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PubMedDate not supplied

Isolation of Vibrio vulnificus and atypical Vibrio from surface water of the Baltic Sea in Germany.

From 1995 to 1997 several defined species like V. alginolyticus, V. anguillarum, V. cholerae (non O1 and non O139), V. mimicus, V. parahaemolyticus and V. vulnificus were isolated during a survey to determine the presence of V. vulnificus in the brackish water of the Baltic Sea in Germany. Moreover atypical Vibrio isolates were detected. Four isolates belonging to a group of atypical Vibrio and possibly representing a new species in the genus Vibrio were characterized in detail. All four strains were isolated from surface costal waters. Based on 16S rDNA sequence analysis they showed the highest relatedness to the species V. navarrensis and V. vulnificus. The strains did not harbor the species specific hemolysin gene vvhA from V. vulnificus as shown by PCR and hybridization experiments. Moreover, they differed in at least two biochemical parameters tested from the hitherto described Vibrio species. All these strains induced hemolysis on washed blood agar dishes and showed phase variations on Luria Bertani agar dishes. Because of the similarity to the eel pathogen V. vulnificus, we infected eels with one of the four atypical strains (CH-291), but no pathogenicity for eels could be detected. Furthermore, Vero cell tests with supernatants of bacterial cultures did not reveal secreted Vero cell cytotoxic compounds. This indicates a nonpathogenic nature of these strains.

Animals↗
PubMed1992

Extracellular acetylcholine changes in rat limbic structures during soman-induced seizures.

Extracellular acetylcholine (ACh) levels were determined, by intracranial microdialysis, in medial septum, amygdala and hippocampus (CA1, CA3, dentate gyrus) of rats during seizures induced by systemic administration of soman (pinacolyl methylphosphonofluoridate), a potent inhibitor of acetylcholinesterase (AChE). In all septo-hippocampal areas a two phase variation was observed: a primary increase in ACh during the pre-seizures period, followed by a decline after 10 to 20 min of seizures and then a second release at 50 min of seizures. In amygdala a progressive increase of the ACh level reached a maximal value at 50 min. ACh levels than returned to basal values in all areas. Hippocampal AChE activity remained totally inhibited throughout the experiment. Possible dynamic phenomena underlying these variations (blood-brain barrier opening, autoregulation of release) are suggested. The present results are compared to previous reports about glutamate changes in the same areas during soman seizures. This comparison gives evidence that in septo-hippocampal areas the glutamatergic system is recruited after an early accumulation of extracellular ACh. The respective roles of ACh and glutamate in triggering and maintenance of soman seizures activity are discussed.

Acetylcholine↗
PubMed2004

Harmonic ultrasound fields through layered liquid media.

Harmonic field generation through a layered liquid media is studied experimentally and theoretically. Lateral and axial beam profiles of the fundamental to the 4th harmonic component of the field from a focused, 19-mm diameter transducer were measured using a calibrated hydrophone in a water tank. Measurements were performed before and after the insertion of a cylindrical phantom containing vegetable oil. A frequency domain numerical solution to the "KZK" equation was used to calculate the beam profile, taking into account the acoustic properties of the medium and phantom. Effects of nonlinear propagation, diffraction, attenuation, and reflection are include in the calculation. Agreement within 5% was obtained between measurements and theoretical predictions throughout the mid- and far-field of the transducer for both the uniform path and the layered media. Measurements also were carried out using an unfocused transducer as a receiver. The shape of the axial beam profile using this receiver agreed very well with the theoretical prediction using the "KZK" equation, after accounting for phase variations over the finite-sized detector in the calculated field.

Algorithms↗
PubMed2004

An evaluation of effective radiuses of bulk-wave ultrasonic transducers as circular piston sources for accurate velocity measurements.

The effective radius of a bulk-wave ultrasonic transducer as a circular piston source, fabricated on one end of a synthetic silica (SiO2) glass buffer rod, was evaluated for accurate velocity measurements of dispersive specimens over a wide frequency range. The effective radius was determined by comparing measured and calculated phase variations due to diffraction in an ultrasonic transmission line of the SiO2 buffer rod/water-couplant/SiO2 standard specimen, using radio-frequency (RF) tone burst ultrasonic waves. Fourteen devices with different device parameters were evaluated. The velocities of the nondispersive standard specimen (C-7940) were found to be 5934.10 +/- 0.35 m/s at 70 to 290 MHz, after diffraction correction using the nominal radius (0.75 mm) for an ultrasonic device with an operating center frequency of about 400 MHz. Corrected velocities were more accurately found to be 5934.15 +/- 0.03 m/s by using the effective radius (0.780 mm) for the diffraction correction. Bulk-wave ultrasonic devices calibrated by this experimental procedure enable conducting extremely accurate velocity dispersion measurements.

