Modular air-liquid interface aerosol exposure system (MALIES) to study toxicity of nanoparticle aerosols in 3D-cultured A549 cells in vitro

We present a novel lung aerosol exposure system named MALIES (modular air-liquid interface exposure system), which allows three-dimensional cultivation of lung epithelial cells in alveolar-like scaffolds (MatriGrids®) and exposure to nanoparticle aerosols. MALIES consists of multiple modular units for aerosol generation, and can be rapidly assembled and commissioned. The MALIES system was proven for its ability to reliably produce a dose-dependent toxicity in A549 cells using CuSO4 aerosol. Cytotoxic effects of BaSO4- and TiO2-nanoparticles were investigated using MALIES with the human lung tumor cell line A549 cultured at the air-liquid interface. Experiments with concentrations of up to 5.93 × 105 (BaSO4) and 1.49 × 106 (TiO2) particles/cm3, resulting in deposited masses of up to 26.6 and 74.0 µg/cm2 were performed using two identical aerosol exposure systems in two different laboratories. LDH, resazurin reduction and total glutathione were measured. A549 cells grown on MatriGrids® form a ZO-1- and E-Cadherin-positive epithelial barrier and produce mucin and surfactant protein. BaSO4-NP in a deposited mass of up to 26.6 µg/cm2 resulted in mild, reversible damage (~ 10% decrease in viability) to lung epithelium 24 h after exposure. TiO2-NP in a deposited mass of up to 74.0 µg/cm2 did not induce any cytotoxicity in A549 cells 24 h and 72 h after exposure, with the exception of a 1.7 fold increase in the low exposure group in laboratory 1. These results are consistent with previous studies showing no significant damage to lung epithelium by short-term treatment with low concentrations of nanoscale BaSO4 and TiO2 in in vitro experiments.

Biomimetic reconstruction of the hematopoietic stem cell niche for in vitro amplification of human hematopoietic stem cells

Hematopoietic stem cell transplantation is successfully applied since the late 1950s; however, its efficacy still needs to be increased. A promising strategy is to transplant high numbers of pluripotent hematopoietic stem cells (HSCs). Therefore, an improved ex vivo culture system that supports proliferation and maintains HSC pluripotency would override possible limitations in cell numbers gained from donors. To model the natural HSC niche in vitro, we optimized the HSC medium composition with a panel of cytokines and valproic acid and used an artificial 3D bone marrow-like scaffold made of polydimethylsiloxane (PDMS). This 3D scaffold offered a suitable platform to amplify human HSCs in vitro and, simultaneously, to support their viability, multipotency and ability for self-renewal. Silicon oxide-covering of PDMS structures further improved amplification of CD34+ cells, although the conservation of naïve HSCs was better on non-covered 3D PDMS. Finally, we found that HSC cultivated on non-covered 3D PDMS generated most pluripotent colonies within colony forming unit assays. In conclusion, by combining biological and biotechnological approaches, we optimized in vitro HSCs culture conditions, resulting in improved amplification, multipotency maintenance and vitality of HSCs.

Gastric cancer in autoimmune gastritis: A case-control study from the German centers of the staR project on gastric cancer research

Objectives

Patients with autoimmune gastritis (AIG) are reported to have an increased risk of developing gastric cancer (GC). In this study, we assess the characteristics and outcomes of GC patients with AIG in a multicenter case-control study.

Methods

Between April 2013 and May 2017, patients with GC, including cancers of the esophagogastric junction (EGJ) Siewert type II and III, were recruited. Patients with histological characteristics of AIG were identified and matched in a 1:2 fashion for age and gender to GC patients with no AIG. Presenting symptoms were documented using a self-administered questionnaire.

Results

Histological assessment of gastric mucosa was available for 572/759 GC patients. Overall, 28 (4.9%) of GC patients had AIG (67 ± 9 years, female-to-male ratio 1.3:1). In patients with AIG, GC was more likely to be localized in the proximal (i.e. EGJ, fundus, corpus) stomach (odds ratio (OR) 2.7, 95% confidence interval (CI) 1.0–7.1). In GC patients with AIG, pernicious anemia was the leading clinical sign (OR 22.0, 95% CI 2.6–187.2), and the most common indication for esophagogastroduodenoscopy (OR 29.0, 95% CI 7.2–116.4). GC patients with AIG were more likely to present without distant metastases (OR 6.2, 95% CI 1.3–28.8) and to be treated with curative intention (OR 3.0, 95% CI 1.0–9.0). The five-year survival rates with 95% CI in GC patients with and with no AIG were 84.7% (83.8–85.6) and 53.5% (50.9–56.1), respectively (OR 0.25, 95% CI 0.08–0.75, p = 0.001).

Conclusions

Pernicious anemia leads to earlier diagnosis of GC in AIG patients and contributes significantly to a better clinical outcome.

Coherent transients in the femtosecond photoassociation of ultracold molecules

We demonstrate the photoassociation of ultracold rubidium dimers using coherent femtosecond pulses. Starting from a cloud of ultracold rubidium atoms, electronically excited rubidium molecules are formed with shaped photoassociation pump pulses. The excited state molecules are projected with a time-delayed probe pulse onto molecular ion states which are detected in a mass spectrometer. Coherent transient oscillations of the excited state population are observed in the wings of the pump pulse, in agreement with the time-dependent solution of the Schrödinger equation of the excitation process.

