Integrating transcriptome and metabolome to identify key genes regulating important muscular flavour precursors in sheep

Flavour precursors are the basis of meat flavour, and their metabolism is regulated by a variety of enzymes. Thus, it is of great significance to identify the key genes related to meat flavour precursors. In this study, the difference in flavour precursors and transcriptome between Hu sheep and Dorper with different intramuscular fat (IMF) content were investigated using widely targeted metabolomics and RNA-sequencing technologies. Then, the key genes regulating the metabolism of vital precursors were explored by integrating transcriptome and metabolome. Consequently, 594 metabolites were detected in sheep longissimus dorsi, and 76 differentially abundant metabolites (DAMs) were identified between Hu sheep and Dorper. No DAMs were observed between distinct IMF content groups within each breed. A total of 10 lysophospholipids (LPs), including four lysophospholipid ethanolamines and six lysophospholipid cholines, were identified as the main differential precursors between Hu sheep and Dorper. Furthermore, the weighted gene coexpression network analysis uncovered three differentially coexpression modules that were significantly associated with the content of differential LPs in Dorper. From the three modules, GLB1, PLD3, LPCAT2, DGKE, ACOT7, and CH25H genes were identified as key genes regulating the metabolism of LPs. This work provides an insight into understanding the difference in flavour between different sheep breeds, as well as a basis for further exploring the regulatory mechanism of key genes on LPs.

[Clinical cure strategies for hepatitis B: direct-acting antiviral drugs]

Direct-acting antivirals (DAAs) play a critical role for the therapy of chronical hepatitis B. DAAs can decrease the production of viral progeny of hepatitis B virus (HBV), breaking the viral dynamic equilibrium between: (1) virion production from hepatocytes and clearance from circulation; (2) replenishment and decay of covalently closed circular (ccc)DNA pool inside infected hepatocytes. Nucleos(t)ide analogues can potently shift the first balance to undetectable viremia in the blood, but have limited or no effect on the second one, thus making it imperative to develop new agents targeting additional step(s) of HBV life cycle. We herein briefly introduce the DAAs currently in development by classifying them as agents affecting the replenishment or the decay of cccDNA pool.

Recent Progress in Small-Molecule Fluorescent Probes for Detecting Mercury Ions

Mercury is a highly toxic and non-essential element that is found in every corner of the globe. The small amount of mercury produced by various pathways eventually enters freshwater and marine ecosystems, circulating through the food chain (especially fish) and causing various environmental problems in aspects including plants, animals, and human. There are several traditional quantitative methods developed for mercury ions (II) analysis in water samples. However, due to the complexity of the detection process, high cost and strong technical expertise, it is difficult to detect mercury ions in real-time. Therefore, in recent years, a large number of researchers have developed small-molecule fluorescent probes for Hg ions detection. Fluorimetry has the advantages of convenient detection, short response time, high sensitivity and good selectivity. This review summarized the small-molecule fluorescent probes for mercuric ion detection developed in recent years according to the chemical structural classification, compared their performances and elaborated the mechanism. We hope that the review will help the researches for the designs of metal ions fluorescent probes and their applications with certain reference value.

Introducing ortho-methoxyl group as a fluorescence-enhancing and bathochromic-shift bi-functional strategy for typical cysteine sensors

A practical strategy of introducing ortho-methoxyl group was explored to achieve the fluorescence-enhancing and bathochromic-shift bi-functional optimization. It was tested in the Cys sensing ISOPH-X series, thus the successful case, ISOPH-2, was obtained. It realized the optimization in a simple and compatible way. The corresponding strategy was basically established during the confirmation of checkpoints including applicable steadiness (over 24 h), wide pH range (7.0-9.0), rapid response (20 min), good biocompatibility, high sensitivity (LOD = 0.072 nm), high selectivity and biological monitoring of Cys in living cells as well as C. elegans. In this work, the o-methoxyl introduction strategy led to a 15 nm red shift and a near 4-fold fluorescence enhancement. This strategy could be combined with the double bond-introducing approach. Compared with reported strategies, by breaking the dilemma between red shift and strong fluorescent intensity, this strategy might offer beneficial information for exploiting better sensors with more fluorophores and mechanisms for their targets.

