Cost and Utility of Routine Contrast-Enhanced Neck MRA in a Pediatric MRI Stroke Evaluation Protocol

BACKGROUND AND PURPOSE

Cervical arterial dissection is one of the frequent causes of pediatric arterial ischemic stroke. Out of concern for missing cervical arterial dissection in patients in whom pediatric stroke is suspected, our tertiary children's hospital added contrast-enhanced 3D neck MR angiography to every pediatric stoke work-up. This research investigated whether the routine use of contrast-enhanced neck MRA in our MR imaging stroke protocol ever detected a cervical arterial abnormality when the DWI, SWI/gradient recalled-echo, or circle of Willis MRA findings from the brain MR imaging were reported as normal.

MATERIALS AND METHODS

The institutional PACS data base was searched for stroke protocol MRIs that included DWI, gradient recalled-echo or SWI, circle of Willis MRA, and 3D contrast-enhanced neck MRA in patients younger than 18 years of age with examinations performed between September 2010 and June 2017.

RESULTS

In only a single case (0.15%) were the DWI, SWI/gradient recalled-echo, or circle of Willis MRA findings all separately reported as normal and the contrast-enhanced neck MRA findings reported as abnormal. To reach these findings, we screened 681 patients, which would have resulted in an estimated >$200,000 in Medicare charges and $80,000 in of out-of-pocket cost to patients.

CONCLUSIONS

In our large series, the addition of a routine contrast-enhanced neck MRA to our pediatric stroke MR imaging protocol was of extremely low yield. We believe the use of neck MRA should reasonably be limited to cases in which abnormalities are initially detected on standard brain sequences or to patients with atypical presentation or recurrent pathology.

Joining of Aluminium Structures with Aluminium Foams

The aim of this work is the evaluation of new construction elements for applications in transportation industry which are based on new designs incorporating commonly applied aluminium structures and aluminium foams. The work includes the characterisation of the joining process, the joining mechanism and the mechanical properties of the joining zone. A testing method for the joints is developed which is based on a common tensile test in order to evaluate the influence of the main laser welding parameters on the toughness of the joints and to afford a comparison between laser beam welding and gluing process. The analysis of the joining mechanism is investigated with the help of metallographic studies. In addition, the energy absorption properties of aluminium hollows filled and joined with foam structures are characterised.

Critical heat stress evaluation of clothing ensembles with different levels of porosity

A common metric of assessing the evaporative cooling potential of protective clothing is to assess the rate of diffusion of water vapour through the fabric. Another mechanism that supports evaporative cooling is convective transfer. Prototype porous coveralls were constructed to promote convective air flow with 0.0024 mm (0.06 inch) holes representing nominal openings of 0, 1, 2, 5, 10 and 20% of the garment surface area (called P00, P01, P02, P05, P10 and P20). The purpose of this study was to evaluate the ability of these porous coverall configurations to support evaporative cooling. The assessment measures were critical wet bulb globe temperature (WBGT) and apparent evaporative resistance via a progressive heat stress protocol. There was a progressive increase in critical WBGT with increases in convective permeability for P00, Saratoga Hammer, P01, work clothes and P02. There was no further increase for P05, P10 and P20. A similar pattern was found for diffusive permeability, with the exception of Saratoga Hammer, which suggested that the convective permeability could explain evaporative cooling better than diffusive permeability. STATEMENT OF RELEVANCE: Protective clothing often interferes with evaporative cooling and thus increases the level of heat stress. While increased diffusion of water vapour is associated with lower evaporative resistances, the convective movement of water vapour is a dominant mechanism and better explains the role of the clothing in heat stress.

Transient Accumulation of Glycine Betaine and Dynamics of Endogenous Osmolytes in Salt-Stressed Cultures of Sinorhizobium meliloti

The fate of exogenously supplied glycine betaine and the dynamics of endogenous osmolytes were investigated throughout the growth cycle of salt-stressed cultures of strains of Sinorhizobium meliloti which differ in their ability to use glycine betaine as a growth substrate, but not as an osmoprotectant. We present (sup13)C nuclear magnetic resonance spectral and radiotracer evidence which demonstrates that glycine betaine is only transiently accumulated as a cytoplasmic osmolyte in young cultures of wild-type strains 102F34 and RCR2011. Specifically, these strains accumulate glycine betaine as a preferred osmolyte which virtually prevents the accumulation of endogenous osmolytes during the lag and early exponential phases of growth. Then, betaine levels in stressed cells decrease abruptly during the second half of the exponential phase. At this stage, the levels of glutamate and the dipeptide N-acetylglutaminylglutamine amide increase sharply so that the two endogenous solutes supplant glycine betaine in the ageing culture, in which it becomes a minor osmolyte because it is progressively catabolized. Ultimately, glycine betaine disappears when stressed cells reach the stationary phase. At this stage, wild-type strains of S. meliloti also accumulate the disaccharide trehalose as a third major endogenous osmolyte. By contrast, glycine betaine is always the dominant osmolyte and strongly suppresses the buildup of endogenous osmolytes at all stages of the growth cycle of a mutant strain, S. meliloti GMI766, which does not catabolize this exogenous osmoprotectant under any growth conditions.

