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PubMed1996

Extracorporeal shockwave lithotripsy or percutaneous nephrolithotomy for lower pole nephrolithiasis?

A controversy has arisen as to whether the initial form of therapy for lower pole nephrolithiasis should be extracorporeal shockwave lithotripsy (SWL) or percutaneous nephrolithotomy (PCNL). We reviewed our results with 968 single lower pole stones treated by SWL and reviewed publications comparing SWL and PCNL for lower pole nephrolithiasis. In our cases, the stone-free rate was 71.2%, the rate of repeat treatment and post-treatment secondary procedures was 6.4%, the complication rate was 0.5%, and the hospital stay was less than 24 hours in 99.3% of patients. In published series of PCNL for lower pole nephrolithiasis, the stone free rate was 70.5% to 100%, repeat treatment rates were 4% to 62.5%, the complication rates were 13% to 38%, and the hospital stay was 3.1 to 6.1 days. The rates of recurrent stone disease with PCNL were 11% to 22%, similar to the rates after SWL. The percentage of renal urolithiasis patients with lower pole calculi since we started our unit in late 1986 has remained essentially constant at 38%. Although the stone-free rate with PCNL is higher than with SWL, the lower complication rate, lower repeat treatment/secondary procedure rate, the shorter hospital stay, and the similar recurrent stone rate with SWL make SWL more clinically effective as the primary therapy for lower pole calculi less than 2 cm in diameter.

Decision Making↗

PubMed1998

Effect of rolling resistance on poling forces and metabolic demands of roller skiing.

OBJECTIVE: To examine the effect of an increase in roller ski rolling resistance on the physiological and upper body demands of roller skiing with the V2-alternate technique. METHODS: Nine highly skilled cross-country skiers roller skied at three paced speeds on a flat oval loop using roller skis with high (HiR) and low (LowR) rolling resistance. Oxygen uptake (VO2), heart rate, and poling forces were measured during the last 30 s and rating of perceived exertion (RPE) was requested immediately after each 4-min bout of roller skiing. RESULTS: VO2 and all force-related variables increased significantly with speed and were higher (P < 0.01) for HiR at given speeds. Poling time was similar between HiR and LowR, whereas poling recovery time was shorter (P = 0.0002) and cycle rate was higher (P = 0.002) for HiR. For given VO2 levels, peak and average forces, heart rates, and RPE values were similar between HiR and LowR, whereas average poling force across the cycle was greater (P = 0.006) and duty cycle (i.e., percentage of cycle when poling forces were applied) was higher (P = 0.0001) with HiR. CONCLUSIONS: 1) The decrease in poling recovery time and increase in cycle rate associated with an increase in roller ski rolling resistance is comparable to the effect previously observed from increasing grade and probably occurs as a means of limiting deceleration. 2) Since changes in rolling resistance do not alter the relationships of RPE and heart rate with VO2, the central cardiovascular adaptations from roller ski training should not be affected by the rolling resistance of the roller skis. 3) Higher resistance roller skis are likely to induce greater upper body aerobic adaptations than lower resistance roller skis.

Adult↗

PubMed1998

Poling forces during roller skiing: effects of grade.

PURPOSE: A substantial proportion of the propulsive forces required for uphill skiing are generated from the upper body, but no study has systematically examined poling forces at different slopes. In the present experiment, poling forces and timing were examined during roller skiing on 2.1% and 5.1% uphills. METHODS: Nine highly skilled cross-country skiers roller skied at paced submaximal and at maximal speeds using the V1 skate (V1) and double pole (DP) techniques. Poling forces and timing were measured with piezoelectric transducers. RESULTS: Peak force (PF), average force (AF) and average force over the entire cycle (ACF) were significantly greater (P < 0.01) at the steeper grade with both techniques. Values for the ratio of V1 to DP did not differ between the two grades for PF, AF, and ACF but tended to increase with velocity for both techniques. With both V1 and DP, upper body recovery time was shorter (P < 0.01) at the steeper grade, and cycle rate was greater (P < 0.01) at the steeper grade. CONCLUSIONS: We conclude that 1) the relative demands on the upper body with V1 compared with DP were similar between the two grades, and 2) the responses to an elevation in grade of increased poling forces, shortened poling recovery times, and increased cycle rate are comparable to the responses to an increase in speed.

Acceleration↗

PubMedDate not supplied

Acute responses to using walking poles in patients with coronary artery disease.

