Silent gene clusters encode magnetic organelle biosynthesis in a non-magnetotactic phototrophic bacterium.

Horizontal gene transfer is a powerful source of innovations in prokaryotes that can affect almost any cellular system, including microbial organelles. The formation of magnetosomes, one of the most sophisticated microbial mineral-containing organelles synthesized by magnetotactic bacteria for magnetic navigation in the environment, was also shown to be a horizontally transferrable trait. However, the mechanisms determining the fate of such genes in new hosts are not well understood, since non-adaptive gene acquisitions are typically rapidly lost and become unavailable for observation. This likely explains why gene clusters encoding magnetosome biosynthesis have never been observed in non-magnetotactic bacteria. Here, we report the first discovery of a horizontally inherited dormant gene clusters encoding biosynthesis of magnetosomes in a non-magnetotactic phototrophic bacterium Rhodovastum atsumiense. We show that these clusters were inactivated through transcriptional silencing and antisense RNA regulation, but retain functionality, as several genes were able to complement the orthologous deletions in a remotely related magnetotactic bacterium. The laboratory transfer of foreign magnetosome genes to R. atsumiense was found to endow the strain with magnetosome biosynthesis, but strong negative selection led to rapid loss of this trait upon subcultivation, highlighting the trait instability in this organism. Our results provide insight into the horizontal dissemination of gene clusters encoding complex prokaryotic organelles and illuminate the potential mechanisms of their genomic preservation in a dormant state.

Diversity of magnetotactic bacteria of the Moskva River.

Diversity of magnetotactic bacteria in the Moskva River at the Strogino area was studied using microscopy and phylogenetic analysis. Magnetotactic cocci were the predominant morphotype. Phylogenetic analysis of the 16S rRNA gene sequences revealed 13 OTUs of the orders Magnetococcales and Rhodospirillales, class Alphaproteobacteria. The shares of the relevant sequences were 90 and 10%, respectively. An axenic culture of magnetotactic spirilla was isolated from the studied community. According to the results of the 16S rRNA gene sequencing, the isolate was identified as a new Magnetospirillum species.

Structural features and oxidative stress towards plasmid DNA of apramycin copper complex.

The interaction of apramycin with copper at different pH values was investigated by potentiometric titrations and EPR, UV-vis and CD spectroscopic techniques. The Cu(II)-apramycin complex prevailing at pH 6.5 was further characterized by NMR spectroscopy. Metal-proton distances derived from paramagnetic relaxation enhancements were used as restraints in a conformational search procedure in order to define the structure of the complex. Longitudinal relaxation rates were measured with the IR-COSY pulse sequence, thus solving the problems due to signal overlap. At pH 6.5 apramycin binds copper(II) with a 2 : 1 stoichiometry, through the vicinal hydroxyl and deprotonated amino groups of ring III. Plasmid DNA electrophoresis showed that the Cu(II)-apramycin complex is more active than free Cu(II) in generating strand breakages. Interestingly, this complex in the presence of ascorbic acid damages DNA with a higher yield than in the presence of H(2)O(2).

[Cooperation model between an university clinic and a peripheral paediatric surgical department]. / Kinderchirurgische Kooperation zwischen einer Schwerpunktklinik und einem Versorgungskrankenhaus.

INTRODUCTION: The lack of young physicians in Germany, who are willing to train in surgery, is caused by several factors. Due to the demographic development and the specialisation in paediatric surgery in university institutions, attracting trained paediatric surgeons became difficult for non-specialised rural paediatric surgical departments, which is often also complicated by economic pressures. Strategies, such as cooperation between hospitals or departments, are required. We present a mid-term analysis of the first paediatric surgical cooperation between a university clinic and a rural paediatric surgical department in Lower Saxony. METHODS: The Department of Pediatric Surgery, Hannover Medical School (MHH), is a university centre with a case load of about 1,700 surgical procedures per year with a case mix index (CMI) of 1.3. The Department of Paediatric Surgery, St. Bernward Hospital Hildesheim (BK), is a peripheral institution with about 1,200 surgical procedures per year and a CMI of 0.5. A cooperation project was inaugurated in October, 2004, between the two departments. The aim of the cooperation was to support the head of the paediatric surgical department at the BK by rotating trained paediatric surgeons from the MHH. Simultaneously, it was planned to offer attractive conditions for research at MHH for participating surgeons. The cooperation further included sufficient economic cover of 1.5 posts for rotating medical staff by the BK. RESULTS: Three trained paediatric surgeons have so far been included in the rotation programme between the two cooperating paediatric surgical departments. The rotating medical staff costs were covered by the BK. Over a period of 2.5 years, MHH surgeons performed about 50 % of all surgical procedures at BK, while undertaking two-thirds of on-call duties there. Analysis of academic research revealed 3 accomplished experimental and 4 clinical studies, as well as 10 published articles. CONCLUSIONS: The paediatric surgical cooperation was rated as a success by the rotating trained paediatric surgeons, the heads of both departments and the hospital administrations. The academic link to a university clinic also increased the attractiveness to work in a paediatric surgical department at a rural hospital.