Age-related changes in triathlon performances

The aim of this study was two-fold: i) to analyse age-related declines in swimming, cycling, and running performances for Olympic and Ironman triathlons, and ii) to compare age-related changes in these three disciplines between the Olympic and Ironman triathlons. Swimming, cycling, running and total time performances of the top 10 males between 20 and 70 years of age (in 5 years intervals) were analysed for two consecutive world championships (2006 and 2007) for Olympic and Ironman distances. There was a lesser age-related decline in cycling performance (p<0.01) compared with running and swimming after 55 years of age for Olympic distance and after 50 years of age for Ironman distance. With advancing age, the performance decline was less pronounced (p<0.01) for Olympic than for Ironman triathlon in cycling (>55 years) and running (>50 years), respectively. In contrast, an age-related decline in swimming performance seemed independent of triathlon distance. The age-related decline in triathlon performance is specific to the discipline, with cycling showing less declines in performance with age than swimming and running. The magnitude of the declines in cycling and running performance at Ironman distance is greater than at Olympic distance, suggesting that task duration exerts an important influence on the magnitude of the age-associated changes in triathlon performance.

Neuromuscular fatigue following constant versus variable-intensity endurance cycling in triathletes

The aim of this study was to determine whether or not variable power cycling produced greater neuromuscular fatigue of knee extensor muscles than constant power cycling at the same mean power output. Eight male triathletes (age: 33+/-5 years, mass: 74+/-4 kg, VO2max: 62+/-5 mL kg(-1) min(-1), maximal aerobic power: 392+/-17 W) performed two 30 min trials on a cycle ergometer in a random order. Cycling exercise was performed either at a constant power output (CP) corresponding to 75% of the maximal aerobic power (MAP) or a variable power output (VP) with alternating +/-15%, +/-5%, and +/-10% of 75% MAP approximately every 5 min. Maximal voluntary contraction (MVC) torque, maximal voluntary activation level and excitation-contraction coupling process of knee extensor muscles were evaluated before and immediately after the exercise using the technique of electrically evoked contractions (single and paired stimulations). Oxygen uptake, ventilation and heart rate were also measured at regular intervals during the exercise. Averaged metabolic variables were not significantly different between the two conditions. Similarly, reductions in MVC torque (approximately -11%, P<0.05) after cycling were not different (P>0.05) between CP and VP trials. The magnitude of central and peripheral fatigue was also similar at the end of the two cycling exercises. It is concluded that, following 30 min of endurance cycling, semi-elite triathletes experienced no additional neuromuscular fatigue by varying power (from +/-5% to 15%) compared with a protocol that involved a constant power.

Relation between preferred and optimal cadences during two hours of cycling in triathletes

OBJECTIVES

To determine whether the integrated electromyographic signal of two lower limb muscles indicates preferred cadence during a two hour cycling task.

METHODS

Eight male triathletes performed right isometric maximum voluntary contraction (MVC) knee extension and plantar flexion before (P1) and after (P2) a two hour laboratory cycle at 65% of maximal aerobic power. Freely chosen cadence (FCC) was also determined, also at 65% of maximal aerobic power, from five randomised three minute sessions at 50, 65, 80, 95, and 110 rpm. The integrated electromyographic signal of the vastus lateralis and gastrocnemius lateralis muscles was recorded during MVC and the cycle task.

RESULTS

The FCC decreased significantly (p<0.01) from P1 (87.4 rpm) to P2 (68.6 rpm), towards the energetically optimal cadence. The latter did not vary significantly during the cycle task. MVC of the vastus lateralis and gastrocnemius lateralis decreased significantly (p<0.01) between P1 and P2 (by 13.5% and 9.6% respectively). The results indicate that muscle activation at constant power was not minimised at specific cadences. Only the gastrocnemius lateralis muscle was affected by a two hour cycling task (especially at 95 and 110 rpm), whereas vastus lateralis remained stable.

CONCLUSION

The decrease in FCC observed at the end of the cycle task may be due to changes in the muscle fibre recruitment pattern with increasing exercise duration and cadence.

Base Composition of Coffea AFLP Sequences and Their Conservation Within the Genus

Amplified fragment length polymorphism (AFLP) is often used for genetic mapping and diversity analysis, but very little information is currently available on their sequence characteristics. Species-specific sequences were analyzed from a single Coffea genome (Coffea pseudozanguebariae) associated with clustered or nonclustered AFLP loci of known genetic position. Compared with the expressed sequence tag (EST) sequence composition, their AT content exhibited a bimodal distribution with AT-poor sequences corresponding mainly to putative coding sequences. AT-rich sequences, apart from the EST distribution, were usually clustered on the genetic map and might correspond to noncoding sequences. Conversion of these AFLP markers into sequence-characterized amplified region (SCAR) anchor markers allowed us to assess sequence conservation within Coffea species with respect to species relatedness.

[Antibacterial effect of two glycine betaine analogues against Escherichia coli]

Strains of enterobacteria that cause urinary tract infections are able to grow in urine with high tonicity. In such conditions bacterias adapt to osmotic forces by incorporation of osmoprotectant compounds including glycine betaine. Accumulation of toxic analogues in bacteria, using inducible betaine transporters, has been previously proposed for development of antibiotics. In this study we report antibacterial effect of two analogues against 82 strains of Escherichia coli isolated form urinary tract infections. Minimal inhibitory concentrations have been measured with and without osmotic stress. The betaine analogues have antibacterial effect against E. coli strains, but only in presence of an osmotic stress.

Effect of cycling cadence on subsequent 3 km running performance in well trained triathletes

OBJECTIVES

To investigate the effect of three cycling cadences on a subsequent 3000 m track running performance in well trained triathletes.

METHODS

Nine triathletes completed a maximal cycling test, three cycle-run succession sessions (20 minutes of cycling + a 3000 m run) in random order, and one isolated run (3000 m). During the cycling bout of the cycle-run sessions, subjects had to maintain for 20 minutes one of the three cycling cadences corresponding to 60, 80, and 100 rpm. The metabolic intensity during these cycling bouts corresponded approximately to the cycling competition intensity of our subjects during a sprint triathlon (> 80% VO(2)max).