Journal Article↗
PubMed1991

Escherichia coli in patients with renal scarring: genotype and phenotype of Gal alpha 1-4Gal beta-, Forssman- and mannose-specific adhesins.

The frequency of Escherichia coli with Gal alpha 1-4Gal beta-specific adhesins is reduced among children who develop renal scars. The adhesion-negative phenotype may be due to the absence of the pap DNA sequences which encode these adhesins or to a phase variation event induced by in vitro culture. In the present study the frequency of pap and pil homologous DNA was determined by dot blot analysis with probes specific for the respective sequence using E. coli strains from children with recurrent pyelonephritis with and without renal scarring. The frequency of pap was 79% in the strains isolated from the nonscarring group compared with 39% in the strains from the scarring group (P less than 0.001). The Gal alpha 1-4Gal beta phenotype was expressed by 89% of the pap-positive strains from the nonscarring group compared with 71% in the scarring group (P less than 0.05). In addition 13 of 77 of the pap-positive E. coli strains agglutinated sheep erythrocytes but not the Gal alpha 1-4Gal beta latex beads; a reaction attributed to reactivity with the Forssman glycolipid. DNA sequences homologous with pil were found in 95% of all strains and there was no significant difference between the nonscarring and the scarring groups. The low frequency of Gal alpha 1-4Gal beta specific strains in the scarring group was therefore due to the absence of pap-homologous DNA sequences and to a reduced rate of phenotypic expression among pap-positive scarring strains. There was no support for a relationship between type 1 fimbriae and renal scarring.

Acute Disease↗
PubMed1991

[Activity of specific and natural killer cells in experimental tuberculosis and vaccination].

The dynamics of activity of specific and natural killers was studied in 125 Balb/c mice by reproducing the BCG vaccinal process and primary and secondary tuberculosis. The activity of specific killers rose after vaccination and infection. Their level reached maximum in secondary tuberculosis reproduction. In tuberculosis development cellular killer activity declined. The vaccinal and tuberculous processes are attended by phase variations of natural killer lymphocyte activity which at first rises and subsequently declines. It is suggested that natural killers might play a role in the self-limitation of the immune response and elimination of the mutant cells formed during lymphocyte reproduction in the course of immune response to antigen.

Animals↗
PubMed1990

Haemophilus influenzae: surface antigens and aspects of virulence.

Haemophilus influenzae type b is a major cause of bacterial meningitis and other invasive diseases in children under four years of age. One surface antigen, the type b capsular polysaccharide, polyribosylribitol phosphate (PRP), is a primary virulence factor of the organism. Antibody directed against PRP is protective; however, the purified polysaccharide is poorly immunogenic in young children. Polysaccharide-protein conjugate vaccines have been prepared which are significantly more immunogenic and efficacious in young children compared to the plain polysaccharide vaccine. Noncapsular surface antigens may also play a role in the virulence of H. influenzae. Some mutants (or phase variants) which differ in lipooligosaccharide (LOS) structure exhibit decreased virulence in the infant rat model of bacteremia. Proteins including the IgA protease, pili, a 98K outer membrane protein (OMP) as well as OMPs P1, P2 and P6 have also been examined in considerable detail, but whether they have a role in the virulence of the organism remains to be determined. However, antibody directed against the 98K OMP as well as P1, P2 and P6 is protective in the infant rat model of bacteremia. The role of antibody directed against LOS epitopes in protection is less clear, due at least in part, to phase variation in LOS antigens. Characterization of one surface antigen of H. influenzae type b, the capsular polysaccharide, already has led to the prevention of many cases of Haemophilus disease. Characterization of the noncapsular antigens together with a more detailed understanding of the mechanisms of virulence, most likely will permit development of even better vaccines, and possibly better treatment modalities, in the future.

Animals↗
PubMed1975

Phase II to phase I conversion of Coxiella burneti in immunosuppressed mice.

Coxiella burneti strains 48 and Nine Mile, serologically in phase II, changed their antigenic properties and virulence for guinea pigs and mice upon passaging in immunosuppressed mice. Conversion to phase I of these strains in a system lacking antibody response throws doubt on the importance of specific antibodies in phase variation of C. burneti.

Animals↗
PubMed1984

[Variability of the sleep-wake cycle stages in the laboratory cat].

In order to study the variability of the phases of the sleep-wakefulness cycle (SWC) in the laboratory cat, eight animals were implanted with the standard array of electrodes for EEG, EOG and EMG recordings. Six twenty-four-hour recordings were obtained from each cat at weekly intervals. Three recordings were carried out in the cat colony while the remaining three were obtained with the cat alone in the sound proof chamber. Furthermore, in four cats, other three longitudinal twenty-four-hour recordings were obtained in the sound-proof chamber. In all situations the animals were under a 12:12 light/dark regime and were fed once a day. Sleep recordings were scored according to the polygraphic criteria for wakefulness (W), drowsiness (D), slow sleep (SS) and paradoxical sleep (PS). In each situation a two way analysis of variance (animals and days) was made. Results showed that W, D and SS were the states of the SWC exhibiting the largest variability among animals, while PS was the most stable phase. Variations of the four states among the different days of weekly intervals were not significant. However, a significant increase in PS was observed on the first day in the cases with longitudinal recordings.

