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Biomedical subjects

J P Duff

Publications and source records attributed to J P Duff.

At least 19 recordsLinked to original sources
PubMed2003

Prevalence of faecal excretion of verocytotoxigenic Escherichia coli O157 in cattle in England and Wales.

During the decade to 1999, the incidence of human infections with the zoonotic pathogen verocytotoxin-producing Escherichia coli O157 (VTEC O157) increased in England and Wales. This paper describes the results of a survey of 75 farms to determine the prevalence of faecal excretion of VTEC O157 by cattle, its primary reservoir host, in England and Wales. Faecal samples were collected from 4663 cattle between June and December 1999. The prevalence of excretion by individual cattle was 4.2 per cent (95 per cent confidence interval [CI] 2.0 to 6.4) and 10.3 per cent (95 per cent CI 5.8 to 14.8) among animals in infected herds. The within-herd prevalence on positive farms ranged from 1.1 to 51.4 per cent. At least one positive animal was identified on 29 (38.7 per cent; 95 per cent CI 28.1 to 50.4) of the farms, including dairy, suckler and fattening herds. The prevalence of excretion was least in the calves under two months of age, peaked in the calves aged between two and six months and declined thereafter. The phage types identified most widely were 4, 34 and 2, which were each found on six of the 29 positive farms.

Animals↗
PubMed2001

Peripheral target contact regulates Ca2+ channels in the cell bodies of bullfrog sympathetic ganglion B-neurons.

Tyrosine-hydroxylase immunohistochemistry demonstrated that a single injection of 120 mg/kg 6-hydroxydopamine (6-OHDA) reversibly disconnected bullfrog sympathetic ganglia from their peripheral targets. This was correlated with a decrease in sympathetic outflow to the eyes and a reversible decrease in pupil diameter. 6-OHDA did not damage the cell bodies of ganglionic neurons. Calcium channel current in ganglionic B-neurons, (measured at -10 mV; holding potential -60 mnV; Ba2+ as charge carrier; IBa) was reduced. It reached a minimum of about 40% of control amplitude 7-14 days after 6-OHDA injection and recovered to 73% of control amplitude after 63 days. 6-OHDA induced loss and recovery of functional sympathetic innervation of peripheral target tissues, as determined by measurement of pupil diameter, occurred at a similar rate. Thus, pupil diameter attained mininum values 7-14 days after 6-OHDA treatment and recovered to 81% of control after 63 days. The properties of Ca2+ channels in sympathetic neurons are, therefore, determined by continuity of contact with peripheral target. 6-OHDA also decreased the peak amplitude and duration of the afterhyperpolarization (a.h.p) that follows the action potential (a.p.). The rate of recovery of a.h.p duration was more rapid than the rate of recovery of peak a.h.p. amplitude. This may reflect known differences in properties of two types of Ca2+-sensitive K currents. IC and IAHP, IC, which is responsible for the peak amplitude of the a.h.p has a low affinity for Ca2+, whereas IAHP, which determines a.h.p. duration, has higher Ca2+ affinity.

Action Potentials↗
PubMed1996

Otitis in a weaned pig: a new pathological role for Actinobacillus (Haemophilus) pleuropneumoniae.

A weaned pig exhibiting clinical signs characteristic of a vestibular syndrome (abnormal head tilt and abnormal gait including a tendency to circle) was examined as a representative example of a condition which, in a 12-month period, affected approximately 400 other pigs on the farm of origin. The condition caused significant morbidity and financial loss but the directly attributable mortality was negligible. Post mortem examination revealed a severe suppurative, left-sided otitis media and interna. Mixed growths of bacteria, including Actinobacillus pleuropneumoniae, were isolated from the pus from the middle ear. Otitis caused by mixed bacterial infections has been described previously in pigs and cattle but infection of the porcine middle ear cavity by A pleuropneumoniae is considered to be a new pathological role for this organism. Other findings in this case indicated that otitis media had followed from bacterial colonisation of the auditory (Eustachian) tube. The condition was effectively controlled by prophylactic antibiotic therapy. The authors consider that vestibular syndrome due to otitis media and interna, whether caused by infection with A pleuropneumoniae or not, is probably a relatively common condition in England but its significance may be underestimated and for this reason it may be underrecorded.

Actinobacillus Infections↗
PubMed1994

European brown hare syndrome in England.

The livers from 50 brown hares (Lepus europaeus) were examined by electron microscopy for calicivirus-like particles typical of the virus of European brown hare syndrome (EBHS). The virus was visible in 23 of the livers which included four taken from hares which died in 1982 and 1985 and which had been stored at -20 degrees C. The clinical histories, post mortem and other findings associated with these 23 hares were similar to those described in cases of European brown hare syndrome in other European countries. The findings were compared with those associated with viral haemorrhagic disease (VHD) of rabbits which, although it did not occur in the United Kingdom until 1992, is also caused by a calicivirus believed to be related to EBHS virus. The finding of the virus in hares which died from the disease in 1982 is the earliest recorded isolation of the organism and predates the description of VHD virus and VHD in China in 1984. A retrospective review of post mortem reports revealed cases of disease between 1976 and 1977 which may have been due to EBHS and it is considered that the disease has occurred sporadically in England for several years. The results from suspected and confirmed cases of EBHS in England between 1976 and 1990 are reported and the epidemiology and emergence of the disease is considered.

Animals↗