RESULTS

A significant effect of the prior cycling exercise was found on middle distance running performance without any cadence effect (625.7 (40.1), 630.0 (44.8), 637.7 (57.9), and 583.0 (28.3) seconds for the 60 rpm run, 80 rpm run, 100 rpm run, and isolated run respectively). However, during the first 500 m of the run, stride rate and running velocity were significantly higher after cycling at 80 or 100 rpm than at 60 rpm (p<0.05). Furthermore, the choice of 60 rpm was associated with a higher fraction of VO(2)max sustained during running compared with the other conditions (p<0.05).

CONCLUSIONS

The results confirm the alteration in running performance completed after the cycling event compared with the isolated run. However, no significant effect of the cadence was observed within the range usually used by triathletes.

Influence of drafting during swimming on ratings of perceived exertion during a swim-to-cycle transition in well-trained triathletes

After the swim to cycle transition of a triathlon, perceived exertion (RPE) during cycling was higher than during a single cycling bout for 8 well-trained triathletes, but swimming in a drafting position led to lower RPE responses and energy cost of cycling than swimming alone.

Comparison of ergonomic risk assessment outputs from Rapid Upper Limb Assessment and the Strain Index for tasks in automotive assembly plants

This paper compares the ergonomic risk assessment of a task for the upper extremities as determined by Rapid Upper Extremity Assessment (RULA) and the Strain Index (SI). The ergonomic risk to the upper extremities of 244 automotive assembly plant tasks were evaluated using RULA and SI. The outcomes of each tool were compared for each task. Results from this study provide practical insight into the methods used in each tool. This study compared only the ergonomic risk outputs from each tool; it does not pursue the question of which tool best predicts injury. The kappa score was 0.11, indicating little agreement between the outputs of the two tools. This is supported by the lack of monotonicity with a gamma score of 0.1. These results indicate that the risk assessment outcome of these two ergonomic assessment tools for the upper extremities do not agree.

Osmoprotection by pipecolic acid in Sinorhizobium meliloti: specific effects of D and L isomers

DL-Pipecolic acid (DL-PIP) promotes growth restoration of Sinorhizobium meliloti cells facing inhibitory hyperosmolarity. Surprisingly, D and L isomers of this imino acid supplied separately were not effective. The uptake of L-PIP was significantly favored in the presence of the D isomer and by a hyperosmotic stress. Chromatographic analysis of the intracellular solutes showed that stressed cells did not accumulate radiolabeled L-PIP. Rather, it participates in the synthesis of the main endogenous osmolytes (glutamate and the dipeptide N-acetylglutaminylglutamine amide) during the lag phase, thus providing a means for the stressed cells to recover the osmotic balance. (13)C nuclear magnetic resonance analysis was used to determine the fate of D-PIP taken into the cells. In the absence of L-PIP, the imported D isomer was readily degraded. Supplied together with its L isomer, D-PIP was accumulated temporarily and thus might contribute together with the endogenous osmolytes to enhance the internal osmotic strength. Furthermore, it started to disappear from the cytosol when the L isomer was no longer available in the culture medium (during the late exponential phase of growth). Together, these results show an uncommon mechanism of protection of osmotically stressed cells of S. meliloti. It was proved, for the first time, that the presence of the two isomers of the same molecule is necessary for it to manifest an osmoprotective activity. Indeed, D-PIP seems to play a major role in cellular osmoadaptation through both its own accumulation and improvement of the utilization of the L isomer as an immediate precursor of endogenous osmolytes.

Influence of the menstrual cycle phase and menstrual symptoms on maximal anaerobic performance

PURPOSE

This study was designed to analyze the effect of the menstrual cycle phase on maximal anaerobic performance during short-term anaerobic tests.

METHODS

Seven eumenorrheic women (NOC) and 10 women using monophasic oral contraceptives (OC) performed three anaerobic tests (force-velocity, multi-jump, and squatting jump tests) during menstruation (M: between days 1 and 4), the midfollicular phase (F: between days 7 and 9), and the midluteal phase (L: between days 19 and 21) of the ovarian cycle. Follicular and luteal phases were confirmed by serum progesterone levels. The order of testing sessions was randomly assigned and a 15-min standardized warm-up preceded each testing session. Rectal temperatures were taken before (Trec(b)) and after (Trec(a)) warm-up.

RESULTS

No significant differences were observed among M, F, and L in Trec(b), Trec(a) maximal cycling power (Pmax(c)), maximal jumping power (Pmax(j)), or maximal height of jump (h(j)) in either NOC or OC. Ten of the women suffered premenstrual or menstrual symptoms (MS); the other seven did not report any premenstrual or menstrual discomfort (NMS). Presence or absence of symptoms was not correlated with oral contraceptive use. No significant differences were observed among the three stages of the menstrual cycle in Pmax(c), Pmax(j), or h(j) in NMS. In MS, only Pmax(j) decreased by 8% in M compared with that in F (P < 0.05).

CONCLUSIONS

Although there were no significant differences in maximal anaerobic performance during different menstrual cycle phases, results of this study suggest that the presence or absence of premenstrual or menstrual syndrome symptoms may have an effect, possibly through an action on the stretch-shortening cycle of tendons and ligaments.