An imidazo[1,5-α]pyridine-derivated fluorescence sensor for rapid and selective detection of sulfite

Sulfur-containing species are essential in the composition and the metabolism of the organisms, thus developing a full set of implements to cover all of them is still a favorable choice. Herein, we chose imidazo [1,5-α]pyridine moiety as the basic fluorophore for the detection of sulfite, and preliminarily completed the toolset since biothiols (GSH, Cys, Hcy), H₂S, and PhSH could be detected by sensors based on the same backbone. The designed sensor, IPD-SFT, with structural novelty and large Stokes shift (130 nm), indicated the most attractive advantages of remarkably rapid response period (within 1 min) and high selectivity for sulfite from all the sulfur-containing species. Other practical properties included high sensitivity (LOD = 50 nM) and wide pH adaptability (5.0-11.0). Furthermore, IPD-SFT could monitor both exogenous and endogenous sulfite. It not only raised a potential tool for sulfite detection, but also preliminarily completed the toolset for all the sulfur-containing species. The development of such toolsets might reveal the sulfur-containing metabolism and corresponding physiology and pathological procedures.

Effects of induced stress from the live LaSota Newcastle disease vaccination on the growth performance and immune function in broiler chickens

This study was conducted to assess the growth performance and immunological effects of vaccination-induced stress on broilers. The chickens were administered 0, 2, 4, 8, and 16 doses of live LaSota Newcastle disease (ND) vaccine and slaughtered on the 1st, 7th, 14th, and 21st day post vaccination. The results showed that the serum antibody titers after Newcastle disease virus (NDV) vaccination were elevated at day 7 post vaccination, peaked at day 14, then declined by day 21. Interestingly, the antibody titers peaked at 2 doses, and no further dose-dependent titer increases were observed. This study demonstrated that vaccination-induced stress increased serum adrenocorticotropic hormone and cortisol, affected growth performance (average daily gain, average daily feed intake, and feed conversion ratio), and triggered apoptosis in spleen lymphocytes by downregulating the ratio of Bcl-2 to BAX and upregulating the gene expressions of caspase-3 and -9, which was concordant with the activation of the enzymatic activities of caspase-3 and -9. This study suggests that NDV vaccine doses in broilers must be controlled judiciously because increasing the number of doses resulted in increased lymphocyte apoptosis while the peak of the antibody titer and optimal growth performance were achieved at a low number of doses (2 doses).

Long non-coding RNA SOX21-AS1 promotes cell proliferation and invasion through upregulating PAK7 expression by sponging miR-144-3p in glioma cells

In this study, the function of long non-coding RNA SOX21 antisense RNA 1 (SOX21-AS1) in the progress of glioma was explored. RNA and protein levels were measured via quantitative reverse transcription-PCR (qRT-PCR) and western blot analysis. In addition, we examined cell proliferation, apoptosis, migration and invasion. The interaction between SOX21-AS1 (PAK7) and miR-144-3p was determined via RNA immunoprecipitation (RIP) assay and Luciferase reporter assay. SOX21-AS1 was upregulated in glioma tissues and cells. SOX21-AS1 knockdown was carried out in glioma cells (U251 and U87 cells). Moreover, in vitro, SOX21-AS1 knockdown repressed proliferation, migration, invasion and enhanced apoptosis in glioma cells. In vivo, SOX21-AS1 knockdown suppressed tumor growth in mice. In addition, SOX21-AS1 could sponge miR-144-3p, which was determined to bind to PAK7. miR-144-3p knockdown promoted proliferation, migration, invasion and inhibited cell apoptosis. Importantly, the effects of SOX21-AS1 knockdown-induced proliferation, migration, invasion, and apoptosis were alleviated in glioma cells co-transfected with SOX21-AS1 and miR-144-3p knockdown. Furthermore, miR-144-3p knockdown also attenuated Wnt/β-catenin pathway-associated protein levels induced by SOX21-AS1 knockdown. These results indicated that SOX21-AS1/miR-144-3p/PAK7 axis played an oncogenic role in glioma cells by regulating Wnt/β-catenin pathway, which suggests a rational therapeutic strategy for glioma.

A selective fluorescent sensor for cysteine detection with potential as a white light emitting fluorophore in living cell imaging

A novel fluorescent sensor CysW-1 was introduced for cysteine detection via the cleavage reaction of two fluorophores. Then a relatively steady and practical white light emitting system was successfully generated. The biocompatibility ensured the living cell imaging and further pre-clinical applications.

