Evidence for lateral transfer and recombination in OspC variation in Lyme disease Borrelia

The ospC gene was amplified by the polymerase chain reaction from each of 76 Lyme disease Borrelia strains. Restriction fragment length polymorphism (RFLP) analysis demonstrated 33 distinct RFLP types; two additional RFLP types were identified from published ospC sequences. For each RFLP type, at least one ospC gene was sequenced and the degree of sequence relatedness examined by construction of an ospC gene tree. The genes were extremely diverse, with sequence identity ranging from 74.4% to 99.0%; the majority of changes are localized within the central portion of the molecule. A comparison of ospC sequences suggests that recombination occurs frequently between ospC alleles; this genetic exchange is proposed to be mediated by lateral transfer of ospC sequences. Evidence indicates that recombination occurs between ospC genes from the same Borrelia species (i.e. B. afzelii and B. garinii) as well as between different Borrelia species (i.e. B. afzelii and B. garinii, B. burgdorferi and genogroup DN127).

Use of mathematical models for predicting the metabolic effect of large-scale enzyme activity alterations. Application to enzyme deficiencies of red blood cells

There are numerous examples showing that the metabolism of cells can be severely impaired if the activity of only one of the participating enzymes undergoes large-scale alterations, resulting, for example, from spontaneous mutations (inherited or acquired enzymopathies), the administration of toxic drugs or self-inactivation of enzymes during cell aging. However, a quantitative relationship between the degree of enzyme deficiency and the extent of metabolic dysfunction is very difficult to establish by experimental means. An alternative is to tackle this problem by mathematical modelling. Our approach is based on a comprehensive mathematical model of the energy and redox metabolism for human erythrocytes. We calculate stationary states of the cell metabolism, varying the activity of each of the participating enzymes by several orders of magnitude. The metabolic states are then evaluated in terms of a performance function which relates the metabolic variables to the overall functional fitness of the cell. The performance function for the erythrocyte takes into account the homeostasis of three essential metabolic variables: the energetic state (ATP), the reductive capacity (reduced glutathione), and the osmotic state. Based on the behaviour of the performance function at varying enzyme activities, we estimate those ranges of enzyme activities, in which the metabolic alterations should be either tolerable, associated with non-chronic or chronic diseases, or lethal. For most enzymopathies, the experimental and clinical observations can be satisfactorily rationalized by the computational results. Moreover, a surprisingly high correlation is found between the range of the activity range where disease is predicted by the model and the observed number of diseased probands. Another objective of our study was to contribute to the theory of metabolic control. The well-elaborated concept of the metabolic control theory is restricted to (infinitely) small activity alterations. In order to quantify the metabolic effect of finite (large-scale) changes in the activity of an enzyme, we propose, as a control measure, the effective activity E alpha, defined as the relative activity of an enzyme (with respect to the activity in a reference state) required to bring about a change in the stationary value of a metabolic variable by the (finite) factor alpha. We demonstrate that none of the existing extrapolation methods using the conventional control coefficient is capable to provide reliable predictions of the effective activities for all enzymes of erythrocyte metabolism.

Expression of the ligand-binding nicotinic acetylcholine receptor subunit D alpha 2 in the Drosophila central nervous system

The D alpha 2 gene encodes a ligand-binding subunit of nicotinic acetylcholine receptors (nAChRs) from Drosophila melanogaster. We have studied the distribution of D alpha 2 transcripts and protein by in situ hybridization and immunohistochemistry, respectively, as well as the regulation of D alpha 2 gene expression in vivo using D alpha 2 promoter fragments fused to the Escherichia coli lacZ gene. Transcripts and protein from the D alpha 2 gene were detected exclusively in the central nervous system. Both in late embryos and adults D alpha 2-like immunoreactivity is widely but not uniformly distributed in the synaptic neuropil, suggesting that the D alpha 2 protein is a subunit of a synaptic nicotinic receptor. Its distribution resembles that of ALS and ARD proteins, two other nAChR subunits of the fly. Five different D alpha 2-lacZ fusion gene constructs were introduced into the Drosophila genome by P-element-mediated gene transfer to identity functional elements of the D alpha 2 promoter. All constructs produce a basic lacZ expression pattern that is compatible with the distribution of D alpha 2 transcripts and protein. A 880 bp upstream fragment harbors the cis elements for the expression of a weak but specific basic D alpha 2 pattern. The next 350 bp further upstream significantly enhance beta-galactosidase expression without influencing the pattern of expression. Between 1.7 and 7.3 kb upstream of the transcription start site one or more elements that are required for D alpha 2 expression in optic lobe tangential cells are located.