Glycine betaine-assisted protein folding in a lysA mutant of Escherichia coli

Osmoprotectants exogenously supplied to a hyperosmotic culture medium are efficiently imported and amassed by stressed cells of Escherichia coli. In addition to their evident role in the recovery and maintenance of osmotic balance, these solutes should play an important role on the behavior of cellular macromolecules, for example in the process of protein folding. Using a random chemical mutagenesis approach, a conditional lysine auxotrophic mutant was obtained. The growth of this mutant was restored by addition of either lysine or osmoprotectants including glycine betaine (GB) in the minimal medium. The growth rate increased proportionally with the augmentation of the intracellular GB concentration. The mutation was located in the lysA gene and resulted in the substitution of the Ser at position 384 by Phe of the diaminopimelate decarboxylase (DAPDC), which catalyzes the conversion of meso-diaminopimelate to L-lysine. We purified both the wild type DAPDC and the mutated DAPDC-sf and demonstrated that GB was capable of activating DAPDC-sf in vitro, thus confirming the in vivo results. Most importantly, we showed that the activation was correlated with a conformational change of DAPDC-sf. Taken together, these results show, for the first time, that GB may actively assist in vivo protein folding in a chaperone-like manner.

Diurnal variations in ventilatory and cardiorespiratory responses to submaximal treadmill exercise in females

Diurnal variations in ventilatory and cardiorespiratory responses to submaximal treadmill exercise were analysed in 11 eumenorrhoeic women and in 10 women using monophasic oral contraceptives. Subjects performed submaximal treadmill exercise at three intensities averaging 7, 8, and 9 km x h(-1), each for 4 min at 0800, 1300 and 1700 hours, assigned randomly on 3 separate days. Rectal temperature was measured before (T(rec(b))) and after (T(rec(a))) exercise. Cardiac frequency (f(c)), ventilation (V(E)), oxygen uptake (VO(2)), carbon dioxide output (VCO(2)), and respiratory exchange ratio (R) were assessed in the last minute of each stage of the exercise. Both T(rec(b)) and T(rec(a)) increased from 0800 to 1700 hours (P < 0.001). For a given submaximal work rate, VO(2) and VCO(2) were higher in the afternoon compared to the morning. Similarly, R was increased at 1700 hours compared to 0800 hours during the recovery period following exercise (P < 0.05). However, V(E) did not vary significantly during the day at any of the running intensities. No significant interactions (group x time of day) were observed in any of the studied parameters. In contrast to ventilation, the VO(2) and VCO(2) of the females during submaximal exercise were both affected by the time of day, without any differences between eumenorrhoeic women and users of oral contraceptives.

Laparoscopic splenectomy: single-centre experience of a district general hospital

We report the results of 20 consecutive laparoscopic splenectomies performed on haematology patients for a number of indications. Our series includes patients up to 77 years of age at the time of surgery and removal of spleens weighing up to 3530 g. The most significant benefit is the early rate of discharge post-operatively (median 2 d); however, there is a risk of conversion to open laparotomy (in this series 3/20, 15%). We show that laparoscopic splenectomy can be offered as a therapeutic option to patients unfit for conventional laparotomy and that even large and bulky spleens can be removed safely using this approach.

Nanomolar levels of dimethylsulfoniopropionate, dimethylsulfonioacetate, and glycine betaine are sufficient to confer osmoprotection to Escherichia coli

We combined the use of low inoculation titers (300 +/- 100 CFU/ml) and enumeration of culturable cells to measure the osmoprotective potentialities of dimethylsulfoniopropionate (DMSP), dimethylsulfonioacetate (DMSA), and glycine betaine (GB) for salt-stressed cultures of Escherichia coli. Dilute bacterial cultures were grown with osmoprotectant concentrations that encompassed the nanomolar levels of GB and DMSP found in nature and the millimolar levels of osmoprotectants used in standard laboratory osmoprotection bioassays. Nanomolar concentrations of DMSA, DMSP, and GB were sufficient to enhance the salinity tolerance of E. coli cells expressing only the ProU high-affinity general osmoporter. In contrast, nanomolar levels of osmoprotectants were ineffective with a mutant strain (GM50) that expressed only the low-affinity ProP osmoporter. Transport studies showed that DMSA and DMSP, like GB, were taken up via both ProU and ProP. Moreover, ProU displayed higher affinities for the three osmoprotectants than ProP displayed, and ProP, like ProU, displayed much higher affinities for GB and DMSA than for DMSP. Interestingly, ProP did not operate at substrate concentrations of 200 nM or less, whereas ProU operated at concentrations ranging from 1 nM to millimolar levels. Consequently, proU(+) strains of E. coli, but not the proP(+) strain GM50, could also scavenge nanomolar levels of GB, DMSA, and DMSP from oligotrophic seawater. The physiological and ecological implications of these observations are discussed.

Toxicity and osmoprotective activities of analogues of glycine betaine obtained by solid phase organic synthesis towards Sinorhizobium meliloti

Seven analogues of the bacterial osmoprotectant glycine betaine (GB, trimethylammonioacetate), in which the methyl groups of the Me3N+ moiety are replaced by various substituents, were obtained by SPOS using Wang resin. Their biological activities (osmoprotection vs toxicity), appeared closely related to their uptake efficiency and their catabolism in the betaine-demethylating model bacterium Sinorhizobium meliloti.

Sucrose is a nonaccumulated osmoprotectant in Sinorhizobium meliloti

Intracellular accumulation of sucrose in response to lowered water activity seems to occur only in photosynthetic organisms. Here we demonstrate, for the first time, the potent ability of this common sugar, supplied exogenously, to reduce growth inhibition of Sinorhizobium meliloti cells in media of inhibitory osmolarity. Independently of the nature of the growth substrates and the osmotic agent, sucrose appears particularly efficient in promoting the recovery of cytoplasmic volume after plasmolysis. Surprisingly, sucrose is not accumulated by the bacteria at an osmotically efficient level. Instead, it strongly stimulates the accumulation of the main endogenous osmolytes glutamate and N-acetylglutaminylglutamine amide (NAGGN). Examining cell volume changes during the hyperosmotic treatment, we found a close correlation between the enhancement of the osmotically active solute pool and the increase in cell volume. Sucrose shares several features with ectoine, another nonaccumulated osmoprotectant for S. meliloti. Overall, osmoregulation in S. meliloti appears to be strongly divergent from that in most bacteria.