Structural organisation of the head-to-tail interface of a bacterial virus

In tailed icosahedral bacteriophages the connection between the 5-fold symmetric environment of the portal vertex in the capsid and the 6-fold symmetric phage tail is formed by a complex interface structure. The current study provides the detailed analysis of the assembly and structural organisation of such an interface within a phage having a long tail. The region of the interface assembled as part of the viral capsid (connector) was purified from DNA-filled capsids of the Bacillus subtilis bacteriophage SPP1. It is composed of oligomers of gp6, the SPP1 portal protein, of gp15, and of gp16. The SPP1 connector structure is formed by a mushroom-like portal protein whose cap faces the interior of the viral capsid in intact virions, an annular structure below the stem of the mushroom, and a second narrower annulus that is in direct contact with the helical tail extremity. The layered arrangement correlates to the stacking of gp6, gp15, and gp16 on top of the tail. The gp16 ring is exposed to the virion outside. During SPP1 morphogenesis, gp6 participates in the procapsid assembly reaction, an early step in the assembly pathway, while gp15 and gp16 bind to the capsid portal vertex after viral chromosome encapsidation. gp16 is processed during or after tail attachment to the connector region. The portal protein gp6 has 12-fold cyclical symmetry in the connector structure, whereas assembly-naïve gp6 exhibits 13-fold symmetry. We propose that it is the interaction of gp6 with other viral morphogenetic proteins that drives its assembly into the 12-mer state.

Distribution of GPI-anchored proteins in the protozoan parasite Leishmania, based on an improved ultrastructural description using high-pressure frozen cells

The cellular distribution of two glycosyl-phosphatidylinositol (GPI)-anchored proteins and a trans-membrane protein and the compartments involved in their trafficking were investigated in the insect stage of Leishmania mexicana, which belongs to the phylogenetically old protozoan family Trypanosomatidae. Electron microscopy of sections from high-pressure frozen and freeze-substituted cells allowed a detailed description of exo- and endocytic structures located in the vesicle-rich, densely packed anterior part of the spindle-shaped cell. A complex of tubular clusters/translucent vesicles is the prominent structure between the trans-side of the single Golgi apparatus and the flagellar pocket, the only site of endo- and exocytosis. A tubulovesicular compartment lined by one or two distinct microtubules and extending along the length of the cell is proposed to be a post-Golgi and probably late endosomal/lysosomal compartment. Using biotinylation experiments, FACS analysis and quantitative immunoelectron microscopy it was found that, at comparable expression levels, 73–75% of the two GPI-anchored proteins but only 13% of the trans-membrane protein are located on the cell surface. The tubulovesicular compartment contains 46%, the ER 5%, the Golgi complex 1.9% and the tubular cluster/translucent vesicle complex 3.6% of the intracellular fraction of the GPI-anchored protease, GP63. The density of GP63 was found to be 23-fold higher on the plasma/flagellar pocket membrane than on the ER and about tenfold higher than on membranes of the Golgi complex or of endo- or exocytic vesicles. These results indicate that there is a considerable concentration gradient of GPI-anchored proteins between the plasma/flagellar pocket membrane and the ER as well as structures involved in exo- or endocytosis. Possible mechanisms how this concentration gradient is established are discussed.

Deletion of the gene for the membrane-bound acid phosphatase of Leishmania mexicana

The membrane-bound acid phosphatase of Leishmania mexicana (LmxMBAP) has been shown to be a heterogeneously N-glycosylated type I transmembrane protein, which is localized predominantly in vesicular structures close to the flagellar pocket in promastigotes and amastigotes. Its expression in both life stages prompted us to analyse its function by performing deletion analysis. Both alleles of the single copy gene were sequentially replaced by resistance marker genes and the resulting deletion mutant was tested for its potential to infect Balb/c mice and peritoneal macrophages. There was no obvious difference detectable between the mutant and the wild-type. Therefore, we conclude that LmxMBAP is neither involved in the infection process nor required for amastigote survival in the infected host cell. LmxMBAP null mutant promastigotes were used to establish a system for homogeneous overexpression of LmxMBAP which will be useful to investigate protein sorting in L. mexicana.

Polymorphic quaternary organization of the Bacillus subtilis bacteriophage SPP1 replicative helicase (G40 P)

The Bacillus subtilis bacteriophage SPP1 gene 40 product (G40P), which belongs to the DnaB-like family of helicases, is essential for SPP1 genome replication. The active form of the enzyme is the hexamer, capable of DNA unwinding with a 5' to 3' polarity fueled by the hydrolysis of a nucleoside 5'-triphosphate. We have used electron microscopy of negatively stained G40P samples and image processing techniques to study the structural characteristics of the hexameric assemblies of this protein. Our results provide the first low resolution data on a hexameric helicase of a Gram-positive bacterial origin. A novel approach has been adopted to analyze possible symmetry heterogeneities, an unsupervised method based on a neural network self-organizing algorithm, which has led to the detection of different subclasses of G40P views. Two different quaternary states of G40P homohexamers sharing a C3 symmetry organization have been found, as well as a minor class that seems to reflect an alternative C6 symmetry architecture. These forms show general features known for other hexameric helicases, such as the ring-like arrangement of monomers around a central hole. A clear structural handedness has also been detected in some of these forms. An analysis of these quaternary states and a model for the structural organization of G40P are presented.