Activity Cycles↗
PubMed1977

Creatine kinase: stability, inactivation, reactivation.

I determined the in vitro biological half-lives or decay constants for creatine kinase isoenzymes at various temperatures. Values at 37 degrees C are consistent with values reported by others in vivo, which suggests that in vivo irreversible inactivation is primarily thermal. Reversible inactivation appears to be an oxidation-reduction phenomenon. Proteins and some inactivators (urate, catecholamines) retard irreversible inactivation and preserve isoenzyme integrity. Dilution and thiols promote reversal of inactivity. Mercaptoethanol is the preferred thiol, particularly for storage and reactivation of isoenzyme MB. MB is sensitive to light and to freeze-thawing. I recommend that specimens be cooled promptly after drawing, that mercaptoethanol (10 mmol/liter) be added, and that they be stored refrigerated. Avoid prolonged exposure to light and freezing. A model of inactivation is proposed, which is based on the assumed existence of four monomer types: active, denatured, oxidized, and insulated. The model is consistent with dilution and thiol reactivation, lag phase variations, and subtype heterogeneity.

Catecholamines↗
PubMedDate not supplied

Assay of oxytetracycline in animal feed by liquid chromatography and microbiological plate assay.

In a proposed method for determining oxytetracycline (OTC) in animal feed, OTC is extracted with acidic methanol, and the extract is centrifuged and assayed by microbiological plate assay and by reversed-phase liquid chromatography (LC). Riboflavin and furazolidone elute at retention times similar to that of OTC. Successful separations are made by using both dimethylformamide and acetonitrile mobile phases. Variation between microbiological and LC results is comparable with variation within the microbiological assay. The relative standard deviation for 6 replicates of feed at the 100 ppm level is 3.6% for the LC assay and 3.1% for the microbiological assay.

Animal Feed↗
PubMed1996

Atomic force microscopy observations of acyl chains in phospholipids.

The potential use of atomic force microscopy (AFM) to image the mode of assembly and to measure the corresponding lattice parameters of model systems consisting of ordered aggregates of cardiolipin molecules has been investigated. An unprecedented resolution of about 0.2 nm has been achieved on suitably prepared specimens. This enables the orientational order and the positional correlations of the individual molecules in the lattice to be defined, and submolecular details, such as the acyl chains and the polar groups, to be imaged. The structural parameters derived from AFM have been compared with those obtained by transmission electron diffraction of the same specimen and found to be in excellent agreement. AFM turns out to be a powerful and probably a unique tool to reveal local phase variations in systems, such as biological membranes, that have non-homogeneous composition and organization.

Aluminum Silicates↗
PubMed1996

Red cell enzymopathies in leukemias.

Red cell glucose-6-phosphate dehydrogenase (G6PD) and pyruvate kinase (PK) levels were estimated in patients with leukemias, to see if there was a consistent enzyme defect and correlation of enzyme levels with stage of the disease with prognostic assessment. G6PD levels were found to be significantly increased or decreased in majority of the patients with acute leukemias. Increased activity was seen in majority of the patients with L1 and decreased activity in L2 subtype of acute lymphocytic leukemia (ALL). In chronic myeloid leukemia (CML) G6PD activity was consistently increased, with levels being highly elevated in chronic phase and moderately in blast phase. Variation in G6PD activity was found to be related to the stage of disease and was of prognostic significance. PK was found to be normal or decreased. Fetal haemoglobin levels were also estimated in 30 patients with leukemias and were found to be elevated in most patients. Red cell G6PD may be useful for staging of the disease, as prognostic indicator and predictor of relapse.

Erythrocytes↗
PubMed1998

[Hematological investigations in conditions of long-term space flights].

In the nearly 15-month mission aboard MIR the cosmonaut-physician and members of three crews (MIR-15, -16, and -17) carried out a program of hematological investigations. Most of the changes related to the red blood system and included reduction in hemoglobin and hematocrit. Erythrocytes had decreased concentration and took on abnormal forms. There were also signs of altered metabolism of erythrocytes. Of interest are phase-by-phase variations in the levels of erythrocytes in the course of long-term stay in microgravity, and absence of a convincing correlation between hemoglobin, erythrocyte and hematocrit levels. But for lymphocytosis that returned to the norm already on the first day of recovery, no material changes occurred to the leukocyte profile. Investigations at the landing site displayed erythropenia, decreased reticulocytes and ensuing reticulocyte reaction, and gradual regain of the erythrocyte number that can be viewed as a normal physiological reaction of the blood system to the set of factors of spaceflight and early readaptation. Besides, the investigations showed a large individually of blood reactions to prolonged stay in space flight.

