Search PubMed⌕ Search

Biomedical subjects

R Harland

Publications and source records attributed to R Harland.

49 records · Page 3Linked to original sources
PubMed1991

Application of interferons in the control of infectious diseases of cattle.

Recovery from infection involves a number of complex interactions between specific cells of the immune system. Many of these interactions are mediated by cytokines, which can activate these cells to kill or reduce the replication rate of the pathogen. Availability of large quantities of recombinant cytokines has provided the opportunity to investigate the mechanism or mechanisms of action of each cytokine in vitro and in vivo. In the present review, we describe the application of interferons to reduce morbidity and mortality of cattle suffering from bovine respiratory disease and mastitis. The potential application of interferons in disease modulation as well as the impediments to their use are discussed.

Animals↗
PubMed1989

2',5' oligoadenylate synthetase activity in bovine peripheral blood mononuclear cells following bovine herpesvirus type-1-induced respiratory disease: a prognostic indicator?

Following aerosol-challenge of nonimmune calves with bovine herpesvirus type-1 (BHV-1) the levels of 2',5' oligoadenylate (2-5A) synthetase in peripheral blood mononuclear cells (PBML) increased significantly to peak 4-5 days after BHV-1 infection. This corresponded temporally to the period of highest susceptibility to secondary bacterial infection. Ten days post virus infection, the enzyme levels had returned to baseline values. Aerosol challenge with bacteria (Pasteurella haemolytica) did not induce 2-5A synthetase activity in PBML, neither did it influence the kinetics of 2-5A synthetase induction by virus infection during a dual viral-bacterial infection. Pretreatment of animals with bovine recombinant interferons (IFNs) 0-96 h prior to virus challenge curtailed the viral infection and thus reduced the levels of 2-5A synthetase induced by endogenously produced IFN. A relationship between 2-5A synthetase levels on day 5 post virus infection and clinical outcome of the dual infection was noted. Moreover, the high 2-5A synthetase levels could be correlated with low plasma Zn levels, another indicator of clinical respiratory disease. These results indicate that these two parameters, 2-5A synthetase and plasma Zn, in combination have potential prognostic value in viral-bacterial infections of the respiratory tract.

2',5'-Oligoadenylate Synthetase↗
PubMed1989

Use of ultrasound to enhance percutaneous absorption of benzydamine.

The influence of ultrasound on the percutaneous absorption of benzydamine hydrochloride from a gel base was investigated in a double-blind, placebo-controlled clinical study of 10 healthy volunteers. Using two similar experimental protocols, the effect of both 1:1 (2 msec on, 2 msec off) pulsed-output ultrasound (3.0 MHz at 1.0 W/cm2 and 0.0 W/cm2 [control]) and continuous-output ultrasound at a range of frequencies (0.75, 1.5, and 3.0 MHz at 1.5 W/cm2) were investigated. A placebo control (benzydamine gel massaged with ultrasound applicator switched off) was incorporated into each protocol. Percutaneous absorption of benzydamine was assessed by measurement of the residual amount of drug in the formulation base after treatment. Drug assay was by reversed-phase high-performance liquid chromatography and ultraviolet detection. Statistical analysis of the results for both continuous and pulsed ultrasound treatment showed that no significant differences existed between data for ultrasound treatment versus no ultrasound. In conclusion, although phonophoresis has been alleged to enhance percutaneous absorption of numerous drugs, ultrasound did not enhance the percutaneous absorption of benzydamine under the experimental conditions of this study.

Adult↗
PubMed1989

Variable allograft responses to pretreatment with donor splenocytes treated with mitomycin C in the rat.