Differential Effects of Dimethylsulfoniopropionate, Dimethylsulfonioacetate, and Other S-Methylated Compounds on the Growth of Sinorhizobium meliloti at Low and High Osmolarities

An extract from the marine alga Ulva lactuca was highly osmoprotective in salt-stressed cultures of Sinorhizobium meliloti 102F34. This beneficial activity was due to algal 3-dimethylsulfoniopropionate (DMSP), which was accumulated as a dominant compatible solute and strongly reduced the accumulation of endogenous osmolytes in stressed cells. Synthetic DMSP also acted as a powerful osmoprotectant and was accumulated as a nonmetabolizable cytosolic osmolyte (up to a concentration of 1,400 nmol/mg of protein) throughout the growth cycles of the stressed cultures. In contrast, 2-dimethylsulfonioacetate (DMSA), the sulfonium analog of the universal osmoprotectant glycine betaine (GB), was highly toxic to unstressed cells and was not osmoprotective in stressed cells of wild-type strains of S. meliloti . Nonetheless, the transport and accumulation of DMSA, like the transport and accumulation of DMSP and GB, were osmoregulated and increased fourfold in stressed cells of strain 102F34. Strikingly, DMSA was not toxic and became highly osmoprotective in mutants that are impaired in their ability to demethylate GB and DMSA. Furthermore, 2-methylthioacetate and thioglycolic acid (TGA), the demethylation products of DMSA, were excreted, apparently as a mechanism of cellular detoxification. Also, exogenous TGA and DMSA displayed similar inhibitory effects in strain 102F34. Thus, on the basis of these findings and other physiological and biochemical evidence, we infer that the toxicity of DMSA in wild-type strains of S. meliloti stems from its catabolism via the GB demethylation pathway. This is the first report describing the toxicity of DMSA in any organism and a metabolically stable osmoprotectant (DMSP) in S. meliloti.

Mutations of the granulocyte-colony stimulating factor receptor in patients with severe congenital neutropenia are not required for transformation to acute myeloid leukaemia and may be a bystander phenomenon

Point mutations of the granulocyte-colony stimulating factor receptor (G-CSFR) resulting in an abnormally truncated receptor have been implicated in the pathogenesis of some cases of severe congenital neutropenia (SCN) and in the transformation of SCN to acute myeloid leukaemia (AML). We report here studies in 11 patients with SCN. No mutations were detected in the one patient who developed AML indicating that development of such mutations is not a prerequisite for transformation. Truncation mutations were detected in a minor percentage of transcripts from two other patients. In one patient the mutation has been constant at a low level (5-10% of total mRNA and 2/40 myeloid colonies) for 2 years. In the other patient the mutation was acquired, remained present at low levels for nearly 3 years and then spontaneously disappeared. Both patients had polyclonal haemopoiesis. We hypothesize that these mutations do not cause SCN, are randomly acquired with the mutant clone being expanded to detectable levels by high levels of exogenous or endogenous G-CSF, and may disappear by clonal succession. In a pre-leukaemic marrow the mutated subclone could achieve high levels, but this does not necessarily indicate a primary role of the mutant receptor in the leukaemogenic process.

Continuous heart rate monitoring over 1 week in teenagers aged 11-16 years

Heart rate (HR) was monitored in 66 French pubertal boys (B, n = 28) and girls (G, n = 38) aged 11-16 years to evaluate habitual physical activity (HPA) over a 1-week period in the winter. The HR and the percentage of heart rate reserve (%HRR) were taken to be indexes of the metabolic activity for the whole day and for the different parts of the day. The HPA was evaluated from the time spent each day below 50%HRR, between 50%-70%HRR and above 70%HRR, which related to the time spent in no or low physical activity (NLPA), moderate physical activity (MPA) and vigorous physical activity (VPA), respectively. No sex differences were observed in the average %HRR each day [%HRRmean, [B 30 (SD 4)%; G 32 (SD 4)%]] or in NLPA [B 715 (SD 61) min, G 711 (SD 81) min] and VPA [B 19 (SD 16) min, G 21 (SD 21) min] throughout the week. During school days, daily %HRRmean was 7% smaller in 14-16 year olds compared to 11-13 year olds. This was linked to a decrease in MPA and a concomitant increase in NLPA (P < 0.05). Daily %HRRmean varied significantly during the week (range: 28-34% HRR). There were significant differences among the periods of the day (P < 0.05). The HR was the greatest during physical education lessons [128 (SD 11) beats x min(-1)], recreation [113 (SD 15) beats x min(-1)] and lunch break [108 (SD 12) beats x min(-1)] and the lowest during the evening [94 (SD 10) beats x min(-1)]. It was only during the lunch breaks that %HRRmean was greater (P < 0.05) on school days than on free days. Of all the teenagers studied 32% were considered active during the week.