Adaptation, Physiological↗
PubMed2003

Variation correction algorithm: analysis of phase suppression and thermal profile fidelity for proton resonance frequency magnetic resonance thermometry at 0.2 T.

PURPOSE: To develop and analyze the performance of the variation correction algorithm (VCA), a phase correction technique that mitigates the contribution of background phase variations by combining accurate alignment of echoes, K-space-based phase correction (as opposed to spatial polynomials), and extraction of alias-free phase difference images. MATERIALS AND METHODS: A series of echo-shifted gradient-recalled echo (GRE) images was processed with K-space alignment and phase corrected with increasing sizes of M x M masks of central K-space coefficients. The extent of background phase variation suppression due to magnet field drift was assessed. Further, a simulated thermal profile was superimposed on the same data in a related experiment. Residual errors in reconstructed simulated thermal profiles were quantitatively characterized to estimate algorithm performance. RESULTS: Using a 3 x 3 K-space mask, the VCA was able to 1) maintain the typical mean background error in a 35 x 35 pixel region of interest (ROI) at -0.1 degrees C; and 2) reconstruct, relative to the applied thermal profile, a phase-corrected profile that typically contains a 1.7 degrees C underestimation of peak temperature difference and a mean error along the 60 degrees C line of -0.8 degrees C. CONCLUSION: The results suggest that thermal profiles can be accurately reconstructed at 0.2 T using the VCA, even in the presence of over 1 ppm spatially and temporally dependent field drift over a 1-hour time frame.

Algorithms↗
PubMed1993

Biological variation of acute phase proteins.

The analytical, within-subject and between-subject components of variation were estimated for serum albumin, transthyretin, alpha 1-acid glycoprotein, alpha 1-antichymotrypsin, haptoglobin, beta 2-microglobulin and C-reactive protein in a cohort of 19 apparently healthy subjects over 20 weeks. Desirable analytical goals based on biological variation should be able to be met except for serum albumin and beta 2-microglobulin for which methodological improvement is warranted. All proteins showed marked individuality which casts doubt on the utility of conventional population-based reference values as interpretative criteria. The critical differences required for significance of changes in serial results differ markedly from protein to protein and the data presented allow generation of objective criteria for monitoring individuals.

Acute-Phase Proteins↗
PubMed1993

Annual variations in hypothalamic serotonin and monoamine oxidase in the catfish Heteropneustes fossilis with a note on brain regional differences of day-night variations in gonadal preparatory phase.

In Heteropneustes fossilis, significant annual variations in serotonin (5-HT) and monoamine oxidase (MAO) were found in the hypothalamus both at 12 and 24 hr with high values of content and turnover index (TI) during gonadal recrudescence, and low values during gonadal quiescence. The 5-HT content reached high levels during April-July (late preparatory, prespawning, and spawning phases). The TI of 5-HT showed two peaks in its midday value; a major peak occurred in March (midpreparatory phase) and a minor one in June (prespawning phase). High MAO activity was seen in June (prespawning phase) and low values during February, March, and April (preparatory phase). Significant day-night variations in 5-HT content and TI, and MAO activity were observed in the hypothalamus and telencephalon in February and March (early and midpreparatory phase), but not at other times of the year. In the whole brain and separate regions such as the thalamus, midbrain, and hindbrain no day-night patterns were seen. A comparison of the data shows that the increase in 5-HT content and TI from February to March was significantly higher in the hypothalamus than in telencephalon and the opposite is true for MAO. The results suggest that the high hypothalamic activities of 5-HT and MAO during recrudescence is related to breeding activity; the day-night variations during the early and midpreparatory phase in these variables may be related to initiation of breeding in this species.

Animals↗
PubMed1977

Effect of strain variation and growth phase of culture on dry weight and hexosamine content of cell wall layers of a marine pseudomonad.

Two variants of marine pseudomonad B-16 (ATCC 19855) differing in that one, variant 3, formed opaque colonies and the other, variant 7, formed translucent colonies were examined to determine if the variants differed in the amount and hexosamine content of their three outer cell wall layers. In both variants, the three outer layers of the cell wall, the loosely bound outer layer, the outer double-track layer, and the underlying (periplasmic space) layer contributed less to the dry weight of the cells when the cells were harvested in the stationary than in the logarithmic phase of growth. The hexosamine content of the layers of variant 3 increased dramatically as the cells went from the logarithmic to the stationary phase. The hexosamine content of the layers of variant 7 changed little by comparison. Thus cells of the variant which forms opaque colonies enrich the outer layers of their cell wall with hexosamine when grown to stationary phase.

Cell Wall↗