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K Lockhart

Publications and source records attributed to K Lockhart.

11 recordsLinked to original sources
PubMed2006

Expression of Mx mRNA following infection with IPNV is greater in IPN-susceptible Atlantic salmon post-smolts than in IPN-resistant Atlantic salmon parr.

The Mx response was compared in parr and post-smolt Atlantic salmon following intra-peritoneal injection of the same dose of Infectious Pancreatic Necrosis Virus (IPNV) per g of fish. Mx gene expression, measured by quantitative RT-PCR in liver, showed a maximum level 3days after injection in parr with undetectable levels on day 7. In post-smolts, similar levels as in parr were attained on day 3, but levels then continued to rise on day 5 and 7 to about 10 times higher than the peak level in parr. Poly I:C injected parr showed Mx levels similar to IPNV injected post-smolts. Mortality from IPN in post-smolts occurred on days 6 and 7. Levels of IPN VP2 transcripts in parr were very low and did not increase with time, suggesting viral replication was low. Individual variation in levels of Mx and IPN VP2 gene transcripts was very high in post-smolts and although data is limited there was an inverse relationship between the levels of Mx and VP2, suggesting that individuals with high Mx levels on day 5 may be able to prevent viral replication. This contrasts with the response in parr, where IPN-resistance was not associated with a high Mx response.

Animals↗
PubMed2005

Kinetics of Mx expression in rainbow trout (Oncorhynchus mykiss) and Atlantic salmon (Salmo salar L.) parr in response to VHS-DNA vaccination.

The duration of the Mx mRNA response to an intramuscular injection of the viral haemorrhagic septicaemia virus (VHSV) glycoprotein (G) gene DNA vaccine as well as to the control plasmid was determined in rainbow trout at 14 degrees C over a period of 11 weeks. The Mx response was detectable on day 7, peaked on day 14 and returned to pretreatment levels on day 21 and thereafter. No increase in Mx expression was detectable to the control plasmid. In further experiments, the kinetics of the Mx response were compared in rainbow trout and Atlantic salmon parr kept at 10 degrees C and injected with the DNA vaccine or the synthetic double-stranded RNA, poly I:C. In both species there was a rapid response to poly I:C detectable from day 1, reaching maximum from days 3 to 9 and decreasing to background level by day 12. The peak level and return to background was reached slightly later in salmon. In both species the response to the VHS/DNA vaccine was slower to begin, not being detectable on days 1 and 3, but elevated levels were found on day 6. However, in the salmon parr, the peak level was on day 6 and the signal disappeared by day 12, while in the rainbow trout, the response peaked at day 12 and lasted until day 21. The kinetics of the Mx response to the VHS/DNA vaccine in rainbow trout correlate with the early non-specific protection against VHS in this species following vaccination. It is speculated that the more transient Mx response in Atlantic salmon parr to the DNA vaccine may be related to the innate resistance of salmon to VHS.

Analysis of Variance↗
PubMed2004

An assessment of immunostimulants as Mx inducers in Atlantic salmon (Salmo salar L.) parr and the effect of temperature on the kinetics of Mx responses.

The aims of this study were (i) to identify alternative Mx stimulatory compounds in Atlantic salmon (Salmo salar L.) and to characterise the kinetics and intensity of the stimulated responses and (ii) to investigate the effect of temperature on such responses by semi-quantitative RT-PCR. Mx transcripts were measured in Atlantic salmon parr kept at 14 degrees C and injected with either LPS, the synthetic double-stranded polyribonucleotide poly I:C, Vibrio anguillarum serotypes I and II-ordalii bacterin, beta-glucan, whole yeast cells or yeast RNA. Sampling periods lasted until transcripts were undetectable or up to three weeks after immunisation. The effect of temperature on poly I:C-induced Mx response was studied by injecting parr kept at 6 degrees C. Newly hatched salmon fry were immersed once, twice or three times in the Vibrio bacterin diluted five or 10 times and sampled for three weeks. None of the yeast compounds induced Mx expression in Atlantic salmon parr. LPS induced a very low Mx response 2 and 3 days after injection. The Vibrio bacterin administered by injection in parr (but not by immersion in fry) resulted in strong Mx induction on days 2 and 3, disappearing by day 6. Poly I: C-induced Mx responses that were more intense and longer lasting than those induced by the bacterin, peaking on day 3 and lasting over 6 days, disappearing by day 9 at 14 degrees C. Lower temperature caused a longer lasting Mx response to poly I:C (at least 21 days), which peaked on days 7-14, with a similar intensity and no delayed onset as compared with the response at 14 degrees C. However, some toxicity of the poly I:C was indicated in treatments at 6 degrees C.

Adjuvants, Immunologic↗
PubMed2004

Poly I:C-induced Mx responses in Atlantic salmon parr, post-smolts and growers.