Effect of Vanadium and Tea Polyphenols on Intestinal Morphology, Microflora and Short-Chain Fatty Acid Profile of Laying Hens

Vanadium (V) is a trace element which can induce dysfunction of gastro-intestine and egg quality deterioration of laying hens. This study was conducted to determine the effect of tea polyphenols (TP) on intestinal morphology, microflora, and short-chain fatty acid (SCFA) profile of laying hens fed vanadium containing diets. A total of 120 Lohman laying hens (67-week-old) were randomly divided into 4 groups with 6 replicates and 5 birds each for a 35-day feeding trial. The dietary treatments were as follows: (1) control (CON), fed a basal diet; (2) vanadium treatment (V10), CON +10 mg V/kg; (3) TP treatment 1 (TP1): V10 + 600 mg TP/kg; (4) TP treatment 2 (TP2): V10 + 1000 mg TP/kg. Fed 10 mg V/kg diets to laying hens did not affect the cecum flora diversity index (H), degree of homogeneity (EH), and richness (S), but hens fed TP2 diet decreased the H, EH, and S (P < 0.05). The cecum butyrate acid concentration was lower in V10 treatment and higher in TP2 treatment (P < 0.05). Addition of 10 mg/kg V resulted in an increased (P < 0.01) duodenal cell apoptosis rate, and 1000 mg/kg TP supplementation overcame (P < 0.01) this reduction effect induced by vanadium. The results indicated that supplementation of 10 mg/kg vanadium increased duodenal cell apoptosis and reduced cecum butyrate acid content. Addition of 1000 mg/kg TP increased the SCFA production to affect cecum flora ecology and protected the duodenal cell from excess apoptosis caused by vanadium.

Effect of tea polyphenols on production performance, egg quality, and hepatic antioxidant status of laying hens in vanadium-containing diets

This study was conducted to determine the effect of tea polyphenols (TP) on production performance, egg quality, and hepatic-antioxidant status of laying hens in vanadium-containing diets. A total of 300 Lohman laying hens (67 wk old) were used in a 1 plus 3 × 3 experiment design in which hens were given either a diet without vanadium and TP supplementation (control) or diets supplemented with 5, 10, or 15 mg V/kg and TP (0, 600, 1,000 mg/kg) diets for 8 wk, which included 2 phases: a 5-wk accumulation phase and a 3-wk depletion phase. During the accumulation phase, dietary vanadium addition decreased (linear, P < 0.01) albumen height and Haugh unit (HU), and TP supplementation mitigated (linear effect, P < 0.01) this reduction effect induced by vanadium. Eggshell thickness (linear, P < 0.01), redness (linear and quadratic, P < 0.05), and yellowness (linear and quadratic, P < 0.05) were decreased by vanadium and increased by the effect of TP when a vanadium-containing diet was fed. In the depletion phase, the bleaching effect on eggshells induced by vanadium disappeared one wk after vanadium withdrawal. Eggshell thickness, eggshell strength, albumen height, and HU were lower (P < 0.05) in the 15 mg/kg vanadium group compared with the control diet until 2 wk post vanadium challenge, but hens fed 15 mg/kg vanadium and 600 mg/kg TP showed no difference from the control diet only after 1 wk withdrawal. In the liver, the activity of glutathione S-transferases and glutathione peroxidase was increased (linear, P < 0.01) with the TP addition at 5 wk in the accumulation phase in the vanadium-containing diet; the malondialdehyde content increased (linear effect, P = 0.02) with the addition of vanadium. The results indicate that supplementation of 10 and 15 mg/kg vanadium resulted in reduced albumen quality, bleaching effect on eggshell color, and antioxidant stress in the liver. The effect of TP addition can prevent laying hens from the adverse effect of vanadium on egg quality, liver antioxidant stress and shorten the recovery time.