Effect of glycaemic control on myocardial sympathetic innervation assessed by [123I]metaiodobenzylguanidine scintigraphy: a 4-year prospective study in IDDM patients

Diabetic cardiovascular autonomic neuropathy (CAN) has been directly characterized by reduced or absent myocardial [123I]metaiodobenzylguanidine (MIBG) uptake, but there is no information available on the relationship between the myocardial adrenergic innervation defects and long-term glycaemic control. In a prospective study over a mean of 4 years we examined myocardial sympathetic innervation in 12 Type 1 (insulin-dependent) diabetic patients using MIBG scintigraphy (absolute and relative global MIBG uptake at 2 h p.i.) in conjunction with cardiovascular autonomic function tests, QTc interval, and QT dispersion. Six healthy non-diabetic subjects served as controls for the MIBG scintigraphy at baseline. HbA1c was measured twice a year. One patient, in whom MIBG accumulation was reduced maximally, died during follow up. Among the remaining patients 5 had good or borderline glycaemic control (mean HbA1c < 7.6%; Group 1), whereas 6 patients were poorly controlled (mean HbA1c > or = 7.6%; Group 2). Absolute global MIBG uptake increased from baseline to follow-up by 260 (-190-540) [median (range)] cpm/g in Group 1 and decreased by -150 (-450-224) cpm/g in Group 2 (p < 0.05 vs Group 1). Relative global MIBG uptake decreased by -1.7 (-3.4-9.4) % in Group 1 and by -4.7 (-17.4-1.3) % in Group 2 (p < 0.05 vs Group 1). No differences between the groups were noted for the changes in the automatic function tests, QTc interval, and QT dispersion. In conclusion, long-term poor glycaemic control constitutes an essential determinant in the progression of left ventricular adrenergic dysinnervation which may be prevented by near-normoglycaemia. Evaluation of susceptibility to metabolic intervention may be superior when CAN is characterized directly by MIBG scintigraphy rather than by indirect autonomic function testing.

The complete nucleotide sequence and functional organization of Bacillus subtilis bacteriophage SPP1

The complete nucleotide sequence of the B. subtilis bacteriophage SPP1 is described. The genome is 44,007 bp in size and has a base composition of 43.7% dG + dC. Only 32.2 kb are essential for phage amplification under laboratory conditions. Transcription using only the 'heavy strand' is asymmetric. Eighty-one orfs organized in five early and four late operons were identified. Experiments have shown that 25 orfs are essential. Of the remaining orfs, functions could be predicted for the products of five of the orfs on the basis of comparison of the deduced amino acid sequence to known proteins. Intergenic regions include most of the 5 PE and the 4 PL promoters. Transcripts are polycistronic. Transcription from the PE promoters is mediated by host RP, whereas recognition of the PL promoters requires an additional unidentified phage-encoded product. Translation of mRNA transcribed from most of the orfs seems to be initiated independently, each from its own ribosomal binding and initiation site, although a few cases of coupled translation have been reported. The organization of SPP1 genes involved in the replication, DNA packaging and phage assembly proteins resembles the organization of genes of equivalent regions of different E. coli double-stranded DNA phages. Absence of aa sequence similarity between analogous proteins of different phages suggested that the conserved gene organization is representative of a primordial bacteriophage.

Evaluation of QT interval length, QT dispersion and myocardial m-iodobenzylguanidine uptake in insulin-dependent diabetic patients with and without autonomic neuropathy

1. An association has been reported between QT interval abnormalities and cardiovascular autonomic neuropathy in diabetic patients. The QT interval abnormalities reflect local inhomogeneities of ventricular recovery time and may be related to an imbalance in cardiac sympathetic innervation. Sympathetic innervation of the heart can be visualized and quantified by single-photon emission-computed tomography with m-[123I]iodobenzylguanidine. In this study we evaluated cardiac sympathetic integrity by m-[123I]iodobenzylguanidine imaging and the relationship between both QT interval prolongation and QT dispersion from standard 12-lead ECG variables and m-[123I]iodobenzylguanidine uptake in insulin-dependent diabetic patients. 2. Three patient groups were studied, comprising six healthy control subjects, nine diabetic patients without cardiovascular autonomic neuropathy (CAN-) and 12 diabetic patients with cardiovascular neuropathy (CAN+). Resting 12-lead ECG was recorded for measurement of maximal QT interval and QT dispersion. The QT interval was heart rate corrected using Bazett's formula (QTc) and the Karjalainen approach (QTk). Quantitative measurement (in counts/min per g) and visual defect pattern of m-[123I]iodobenzylguanidine uptake were performed using m-[123I]iodobenzylguanidine single-photo emission-computed tomography. 3. Global myocardial m-[123I]iodobenzylguanidine uptake was significantly reduced in both diabetic patient groups compared with control subjects. The visual defect score of m-[123I]iodobenzylguanidine uptake was significantly higher in CAN+ diabetic patients than in control subjects and in CAN- patients. This score was not significantly different between control subjects and CAN- patients. QTc interval and QT dispersion were significantly increased in CAN+ diabetic patients as compared with control subjects (QTc: 432 +/- 15 ms versus 404 +/- 19 ms, P < 0.05; QT dispersion: 42 +/- 10 versus 28 +/- 8 ms, P < 0.05). QT dispersion was also significantly longer in CAN- diabetic patients than in control subjects (41 +/- 9 ms versus 28 +/- 8 ms, P < 0.05). QTc interval was significantly related to global myocardial m-[123I]iodobenzylguanidine uptake and defect score in diabetic patients (r = -0.648, P < 0.01, and r = 0.527, P < 0.05, respectively). There was no correlation between QT dispersion and both m-[123I]iodobenzylguanidine uptake measures. 4. In conclusion, these findings suggest that m-[123I]iodobenzylguanidine imaging is a valuable tool for the detection of early alterations in myocardial sympathetic innervation in long-term diabetic patients without cardiovascular autonomic neuropathy. Insulin-dependent diabetic patients with cardiovascular autonomic neuropathy have a delayed cardiac repolarization and increased variability of ventricular refractoriness. The cardiac sympathetic nervous system seems to be one of the determinants of QT interval lengthening, but does not appear to be involved in dispersion of ventricular recovery time. It is assumed that QT dispersion is based on more complex electrophysiological mechanisms which remain to be elucidated.