Synthesis and properties of tetra(hexa)hydropyrazolo [1,2-a]pyrido[3,4-d]pyridazine derivatives.

The synthesis of tetra(hexa)hydropyrazolo[1,2-a]pyrido[3,4-d]pyridazine derivatives (14-21) and the results of pharmacological screening are described in this paper. All compounds tested were non-toxic and showed a significant analgesic action. The analgesic effects were associated with the suppression of the spontaneous locomotor activity. Furthermore most of the synthesized compounds displayed a weak antimycobacterial action in the preliminary screening.

Lead levels in body fluids of workers of an automobile factory with clinically diagnosed arterial hypertension.

The aim of the study is the evaluation of lead levels in body fluids in a chosen study group with diagnosed arterial hypertension employed in a car factory. The study was carried out on workers diagnosed with various stages of arterial hypertension who had been subjected to long-term lead exposure at different workplaces. The examination of the patients included medical history, physical examination and biochemical tests of blood and urine, following routine in the laboratory diagnosis in order to assess medical condition in terms of subclinical symptoms of lead exposure. Mean values of the lead level in blood and urine of studied population are insignificantly higher than in the control group. The obtained results seem insufficient to confirm the effect of occupational exposure to lead in subthreshold doses on the development of arterial hypertension, and are within the recommended hygienic standards.

The effects of citicoline and/or MK-801 on survival, neurological and behavioral outcome of mice exposed to transient hyperglycemia and oligemic hypoxia.

UNLABELLED: The effects of citicoline and/or low dose of MK-801 (sufficient to prevent the development of seizures) on survival, neurological and behavioral recovery following transient hyperglycemic-oligemic-hypoxic insult have been evaluated in mice. Neurological recovery was assessed semi-quantitatively on the third and the 10th day after the insult, and behavioral tests evaluating spontaneous locomotor activity, motor coordination and spontaneous alternation performance were performed on day 10. Neither drug given alone did influence survival rate, but the combination of MK-801 and higher citicoline dose decreased mortality on day 10. Behavioral performance was markedly compromised by the insult. Citicoline, but not MK-801, slightly but significantly improved behavioral outcome in all three tests. CONCLUSION: when brain ischemic insult is complicated with acute hyperglycemia, post-treatment with citicoline combined with MK-801 in low anti-convulsive dose improves survival and neurological recovery, and citicoline but not MK-801 enhances behavioral recovery.

2-deoxyglucose enhances epileptic tolerance evoked by transient incomplete brain ischemia in mice.

The aim of the study was to assess the influence of chronic treatment with a non-metabolisable glucose analogue, 2-deoxyglucose (2-DG) at a 150 mg/kg dose on long-term epileptic tolerance (ET) evoked by 30 min bilateral carotid artery clamping (BCCA) in mice. The effects of protein synthesis inhibition with cycloheximide (CHX), given in three daily doses of 2.5 mg/kg starting either 1 day before (peri-insult regimen) or 1 day after the priming insult (post-insult regimen), on ET development was also studied. Seizures were induced 14 days after BCCA with 3.5 mg/kg of bicuculline; this dose (CD97) evokes convulsions in 97% of normal untreated mice. BCCA resulted in decreased mortality, prolonged latency to the onset of generalised convulsions and decreased overall seizure score. CHX given in the post-insult regimen did not influence, while the peri-insult regimen abolished, all signs of BCCA-evoked ET. 2-DG treatment of sham-operated animals resulted in a moderate but significant decrease in mortality rate and a tendency toward a lower seizure score. BCCA combined with 2-DG treatment resulted in a marked decrease in mortality rate, as well as reduction in all indicators of seizure susceptibility. CHX abolished the antiepileptic effects of BCCA alone, as well as BCCA combined with 2-DG, while it did not influence the 2-DG-related decrease in mortality. We conclude that the development of BCCA-induced epileptic tolerance, as well as unmasking antiepileptic effects of 2-DG by BCCA, is dependent on protein synthesis.

