The spatial and temporal determinants of campylobacteriosis notifications in New Zealand, 2001-2007.

Despite recent improvements, New Zealand still has one of the highest per-capita incidence rates of campylobacteriosis in the world. To reduce the incidence, a thorough understanding of the epidemiology of infection is needed. This retrospective analysis of 36 000 notified human cases during a high-risk period between 2001 and 2007 explored the spatial and temporal determinants of Campylobacter notifications at a fine spatial scale in order to improve understanding of the complex epidemiology. Social deprivation was associated with a decreased risk of notification, whereas urban residence was associated with an increased risk. However, for young children rural residence was a risk factor. High dairy cattle density was associated with an increased risk of notification in two of the three regions investigated. Campylobacter notification patterns exhibit large temporal variations; however, few factors were associated with periods of increased risk, in particular temperature did not appear to drive the seasonality in campylobacteriosis.

Molecular and spatial epidemiology of human campylobacteriosis: source association and genotype-related risk factors.

The epidemiology of human campylobacteriosis is complex but in recent years understanding of this disease has advanced considerably. Despite being a major public health concern in many countries, the presence of multiple hosts, genotypes and transmission pathways has made it difficult to identify and quantify the determinants of human infection and disease. This has delayed the development of successful intervention programmes for this disease in many countries including New Zealand, a country with a comparatively high, yet until recently poorly understood, rate of notified disease. This study investigated the epidemiology of Campylobacter jejuni at the genotype-level over a 3-year period between 2005 and 2008 using multilocus sequence typing. By combining epidemiological surveillance and population genetics, a dominant, internationally rare strain of C. jejuni (ST474) was identified, and most human cases (65.7%) were found to be caused by only seven different genotypes. Source association of genotypes was used to identify risk factors at the genotype-level through multivariable logistic regression and a spatial model. Poultry-associated cases were more likely to be found in urban areas compared to rural areas. In particular young children in rural areas had a higher risk of infection with ruminant strains than their urban counterparts. These findings provide important information for the implementation of pathway-specific control strategies.

Magnetic resonance imaging of masticatory muscles in basset hounds.

OBJECTIVES: To describe low- and high-field MRI characteristics of occult masticatory muscle lesions in basset hounds. MATERIALS AND METHODS: Retrospective review of the MR images of the heads of 44 basset hounds that had been imaged for reasons unrelated to suspected muscle disease. RESULTS: In most basset hounds, there was reduced bulk of the superficial part of the temporalis and masseter muscles together with bilaterally symmetrical T2W and T1W hyperintense signal with reduced contrast enhancement compared to normal muscle. Interpretation of various pulse sequences suggested that the affected muscle areas contained adipose tissue with no evidence of inflammation, and this was confirmed on biopsy in one dog. This pattern of changes is different from MRI changes in inflammatory myopathies. CLINICAL SIGNIFICANCE: Poor muscle bulk and MRI signal changes in the superficial parts of the temporalis and masseter muscles in basset hounds appear to be normal findings in this breed and should not be misinterpreted as evidence of an inflammatory myopathy.

Inferring source attribution from a multiyear multisource data set of Salmonella in Minnesota.

Salmonella enterica is a global health concern because of its widespread association with foodborne illness. Bayesian models have been developed to attribute the burden of human salmonellosis to specific sources with the ultimate objective of prioritizing intervention strategies. Important considerations of source attribution models include the evaluation of the quality of input data, assessment of whether attribution results logically reflect the data trends and identification of patterns within the data that might explain the detailed contribution of different sources to the disease burden. Here, more than 12,000 non-typhoidal Salmonella isolates from human, bovine, porcine, chicken and turkey sources that originated in Minnesota were analysed. A modified Bayesian source attribution model (available in a dedicated R package), accounting for non-sampled sources of infection, attributed 4,672 human cases to sources assessed here. Most (60%) cases were attributed to chicken, although there was a spike in cases attributed to a non-sampled source in the second half of the study period. Molecular epidemiological analysis methods were used to supplement risk modelling, and a visual attribution application was developed to facilitate data exploration and comprehension of the large multiyear data set assessed here. A large amount of within-source diversity and low similarity between sources was observed, and visual exploration of data provided clues into variations driving the attribution modelling results. Results from this pillared approach provided first attribution estimates for Salmonella in Minnesota and offer an understanding of current data gaps as well as key pathogen population features, such as serotype frequency, similarity and diversity across the sources. Results here will be used to inform policy and management strategies ultimately intended to prevent and control Salmonella infection in the state.