The replisome organizer (G38P) of Bacillus subtilis bacteriophage SPP1 forms specialized nucleoprotein complexes with two discrete distant regions of the SPP1 genome

Initiation of Bacillus subtilis bacteriophage SPP1 DNA replication requires the products of genes 38, 39 and 40 (G38P, G39P and G40P). G38P specifically binds two discrete regions, which are 32.1 kb apart in a linear map of the SPP1 genome. One of these target sites, which maps at the left end of the phage genome, within gene 38, was shown to function as an origin of replication and was therefore termed left origin (oriL). The other site, which lies within a non-coding segment in the late transcribed region on the right end of the genome, was termed oriR. Both sites contain two types of repeated elements (termed Box AB and A + T-rich region). The K(app) for the G38P-oriL DNA and G38P-oriR DNA complexes was estimated to be 1 nM and 4 nM, respectively. G38P binds to the distant oriL and oriR sites cooperatively. DNase I footprinting experiments showed protection by G38P in Box AB, but not in the A + T-rich region. Electron microscopy analysis showed that G38P forms a higher-order nucleoprotein structure with the SPP1 oriL and oriR sites through protein-protein interaction. G38P binding at its cognate sites does not seem to modify the length of the DNA, but to bend it. These results suggest that G38P forms a nucleoprotein complex on the regions where the SPP1 replication origins were previously predicted.

Site-specific recombination in gram-positive theta-replicating plasmids

This review summarises current information on the site-specific recombinases encoded by the plasmids of the Gram-positive bacteria that have low guanine and cytosine content in their DNA. It focuses on the peculiar biological features of the recombination systems encoded by the theta-replicating plasmids and compares them with the site-specific recombinases encoded by transposons or plasmids originally isolated from Gram-negative bacteria.

Spectral analysis of systolic blood pressure and heart rate oscillations related to respiration

1. Non-invasive assessment of short-term systolic blood pressure (SBP) and heart rate (HR) variability was obtained with the plethysmographic finger blood pressure measurement device. Respiration was measured with a respiratory inductive plethysmograph, which was calibrated prior to each study. 2. The effects of breathing pattern on the respiratory (high frequency, HF) component of the SBP or HR spectrum were analysed by Fourier transform. 3. Our quantification of the changes in the HF (respiratory) peak of the HR or SBP spectrum with changes in tidal volume (VT) and breathing frequency (BF) indicates that the modulus of this component may be predicted for any combination of depth and frequency of breathing. 4. The modulus of this HF component for the HR or SBP spectrum was linearly related to the respiratory sinus arrhythmia (RSA) or to the SBP oscillation related to respiration.

Effect of hemodialysis on cardiovascular rhythms in end-stage renal failure

The purpose of this investigation was to determine non-invasively the alteration in autonomic cardiovascular control observed in end-stage renal disease (ESRD) patients submitted to a hemodialysis (HD) treatment. The effect of HD on finger blood pressure (BP) and heart rate (HR) variability was studied by means of spectral analysis in 12 ESRD patients at supine and during 45 degrees head-up tilt. Amplitude spectra of BP and HR rhythmicity were estimated and integrated amplitudes of the low (60 to 140 mHz, Mayer waves) and high frequency (area under the curve at mean respiration rate +/- 50 mHz) components were computed. The overall variability of a signal was given by the total area under the curve of the spectrum between 20 and 500 mHz. The transfer function was calculated between systolic BP and HR fluctuations using cross-spectral analysis. The principle findings are as follows: (1) Before HD, overall variability in systolic and diastolic BP as well as in the low frequency component in BP spectra were markedly reduced in ESRD patients compared to control subjects. Dialysis produced an immediate improvement in overall BP variability and the LF BP rhythmicity. (2) Before HD, there was an alteration of the HR spectral profile in uremic patients. (3) Chronic uremia and HD induced no changes in the transfer gain characteristic of modulation of HR by systolic BP. Taken together, these findings suggest that volume depletion in ESRD patients during a dialysis treatment is responsible for the improvement of overall BP variability and its spectral components.