In an attempt to investigate the nonspecificity of the effect of administration of donor splenocytes treated with mitomycin C (MMC) 7 days before transplantation in inducing immunological unresponsiveness, the survival rates of liver, heart, small bowel, and skin allografts were compared in the RT1-incompatible ACI(RT1a) to LEW(RT1l) rat combination. ACI donor splenocytes (3 x 10(6)) treated with MMC were administered i.p. or i.v. via the penile vein 7 days before transplantation. Both routes of administration prolonged the survival of hepatic allografts (greater than 87.2 +/- 22.2 days and greater than 78.9 +/- 28.2 days, respectively), compared with controls (10.6 +/- 0.5 days). Cardiac allograft survival in untreated controls was 6.0 +/- 0.4 days. A single i.v. injection of 3 x 10(6) donor splenocytes resulted in significantly prolonged survival (10.0 +/- 4.3 days), whereas i.p. injection showed rejection at a mean of 6.0 +/- 1.2 days. A single i.p. injection of 3 x 10(6) splenocytes did not increase survival of small bowel allografts (10.3 +/- 4.8 days), compared with controls (8.8 +/- 1.8 days). On the other hand, a single i.v. injection of donor splenocytes prior to transplantation significantly prolonged survival of small bowel allografts (13.4 +/- 3.5 days). No signs of graft-versus-host reaction (GVHR) were observed during these experiments. Neither a single i.p. nor a single i.v. injection of donor splenocytes resulted in prolonged survival of ACI-to-LEW skin allografts (6.3 +/- 0.8 days and 6.6 +/- 0.9 days, respectively), compared with controls (5.7 +/- 0.5 days). Interestingly, we confirmed the relative ease with which survival of hepatic allografts can be prolonged in the rat by donor antigen treatment alone, even in a strongly rejecting RT1-incompatible rat strain combination, in contrast to other organ allografts such as heart, small intestine, and skin. The discrepancy in survival of different organ allografts following pretreatment with donor splenocytes treated with MMC may be explained by a difference in the immunogenicity of the organs transplanted or other factors.

Animals↗
PubMed1988

Stability of RNA in developing Xenopus embryos and identification of a destabilizing sequence in TFIIIA messenger RNA.

Synthetic capped RNA transcripts injected into fertilized eggs of Xenopus laevis have a half-life of 3-4 h. Addition of a long (approximately 200 nucleotide) poly(A) tail increases the half-life to 6-8 h which approaches the half-life of natural polyadenylated globin RNA injected into embryos. Since exonucleolytic action alone could account for the degradation of RNA, we tested whether circular RNA is stable after injection and find that circles are exceptionally stable (half-life greater than 40 h). After the midblastula transition, polyadenylated chloramphenicol transferase (CAT) mRNAs transcribed from injected plasmids have a half-life of 2.5 h. Insertion of a 1000 nucleotide 3' untranslated region from the Xhox-36 gene into the transcripts does not affect the half-life. In contrast to the finding that internal sequences do not affect stability, we find that sequences from the TFIIIA message reduce the half-life of CAT mRNA from 2.5 h to less than 30 min. We conclude that most RNAs are degraded exonucleolytically from the 3' end, but specialized internal sequences can greatly destabilize the RNA, possibly by acting as a site for an endonuclease.

Animals↗
PubMed1985

Translation of mRNA injected into Xenopus oocytes is specifically inhibited by antisense RNA.

The bacteriophage SP6 promoter and RNA polymerase were used to synthesize sense and antisense RNAs coding for the enzymes thymidine kinase (TK) and chloramphenicol acetyl transferase (CAT). Injection of antisense CAT RNA into frog oocytes inhibited expression of sense CAT mRNA. Similarly, antisense TK RNA inhibited expression of sense TK mRNA. Antisense RNAs were stable in oocytes and had no detectable effect on either the expression of endogenous proteins or on the expression of nonhomologous RNA transcripts. CAT activity expressed from a plasmid transcribed in the oocyte nucleus was also inhibited by antisense RNA injected into the oocyte cytoplasm. The data suggest that antisense RNA will be useful in identifying the function of specific mRNA sequences during early development of the frog.

Acetyltransferases↗
PubMed1985

The effect of ultrasound on the percutaneous absorption of lignocaine.

The influence of ultrasound on the percutaneous absorption of lignocaine from a cream base was investigated in a double-blind cross-over trial in healthy volunteers. Mean data indicated that there was a slightly faster onset time for local anaesthesia when ultrasound was administered when compared with control values (no ultrasound). However, the differences were not statistically significant. Further controlled clinical studies are required into the effect of ultrasound on percutaneous absorption since the technique (phonophoresis) has been alleged to enhance percutaneous penetration of a number of drugs.

Double-Blind Method↗
PubMed1980

Transcription of tRNA genes in vivo: single-stranded compared to double-stranded templates.

The expression of cloned tRNA genes has been studied by injecting single-stranded and double-stranded DNA templates into Xenopus oocyte nuclei. In both forms the genes are faithfully transcribed after injection. Some single-stranded DNA is converted into double-stranded DNA in the oocyte nucleus. This conversion is necessary for the expression of the injected tRNA gene: no tRNA transcription is observed when DNA synthesis is inhibited. We conclude that single-stranded DNA does not serve as a template for faithful transcription of this gene in injected oocytes.

Coliphages↗