Time-of-day effects in maximal anaerobic leg exercise

Time of day variations in maximal anaerobic leg exercise were studied in 23 men mean age 23 (SD 3) years. All the subjects performed two anaerobic tests (force-velocity and multi-jump tests) and those familiar with sprinting ran an additional 50-m dash (n = 16). The maximal anaerobic powers for cycling and jumping (Pcycling and Pjump) and maximal anaerobic velocity (vpeak) were performed consecutively in the same order for all tests. The force-velocity and force-power relationships were established to determine Pcycling. The flight time (tf) and the ground contact time (tc) were recorded from five consecutive jumps on a jump-ergometer to calculate Pjump. The vpeak was measured between the 35th and the 45th m during the dash-run. The test schedules were at 0900, 1400 and 1800 hours on separate days in random order. Rectal temperatures (Tre) and body mass (mb) were measured before each test. The Tre increased significantly from 0900 to 1800 hours (P < 0.001) but mb did not vary during the day (P > 0.05). The Pcycling and Pjump were higher at 1400 and 1800 hours than at 0900 hours. The differences between the morning and the afternoon reached 3% (P < 0.05) for Pcycling and 5%-7% for Pjump (P < 0.01). The time-of-day effect was significant for tf (P < 0.05) but not for tc. During the dash-run tests, the differences almost reached significance for vpeak between 0900 and 1800 hours (P = 0.0544). No significant variations were observed between 1400 and 1800 hours for cycling, jumping and running tests. A time-of-day effect in the maximal anaerobic power of cycle and multi-jump tests existed. Such variations would have pronounced effects when expressed in competitions.

Relationships between oxygen consumption and heart rate in transitory and steady states of exercise and during recovery: influence of type of exercise

Relationships between percentage of maximal oxygen consumption (%VO2max) and percentage of maximal heart rate reserve (%f(cr)) were compared during steady states of exercise (S), transitory states of exercise (T) and a 5-min recovery period (R). Male adults [mean age 27 (SD 10) years] were studied exercising on a treadmill (TR, n = 26), cycle ergometer (CE, n = 14) and arm traction bench (ATB, n = 14). The exercise intensity was adjusted according to the subjects in order to reach exhaustion in 4-5 steps of 2 min (ATB) or 3 min (TR, CE). The 1st min of each stage was considered as T and the last minute of each stage as S. The oxygen consumption (VO2) and heart rate (f(c)) were recorded simultaneously. Significant correlations were observed for each type of exercise and for each state between %f(cr) and %VO2max (r range 0.87-1.00). During T and R, the %VO2max versus %f(cr) relationships were laterally shifted, suggesting a resetting of f(c) control mechanisms. In S, the intercept was greater than in T and R; in T, the slope was greater than in S and R. The VO2 could be predicted from individual %VO2max versus %f(cr) relationships during T and R as is usually done in S using specific equations. Taking into consideration the average relationships established on the three ergometers, the standard error of the predicted VO2 during S and T reached 10%-20% and 22%-38% in R. During exercise, the higher the intensity the better was the prediction of VO2 from f(c) (r range 0.46-0.60, P < 0.001). Therefore except at high exercise intensities, it was found that individual relationships had to be used to obtain an accurate estimation of VO2.

Evaluation of habitual physical activity from a week's heart rate monitoring in French school children

Habitual physical activity (HPA) was studied in 30 boys and 34 girls aged 6-11 years. All the children performed a shuttle run test (SRT) to assess maximal heart frequency (fcmaxSRT) and to evaluate maximal oxygen uptake (VO2maxSRT). Heart rate (fc) was measured continuously from Monday to Sunday, using a heart rate counter. The time spent at fc greater than 140 beats. min-1 (tfc > 140) and at fc greater than 160 beats. min-1 (tfc > 160) permitted HPA to be evaluated. The daily heart rate (fcd) and the percentage of heart rate reserve (%fcrd) were calculated to evaluate the metabolic activity. In the boys and girls, fcd and % fcrd varied little with age. The metabolic activity varied in a rhythmical way during the week and was higher during school days than during free days (P < 0.001). The children were more active during school days (ds) than during the free days (df). This observation was particularly marked in the boys having tfc > 140 being twice as high during ds compared to df [tfc > 140, ds 85 (SD 25), df 40 (SD 26) min; tfc > 160, ds 36 (SD 19), df 16 (SD 13) min]. During ds tfc > 160 was greater in the boys than in the girls (P < 0.01). The same held for tfc > 140 and % fcrd from the age of 9 years (P < 0.001). It was during the recreation periods that the differences between the boys and the girls were observed (P < 0.01). There was no significant difference between the boys and the girls during lessons, in the evening and during df (% fcrd 26-28%, tfc > 140 35-45 min, tfc > 160 10-18 min). In contrast, the children who were physically active in a sports club, had less spontaneous physical activity and % fcrd, tfc > 140, tfc > 160 and VO2maxSRT were identical to those of the other children.

Analysis of granulocyte colony stimulating factor receptor isoforms, polymorphisms and mutations in normal haemopoietic cells and acute myeloid leukaemia blasts

Deletion mutants of the intracytoplasmic domain of the granulocyte colony stimulating factor receptor (G-CSFR) have shown that it contains a membrane-proximal region which must be conserved to allow the receptor to transduce a mitotic signal, and a C-terminal region necessary for transduction of cell differentiation. Changes in the intracytoplasmic domain may result in the uncoupling of these two processes, as in acute leukaemia, and such alterations could occur either as isoforms or mutations. We have studied the transmembrane domain and intracytoplasmic tail of the G-CSFR in RNA from blood or bone marrow of 11 haematologically normal controls and 40 patients with acute myeloid leukaemia (AML). Two novel transcripts of the receptor were identified, both were minor components and are unlikely to be of major physiological significance. We could find no evidence for altered levels of expression of these transcripts in the AML patients. In addition, only one point mutation was detected in the 40 patients screened by RT-PCR-SSCP, a C-->A substitution at nucleotide 2088 which changes a threonine to asparagine in the transmembrane domain and is probably a polymorphism. These results suggest that abnormalities in the G-CSFR are uncommon in AML.