The Bacillus subtilis histone-like protein Hbsu is required for DNA resolution and DNA inversion mediated by the beta recombinase of plasmid pSM19035

The beta recombinase, encoded by the Gram-positive bacterial plasmid pSM19035, is unable to mediate DNA recombination in vitro unless a host factor is provided. The factor has now been identified as the Bacillus subtilis Hbsu protein. Hbsu is a nonspecific DNA-binding and DNA-bending protein. The beta recombinase, in the presence of highly purified Hbsu protein, is able to catalyze in vitro intramolecular recombination between two specific recombination sites on a supercoiled DNA molecule. DNA resolution was obtained when the two crossing over sites (six sites) were directly oriented, whereas DNA inversion was the product when the six sites were in inverse orientation. The ability of the Escherichia coli chromatin-associated proteins HU, IHF, Fis, and H-NS to substitute for Hbsu was investigated. HU efficiently stimulated beta-mediated recombination, while the effect of IHF was partial and that of Fis and H-NS was undetectable. In addition, the beta protein was able to mediate DNA recombination in both wild-type and IHF-deficient E. coli cells, but failed to do so in an HU-deficient strain. The data presented provide direct evidence that a chromatin-associated protein is strictly required for beta-mediated recombination.

Effect of head-down tilt on cardiovascular control in healthy subjects: a spectral analytic approach

1. The purpose of this investigation was to determine non-invasively the changes in autonomic cardiovascular control observed in normal subjects submitted to acute cardiopulmonary blood volume expansion by 100 degrees head-down tilt. The effect of head-down tilt on finger blood pressure and heart rate fluctuations was studied by means of power spectral analysis in 12 healthy men. 2. Amplitude spectra of heart rate and blood pressure rhythmicity were estimated at the low-frequency (60-140 mHz, 10-s rhythm) and high-frequency (area under the curve at mean respiration rate +/- 50 mHz) component. Transfer gain and phase were calculated between systolic blood pressure and heart rate. Forearm vascular resistance was estimated to validate the head-down procedure. 3. Forearm vascular resistance decreased significantly from 19.82 (16.34-26.46) mmHg ml-1 min 100 ml to 18.05 (13.69-22.88) mmHg ml-1 min 100 ml (P < 0.01) during head-down tilt (values are medians and 25 and 75 percentiles). The overall variability (total area under the curve of the spectrum from 20 to 500 mHz) of blood pressure and heart rate time series was consistently reduced with head-down tilt. 4. The spectral pattern of systolic blood pressure showed a diminution of the absolute and relative low-frequency component during head-down tilt: absolute log-transformed values, 2.86 (2.80-2.94) mmHg/Hz1/2 versus 2.77 (2.72-2.82) mmHg/Hz1/2 (P < 0.05); relative values, 35% (32-37%) versus 32% (29-32%) (P < 0.05). In heart rate spectra only the absolute low-frequency component decreased.(ABSTRACT TRUNCATED AT 250 WORDS)

Nucleotide sequence and complementation studies of the gene 35 region of the Bacillus subtilis bacteriophage SPP1

Genetic analysis of the Bacillus subtilis bacteriophage SPP1 defective in gene 35 shows that the gene 35 product (G35P) is essential for SPP1 growth. The defect in growth of SPP1tsl17 and SPP1tsl20F at nonpermissive temperature is overcome by wild-type gene 35 expressed from a plasmid. The region where gene 35 maps was cloned and sequenced. Analysis of the nucleotide sequence (5884-bp) around gene 35 revealed 13 open reading frames (orfs). We have assigned the term gene to three of these orfs; gene 35, gene 36, the product of which shares homology with SSB proteins, and gene 38, given the gene order orf 34-orf 34.1-orf 34.2-orf34.3-orf34.4-gene 35-gene 36-orf 36.1-orf 37-orf 37.1-orf 37.2-orf 37.3-gene 38. Gene 35 encodes a protein of 32.0 kDa. By using the T7 promoter-expression system for gene 35 a radioactive band of the expected molecular mass was detected.

Analysis of cis and trans acting elements required for the initiation of DNA replication in the Bacillus subtilis bacteriophage SPP1

The development of SPP1 has been studied in several B. subtilis mutants conditionally defective in initiation of DNA replication. Initiation of SPP1 replication is independent of the host DnaA (replisome organizer), DnaB, DnaC and DnaI products, but requires the DnaG (DNA primase) and the DNA gyrase. Furthermore, SPP1 replication is independent of the DnaK (heat shock) protein. The phage-encoded products required for initiation of SPP1 replication have been genetically characterized. Analysis of the nucleotide sequence (3.292 kilobases) of the region where SPP1 initiation replication mutants map, revealed five open reading frames (orf). We have assigned genes 38, 39 and 40 to three of these orfs, which have the successive order gene 38-gene 39-orf39,1-gene 40-orf41. The direction of transcription of the reading frames, the lengths of the mRNAs as well as the transcription start point, upstream of gene 38 (PE2), were identified. Proteins of 29.9, 14.6 and 46.6 kDa were anticipated from translation of gene 38, gene 39 and gene 40, respectively. The purified G38P and G39P have estimated molecular masses of 31 and 15 kDa. G38P and G39P do not share significant identity with primary protein sequences currently available in protein databases, whereas G40P shares substantial homology with a family of DNA primase-associated DNA helicases. G38P binds specifically to two discrete SPP1 DNA restriction fragments (EcoRI-4 and EcoRI-3). The G38P binding site on EcoRI-4 was localized on a 393 bp DNA segment, which lies within the coding sequence of gene 38. The putative binding site on EcoRI-3 was inferred by DNA sequence homology, it maps in a non-coding segment. G39P, which does not bind to DNA, is able to form a complex with G38P. The organization of the SPP1 genes in the gene 38 to gene 40 interval resembles that one found in the replication origin regions of different Escherichia coli double-stranded DNA phages (lambda, phi 80 and P22). We propose that the conserved gene organization is representative of the replication origin region of a primordial phage.

