Specific association of growth-associated protein 43 with calcium release units in skeletal muscles of lower vertebrates.

Growth-associated protein 43 (GAP43), is a strictly conserved protein among vertebrates implicated in neuronal development and neurite branching. Since GAP43 structure contains a calmodulin-binding domain, this protein is able to bind calmodulin and gather it nearby membrane network, thus regulating cytosolic calcium and consequently calcium-dependent intracellular events. Even if for many years GAP43 has been considered a neuronal-specific protein, evidence from different laboratories described its presence in myoblasts, myotubes and adult skeletal muscle fibers. Data from our laboratory showed that GAP43 is localized between calcium release units (CRUs) and mitochondria in mammalian skeletal muscle suggesting that, also in skeletal muscle, this protein can be a key player in calcium/calmodulin homeostasis. However, the previous studies could not clearly distinguish between a mitochondrion- or a triad-related positioning of GAP43. To solve this question, the expression and localization of GAP43 was studied in skeletal muscle of Xenopus and Zebrafish known to have triads located at the level of the Z-lines and mitochondria not closely associated with them. Western blotting and immunostaining experiments revealed the expression of GAP43 also in skeletal muscle of lower vertebrates (like amphibians and fishes), and that the protein is localized closely to the triad junction. Once more, these results and GAP43 structural features, support an involvement of the protein in the dynamic intracellular Ca2+ homeostasis, a common conserved role among the different species.

Spatial variation of wear on Charité lumbar discs.

Total disc replacement (TDR) is a modern technique employed to treat degenerative disc disease that has the benefit of preserving motion compared with the clinically established spinal fusion. The wear performance of implants based on articulating designs is a key factor that determines their longevity and it is hypothesized that this will be the case for TDR devices. A detailed analysis of the surface of Charité lumbar disc replacements during simulated wear for five million cycles (MC), with inputs defined by the ISO18192-1 standard, is presented. After each million cycles the disc asperity heights, asperity curvature radii and their distributions on the surface of the core of the implant were determined at different locations. Two distinct areas on the surface of Charité polyethylene disc were identified based on the surface topography change during the wear simulation process. Within the area corresponding to the dome the initial roughness decreased, but after 2 MC the surface appeared to roughen with material build-up. More peripherally on the dome the surface roughness decreased after the first MC and remained constant. No effect was noticed on the rim. Furthermore, no statistical difference was noticed between the inferior and superior sides of the core of the disc. The study demonstrated that the wear on the two surfaces of the disc was uneven. This spatial variation is important in modelling the wear processes and providing strategies for reducing wear through enhanced design and modifications to the biotribological properties of the device.

Marked intra-strain variation in response of Listeria monocytogenes dairy isolates to acid or salt stress and the effect of acid or salt adaptation on adherence to abiotic surfaces.

During food processing, and particularly in cheese manufacturing processes, Listeria monocytogenes may be exposed routinely to environments of low pH or high salt concentration. It has been suggested that these environmental conditions may contribute to bacterial adherence to abiotic surfaces and increased resistance to disinfection. In this study strains isolated from the environment of artisanal cheese-making dairies were used to investigate the behaviour of L. monocytogenes in response to acid and salt stress and clear differences between strains was observed. In planktonic culture, strains varied in resistance to low pH or high NaCl concentration and in the occurrence of an adaptive response to moderate acid or NaCl. There was dislocation in responses to salt and acid. Strains resistant, or adaptive, to acid were not resistant or adaptive to NaCl. The reverse also was observed. Exposure to moderate acid did not promote adherence to polystyrene but survival, at low pH or high NaCl concentration, of cells adherent to stainless steel was increased, even for strains that had no adaptive response planktonically, but the detail of these observations varied between strains. In contrast to acid adaptation, with some strains salt adaptation enhanced adherence of L. monocytogenes to polystyrene but this was not true for all strains. For some strains salt- or acid adaptation may enhance the survival of sessile cells exposed to hypochlorite disinfection.