Pharmacologic effects of L-dopa are not closely linked temporally to striatal dopamine concentration.

In an attempt to gain insight into the mechanism of the "long-term response" to L-dopa in parkinsonians, we studied the temporal relationship between turning behavior and striatal dopamine (DA) levels after L-dopa administration to rats with unilateral nigral lesions. Turning behavior peaked at 30 minutes (9.0 +/- 1.5 turns per rat per minute), diminished in intensity, reached a new peak (10.8 +/- 1) at 3 hours, and persisted for 280 minutes after L-dopa administration. In contrast, dopamine levels in the striatum ipsilateral to the lesion peaked at 20 minutes and returned to control levels by 90 minutes after L-dopa administration. These data suggest that behaviors elicited by an increase in brain (striatal) dopamine levels may persist long after the dopamine concentration has returned to control levels.

Altered pharmacokinetics of L-dopa metabolism in rat striatum deprived of dopaminergic innervation.

Rats with unilateral lesions of the substantia nigra were treated with L-dopa 25 mg/kg subcutaneously 30 minutes after treatment with carbidopa 25 mg/kg intraperitoneally. In the ipsilateral striatum, dopamine levels achieved a peak of 1.57 +/- 0.63 micrograms/g (control 0.19 +/- 0.05 micrograms/g) at 20 minutes and did not differ from controls by 90 minutes after L-dopa administration. Dopamine levels peaked in the contralateral striatum at 45 minutes (11.96 +/- 0.14 micrograms/g, where control levels were 7.74 +/- 0.22 micrograms/g) and returned to control values by 180 minutes. These data suggest that in patients with advanced Parkinson's disease, L-dopa administration results in a smaller increase and a shorter duration of elevation in striatal dopamine concentration than in controls. These observations support the hypothesis that the "wearing-off" phenomenon that occurs during the treatment of patients with Parkinson's disease occurs as a consequence of a reduction in the rate of conversion of L-dopa to dopamine and perhaps diminished capacity for the storage of dopamine.

Chorea-amyotrophy with chronic hemolytic anemia: a variant of chorea-amyotrophy with acanthocytosis.

We studied two siblings with chorea and amyotrophy of adult onset and spherocytic hemolytic anemia. Autopsy revealed an atrophic striatum with iron deposition and spheroid bodies. Degeneration of the substantia nigra and spinal cord anterior horns was seen without iron deposition. The disorder seems to be a variant of the chorea-amyotrophy-acanthocytosis syndrome, and the pathology may account for evidence of parkinsonism and amyotrophy in that syndrome. Acanthocytosis may not be the only hematologic abnormality in this disorder.

Antiepithelial cell antibodies do not impair paediatric renal allograft survival but appear to be associated with acute viral infections.

There is a reported association between antiepithelial cell (AEC) antibodies and increased renal allograft loss in paediatric recipients. Our unit experienced a dramatic fall in 1-year graft survival so we undertook a study to determine if AEC antibodies could account for such losses. We also studied healthy children and adults as well as a group of individuals with serologically proven viral infection in an attempt to determine the prevalence and possible aetiology of these antibodies. Sera were screened for AEC antibodies in a microcytotoxicity test using a lung epithelial cell line (A549) as target. The prevalence of these antibodies in our paediatric recipients was similar to that reported elsewhere but we found no correlation between the presence of AEC antibody and allograft loss. Within the control populations, we found the antibody was more prevalent in children than in adults (p < 0.0001). We also found a strong age banding pattern, with antibody being present in 50% of children under 10 years and declining with increasing age, so that by the age of 16 years the seroprevalence was similar to that found in our adults. However, AEC antibody had a significantly higher prevalence in individuals with active viral infection than in our healthy control groups (p = 0.00003). A positive association was noted between rubella and respiratory syncytial virus and AEC antibody presence and a negative association with varicella zoster. We conclude that AEC antibodies do not correlate with increased paediatric renal allograft loss but appear to be linked to certain viral infections.