Effects of the cold pressor test on short-term fluctuations of finger arterial blood pressure and heart rate in normal subjects

The effect of the cold pressor test on autonomic cardiovascular control was studied non-invasively by means of spectrum analysis of periodic heart rate and blood pressure fluctuations in ten normal subjects. Fast Fourier Transform algorithm based on a 256-point time series (sampling rate 2 Hz, i.e. 2-min and 8-s) was used to estimate the amplitude spectra of heart rate and blood pressure rhythmicity at the low frequency (70-140 mHz) and respiration related frequency (230-270 mHz) band. Respiration rate was controlled at 250 mHz. Auto- and cross-spectral techniques were used to determine the complex relationship between systolic blood pressure and heart rate fluctuations in the frequency domain. The spectral pattern of systolic and diastolic blood pressure showed a marked increment of the absolute and relative (100 multiplied with absolute value/total area under the curve of the amplitude spectrum from 15-500 mHz) low frequency component: control vs. cold pressor test--systolic blood pressure--absolute values (in [mmHg/Hz1/2]): 634.4 +/- 48.9 vs. 827.4 +/- 69.9*; relative values (in [%]): 26 +/- 2 vs. 32 +/- 2*; diastolic blood pressure--absolute values: 433.2 +/- 42.3 vs. 537.2 +/- 45.8*; relative values: 35 +/- 3 vs. 40 +/- 2*, (average +/- SEM, *P < 0.05). The cold pressor test induced no change in average heart rate; the absolute low frequency component in heart rate spectra increased clearly during the test: low frequency component (in [bpm/Hz1/2]): 586.9 +/- 89.9 vs. 712.0 +/- 91.4*, while the relative low frequency component did not change: 29 +/- 3 vs. 30 +/- 3.(ABSTRACT TRUNCATED AT 250 WORDS)

Purification of the beta product encoded by the Streptococcus pyogenes plasmid pSM19035. A putative DNA recombinase required to resolve plasmid oligomers

Genetic evidence suggests that the gene beta product of Streptococcus pyogenes plasmid pSM19035 is required for converting plasmid multimers into monomers. The beta protein was purified from cells overexpressing the cloned gene. N-terminal protein sequence analysis demonstrated that the purified protein had the predicted sequence, except that the N-terminal initiator methionine was not present. Native beta protein consists of a dimer of two identical subunits with a molecular mass of 23.8 kDa (25 kDa in SDS-PAGE). The beta protein (isoelectric point of 9.7) binds specifically to a DNA fragment (312 bp in length) which contains the promoter region of the orf alpha-gene beta operon and two regions (sites I and II) that show dyad axes of symmetry. It is proposed that protein beta binds to sites I and II to mediate resolution of plasmid oligomers.

[Pressure variability in the cold-pressure response test]

The effect of the immersion of the hand in ice water for 5 minutes on the short-term variability of blood pressure (BP) and heart rate (HR) was evaluated in 10 normal subjects. Indirect finger BP was measured by a non-invasive device (Finapres). Analogue-to-digital conversion of the BP was used to determine systolic, diastolic BP and HR every 0.5 second. The equidistant sampling allowed a direct spectral analysis using a fast Fourier transform algorithm on 256 point time series of a stationary period. BP was increased (+28 mmHg for systolic BP and +13 mmHg for diastolic BP) and an increased overall variability of BP and HR was observed during the cold pressor test. The increased areas under the curve of the systolic, diastolic BP and HR spectra were documented with the selective analysis of the two main components of the spectra: the increase in the oscillations of BP and HR during the test predominated in the 70-140 mHz region (+30% for systolic BP, +24% for DBP and +21% for HR), corresponding to Mayer waves. The high-frequency (respiratory) component of BP and HR variability was unchanged. The significant increase in the 10 second period oscillations of BP could reflect the cold-induced sympathetic vasoconstriction.

Effects of plasmapheresis on short-term variability of blood pressure in healthy donors

The acute effect of mild central hypovolaemia induced by plasmapheresis on the short-term variability of blood pressure and heart rate was evaluated in ten healthy donors. Indirect finger blood pressure was measured by a non-invasive device (Finapres). Analogue-to-digital conversion of the blood pressure was used to determine systolic, diastolic and mean blood pressure and heart rate every second. The equidistant sampling allowed a direct spectral analysis using a fast Fourier transform algorithm. Blood pressure and heart rate were maintained while an increased overall variability of blood pressure was observed after plasmapheresis. The increased total area under the curve of the systolic and diastolic blood pressure spectra was documented with the selective analysis of the three main components of the spectra: the increase in the oscillations of blood pressure following plasmapheresis predominated in the 66-129 mHz region, corresponding to Mayer waves. The spectral profile of HR was unaffected by plasmapheresis. The significant increase in the 10-s period oscillations of blood pressure after the mild central hypovolaemia could result from the unloading of cardiopulmonary (and arterial) baroreceptors which in turn could buffer the arterial pressure through sympathetic activation, detected on the systolic and diastolic pressure spectra in the low-frequency range.

