Comparison of Campylobacter jejuni isolates from human, food, veterinary and environmental sources in Iceland using PFGE, MLST and fla-SVR sequencing.

AIMS: Campylobacter jejuni isolates from various sources in Iceland were genotyped with the aim of assessing the genetic diversity, population structure, source distribution and campylobacter transmission routes to humans. METHODS AND RESULTS: A collection of 584 Campylobacter isolates were collected from clinical cases, food, animals and environment in Iceland in 1999-2002, during a period of national Campylobacter epidemic in Iceland. All isolates were characterized by pulse field gel electrophoresis (PFGE), and selected subset of 52 isolates representing the diversity of the identified PFGE types was further genotyped using multilocus sequence typing (MLST) and fla-SVR sequencing to gain better insight into the population structure. CONCLUSIONS: The results show a substantial diversity within the Icelandic Campylobacter population. Majority of the human Campylobacter infections originated from domestic chicken and cattle isolates. MLST showed the isolates to be distributed among previously reported and common sequence type complexes in the MLST database. SIGNIFICANCE AND IMPACT OF THE STUDY: The genotyping of Campylobacter from various sources has not previously been reported from Iceland, and the results of the study gave a valuable insight into the population structure of Camp. jejuni in Iceland, source distribution and transmission routes to humans. The geographical isolation of Iceland in the north Atlantic provides new information on Campylobacter population dynamics on a global scale.

Functional and molecular interactions between aquaporins and Na,K-ATPase.

The water channel aquaporin 4 (AQP4) is abundantly expressed in astrocytes and provides a mechanism by which water permeability of the plasma membrane can be regulated. Astrocytes play a key role in the clearance of both potassium (K(+)) and glutamate released during neuronal activity. Emerging evidence suggests that AQP4 facilitates K(+) clearance by astrocytes and contributes to recovery of neuronal excitability. Here we report that AQP4 can assemble with its regulator metabotropic glutamate receptor 5 (mGluR5) and with Na,K-ATPase; the enzyme responsible for active K(+) transport and for establishing the electrochemical gradient across the cell plasma membrane. We have, by use of pull down assays in rat brain tissue, identified the segment in the AQP4 NH(2)-terminus containing the amino acid residues 23-32 as the site for interaction with Na,K-ATPase catalytic subunit and with mGluR5. Mutagenesis studies revealed that the AQP4 amino acids K27 and W30 are of key importance for interaction with both Na,K-ATPase and mGluR5. To confirm that interaction also occurs within intact cells, we have performed fluorescence resonance energy transfer (FRET) studies in primary astrocytes derived from rat striatum. The results indicate close proximity of wild type AQP4 and Na,K-ATPase in the plasma membrane of rat astrocytes. FRET efficiencies observed with the mutants AQP4 K27A and AQP4 W30A were significantly lower, highlighting the importance of these residues for the interaction between AQP4 and Na,K-ATPase. We conclude that AQP4/Na,K-ATPase/mGluR5 can form a macromolecular complex/transporting microdomain in astrocytes. This complex may be of functional importance for the regulation of water and K(+) homeostasis in the brain, as well as for neuron-astrocyte metabolic crosstalk.

Lead induces increased water permeability in astrocytes expressing aquaporin 4.

The water channel aquaporin 4 (AQP4) is abundantly expressed in astrocytes. There is now compelling evidence that AQP4 may contribute to an unfavorable course in brain edema. Acute lead intoxication is a condition that causes brain damage preceded by brain edema. Here we report that lead increases AQP4 water permeability (P(f)) in astrocytes. A rat astrocyte cell line that does not express aquaporin 4 was transiently transfected with aquaporin 4 tagged with green fluorescent protein (GFP). Using confocal laser scanning microscopy we measured water permeability in these cells and in AQP4-negative cells located on the same plate. AQP4-expressing astrocytes had a three-fold higher water permeability than astrocytes not expressing AQP4. Lead exposure induced a significant, 40%, increase in water permeability in astrocytes expressing AQP4, but had no effect on P(f) in astrocytes not expressing AQP4. The increase in water permeability persisted after lead washout, while treatment with a lead chelator, meso-2,3-dimercaptosuccinic acid, abolished the lead-induced increase in P(f). The effect of lead was attenuated in the presence of a calcium (Ca(2+))/calmodulin-dependent protein kinase II (CaMKII) inhibitor, but not in the presence of a protein kinase C inhibitor. In cells expressing AQP4 where the consensus site for CaMKII phosphorylation was mutated, lead failed to increase water permeability. Lead exposure also increased P(f) in rat astroglial cells in primary culture, which express endogenous AQP4. Lead had no effect on P(f) in astrocytes transfected with aquaporin 3. In situ hybridization studies on rat brain after oral lead intake for three days showed no change in distribution of AQP4 mRNA. It is suggested that lead-triggered stimulation of water transport in AQP4-expressing astrocytes may contribute to the pathology of acute lead intoxication.

Regulation of brain aquaporins.