Centrally administered bombesin modulates gastric motility.

Intracerebroventricular bombesin alters arterial pressure and gastrointestinal transit in rats. In order to evaluate the influence of bombesin on arterial and gastric intraluminal pressure in a specific site in the central nervous system, we microinjected bombesin into the medial subnucleus of the nucleus tractus solitarius (mNTS) in 28 rats anesthetized with choralose. Bombesin (78 pmole in 25 nl), but not vehicle, caused an increase of tonic gastric intraluminal pressure (2.6 +/- 0.5 cm H2O) and of phasic gastric intraluminal pressures but did not acutely alter arterial pressure. The effect on tonic and phasic gastric intraluminal pressure was dose-dependent. The threshold dose was 7.8 pmole. Intravenous bombesin caused a similar dose-dependent rise in tonic gastric intraluminal pressure but did not significantly change the mean amplitude of phasic gastric intraluminal pressures. Transection of the cervical spinal cord and both cervical vagus nerves blocked the effect of centrally but not peripherally administered bombesin. We conclude that bombesin microinjected into the mNTS does not influence arterial pressure but does raise tonic and phasic gastric intraluminal pressures. Bombesin may act in the NTS as a central modulator of gastric motility.

Central modulation of gastric pressure by substance P: a comparison with glutamate and acetylcholine.

We have sought to determine if changes in arterial and gastric pressure occurred with selective chemical stimulation of the dorsomedial NTS. Substance P (SP) and L-glutamate (L-glu), but not acetylcholine (ACh), elicited a dose-dependent decrease in tonic gastric pressure and inhibited gastric phasic activity. As previously reported, L-glu and ACh, but not SP elicited dose-dependent arterial hypotension. The data support a putative role for SP in visceral reflexes mediated by vagal nerves.

L-glutamate stimulation of the zona incerta in the rat decreases heart rate and blood pressure.

Microinjections of L-glutamate into the zona incerta of pentobarbital anesthetized rats caused decreases in blood pressure and heart rate. The bradycardic response was reduced by approximately 70% after i.v. administration of atropine methyl nitrate. After combined muscarinic and beta-adrenergic blockade the bradycardic response was reduced to 90% of the control value. This suggests that the bradycardia was mediated primarily by activating the vagal outflow. Blood pressure decreases elicited after pharmacological blockade of the heart with both atropine and timolol were approximately 50% of the control values. This indicates that the zona incerta is also capable of altering stroke volume and/or inhibiting the sympathetic outflow controlling the peripheral blood vessels. By using an injectate containing L-glutamate mixed with [3H]L-glutamate and subsequent analysis of autoradiographic tissue sections, we have determined that the most reactive site is the region of the ventral zona incerta.

L-glutamate mapping of cardioreactive areas in the rat posterior hypothalamus.

The posterior hypothalamus has long been regarded as a CNS region that provides a sympatho-excitatory influence on the cardiovascular system and functions in thermoregulation as a heat-producing center. These ideas have been based on data derived from electrical stimulation and lesion experiments. These methods are now regarded as inadequate for accurate localization of CNS functions. In order to re-examine the function of the posterior hypothalamus, a chemical stimulation study was performed. Microinjections of the excitatory amino acid L-glutamate were made in the posterior hypothalamus of pentobarbital-anesthetized rats. This method was used in combination with autoradiography to localize [3H]glutamate, which was included with the injectate. No pressor responses were elicited from any site within the posterior hypothalamus. In contrast, chemical stimulation of the posterior periventricular hypothalamus produced large decreases in blood pressure (delta BP = 25 mm Hg) and in heart rate (delta HR = 30 bpm). Injections in the posterior hypothalamic nucleus elicited small reductions in blood pressure and heart rate. Injections in the dorsal hypothalamic area produced a similar small response. Injections ventral to the periventricular zone were also weakly reactive, but a significant elevation in rectal temperature was seen. To summarize, the most cardioresponsive area was within the periventricular zone caudal to the posterior hypothalamic nucleus and was situated near the fasciculus retroflexus.