Synthesis and in vivo pharmacology of new derivatives of isothiazolo[5,4-b]pyridine of Mannich base type.

Recently we reported on 2H-4,6-dimethyl-2-[(4-phenylpiperazin-1-yl)methyl]-3-oxo-2,3-dihydroisothiazolo[5,4-b]pyridine (V), which exhibited high anorectic action in animal models as a result of stimulation of serotoninergic system. This paper describes the synthesis of the series 3-5 of analogues of V prepared from 2-hydroxymethyl-4,6-dimethylisothiazolopyridine (2) and corresponding 4-substituted-piperazines(piperidines) or tetrahydroisoquinoline. The 12 compounds obtained were screened in standard CNS tests in in vivo (mice and rats). In contrast to V, none of its analogues showed serotoninergic activity, whereas several of these compounds were found to be active as weak to moderate analgesic agents. According to X-ray and molecular modeling studies the different pharmacological profile of V and its o-OCH3 analog 3a, taken as an example, should be referred back to the conformational restriction incorporated by the o-substitution rather than effects of different lipophlicity or basicity of these compounds.

Effect of adenosine A1 and A2 receptor stimulation on hypoxia-induced convulsions in adult mice.

Clinical observations indicate that seizures induced by hypoxia are common kind of convulsive activity in both infants and elderly patients. The occurrence of seizure episode during hypoxia is important risk factor of epilepsy development in the future. Experimental hypoxia was obtained by exposure of adult (20-23 g) Albino Swiss mice to spontaneous breathing in gas mixture composed of 5% oxygen and 95% nitrogen. The latency time to convulsive activity was determined. Single sublethal episode of seizures induced by hypoxia (HS) resulted in higher susceptibility to pentetrazol (PTZ), bicuculline (BCC), N-methyl-D-aspartic acid (NMDA) but not in electrically induced convulsions. Adenosine A1 receptor agonist, R(-)N6-(2-phenyl-isopropyl)adenosine (R-PIA) (0.01; 0.05; 0.1 mg/kg, i.p.) prolonged the latency to HS-induced convulsions. A1 receptor antagonist, 8-cyclopentyltheophylline (CPT), reversed the protective action of R-PIA. A2 receptor agonist, N(6)-[2-(3,5-dimethoxyphenyl)-2-(2-methylphenyl)]ethyladenosine (DPMA), only at the highest dose (5 mg/kg i.p.) prolonged the latency time to convulsive activity. This effect was only partially reversed by A2 antagonist 3,7-dimethyl-1-propargylxanthine (DMPX). Administered immediately after episode of HS R-PIA diminished the higher susceptibility to PTZ, BCC, NMDA at 3rd day after HS, while DPMA appeared to be ineffective. These results confirm the important role of adenosine A1 receptor agonist in protection against acute and chronic epileptogenic effect of hypoxia. The role of adenosine A2 receptors seems to be of minor importance.

Brain tolerance and preconditioning.

In this review article the authors describe a phenomenon of "brain tolerance" which represents transient resistance of brain tissue to a lethal insult established by preconditioning with a mild insult of short duration. Tolerance evoked by brief ischemia resembles transient ischemic attack(s) (TIA) often preceding full-blown ischemic stroke in a clinical setting. A series of recent studies have described another relevant phenomenon termed "chemical preconditioning". Several substances interfering with cellular energy metabolism applied in subtoxic doses may provide protection against lethal insults of a different type. For example, 3-nitropropionic acid (3-NP), antibiotics erythromycin and kanamycin, acetylsalicylic acid, and 2-deoxyglucose have been shown to evoke tolerance. Recently, we have reported that NMDA receptor antagonists and 2-deoxyglucose used at relatively low doses were potent agents to potentiate the protective anticonvulsant effect induced by transient brain mild ischemia. Further studies are expected to prove similar action of these drugs in other experimental models. Based on the accumulated experimental and clinical data the brain tolerance subsequently reinforced by pharmacological intervention might become a successful prophylactic strategy against serious brain insults in patients.

The evaluation of noise level in different points of urban area.

The aim of the study was measuring noise intensity in the selected points of traffic routes in the city of Lublin. Investigations were carried out at 11 points located in the centre of the city and at escape roads. Noise value levels showed variable intensity, the highest being observed in the morning and afternoon hours. The highest mean level of noise intensity was recorded at the crossing of Solidarnosci Avenue and Sikorskiego Street, and the lowest in Narutowicza Street.