Marine macroalgae as a source for osmoprotection for Escherichia coli

At elevated osmolarity of the mineral medium M63, marine macroalgae constitute important osmoprotectants and nutrients sources for Escherichia coli. Growth of bacterial population (16 strains) was improved by supplementing M63 salts medium with either aqueous or ethanolic algal extracts obtained from Ascophyllum nodosum, Fucus serratus, Enteromorpha ramulosa, Ulva lactuca, and Palmaria palmata. In their presence, growth was still observed even at 1.02 M NaCl. Furthermore, the E. coli ZB400 growth in presence of whole macroalgae thalli in M63/0.85 M NaCI reached its maximum within 24 h (5 × 10(7) - 5 × 10(8) colony-forming units [CFU] per milliliter). In the presence of A. nodosum, bacterial growth was inhibited. In the same experimental conditions, ethanolic extracts improved E. coli growth significantly, because the yield reached 10(11) CFU per milliliter. Ulva lactuca and P. palmata allowed the better growth. The Dragendorff-positive compounds extracted from bacterial cells growing on each ethanolic extract exhibited an osmoprotective effect as proved by a disk-diffusion assay. On the other hand, the -onium compounds (quaternary ammonium [betaines] and tertiary sulphonium) and total free amino acid contents of U. lactuca ethanolic extracts were higher than in others. Fucaceae extracts demonstrated especially high protein content. Algal extracts constitute not only an appreciable osmoprotection source for E. coli but also nutrient sources.

Flow cytometric analysis of uterine sarcomas

Eighty-four women with sarcoma uteri were evaluated on the basis of histopathological examination findings. In 45 of the 84 cases, a flow cytometric measure of DNA content and S-phase fraction was performed. Thirty-seven cases of the 45 were available for estimation of S-phase fraction. The histopathologic examination of paraffin-embedded tumor tissue revealed 44% leiomyosarcomas, 25% homologous mixed mullerian tumors, 17% endometrial stromacell sarcomas, 7% heterologous mixed müllerian tumors, 1% rhabdomyosarcomas, and 6% unclassified sarcomas. Eighty-six percent of the tumors were aneuploid, 14% were peridiploid, and the 5-year survivals were 20 and 60%, respectively. Clinical stage and lymphocytic reaction were found to be good prognostic parameters. Multivariate analysis of 5-year survival adjusted for age at menopause, clinical stage, mitotic frequency, lymphocytic response, and S-phase fraction did not give any further significant prognostic factors.

Mitoxantrone, chlorambucil and prednisolone in the treatment of non-Hodgkin's lymphoma

The management of low grade lymphoma, both de novo and relapsed disease, is a contentious area in which there has been little real progress in recent years. Regimens which increase the intensity of treatment may accelerate the response but are inevitably associated with greater toxicity. This cannot be justified in a disease whose median survival is between 4 and 10 years and where the median age at presentation is 57. We have assessed the response of 144 patients treated with a combination of mitoxantrone, chlorambucil and prednisolone in a heterogeneous group with lymphoma, both de novo and relapsed disease. In the subgroup with low grade relapsed/refractory disease our results suggest that this combination is clinically effective, low in toxicity and suitable for the outpatient management of this usually elderly patient population.

Osmoadaptation in rhizobia: ectoine-induced salt tolerance

After having shown that ectoine (a tetrahydropyrimidine) displays osmoprotective properties towards Escherichia coli (M. Jebbar, R. Talibart, K. Gloux, T. Bernard, and Blanco, J. Bacteriol. 174:5027-5035, 1992), we have investigated the involvement of this molecule in the osmotic adaptation of Rhizobium meliloti. Ectoine appeared almost as effective as glycine betaine in improving the growth of R. meliloti under adverse osmotic conditions (0.5 M NaCl). Moreover, improvement of growth of rhizobial strains insensitive to glycine betaine was also observed. Ectoine transport proved inducible, periplasmic protein dependent, and, as shown by competition experiments, distinct from the transport of glycine betaine. Medium osmolarity had little effect on the uptake characteristics, since the rate of influx increased from 12 to only 20 nmol min-1 mg of protein-1 when NaCl concentrations were raised from 0 to 0.3 or 0.5 M, with a constant of transport of 80 microM. Natural-abundance 13C-nuclear magnetic resonance and radiolabelling assays showed that ectoine, unlike glycine betaine, is not intracellularly accumulated and, as a consequence, does not repress the synthesis of endogenous compatible solutes (glutamate, N-acetylglutaminylglutamine amide, and trehalose). Furthermore, the strong rise in glutamate content in cells osmotically stressed in the presence of ectoine suggests that, instead of being involved in osmotic balance restoration, ectoine should play a key role in triggering the synthesis of endogenous osmolytes. Hence, we believe that there are at least two distinct classes of osmoprotectants: those such as glycine betaine or glutamate, which act as genuine osmolytes, and those such as ectoine, which act as chemical mediators.

Pipecolic acid is an osmoprotectant for Escherichia coli taken up by the general osmoporters ProU and ProP

Exogenously supplied L-pipecolic acid was accumulated by Escherichia coli cells and protected them while growing at inhibitory osmolarity. Using specific uptake mutants and competitive assays, we established that the imino acid enters the cells through the ProP and ProU systems with Km values of 225 and 53 microM, respectively. Surprisingly, in spite of the requirement for the wild-type proX gene for osmoprotective ability, no binding activity of labelled pipecolate with the periplasmic protein encoded by proX could be detected. In an attempt to demonstrate whether the two porters (ProP and ProU) are the only carriers involved in osmoregulation, a variety of molecules known for their intracellular osmolarity-dependent accumulation in various organisms were investigated. N-Dimethylproline (proline betaine), N-dimethylglycine, homobetaine (beta-alanine betaine), gamma-butyrobetaine and dimethylsulfoniopropionate were found to be capable of promoting the growth of osmotically stressed E. coli. All of these molecules enter bacterial cells via ProP and ProU porters. None of the osmoprotectants except N-dimethylproline was able to bind the periplasmic protein encoded by proX, while this protein was necessary for their uptake. Apparently, ProP and ProU are the sole osmoporters involved in osmolyte influx into E. coli cells.