Emerging evidence suggests that brain aquaporins (AQP) play important roles for the dynamic regulation of brain water homeostasis and for the regulation of cerebrospinal fluid production. This review deals with the short- and long-term regulation of AQP4 and AQP9, both expressed in astrocytes, and of AQP1, expressed in the choroid plexus. AQP1 and 4 have in other cell types been shown to be regulated by phosphorylation. Phosphorylation affects the gating of AQP4 and the trafficking and insertion into membrane of AQP1. Mercury inhibits the water permeability of AQP1 and AQP9, but not AQP4. The permeability of AQP4 is increased by lead. AQP4 is also regulated by protein-protein interaction. The assembly between AQP4 and syntrophin is required for the proper localization of AQP4 in the astrocyte plasma membrane that faces capillaries. There is evidence from studies on peripheral tissues that steroid hormones regulate the expression of AQP1, AQP4 and AQP9. There is also evidence that the expression of AQP1 can be regulated by ubiquitination, and that osmolality can regulate the expression of AQP1, AQP4 and AQP9. Further insight into the mechanisms by which brain AQPs are regulated will be of utmost clinical importance, since perturbed water flow via brain AQPs has been implicated in many neurological diseases and since, in brain edema, water flow via AQP4 may have a harmful effect.

A wireless ECG system for continuous event recording and communication to a clinical alarm station.

Development of new wearable biomedical sensors within a wireless infrastructure opens up possibilities for new telemedical applications leading to significant improvements in continuous monitoring, and thereby to better quality of patient care. In this paper we describe a new concept for a wireless electrocardiogram (ECG) system intended for continuous monitoring of ECG activity especially designed for arrhythmia diagnostic purposes. The patient is wearing an ECG sensor, "a smart electronic electrode", with wireless transmission of ECG signals to a dedicated hand held device (HHD). This device is monitoring the continuously recorded ECG signal, and can detect abnormal ECG activity using an automatic arrhythmia detector. Based on this, the device will transmit alarm conditions to a remote clinical alarm station (CAS). The system will act as a continuous event recorder, which can be used to follow up patients who have survived cardiac arrest, ventricular tachycardia or cardiac syncope but also for diagnostic purposes for patients with diffuse arrhythmia symptoms. This paper describes the principle design requirements for the new wireless ECG sensor and system design for the HHD in order to transfer detected alarms to the CAS.

[The effect of dietary fish oil on bacterial growth in vivo.].

OBJECTIVE: Epidemiological studies have indicated that high intake of w-3 fatty acids influence various diseases such as cardiovascular diseases and autoimmune disorders. These fatty acids are essential in the diet since the body can not form them de novo. Fish oil is rich in w-3 fatty acids but the w-3 content of vegetable oil is low. The research group has shown increased survival of mice fed cod liver oil enriched diet versus mice fed corn oil enriched diet when infected with Klebsiella pneumoniae intramuscularly. In the present study we investigated the effect of dietary fish oil on bacterial growth in vivo. MATERIAL AND METHODS: Mice were fed fish oil enriched diet and a control group was fed corn oil enriched diet for six weeks and then the mice were infected with Klebsiella pneumoniae intramuscularly. The mice were sacrificed at various time intervals and bacteria were counted in blood and in the infected muscle. RESULTS: The bacteria count in blood and tissue was not significantly different between the two groups although a trend was noted towards more growth in the control group. CONCLUSIONS: We conclude that fish oil does not significantly affect bacterial growth in vivo. Hopefully, future research will reveal the pathophysiological effect of fish oil.

Identification of a new form of AQP4 mRNA that is developmentally expressed in mouse brain.

The water channel aquaporin 4 (AQP4) is abundantly expressed in the brain, and also in lung and kidney. Previous studies have suggested that there are at least two AQP4 mRNA. The two mRNA encode for two AQP4 proteins that differ with regard to the length of the N-terminal: AQP4.M1 and AQP4.M23. Here we report, by use of reverse transcriptase PCR and comparison of genomic and cDNA structures, the presence of a third form of mouse AQP4 mRNA. The upstream sequence of this form of mRNA originates from an additional exon, interspaced between exon 0 and exon 1, and an alternatively spliced form of exon 1. Analysis of nucleotide sequence suggests that this new form of AQP4 mRNA also encodes for the AQP4.M23 protein. The two forms of AQP4 mRNA that presumably both encode for M23 have a tissue- and age-specific expression. The new AQP4 mRNA was predominantly expressed in brain. The expression was approximately twofold higher in the adult brain than in the infant brain. In contrast, the expression levels of the new mRNA were low in both infant and adult lung and kidney. The previously described mRNA encoding for AQP4.M23 was predominantly expressed in lung and kidney. In lung, the expression of this form was higher in infancy than in adulthood. In conclusion, we have identified a new form of AQP4 mRNA that is predominantly expressed in the brain and that is developmentally regulated.

[Prehospital thrombolytic therapy of myocardial infarction in Northern Norway. How to improve the service for patients in sparsely-populated areas?]. / Prehospital trombolytisk behandling av hjerteinfarkt i nord-norge. Hvordan forbedre tilbudet til befolkningen i tynt befolkede områder?

Up to now, thrombolytic treatment in myocardial infarction has been restricted to coronary care departments in Norwegian hospitals. Owing to the highly significant impact of the time elapsing between onset of symptoms and thrombolytic treatment, it has been a challenge to offer patients in remote areas early treatment. The rescue helicopter in Northern Norway is manned by an anaesthesiologist. By taking advantage of this, in combination with strict diagnostic criteria, prehospital treatment with streptokinase is now offered in addition to pain relief, oxygen, nitrates and aspirin, and observation against arrhythmia. By these means, patients in remote areas can receive thrombolytic treatment without the delay caused by transportation and in-hospital examination, and a high level of safety is maintained. It still remains, however, to shorten the patients' and the doctors' delay in notifying the helicopter. It is suggested, that all anaesthesiologist-manned air ambulances implement this technique after consulting local general practitioners and cardiologists.