Effect of temperature change on power generation of microbial fuel cell

Microbial fuel cell (MFC), which can directly generate electricity from biodegradable materials, has been receiving increasing attention. Effects of temperature change on power density, electrode potential, columbic efficiency, chemical oxygen demand removal and internal resistance in two chambers MFCs were examined in this paper. The maximum power density of 7.89 W/m3 was achieved at 37 degrees C, with 199% higher at 10 degrees C (2.64 W/m3), 24% higher at 30 degrees C (6.34 W/m3) and 21% higher at 43 degrees C, no steady power generation was observed at 55 degrees C. Low temperature to 10 degrees C might have a huge effect on anode potential, especially at higher current, but increasing the temperature to 43 degrees C had a main effect on the cathode performance when the MFCs have been established at 37 degrees C. The internal resistance of MFC was about 29 omega at 37 degrees C, and increased 62% and 303% when MFC switched to 30 degrees C and 10 degrees C. Similarly, internal resistance increased 48% at 43 degrees C. The effect of temperature on MFC performance was expressed by internal resistance, the higher the internal resistance of MFC, the lesser the power density obtained. The Columbic efficiencies were 8.65% at 30 degrees C, 8.53% at 37 degrees C, and 13.24% at 43 degrees C. These results demonstrate that MFCs can effectively be operated over a wide range of temperatures.

Primary molecular features of self-incompatible and self-compatible F(1) seedling from apricot (Prunus armeniaca L.) Katy x Xinshiji

Expression of the S-RNase genes in the self-compatible (SC) apricot (Prunus armeniaca L.) cultivar Katy, the self-incompatible (SI) cultivar Xinshiji and their F(1) seedling was examined in this study. Three S-genotypes, S(9)Sc (Sc, self-compatibility S-gene absent from the style), S(8)S(9), and S(8)S(10), were obtained. Seedlings with S-RNase that migrated as a single band in gel electrophoresis were SC, despite high transcript abundance, and those with S-RNase that migrated as two bands were SI with high transcript abundance or SC with low transcript expression. S(8)-RNase was induced in SI cultivars only 24 h after self-pollination, indicating post-transcriptional regulation of S(8)-RNase in SI apricots. A Proteomic study showed that 35 protein spots were synthesized differently between SC and SI pistils. Fifteen of the 35 protein spots were identified; nine proteins, including receptor protein kinase-like protein, reversibly glycosylated polypeptide-2, and isoflavone reductase-like protein, were detected only in the SC pistils; while nine proteins, including actin 7, a putative serine/threonine kinase, and S-RNase, were detected only in the SI pistils. A mitochondrial NAD-dependent malate dehydrogenase and a probable elongation factor G were up-regulated, while heat shock cognate 70 was down-regulated in the SC pistils compared to those in the SI pistils. The results suggest that the proteins responsible for self-compatibility and self-incompatibility may be different.

Effects of cyadox and olaquindox on intestinal mucosal immunity and on fecal shedding of Escherichia coli in piglets

A 2 x 3 factorial arrangement of treatments was used to determine the effects of olaquindox and cyadox on the intestinal mucosal immune response and on fecal shedding of Escherichia coli in Landrace x Large White barrows that had been orally given 10(10) cfu of E. coli (O139:K88). Factors included 1) E. coli inoculation or no inoculation, and 2) no antimicrobial, 100 mg of olaquindox/kg, and 100 mg of cyadox/kg in the basal diet, respectively. The effects of cyadox and olaquindox were assessed in terms of fecal shedding of E. coli, the number of intraepithelial lymphocytes (IEL), immunoglobulin A-positive cells (APC) in the intestinal lamina propria, and ADG. There was no difference in the fecal shedding of total E. coli or the inoculated E. coli between olaquindox-supplemented pigs and cyadox-supplemented pigs during the experiment. However, fecal shedding of the inoculated E. coli in olaquindox- or cyadox-supplemented pigs was less (P < 0.05) than that in nonsupplemented pigs. Escherichia coli inoculation increased IEL and APC in the jejunum and ileum, but olaquindox or cyadox decreased IEL and APC (P < 0.05). Jejunal APC in cyadox-supplemented pigs was less (P < 0.05) than that in olaquindox-supplemented pigs. Escherichia coli inoculation reduced (P < 0.05) ADG, whereas the supplementations improved ADG (P < 0.01) during the experiment. Average daily gain in cyadox-supplemented pigs was greater (P < 0.05) than that in olaquindox-supplemented pigs. The data indicated that olaquindox and cyadox reduced the number of intestinal E. coli and suppressed E. coli-induced immune activation, which might be responsible for the enhanced growth that was observed.

