridization assays. The specificity of each probe was tested against genomic dsRNA from: (1) porcine Gp A, B, and C rotaviruses; (2) Gp C rotaviruses from different species; and (3) porcine Gp C rotavirus field strains with varying electropherotype patterns. Neither probe hybridized with ds RNA from the porcine Gp A and B strains under the stringency conditions employed in the study. However, the gene 5 probe hybridized with the corresponding gene from the homologous porcine and the heterologous human and bovine Gp C rotaviruses tested. The gene 6 probe hybridized with the corresponding gene from the homologous Cowden strain, but hybridized weakly with gene 6 from the human and bovine Gp C rotaviruses. Both probes recognized all six different porcine Gp C field strains, although with varying intensities. Our results demonstrate that the gene 5 and 6 probes used in this study are specific for Gp C rotaviruses. However, evidence for greater genetic variation in the gene 6 among porcine, bovine and human Gp C strains suggested that the gene 5 probe may prove more broadly reactive among Gp C strains from different species. cDNA probes used in our study should prove useful for the detection of Gp C rotaviruses in feces and facilitate epidemiologic studies.

Molecular analysis of the gene 6 from a porcine group C rotavirus that encodes the NS34 equivalent of group A rotaviruses.

The complete nucleotide sequence of the gene 6 from the porcine group (Gp) C rotavirus strain Cowden was determined from gene 6-specific clones selected from a cDNA library and from viral transcript RNA. The gene is 1348 nucleotides in length with a potential initiation codon beginning at nucleotide 25 and a stop codon at nucleotide 1231. The deduced protein contains 402 amino acids. Comparison of the gene 6 from this Gp C strain with sequences in the GenBank data base indicated that this gene shared homology with gene 7 of Gp A rotavirus strain SA-11 (22.9%) and gene 9 of Gp A rotavirus strain UK (22.6%), both of which encode the NS34 protein. In vitro translation products produced from transcripts generated from a gene 6 clone containing the entire open reading frame were not immunoprecipitated with either hyperimmune serum specific for the Gp C Cowden strain or a monoclonal antibody directed against the group antigen (VP6) of the Cowden strain. However, products generated from a full-length gene 5 clone of the Cowden strain were immunoprecipitated by each of these antibodies. These data suggest that in contrast to the Gp A viruses in which the gene 6 encodes the major inner capsid protein VP6, the gene 6 of the Cowden Gp C strain encodes a nonstructural protein corresponding to the NS34 of Gp A rotaviruses.

Isolation, characterization, and serial propagation of a bovine group C rotavirus in a monkey kidney cell line (MA104).

A virus (designated the Shintoku strain) which was morphologically indistinguishable from group A rotaviruses was detected in the feces of adult cows with diarrhea in Japan. The virus contained 11 segments of double-stranded RNA and had an electrophoretic migration pattern in polyacrylamide gels similar to that of other group C rotaviruses (4-3-2-2). Feces containing the bovine virus reacted with antiserum to porcine group C rotavirus (Cowden strain) but not group A or B rotaviruses in immunoelectron microscopy. The virus was adapted to serial propagation in roller tube cultures of a rhesus monkey kidney cell line (MA104) by using high concentrations of trypsin. Evidence for viral replication in MA104 cell cultures was demonstrated by immunoelectron microscopy and indirect immunofluorescence by using antiserum to porcine group C rotavirus and by electrophoretic analysis of extracted viral double-stranded RNA. A significant antibody response against the isolate was detected in convalescent-phase sera of cows which excreted the virus: no increased antibody response to bovine group A rotavirus was observed. To our knowledge, this is the first isolation of a group C rotavirus from cattle.

Reactivity of monoclonal antibodies to the 41-kilodalton protein of porcine group C rotavirus with homologous and heterologous rotavirus serogroups in immunofluorescence tests.

Three monoclonal antibodies (MAbs) to porcine group C rotavirus immunoprecipitated the major inner capsid protein (41 kDa) but failed to precipitate group A rotavirus proteins. In immunofluorescence tests of rotavirus-infected cell cultures or pig intestines, the MAbs recognized porcine and bovine group C rotaviruses but not group A or B rotaviruses. These MAbs may recognize the group C rotavirus counterpart to VP6 of group A rotaviruses and may be useful as diagnostic reagents.

Sequence conservation of gene 8 between human and porcine group C rotaviruses and its relationship to the VP7 gene of group A rotaviruses.

cDNA libraries from porcine group (Gp) C rotavirus strain Cowden and a human Gp C rotavirus strain were generated. The complete nucleotide sequence of gene 8 from the Cowden strain was determined from gene 8-specific clones and viral transcript RNA. A full-length gene 8 clone was generated from the human Gp C virus by polymerase chain reaction (PCR) using primers deduced from the 3' and 5' ends of the Cowden strain gene 8, and the sequence of the human Gp C gene 8 was determined from this clone and gene 8 clones in the cDNA library. The gene 8 from the Cowden or the human Gp C strain is 1063 nucleotides in length and contains a long open reading frame beginning at the 49th nucleotide from the 5' end and terminating with a stop codon 16 bases from the 3' end. The encoded protein contains 332 amino acids (predicted molecular weight of 37.3 kDa) with two potential N-linked glycosylation sites in the porcine strain and three in the human strain. The polypeptide products derived from in vitro translation of the transcript RNA generated from a porcine gene 8 clone containing the entire open reading frame were analogous in size with the Gp A VP7. The gene 8 of porcine and human Gp C rotaviruses exhibited considerable nucleotide and deduced amino acid sequence identity (83.8 and 88.0%, respectively). Comparison of the Gp C gene 8 protein sequence with the VP7 protein of Gp A rotavirus revealed structural similarities, although the overall amino acid identity was low (less than 30%). These data suggest that the gene 8 of the porcine or human Gp C rotavirus encodes a protein corresponding to the VP7 outer capsid glycoprotein of Gp A rotaviruses and that the eighth gene is highly conserved in the porcine and human Gp C strains examined in this study.