Delta aminolevulinic acid urinary excretion in rural region inhabitants.

The purpose of the work was to estimate to what extent the inhabitants of a typical agricultural region are exposed to the influence of lead compounds. 132 people at the age of 9 to 74 were included in the research. Urinary delta aminolevulinic acid (ALA) excretion was determined. The highest excretion of ALA was observed among the examined who were up to 18 years old, while the lowest was among those who were above 60 years old. These differences, however, were not statistically significant.

Vitamin E influence on selected parameters in rats after ochratoxin A intoxication.

The aim of the research was to evaluate vitamin E influence on ochratoxin A (OTA) toxicity based on analysis of selected parameters of white and red cell system in rats. The animals were divided into groups: I--control, II--treated with OTA, III--treated with OTA and vitamin E. In group II a significant decrease in the values of hematocrit, hemoglobin level, red and white cell counts was observed. In group III an average hematocrit, hemoglobin level were significantly lower than in control group, nevertheless they were higher than in group II.

The evaluation of intensity of traffic noise in different points of town routes.

The aim of the study was measuring noise intensity in the selected points of traffic routes in the town of Lublin. Investigations were carried out at 11 points located in the centre of the town and at escape roads. Noise value levels showed variable intensity, the highest being observed in the morning and afternoon hours. The highest mean level of noise intensity was recorded at the crossing of Solidarnosci Avenue and Sikorskiego Street, and the lowest in Narutowicza Street.

The role of opioid receptors in hypoxic preconditioning against seizures in brain.

Preconditioning is defined as an adaptive mechanism produced by short periods of hypoxia/ischemia, resulting in protection against subsequent ischemic insult, and development of seizures. Results of the present study demonstrate that an episode of normobar hypoxia reduces the susceptibility to convulsions induced by pentylenetetrazol (PTZ) 30 min, 24 h, as well as 4 and 7 days later. Administration of morphine showed similar effects after 24 h. Naloxone, given before ischemic preconditioning, as well as morphine, blocked the development of the protection. Administration of D-Ala-Met-enkephalin-Gly-ol (DAMGO - a selective mu-opioid receptor agonist), as well as trans-3, 4-dichloro-N-methyl-N-[7-(1-pyrrolidinyl) cycloexilbenzeneacetamide ethane sulfonate] (U-69,593 - a selective kappa-opioid receptor agonist), mimicked the effects of hypoxic preconditioning (HPC). (-)-N-(Cyclopropylmethyl)-4,14-dimethoxymorphinan-6-one (cyprodime - a selective mu-opioid receptor antagonist, as well as nor-binaltorphimine dihydrochloride (nor-BNI - selective kappa-opioid receptors antagonist), given before HPC as well as before respective opioid receptor agonists, blocked the development of the protection. This study provides evidence that mu- and kappa-opioid receptors are involved in HPC against seizures in the brain.

The influence of MK-801 on bicuculline evoked seizures in adult mice exposed to transient episode of brain ischemia.

The aim of the study was to examine the role of NMDA receptors in modulation of protective effect against bicuculline toxicity after transient brain ischemia in mice. Animals were exposed for 30 min to bilateral clamping of the common carotid arteries (BCCA) in anaesthesia. MK-801 was administered intraperitoneally in two paradigms: a) acute treatment: twice, 1.0 mg/kg; 1 hour before clamping and 6 hours after re-circulation and b) chronic treatment: 0.1 mg/kg; started 24 hours after re-circulation and continued once daily for 13 days, the last injection was administered 24 hours before seizure induction. 14 days after BCCA, the animals were injected with bicuculline (3.5 mg/kg s.c). A significant decrease in seizure susceptibility could be observed in BCCA treated mice compared with sham-operated controls. Acute treatment with MK-801 did not affect seizure activity both in sham and BCCA mice. Chronic treatment with the drug potentiated anticonvulsant effect of brain ischemia but had no influence on seizure activity in sham-operated mice. The analysis of GABA content in brain tissue performed 14 days after BCCA showed a moderate increase in vehicle-treated mice and significant elevation after chronic treatment with MK-801. It can be suggested that NMDA receptors are not involved in the induction of a protective effect against bicuculline toxicity after transient brain ischemia. The prolonged treatment with low doses of MK-801 may potentiate a developed process in a mechanism of chemical preconditioning.