Osmoprotection of Escherichia coli by ectoine: uptake and accumulation characteristics

Ectoine (1,4,5,6-tetrahydro-2-methyl-4-pyrimidinecarboxylic acid) is a cyclic amino acid, identified as a compatible solute in moderately halophilic bacteria. Exogenously provided ectoine was found to stimulate growth of Escherichia coli in media of inhibitory osmotic strength. The stimulation was independent of any specific solute, electrolyte or nonelectrolyte. It is accumulated in E. coli cells proportionally to the osmotic strength of the medium, and it is not metabolized. Its osmoprotective ability was as potent as that of glycine betaine. The ProP and ProU systems are both involved in ectoine uptake and accumulation in E. coli. ProP being the main system for ectoine transport. The intracellular ectoine pool is regulated by both influx and efflux systems.

Monoclonal antibodies preventing the development of polyarthritis in rats induced by experimental infection with erysipelas bacteria

Monoclonal IgM-antibodies specific for arthritogenic erysipelas bacteria (Erysipelothrix rhusiopathiae, serovar 2, strain T28) were isolated from rats suffering from erysipelas polyarthritis. Four of them (C52, D9, E51, R117) were administered to syngeneic Lewis rats. While D9 and an unrelated rat-IgM-antibody showed no effect, C52 protected partially and R117 as well as E51 fully from all symptoms of erysipelas polyarthritis. Prevention of the disease was associated with a lack of antibody-formation against the erysipelas bacteria. There is evidence that prevention is not due to classical passive immunization, but rather to induction of host mechanisms efficiently activated by "inductive" monoclonal antibodies.

Identification of bacterial periplasmic glycine betaine-binding protein after electrophoresis and affinity labeling

Antibodies were elicited in rabbits against periplasmic proteins obtained by cold osmotic shock from the Gram-negative eubacterium Rhizobium meliloti. When analyzed by crossed immunoelectrophoresis (CIE), the periplasmic proteins gave rise to 20 distinct immunoprecipitates corresponding to the same number of bands in polyacrylamide gel electrophoresis (PAGE) under non-denaturing conditions and in SDS-PAGE. The periplasmic glycine betaine-binding protein (GB-BP) was identified by autoradiography after affinity labeling with [14C]glycine betaine in PAGE and in CIE gels. The binding proved to be quite specific to glycine betaine, since the GB-BP was not labeled by choline (a metabolic precursor of glycine betaine in Escherichia coli and Rhizobium meliloti) and 15 distinct L-amino acids, including L-proline which, like glycine betaine is also an osmoprotectant. Affinity labeling of the GB-BP with [14C]glycine betaine after protein separation by PAGE or CIE is a simple and sensitive technique permitting the GB-BP to the unambiguously detected and identified in samples of complex protein mixtures containing down to 2 micrograms of GB-BP in PAGE and only 0.2 micrograms in CIE.

Characterization of three choline transport activities in Rhizobium meliloti: modulation by choline and osmotic stress

Choline has both a nutritional and osmoregulatory role in Rhizobium meliloti (T. Bernard, J. A. Pocard, B. Perroud, and D. Le Rudulier, Arch. Microbiol. 143:359-364, 1986). In view of this fact, choline transport was studied in R. meliloti 102F34 to determine how the rate of choline uptake is modulated. The effects of the cultural conditions on the kinetics of transport are presented. A high-affinity activity and a low-affinity activity were found in cells grown in minimal medium. The addition of 0.3 M NaCl or other osmolytes to the medium resulted in a marked decrease in the high-affinity activity, whereas the low-affinity activity remained fairly constant. Furthermore, results from osmotic upshock and downshock experiments indicate that the response of the cell to high osmolarity is rapid; hence, the mechanism of regulation by salt likely does not involve gene induction. A second high-affinity transport activity was induced by choline itself. Like the constitutive low-affinity transport activity, this activity was not greatly altered when the cells were grown in media of elevated osmotic strength. We conclude that although all three kinetically distinct transport systems are efficient at low osmolarity, only the induced high- and low-affinity activities are important for osmoregulation. The characteristics of the three transport activities from R. meliloti are compared with those from other bacterial species that use choline for growth and/or osmoregulation.

Osmotic control of glycine betaine biosynthesis and degradation in Rhizobium meliloti

Intracellular accumulation of glycine betaine has been shown to confer an enhanced level of osmotic stress tolerance in Rhizobium meliloti. In this study, we used a physiological approach to investigate the mechanism by which glycine betaine is accumulated in osmotically stressed R. meliloti. Results from growth experiments, 14C labeling of intermediates, and enzyme activity assays are presented. The results provide evidence for the pathway of biosynthesis and degradation of glycine betaine and the osmotic effects on this pathway. High osmolarity in the medium decreased the activities of the enzymes involved in the degradation of glycine betaine but not those of enzymes that lead to its biosynthesis from choline. Thus, the concentration of the osmoprotectant glycine betaine is increased in stressed cells. This report demonstrates the ability of the osmolarity of the growth medium to regulate the use of glycine betaine as a carbon and nitrogen source or as an osmoprotectant. The mechanisms of osmoregulation in R. meliloti and Escherichia coli are compared.