CNS projections to the pterygopalatine parasympathetic preganglionic neurons in the rat: a retrograde transneuronal viral cell body labeling study.

The retrograde transneuronal viral cell body labeling method was used to study the CNS nuclei that innervate the parasympathetic preganglionic neurons which project to the pterygopalatine ganglion. Small injections of a suspension of pseudorabies virus (PRV) were made in the pterygopalatine ganglion of rats and after 4 days their brains wer e processed for immunohistochemical detection of PRV. Some of the tissues were stained with a dual immunofluoresence method that permitted the visualization of PRV and neurotransmitter enzyme or serotonin immunoreactivity in the same cell. Retrograde cell body labeling was detected in the ipsilateral ventrolateral medulla oblongata in the region that has been termed the superior salivatory nucleus. This area was the same region that was retrogradely labeled after Fluoro-Gold dye injections in the pterygopalatine ganglion. Retrograde transneuronally infected cell bodies that provide putative afferent inputs to the pytergopalatine parasympathetic preganglionic neurons were mapped throughout the brain. In the medulla oblongata, transneuronally labeled neurons were seen in the nucleus tractus solitarii, dorsomedial part of the spinal trigeminal nucleus and gigantocellular reticular nucleus. In most experiments, some A1 catecholamine cells and serotonin neurons of the raphe magnus, raphe pallidus, raphe obscurus, and parapyramidal nuclei were labeled. In the pons, labeled cells were found in the parabrachial nucleus. A5 catecholamine cell group, and non-catecholamine part of the subcoeruleus region. In the midbrain, cell body labeling was located in the central gray matter and retrorubral field. In the diencephalon, labeling was found mainly in the hypothalamus. The areas included the lateral hypothalamic area, lateral preoptic area, dorsomedial and paraventricular hypothalamic nuclei, and ventral zona incerta. Contralateral second order cell body labeling was seen in the tuberomammillary nucleus of the hypothalamus. Some of these cells were histidine decarboxylase-immunoreactive. In the forebrain, the bed nucleus of the stria terminalis, substantia innominata, and an area of the cerebral cortex called the amygdalopiriform transition zone were labeled.

Origin of porcine brain natriuretic peptide-like immunoreactive innervation of the middle cerebral artery in the rat.

We recently demonstrated that porcine brain natriuretic peptide-like immunoreactive (pBNPir) fibers innervate parts of the cardiovascular system, including the arteries comprising the circle of Willis. To determine the origin of this innervation, we used the retrograde fluorescent tracer Fast Blue dye combined with pBNP immunocytochemistry. Cells which project to the middle cerebral artery and were also pBNPir were found in the trigeminal, pterygopalatine and superior cervical ganglia bilaterally but not in the geniculate or otic ganglia. The majority of these double-labelled cells were found in the ipsilateral trigeminal (46%) and superior cervical ganglia (34%). A pBNP-like substance may be a natural vasodilator in sympathetic, sensory and to a lesser extent parasympathetic neurons innervating the cerebrovascular system.

Utilizing a combination of molecular and spatial tools to assess the effect of a public health intervention.