Olaquindox and cyadox stimulate growth and decrease intestinal mucosal immunity of piglets orally inoculated with Escherichia coli

One hundred and fifty piglets were randomly allotted to one of six treatments to determine the effects of olaquindox and cyadox on growth and intestinal immune response including the number of intraepithelial lymphocytes and immunoglobulin A secreting cells (ASCs) during the three-week period. A 2 x 3 factorial arrangement of treatments was employed with the following factors: (1) Escherichia coli (O(139):K(88), 10(10) CFU) inoculation or control and (2) no antimicrobials, 100 mg/kg olaquindox and 100 mg/kg cyadox in the basal diet respectively. The antimicrobial supplementations improved (p < 0.01) average daily gain and feed conversion ratio (FCR) during the experiment. Average daily gain and FCR in the cyadox-supplemented pigs were higher (p < 0.05) than those in the olaquindox-supplemented pigs. Intraepithelial lymphocytes and ASCs decreased (p < 0.05) when the diets were supplemented. Jejunal ASCs in the cyadox-supplemented pigs were lower (p < 0.05) than those in the olaquindox-supplemented pigs. Olaquindox and cyadox suppressed E. coli-induced intestinal immune activation, which may be involved in the observed growth promotion.

Roles of the polypyrimidine tract and 3' noncoding region of hepatitis C virus RNA in the internal ribosome entry site-mediated translation

Hepatitis C virus (HCV) genome contains a 3'noncoding region (3'NCR) consisting of a variable region, a polypyrimidine tract (polyU/UC) and the X region. To examine the roles of 3'NCR and polyU/UC tract in the internal ribosome entry site (IRES)-mediated translation process, a variety of 3'NCRs containing different lengths of polyU/UC tract were obtained from HCV infected patients and cloned respectively to the downstream of the firefly luciferase coding gene linked to HCV 5'NCR and 30 nucleotides of core gene (containing IRES element). The results of in vitro translation in rabbit reticulocyte lysate (RRL) and cell transfection assay in mammalian cells showed that the IRES-mediated translation efficiency could be enhanced by the full-length of 3'NCR of HCV RNA. However, contradictory results were observed when the role of polyU/UC tract in the IRES-mediated translation was studied. While the IRES-mediated translation efficiency was inhibited by the presence of polyU/UC tract in in vitro translation experiments, transfection of these expression cassettes into hepatic cell line showed that polyU/UC tract enhanced IRES-mediated translation efficiency in vivo. Cellular-fraction complement experiments showed that cellular factors were required for the enhancement by the polyU/UC tract. Further antibody blocking assay and UV cross-linking assay suggested the correlation of IRES-mediated translation with host factors, including the La protein. The data above also indicated that the modulations of the IRES-mediated translation by the HCV 3'NCR and the polyU/UC tract were in a length-independent manner.

Comparing the immunogenicity of hepatitis B virus S gene variants by DNA immunization

DNA immunization was used to compare the immunogenicity of hepatitis B virus S gene variants. Four recombinant plasmid DNAs containing the full-length virus genome with different S gene inserts were used to immunize BALB/c and C57/BL/6 mice. These inserts were cloned from 129L (residue 129, glutamine to leucine), 129H (residue 129, glutamine to histidine) 145R (residue 145, glycine to arginine) variants and the wild-type virus. The titer of hepatitis B virus core antibodies (anti-HBc) in immunized mice was used as the control for the efficiency of DNA immunization. Serum hepatitis B surface antibody (anti-HBs) titer and cytokines induced in splenocytes stimulated with hepatitis B surface antigen (HBsAg) were monitored as specific immune responses induced by different plasmid DNAs. 129L DNA induced significantly lower anti-HBs antibodies (IgG, IgG1, and IgG2a) and less interferon-gamma, compared to those in mice immunized with the 129H variant and the wild-type HBV DNA (p < 0.05). Computer modeling showed that a change from glutamine to leucine at 129 residue led to higher hydrophobicity and could result in decreased immunogenicity. Results indicate that DNA immunization can be used to compare the humoral and cellular immunogenicity among different HBV S variants.