Age-related changes of heart rate power spectra in a diabetic man during orthostasis

We used spectral analysis of heart rate variability during orthostatic load in diabetic patients in order to provide quantitative information about first, the alterations of vagal and beta-adrenergic nervous system influence on the heart and secondly, the relation of spectral components of heart rate variability to age. The respiration-related power, and indirect estimate of vagal cardiac control, was significantly reduced in diabetics as compared with controls in both the supine (diabetics: 0.39 (0.18-1.15) l/min2 [median and 25-75% percentiles], controls: 1.52 (0.54-3.84) l/min2, 2P less than 0.01) and the standing (diabetics: 0.27 (0.12-0.84) l/min2, controls: 2.22 (0.67-5.14) l/min2, 2P less than 0.0001) body posture. The difference between supine and standing values of mid-frequency power (delta MF power) that represents beta-adrenergically mediated heart rate variability was significantly smaller in diabetics (delta MF: 0.79 (0.18-3.84) l/min2) than in controls (delta MF: 8.07 (4.35-17.99) l/min2) (2P less than 0.0001). Power of almost all frequency components declined exponentially with age in both positions and groups studied. The decline in power of heart rate variability was more pronounced in controls than in diabetics for either posture. An age-associated significant decrease in delta MF was found in controls (Y = 33.16-0.60X, P less than 0.05, r = -0.49) as compared to diabetics (Y = 8.70-0.16X, P greater than 0.05, r = -0.24). Our results suggest a decreased vagal and sympathetic nervous system input into the heart in diabetics. The premature loosened coupling between heart rate spectral power and age suggests that diabetes mellitus accelerates the aging process. Computerized spectral analysis of heart rate variability seems to be a very sensitive tool to evaluate the influence of the autonomic nervous system on the heart.

A non-invasive approach to cardiac autonomic neuropathy in patients with diabetes mellitus

The purpose of this study was to obtain information regarding the participation of the sympathetic nervous system in cardiac autonomic neuropathy in patients suffering from diabetes mellitus employing spectral analysis of heart rate variability in the supine and standing posture. Ten insulin-dependent diabetic patients (29 +/- 2 years) with a short to moderately long duration of diabetes (11 +/- 1 years) and cardiac vagal neuropathy based on measurements of respiratory sinus arrhythmia were compared to 10 healthy volunteers (27 +/- 1 years) before and after the administration of atropine and atropine plus propranolol. In diabetic patients the reactivity in total power (delta TP) from supine to upright position was significantly lower compared to control subjects before and after atropine. There was no significant difference in delta TP between diabetics and controls after atropine plus propranolol. The magnitude of TP increase is essentially due to the increase of blood pressure related heart rate fluctuations (delta MF) from lying to standing and dependent on beta-adrenergical efferent activity to the heart. In diabetic patients as well as in normal subjects under the influence of atropine plus propranolol the delta MF power was significantly lower compared to the unmedicated control and atropine group. There was no significant difference between diabetics and controls after combined autonomic blockade. It was concluded that delta MF heart rate spectral power could serve as an indirect, non-invasive, quantitative and sensitive marker of early cardiac sympathetic damage.

Heart rate variability in diabetic patients during orthostatic load--a spectral analytic approach

Spectral analysis of heart rate variability (HRV) was used to assess the autonomic nervous control of cardiac function during orthostatic load in insulin-dependent diabetic patients and healthy subjects. The diabetic patients were divided into three groups: diabetics without neuropathy (group 1), diabetics with peripheral neuropathy (group 2), and diabetics with peripheral and autonomic neuropathy (group 3). Resting mid-frequency (MF, 0.05-0.15 Hz) and respiration-related (RF, power around respiration rate) HRV were significantly lower in group 2 and 3 diabetics than in controls, indicating a reduced parasympathetic nervous system influence on the heart. Standing MF and RF spectral power data were significantly lower in all diabetic groups than in controls, suggesting marked alterations in the autonomic cardiovascular control during a mild physical load not only in symptomatic diabetics but also in patients with no signs and symptoms of neuropathy. The difference between supine and standing MF power, an estimate of beta-adrenergic influence on the heart, was significantly lower in all diabetic subject groups studied than in controls. This suggests a reduced sympathetic nervous system influence on the heart in diabetic patients. Our data suggest that computerized spectral analysis of HRV during orthostatic load seems to be a very sensitive method of evaluating of the autonomic nervous systems influence on the heart in patients suffering from diabetes mellitus.

Effect of low-dose atropine on heart rate fluctuations during orthostatic load: a spectral analysis

Spectral analysis was utilized in order to determine the influence of low (0.7 microgram/kg)-dose atropine sulfate injections on the isolated spectral power components of heart rate fluctuations in contrast to moderate (0.02 mg/dose)-dose atropine and unmedicated states in human subjects during orthostatic load. Low-dose atropine decreased mean heart rate and increased respiration-related spectral power compared with controls in both the supine and standing posture. In supine subjects total power (0.01-0.5 Hz) was unchanged compared with controls due to a decreasing trend of low-frequency (0.01-0.05 Hz) and mid-frequency (0.05-0.15 Hz) heart rate spectral power. Standing upright, there was a distinct increase in total power with significantly higher values than in the controls resulting from an enormous activation of mid-frequency heart rate fluctuations. The peak frequency of the mid-frequency component was increased with a strong tendency compared with controls. Moderate-dose atropine increased mean heart rate and decreased total power, mid-frequency and respiration-related heart rate spectral power and peak frequency compared with controls in both positions. Our results suggest that low-dose atropine affects the interaction between sympathetic and parasympathetic limbs in the autonomic control of cardiac function in a complex manner producing a differentiated pattern of heart rate fluctuations dependent on the body posture. We suggest that low-dose atropine augments and moderate-dose atropine attenuates the vagal cardiac efferent activity in each position.