Until recently New Zealand had one of the highest rates of human campylobacteriosis reported by industrialized countries. Since the introduction of a range of control measures in the poultry production chain a reduction in human cases of around 50% has been observed nationwide. To inform risk managers a combination of spatial, temporal and molecular tools - including minimum spanning trees, risk surfaces, rarefaction analysis and dynamic source attribution modelling - was used in this study to formally evaluate the reduction in disease risk that occurred after the implementation of control measures in the poultry industry. Utilizing data from a sentinel surveillance site in the Manawatu region of New Zealand, our analyses demonstrated a reduction in disease risk attributable to a reduction in the number of poultry-associated campylobacteriosis cases. Before the implementation of interventions poultry-associated cases were more prevalent in urban than rural areas, whereas for ruminant-associated cases the reverse was evident. In addition to the overall reduction in prevalence, this study also showed a stronger intervention effect in urban areas where poultry sources were more dominant. Overall a combination of molecular and spatial tools has provided evidence that the interventions aimed at reducing Campylobacter contamination of poultry were successful in reducing poultry-associated disease and this will inform the development of future control strategies.

Modulation of gastric and arterial pressure by nucleus tractus solitarius in rat.

By using L-glutamate as a physiological tool to selectively stimulate neurons in specific subnuclear regions of the nucleus tractus solitarius (NTS), we have sought to differentiate those regions that modulate cardiovascular activity from those that modulate gastric activity. Microinjections of L-glutamate (300 pmol/25 nl) into the dorsomedial NTS of alpha-chloralose-anesthetized rats elicited dose-dependent falls in arterial pressure (AP) of 37.5 +/- 7.7 Torr from a base line of 130 +/- 5.8 Torr and gastric pressure (GP) of 0.8 +/- 0.1 cmH2O and inhibited the usual 5-6 waves/min phasic activity. Microinjection into the ventromedial NTS did not affect AP but transiently lowered GP by 1.6 +/- 0.2 cmH2O and eliminated phasic waves. The GP changes were vagally mediated. Microinjections into the area postrema or the hypoglossal nucleus elicited neither AP nor GP changes. Microinjections in other NTS areas at the same rostral-caudal level did not alter GP consistently. This study suggests that local stimulation of neurons in a specific region of the NTS elicits vagally mediated alterations of tonic GP and phasic activity and that AP and GP can be influenced independently in the medial NTS region.

Cardiovascular effects produced by L-glutamate stimulation of the lateral hypothalamic area.

L-Glutamate microinjections into the tuberal region of the lateral hypothalamic area (LHAt) caused a fall in blood pressure and heart rate in pentobarbital-anesthetized rats. The bradycardia was mediated by both beta-adrenergic and muscarinic mechanisms as demonstrated with pharmacological blockade. The hypotension was due to a decrease in cardiac output, not a decrease in total peripheral resistance. In addition, there was a reduction in coronary blood flow. If heart rate was held constant by pharmacological blockade or by electrical cardiac pacing, L-glutamate stimulation of the LHAt still caused a fall in blood pressure. When the electrically paced model was used, this hypotension was due to a fall in cardiac output. In contrast, with the pharmacological blockade of the heart, the hypotension was due to a decrease in the total peripheral resistance. The cardiac output reduction in the paced condition was not mediated solely by either beta-sympathetic or parasympathetic mechanisms as determined by pharmacological blockade. With heart rate held constant by either drugs or pacing, LHAt stimulation did not alter regional blood flow or resistance in any vascular bed, including the coronary circulation. We conclude that L-glutamate stimulation of the LHAt lowers the cardiac output and heart rate by both parasympathetic and beta-adrenergic mechanisms and elicits hypotension by lowering cardiac output in the naive and electrically paced model.

Nonproduction of toxic shock syndrome toxin 1 by coagulase-negative staphylococci.

We tested 187 strains of coagulase-negative staphylococci (CNS) for the production of toxic shock syndrome toxin 1 (TSST-1). A total of 111 CNS strains were isolated from the tampons of menstruating women and 74 were isolated from unused tampons. Two strains were isolated from the genital tract of a patient with toxic shock syndrome. Strains were cultivated by the membrane-over-agar method to enhance production of TSST-1, and culture supernatants were tested by two exquisitely sensitive enzyme-linked immunosorbent assays. None of the 187 CNS strains produced TSST-1. We conclude that CNS colonizing the genital tracts of menstruating women and unused tampons produce TSST-1 infrequently, if ever, and are unlikely to play a role in toxic shock syndrome.