Bacterial cells exposed to nanosecond pulsed electric fields show lethal and sublethal effects.

Cell suspensions of Escherichia coli K12 and Salmonella typhimurium were exposed to electrical pulses of 32 ns duration at a field intensity of 100 kV/cm and a repetition rate of 30 pulses per second for a total of 300 s. Treated cells were plated onto Tryptone Soya Agar (TSA) and TSA supplemented with NaCl, and cell counts were monitored daily for 3 days. The concentrations of NaCl used were 3 and 4% (w/v) for E. coli and 4 and 5% (w/v) for S. typhimurium. Treatment under these conditions resulted in a 2 log(10) reduction for E. coli and approximately a single log(10) reduction for S. typhimurium. For both species of bacteria it was discovered that the surviving population was composed of only 1% of uninjured cells. Moreover, the proportion of sublethally injured cells increased more rapidly than the total recoverable population suggesting a process of injury accumulation culminating in death rather than an 'all or nothing' mechanism. Sublethal injury manifested itself in a proportion of the injured population of both species by an extended lag phase at longer treatment times. Finally, possible mechanisms by which nanosecond electric pulses inactivate bacteria are discussed.

Effects of cell surface loading and phase of growth in cold atmospheric gas plasma inactivation of Escherichia coli K12.

AIMS: To determine the effects of surface cell concentration and phase of growth on the inactivation of Escherichia coli cells using an atmospheric nonthermal plasma. METHODS AND RESULTS: Cells of E. coli K12 were deposited onto the surface of membrane filters and exposed to the plume from a cold atmospheric gas plasma. Scanning electron microscopy revealed severe loss in structural integrity of plasma-treated cells, and optical emission spectra indicated that inactivation was brought about by reactive plasma species. The survival of E. coli cells was found to depend on the cell surface density: as the surface density increased from 10(7) to 10(11) CFU cm(-2), the rate constant in the Baranyi inactivation model decreased from 19.59 to 1.03 min(-1). Cells harvested from mid-exponential, late exponential and stationary phases of growth displayed differences in their resistances to the effects of the plasma however, exponential phase cells were not more susceptible than those from the stationary phase. CONCLUSIONS: High surface concentrations of cells affects the penetration of plasma species and treatment effectiveness. The physiological state of cells, as determined by phase of growth, affects their resistance to plasma inactivation. SIGNIFICANCE AND IMPACT OF THE STUDY: In designing inactivation treatments, surface concentration and cell physiology need to be taken into account.

Antenatal umbilical coiling index and Doppler flow characteristics.

OBJECTIVE: To evaluate whether a relationship exists between the antenatal umbilical coiling index (UCI) and umbilical cord Doppler flow characteristics. METHODS: During the fetal anatomical survey in 200 consecutive pregnant patients at 18-23 weeks' gestation, we recorded umbilical coiling patterns and blood flow characteristics. The antenatal UCI, calculated as a reciprocal value of the distance between a pair of umbilical cord coils, was compared with Doppler parameters including umbilical vein blood flow volume (in mL/min/kg), and mean resistance index (RI) and peak systolic velocity (PSV in cm/s) averaged from both umbilical arteries. RESULTS: A total of 154 patients met the inclusion criteria of singleton pregnancy and having adequate sonographic umbilical cord images, Doppler flow indices, and all demographic, antenatal and labor data. The mean antenatal UCI was 0.40, with 10th and 90th centiles of 0.20 and 0.60, respectively. The mean +/- SD umbilical artery RI and PSV and umbilical vein blood flow volume were 0.74 +/- 0.07, 25.1 +/- 6.4 cm/s, and 264 +/- 106 mL/min/kg, respectively. All Doppler variables correlated significantly with antenatal UCI, with lower RI and higher PSV and umbilical vein blood flow volume values being associated with higher antenatal UCI (P = 0.016, P < 0.001, and P = 0.032, respectively). However, when stratified by antenatal UCI into hyper- (above 90th centile), normo- (10th-90th centile), and hypocoiled (below 10th centile) umbilical cord groups, a significant difference was observed for PSV only (P = 0.016). CONCLUSION: It appears that umbilical cord coiling modulates noticeably blood flow through the umbilical cord. We speculate that more prominent umbilical coiling (higher antenatal UCI values) has a protective effect on blood flow in terms of decreased arterial resistance and higher blood flow velocities, as well as increased venous blood flow. However, due to lack of significant differences between Doppler characteristics when stratified by antenatal UCI into hypo-, normo-, and hypercoiled groups, the clinical implications of this observation are uncertain.