Cooperative social coordination and aggression: II. Effects of sex and housing among three strains of intact laboratory rats differing in aggressiveness

Pairs of laboratory rats were rewarded with sugar solution for cooperating by means of synchronized shuttling in a rectangular chamber. Learning and performance were compared in males and females of three strains--S3, Charles River, and Wistar--ordered in terms of decreasing levels of aggressiveness. In addition, same-sex pairs of each strain were housed either together or individually. When housed together, males and females of all strains eventually cooperated at comparable levels, with rates of acquisition across strains inversely related to their aggressiveness. Individual housing, in contrast, was associated with severe deficits in males of the S3 and CR strains linked to violent fighting and prolonged freezing by animals who had previously been defeated. All other individually housed groups, including males of the Wistar strain and females of all strains, were able to cooperate, including S3 females whose violent fighting was not associated with immobility by defeated animals. In general, the majority of groups were able to cooperate despite differences in aggressiveness associated with sex, strain, and housing. Possible processes in this accommodation are discussed.

Metabolic flux determination in C6 glioma cells using carbon-13 distribution upon [1-13C]glucose incubation

A mathematical model of mammalian cell intermediary metabolism is presented. It describes the distribution of the carbon-13 isotope (13C) at the different carbon positions of metabolites in cells fed with 13C-enriched substrates. The model allows the determination of fluxes through different metabolic pathways from 13C- and 1H-NMR spectroscopy and mass spectrometry data. The considered metabolic network includes glycolysis, gluconeogenesis, the citric acid cycle and a number of reactions corresponding to protein or fatty acid metabolism. The model was used for calculating metabolic fluxes in a rat tumor cell line, the C6 glioma, incubated with [1-13C]glucose. After evolution to metabolic and isotopic steady states, the intracellular metabolites were extracted with perchloric acid. The specific enrichments of glutamate, aspartate and alanine carbons were determined from 13C-, 1H-NMR spectroscopy, or mass spectrometry data. Taking into account the rate of glucose consumption and of lactate formation, determined from the evolution of glucose and lactate contents in the cell medium, and knowing the activity of the hexose monophosphate shunt, it was possible to estimate the absolute values of all the considered fluxes. From the analysis the following results were obtained. (a) Glucose accounts for about 78% of the pyruvate and 57% of the CoASAc. (b) A metabolic channelling occurs at the citric acid cycle level; it favours the conversion of carbons 2, 3, 4, and 5 of 2-oxoglutarate into carbons 1, 2, 3, and 4 of oxaloacetate, respectively. The percentage of channelled metabolites amounts to 39%. (c) The pyruvate carboxylase activity and the efflux from the citric acid cycle are estimated to be very low, suggesting a lack of glutamine production in C6 cells. The results emphasize different metabolic characteristics of C6 cells when compared to astrocytes, their normal counterpart.

Immunohistochemical localization of a ligand-binding and a structural subunit of nicotinic acetylcholine receptors in the central nervous system of Drosophila melanogaster