Intraperitoneal injection of 500 microg poly I:C/fish into Atlantic salmon parr in freshwater and post-smolts and growers in seawater (all at 11 degrees C) induced enhanced expression of Mx mRNA in liver tissue 24 h post-injection. The level of Mx transcripts peaked at day 3 (Mx:beta-actin ratio of about 0.8) and the response disappeared by day 7. In post-smolts, mortalities occurred up to day 14 post-injection, which was dose-dependent. Histological examination of tissues revealed severe pathological changes in the liver of poly I:C injected post-smolts resulting from apoptosis and necrosis of hepatocytes. All other organs appeared histologically normal. Levels of Mx mRNA expression on day 3 post-injection were similar for fish with normal and pathological livers. In untreated or control fish injected with PBS, low levels of Mx transcripts (Mx:beta-actin ratio about 0.1) were sometimes detectable in parr but not in growers. Constitutive Mx expression was variable in post-smolts. Some populations had no detectable transcripts while in others moderate ratios (about 0.3) were detectable over a 3-week period of sampling. Poly I:C administered to parr by bath or orally did not induce upregulation of Mx expression.

Analysis of Variance↗
PubMed2004

Mx expression in Atlantic salmon (Salmo salar L.) parr in response to Listonella anguillarum bacterin, lipopolysaccharide and chromosomal DNA.

Mx genes are inducible by Type I interferons and are involved in antiviral defences. A commercially available vibrio bacterin, intended for immersion vaccination, was shown to be a potent inducer of Mx gene expression in Atlantic salmon parr following intraperitoneal injection. The response was dose and temperature dependent. At 10 degrees C and 10 times concentration the bacterin induced Mx response kinetics similar to that induced by poly I:C. At 10 degrees C, enhanced Mx responses were detected from days 1 to 9 with both 1 times (1x) and 10 times (10x) concentrated bacterin, with a tendency for a higher response to the concentrated bacterin on days 1 and 3. Basal levels of Mx mRNA were detected on day 12 after injection to both concentrations. The response induced by poly I:C was higher on day 1 and it was still present at day 12, with basal levels being reached on day 18. At 6 degrees C, there was a more definitive dose effect of the vibrio bacterin and the Mx response was delayed in comparison to that at 10 degrees C. Increased Mx expression did not appear until day 6 and with the 1x dose it had disappeared by day 9. However, the 10x dose continued to induce Mx at day 12, disappearing by day 18. The Mx response to the purified Listonella anguillarum lipopolysaccharide (LPS) and DNA in fish held at 10 degrees C showed some differences in the rate of onset. The response to DNA was faster, beginning on day 1 compared with day 3 for the LPS. The response to DNA peaked on day 3 while for LPS the peak was on day 9. However, the response to both components had disappeared by day 12. The response kinetics to the L. anguillarum DNA was essentially similar to the 10x dose of the vibrio bacterin and to poly I:C at 10 degrees C.

Animals↗
PubMed2004

IPNV carrier Atlantic salmon growers do not express Mx mRNA and poly I:C-induced Mx response does not cure the carrier state.

Injection of infectious pancreatic necrosis virus (IPNV) in post-smolt Atlantic salmon induced a rapid and persistent expression of Mx mRNA from day 1 to at least day 11 when Mx:beta actin ratios were still at peak values of about 1.0. In contrast, an Atlantic salmon grower population, shown to be carriers of IPNV by culture of the virus from plastic adherent kidney leucocytes, showed no evidence of the expression of Mx transcripts. Nevertheless, IPNV-carrier growers showed a typical Mx response following injection of poly I:C, beginning on day 1, peaking on day 3 (mean Mx:beta actin ratio 0.82) and disappearing by day 7. Notwithstanding such treatment, IPNV continued to persist in growers as the virus could still be isolated 14 days after poly I:C injection.

Actins↗
PubMed1999

MDCK (Madin-Darby canine kidney) cells: A tool for membrane permeability screening.

The goal of this work was to investigate the use of MDCK (Madin-Darby canine kidney) cells as a possible tool for assessing the membrane permeability properties of early drug discovery compounds. Apparent permeability (Papp) values of 55 compounds with known human absorption values were determined using MDCK cell monolayers. For comparison, Papp values of the same compounds were also determined using Caco-2 cells, a well-characterized in vitro model of intestinal drug absorption. Monolayers were grown on 0. 4-microm Transwell-COL membrane culture inserts. MDCK cells were seeded at high density and cultured for 3 days, and Caco-2 cells were cultured under standard conditions for 21 to 25 days. Compounds were tested using 100 microM donor solutions in transport medium (pH 7.4) containing 1% DMSO. The Papp values in MDCK cells correlated well with those in Caco-2 cells (r2 = 0.79). Spearman's rank correlation coefficient for MDCK Papp and human absorption was 0.58 compared with 0.54 for Caco-2 Papp and human absorption. These results indicate that MDCK cells may be a useful tool for rapid membrane permeability screening.

Algorithms↗
PubMed1993

Mood disorders among mothers of infants admitted to a mothercraft hospital.

The mothers (n = 100) of consecutive infants admitted to a mothercraft residential facility were asked to complete the Edinburgh Postnatal Depression Scale (EPDS). Only one of the women had been identified prior to the infant's admission as having postnatal depression, but 39% scored above the cut-off point for likely major depressive disorder. No specific infant problem correlated significantly with a higher depression score. The extent of serious mood disorders in the post-partum population has remained generally unacknowledged despite an upsurge of recent research activity in the field. Nevertheless, this problem has considerable public health significance, impinging as it does on the health of all members of the family. Possible screening and intervention strategies are discussed.

Adult↗