A single amino acid in the reverse transcriptase domain of hepatitis B virus affects virus replication efficiency

To explore functional domains in the hepatitis B virus (HBV) polymerase, two naturally occurring HBV isolates (56 and 2-18) with 98.7% nucleic acid sequence homology but different replication efficiencies were studied. After transfection into HepG2 cells, HBV DNA isolated from intracellular virus core particles was much higher in 56-transfected cells than in cells transfected with 2-18. The structural basis for the difference in replication efficiency between these two isolates was studied by functional domain gene substitution. The complete polymerase (P) gene and its gene segments coding for the terminal protein (TP), spacer (SP), reverse transcriptase (RT), and RNase H in 2-18 were separately replaced with their counterparts from 56 to construct full-length chimeric genomes. Cell transfection analysis revealed that substitution of the complete P gene of 2-18 with the P gene from 56 slightly enhanced viral replication. The only chimeric genome that regained the high replication efficiency of the original 56 isolate was the one with substitution of the RT gene of 2-18 with that from 56. Within the RT region, amino acid differences between isolates 2-18 and 56 were located at positions 617 (methionine versus leucine), 652 (serine versus proline), and 682 (valine versus leucine). Point mutation identified amino acid 652 as being responsible for the difference in replication efficiency. Homologous modeling studies of the HBV RT domain suggest that the mutation of residue 652 from proline to serine might affect the conformation of HBV RT which interacts with the template-primer, leading to impaired polymerase activity.

Cloning and Expression of Chinese Duck Interferon-gamma Gene

The efficacy of cytokine therapy has been demonstrated in several viral diseases. Interferon-gamma is a cytokine that has potent antiviral property and immunomodulatory activity. To investigate the role of IFN-gamma in viral clearance during natural infection and to define the antiviral mechanism, DHBV-infected ducks was used as an animal model. To clone, express, and develop the method of quantifying DuIFN-gamma gene transcription and expression, DuIFN -gamma cDNA was amplified by RT-PCR from PHA stimulated duck PBMC. Recombinant plasmid expressing DuIFN-gamma was used to transfect COS-7, and the cell culture supernatant was analyzed by CPE inhibitory assay and MTT methods to determine the antiviral titer of IFN-gamma. The GST-DuIFN-gamma fusion protein was expressed in E.coli and purified using the GST sepharose 4B. Results indicated that the supernatant collected from COS-7 cells transfected with DuIFN-gamma cDNA was able to prevent duck fibroblasts from VSV induced CPE in a dose dependent manner. An anti-DuIFN-gamma antibody neutralized this antiviral activity.

[Plant regeneration from protoplast culture in flax (Linum usitatissimum)]

Shoot protoplasts of four fiber flax (Linum usitatissimum) varieties (7309, 948, Belinka and Viking) were isolated and cultured. The optimal condition for higher protoplast yield 1.8 x 10(6)/gFW and activity 85.5% (c.v. 948) were from 10 day old seedings. Culture in V-KM Agroase-island medium led to first divisions after 3 days (c. v. 948), and after twenty days with an efficiency of 36% of divided cells and 5.2% in plating efficiency. Plant regeneration was obtained in 7309 and Belinka on agar media B5-2, MS3 containing 0.6 mg/L 6-BA and 0.1 mg/L NAA. Roots and leaves regeneration were observed in Viking and 948 respectively.

Effect of plasmid DNA on immunogenicity of HBsAg-anti-HBs complex

Hepatitis B surface antigen (HBsAg) complexed with anti-HBs is more immunogenic than HBsAg alone in mice. This complex is usually used with alum as an adjuvant, which can enhance humoral response but inhibits cell-mediated immune responses. To improve the immunogenicity of HBsAg-anti-HBs, we immunized mice with a combination of this immunogenic complex and pCMVHBs, a plasmid encoding HBsAg, or the vector pCMV. Both plasmids enhanced the anti-HBs response induced by the immunogenic complex. We found 20 microg of plasmid or vector enhanced the anti-HBs response in all mice, whereas 1 microg was less effective. Splenocytes from different immunized groups were stimulated with HBsAg in vitro, and the highest level of IL-2 detected in the supernatant was found in mice immunized with HBsAg-anti-HBs plus pCMVHBs. A plasmid (pcDNA3c191) encoding core protein of hepatitis C virus (HCV) was used as an adjuvant to the immunogenic complex. A preliminary result showed that pcDNA3c191 not only enhanced the immunogenicity of HBsAg-anti-HBs, but also induced anti-HCV core antibodies. Immunization using a plasmid DNA encoding one viral antigen in combination with antigen and antibody complex of another microbial origin could be a new approach to the development of multivalent vaccines.