The distribution of two subunits of nicotinic acetylcholine receptors in the developing and the differentiated central nervous system of Drosophila melanogaster was studied. With subunit-specific antibodies raised against the ligand-binding alpha-like subunit ALS and the putative non-ligand-binding subunit ARD, we find both ALS-like and ARD-like immunoreactivity widely distributed in most neuropiles of the optic lobes, the protocerebrum, the deutocerebrum and the thoracic ganglion of the adult fly. With a single exception, namely in the lamina of the visual system, the antigens recognized by the two types of antibodies are colocalized. This observation is consistent with previous immunoprecipitation data indicating that the ALS and ARD proteins are integral components of the same hetero-oligomeric receptor that binds the nicotinic antagonist alpha-bungarotoxin with high affinity. During embryonic development ARD-like immunoreactivity is first detectable in approximately 10 hour old embryos. Both subunits are consistently detected in the central nervous system of the late embryo, the three larval stages, and all prepupal and pupal stages. During metamorphosis the optic stalk is transiently immunoreactive with anti-ARD, but not with anti-ALS antiserum. Although in larvae and adults, immunoreactivity with both types of antibodies is most abundant in synaptic regions, in embryos and pupae strong staining of cortical cell body layers is observed, in particular with anti-ARD antisera. As these developmental periods coincide with strong accumulation of ARD transcripts, the cell body staining may reflect newly synthesized and assembled receptors, while the functional ARD- and ALS-containing receptor may be destined for synapses.

[Compliance of children with bronchial asthma in long-term therapy with theophylline retard preparations]

427 samples of the saliva of 235 children were taken on an outpatient basis to follow up long-term theophylline treatment. 37 samples from 34 children did not reveal the presence of any theophylline. The absolute non-compliance found in this manner is 21% in the 9 to 12 years age bracket and significantly higher than with the children below 9 years and above 14 years of age (8 and 10%, respectively). Better differentiation of compliance and separation from underdosing was achieved in 38 children by comparing the outpatient-controlled theophylline levels with the values obtained on an inpatient basis. For 10 patients this method definitely revealed non-compliance, whereas compliance was doubtful with 12 children and 15 children had strictly adhered to the prescribed dosage regimen. To improve the intake discipline the theophylline levels should be regularly followed up under outpatient conditions and evaluated in cooperation with the patients.

Giant lipomas of the hand and forearm

Giant lipomas of the upper extremity are infrequently reported. They can alter function by restricting motion or producing compressive neuropathies. This report of four cases of giant lipoma in the hand and forearm illustrates these functional losses. The role of MRI and CT in preoperative evaluation of these lesions is discussed and a report of an anterior interosseous syndrome caused by a giant lipoma is presented.

[Oral ciprofloxacin therapy in juvenile patients with cystic fibrosis--results of a prospective pilot study]

Efficacy and safety of oral ciprofloxacin were studied in a prospective study at three cystic fibrosis centres, covering 24 in-patients suffering from cystic fibrosis and acute bronchopulmonary exacerbation. The patients were between 10 and 17 years of age. Pseudomonas infection was present in 75% of these patients. Despite frequent persistence of the pathogens, clinical improvement was noted in 75% of the treated children. A definite increase of the average MIC was not seen in 20 cases of persisting strains. No serious side effects occurred during the 14-day oral treatment course. Ciprofloxacin is a useful alternative to conventional parenteral treatment with antibiotics in patients suffering from cystic fibrosis and infections of the airways.

[Contributions to the parasite fauna of local hosts. 10. On the endoparasitic fauna of Felis silvestris]

The investigations based on examination of the internal organs of 25 wild cats of the Harz population died from different causes in the period from 1982 to 1989. 22 animals (= 88%) were positive for parasites. The following species were found: Hydatigera taeniaeformis, Taenia crassiceps, T. martis larv. (spurious parasite), Mesocestoides litteratus, Capillaria plica, Capillaria sp. (aerophila?), Toxocara mystax, Cystoisopora felis. Toxocara mystax and Hydatigera taeniaeformis were the most often diagnosed helminths. Their number ranged up to 247 and 30 specimen respectively. The stated parasite fauna is comparable with findings in run wild domestic cats in rural areas. Voles contained in the stomach content of most of the cats play a role in the epizootiology of wild cat endoparasites.

[A case of an Oslerus osleri infection (nematoda) in a dog]

Nodules had been found in the mucous membrane of trachea and bronchiae of an 8 month old male miniature poodle suffering from dyspnoea. Besides worm fragments one female and one male nematode as well as a number of nematode eggs and larvae were discovered by parasitological examination of tracheal rinse liquid. They could be identified as Oslerus osleri. A literature survey is given on peculiarities in the life cycle, on the epidemiology, the clinical signs, the diagnostic and the treatment of this helminthosis rarely diagnosed in Europe.