Heart rate fluctuations in diabetic patients with cardiac vagal dysfunction: a spectral analysis

The autonomic nervous control of cardiac function during active orthostatic load has been studied by measuring the power spectrum of heart rate fluctuations in 16 insulin-dependent diabetic patients and 14 age-matched control subjects. The patients were subdivided into two groups: 8 with normal respiratory sinus dysrhythmia (RSA+) and 8 with reduced respiratory sinus dysrhythmia (RSA-). In RSA- patients the total power (0.01-0.50 Hz) was significantly reduced compared with control subjects (4.7 versus 15.5 min-2, 2p less than 0.05) and the pattern of heart rate fluctuations was characterized by a relative increase in the low-frequency component (0.01-0.05 Hz) as compared with RSA+ patients and control subjects (45% versus 24% and 27%, both 2p less than 0.01). There was also a significant reduction in the high-frequency component (0.15-0.50 Hz) as compared with RSA+ patients and control subjects (17% versus 36% and 33%, both 2p less than 0.05). During standing, a significant increase in total power was found only in control subjects (2p less than 0.01) and the difference between control subjects, and RSA+ and RSA- patients reached significance (32.2 versus 15.1 and 12.7 min-2, 2p less than 0.02 and 2p less than 0.01). The pattern of heart rate fluctuations in RSA- patients showed no significant change on standing. These results suggest that the reduced overall heart rate variability in diabetic patients with cardiac autonomic neuropathy is associated with a typical heart rate fluctuation pattern.

Contributions of sympathetic and vagal mechanisms to the genesis of heart rate fluctuations during orthostatic load: a spectral analysis

Spectral analysis was utilized in order to determine the influence of postural change on heart rate fluctuations and respiratory frequencies and to evaluate the frequency-specific contributions of both vagal and beta-adrenergic mechanisms to the genesis of the heart rate fluctuations during change in posture. In unmedicated subjects the total power (0.01-0.5 Hz) of heart rate fluctuations and the relative power at the mid-frequency band (0.05-0.15 Hz) were significantly increased in response to postural change, while the relative power of high-frequency fluctuations (0.15-0.5 Hz) was significantly depressed. Low-frequency fluctuations (0.01-0.05 Hz) were unchanged. The respiratory frequency was non-significantly slowed. The coherence between heart rate and respiration showed a significant reduction during orthostatic load. The heart rate fluctuations above 0.05 Hz were abolished by vagal blockade, during supine rest, while beta-adrenergic blockade reduced fluctuations at the mid-frequency band. Combined blockade caused a depression of heart rate fluctuations over the entire frequency range. On standing, vagal blockade or autonomic double blockade caused a decrease in heart rate fluctuations at each frequency band. After beta-adrenergic blockade alone, mid-frequency and high-frequency fluctuations were significantly reduced. The coherence between heart rate and respiration was nearly abolished under vagal blockade in each body posture. We conclude that the increased sympathetic outflow during orthostatic load is reflected by a marked increase in heart rate spectral power densities in the mid-frequency range.(ABSTRACT TRUNCATED AT 250 WORDS)

Heart rate variability in chronic alcoholics: a follow-up study

Heart rate variability (HRV) was studied in 11 chronic alcoholic subjects, 1-30 days after the beginning of abstinence and again 5, 12 and 24 weeks later. Two patients could be re-examined after 19 and 22 months, respectively. In the follow-up study, the total patient group showed a statistically significant increase in HRV with prolonged abstinence of at least 6 months. No recovery of efferent vagal function was found in 4 patients. It is suggested that the vagal neuropathy may improve in chronic alcoholics, but perhaps only in patients with a short to moderately long duration of drinking history or a functional rather than an organic vagal damage.

Acute alcohol ingestion reduces heart rate variability

Blood pressure, heart rate and heart rate variability (HRV) prior and during acute ethanol intoxication (0.7 g/kg) were studied in 8 healthy volunteers. Blood pressure and heart rate remained unaltered during intoxication. While HRV was significantly reduced immediately after ingestion (2P = 0.01). It is speculated that the reduction of HRV after heavy ethanol consumption contributes to the genesis of cardiac arrhythmias in chronic alcoholics with or without clinical evidence of heart disease.

[Course of heart beat variability following acute alcohol intake]

Blood pressure, heart rate and mean momentary arrhythmia were measured in 16 healthy test persons before and after acute alcohol ingestion. While the blood pressure remained unchanged, heart rate and mean momentary arrhythmia showed significant differences in comparison to the initial value, in which case the clearer change of the mean momentary arrhythmia in relation to the heart rate emphasizes the sensitivity of the parameter. The results are discussed as a sequel of the increase of sympathetic activity of alcohol/acetaldehyde.