Pharmacokinetics of ampicillin and sulfadimidine in pigs infected experimentally with Streptococcus suum

Twenty-three hybrid pigs (23 +/- 3 kg body wt) were assigned to three groups to investigate the pharmacokinetics of ampicillin (APC, 10 mg/kg) administered intravenously (i.v.) and intramuscularly (i.m.), and sulfadimidine (SDM, 50 mg/kg) administered intravenously as a bolus injection. In the first series of experiments the animals remained healthy. Subsequently, the pigs were infected with Streptococcus suum by subcutaneous (s.c.) inoculation and the experiments were repeated. The total apparent distribution volume of APC given intravenously was increased from 0.512 +/- 0.026 L/kg in uninfected pigs to 0.68 +/- 0.06 L/kg (P < 0.01) in infected pigs, whereas there were no significant changes in the same parameter for SDM (P > 0.05). The clearance of APC was increased markedly from 0.52 +/- 0.07 L/kg/h in uninfected pigs to 0.62 +/- 0.10 L/kg/h in infected pigs. In contrast, SDM clearance was decreased markedly from 0.023 +/- 0.003 L/kg/h to 0.017 +/- 0.003 L/kg/h (P < 0.05). As a result, the biological half-lives of the drugs were altered to varying degrees in infected pigs. The half-life of SDM was increased from 15.0 +/- 3.0 h in uninfected pigs to 20 +/- 7h in infected pigs (P < 0.05), but differences in APC half-lives between uninfected and infected animals were not observed (P > 0.05). There were no statistically significant differences in pharmacokinetic parameters of APC administered by intramuscular injection between the healthy and the diseased status, although its half-life was shortened from 0.76 +/- 0.22 h in the healthy to 0.57 +/- 0.23 h in the diseased. The results suggest that blood concentrations of APC and SDM are affected differently by the same disease due to its specific effects on their distribution and elimination.

Expression, purification, and partial characterization of HCV RNA polymerase

The product of the NS5B gene of Hepatitis C Virus (HCV) has been expressed in Escherichia Coli both as a fusion protein with glutathione-S-transferase (GST) of molecular weight 91 KDa and at high level as a single protein of molecular weight 65 KDa. The protein was sequestered within inclusion bodies and a variety of procedures designed to minimize inclusion body formation proved unsuccessful. The method finally adopted involved the purification of inclusion bodies followed by the solubilization, purification, and refolding of the expressed protein. A good recovery and protein purity of the order of 80-90% were achieved. The purified protein was shown to possess RNA polymerase activity in an assay using polyA/oligoU as template. The enzymatic activity is rifampicin resistant, poly A dependent, and requires Mg++. The availability of purified HCV RNA polymerase will allow the study of viral replication and constitute the basis for testing new anti-viral drugs.

Pharmacokinetics of sulfadimidine and its N4-acetyl metabolite in healthy and diseased rabbits infected with Pasteurella multocida

The pharmacokinetics of sulfadimidine (SDM) and its N4-acetyl metabolite (N4SDM) were investigated after intravenous bolus injection of a single dose (200 mg/kg) of SDM in normal and diseased New Zealand white rabbits. The apparent distribution volume at steady state, total body clearance and elimination half-life of SDM in normal animals were 0.7 +/- 0.3 l/kg, 0.57 +/- 0.24 l/kg/h and 1.6 +/- 1.3 h, respectively. Of the administered dose, 62.1% was metabolized by N4-acetylation, and 12.7 +/- 1.1 and 2.8 +/- 1.8% of the dose was excreted as free drug by the kidney and gastrointestinal tract, respectively. The 'apparent' formation and elimination half-lives of N4SDM were 0.6 +/- 0.4 and 2.2 +/- 1.1 h, respectively. The metabolite was eliminated mainly by excretion through the kidney. There was no significant effect of acute pasteurellosis on the pharmacokinetics of either SDM or N4SDM in rabbits.