Intraobserver and interobserver reproducibility of fetal biometry.

OBJECTIVE: To assess the intra- and interobserver reproducibility of ultrasound measurements of fetal biometric parameters. METHODS: We assessed the intraobserver and the interobserver agreement in measurements of fetal biparietal diameter (BPD), abdominal circumference (AC), head circumference (HC) and femur length (FL) on 122 singleton pregnancies. Patients were each examined twice by the first sonographer to determine the intraobserver reliability of measurements of fetal biometry. Subsequently, during the same ultrasound examination, a second blinded sonographer measured fetal biometric parameters to assess interobserver reliability. The consensus between and among observers was analyzed using the intraclass correlation coefficient (intra-CC) and interclass correlation coefficient (inter-CC) and the reliability coefficients (RC, alpha) for the four biometric measurements. A value > 0.75 was considered a reliable consensus for the intra-CC and inter-CC. A Bland and Altman plot was also created for the fetal biometric parameters to assess the repeatability of the measurements. RESULTS: Reliable consensus was observed for both the intra-CC and inter-CC and RC for all four biometric parameters. The intra-CC with the 95% CI and RC for the BPD, AC, HC and FL were as follows: 0.996 (0.995, 0.997), alpha 0.998; 0.994 (0.992, 0.996), alpha 0.997; 0.996 (0.994, 0.997), alpha 0.998; and 0.994 (0.992, 0.996), alpha 0.997, respectively. Similarly, the inter-CC with the 95% CI and RC for the same parameters were as follows: 0.995 (0.993, 0.997), alpha 0.998; 0.980 (0.971, 0.990), alpha 0.990; 0.994 (0.992, 0.996), alpha 0.997; and 0.990 (0.985,0.993), alpha 0.995, respectively. The Bland and Altman plots demonstrated a high degree of repeatability of BPD, AC, HC, and FL measurements. CONCLUSION: Our results demonstrate that the intra- and interobserver reproducibility of ultrasound measurements of fetal biometry are highly reliable.

Proteus mirabilis bacteremia: a review of 176 cases during 1980-1992.

Patients with Proteus mirabilis bacteremia at a large community teaching hospital during a 13-year period (1980-1992) were retrospectively reviewed. There were 176 patients whereof 44 (25%) had polymicrobial bacteremia. The median age of patients was 75 years and 64.2% were 70 years or older. Of the patients 56.8% came from a nursing home, 64.2% had an indwelling Foley catheter, and 20.5% nosocomial bacteremia. The most common source of bacteremia was the urinary tract (52.8%) whereas the lower respiratory tract was an uncommon source. Hypotension was present in 30.1% of patients. The overall mortality rate was 29.0% with an attributable mortality rate of 25.6%. The mortality rate of polymicrobial bacteremia (38.6%) was higher than that of monomicrobial bacteremia (25.8%). For patients with monomicrobial bacteremia, significant increase in mortality was found in patients who had nosocomial infection (p < 0.02), whose source of bacteremia was other than the urinary tract (p < 0.01), who had ultimately fatal underlying conditions (p < 0.01), who had hypotension (p < 0.001), who had increase in serum creatinine (p < 0.05), or who had increase in serum bilirubin (p < 0.05).