PURPOSE: This study was designed to assess the safety and effectiveness of walking when using 1-lb walking poles in Phase III/IV cardiac rehabilitation patients. METHODS: Following instruction on the proper use of the poles and adequate time to practice, each subject completed two 8-minute walking trials on a level treadmill either with or without walking poles. Each trial was conducted at an identical speed for each subject in a randomized order. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and ratings of perceived exertion (RPE) were recorded every 2 minutes during each trial, while ECG responses (ST segment changes and dysrhythmias) were monitored continuously. RESULTS: Walking with poles significantly (P < .05) increased the energy cost of walking by 21% (3.8 mL/kg/min) compared to walking without poles. There were also significant (P < .05) increases in HR (14 bpm), SBP (16 mm Hg), and DBP (4 mm Hg) when comparing conditions. Calculated oxygen pulse (mL O2.heart beat) values indicated that changes in HR were consistent with the increase in VO2 and were not related to a pressor response mechanism. The only dysrhythmias noted were isolated PVCs, with no differences in the frequency of occurrence between trials. There were no adverse ST segment changes with either trial. CONCLUSIONS: These data demonstrate that at a given speed, the use of 1-lb walking poles can safely increase the intensity of walking exercise in Phase III/IV cardiac rehabilitation patients.

Aged↗

PubMed1990

Posterior localization of vasa protein correlates with, but is not sufficient for, pole cell development.

The protein product of the Drosophila maternal-effect posterior group gene vasa is localized to the posterior pole of the oocyte and is sequestered by the pole cells as they form. It is, however, present at easily detectable levels throughout the oocyte and pre-blastoderm embryo. The protein is present in the pole cells and their germ line derivatives throughout all stages of development. An antiserum against this protein recognizes a pole-cell-specific antigen in seven other Drosophila species. Of six other maternal-effect loci essential for embryonic pole cell development, none affects expression of vasa, mutations in four abolish vasa protein localization, and mutations in two, tudor and valois, have little, if any, effect on vasa expression or localization. This indicates that vasa protein, when properly localized, is not sufficient for induction of pole cell development, and that at least the tudor and valois wild-type functions are also required specifically for this process. These results are discussed with respect to the multiple functions of the vasa gene.

Animals↗

PubMed1978

Linear prediction analysis of speech based on a pole-zero representation.

Speech analysis and synthesis by linear prediction is based on the assumption that the short-time spectral envelope of speech can be represented by a number of poles. An all-pole representation does not provide an accurate description of speech spectra, particularly for nasals and nasalized sounds. This paper presents a method for characterizing speech in terms of the parameters of a pole-zero model. In this method, an impulse response representing the composite filtering action of the glottal wave, the vocal tract, the radiation, and the speech recording system is first constructed from the speech signal. This impulse response is obtained by performing several stages of all-pole LPC analysis. The pole-zero parameters are determined from the impulse response by solving a set of simultaneous linear equations. The method, being noniterative, is very suitable for automatic analysis of speech. The method has been applied to real speech data and the results show that the speech spectra derived from the pole-zero model agree very closely with the actual spectra derived by direct Fourier analysis.

Acoustics↗

PubMed1998

Fluxes of fast and epithermal neutrons from Lunar Prospector: evidence for water ice at the lunar poles.

Maps of epithermal- and fast-neutron fluxes measured by Lunar Prospector were used to search for deposits enriched in hydrogen at both lunar poles. Depressions in epithermal fluxes were observed close to permanently shaded areas at both poles. The peak depression at the North Pole is 4.6 percent below the average epithermal flux intensity at lower latitudes, and that at the South Pole is 3.0 percent below the low-latitude average. No measurable depression in fast neutrons is seen at either pole. These data are consistent with deposits of hydrogen in the form of water ice that are covered by as much as 40 centimeters of desiccated regolith within permanently shaded craters near both poles.

Extraterrestrial Environment↗

PubMed1991

Carrying loads with springy poles.

People throughout Asia use springy bamboo poles to carry the loads of everyday life. These poles are a very compliant suspension system that allows the load to move along a nearly horizontal path while the person bounces up and down with each step. Could this be an economical way to carry loads inasmuch as no gravitational work has to be done to lift the load repeatedly? To find out, an experiment was conducted in which four male subjects ran at 3.0 m/s on a motorized treadmill with no load and while carrying a load equal to 19% body wt with compliant poles. Oxygen consumption rate, vertical ground reaction force, and the force exerted by the load on the shoulders were measured. Oxygen consumption rate increased by 22%. The same increase has previously been observed when loads are carried with a backpack. Thus compliant poles are not a particularly economical method of load carriage. However, pole suspension systems offer important advantages: they minimize peak shoulder forces and loading rates. In addition, the peak vertical ground reaction force is only slightly increased above unloaded levels when loads are carried with poles.

Adult↗

PubMed2005

The effects of walking poles on shoulder function in breast cancer survivors.

Breast cancer treatment often results in impaired shoulder function, in particular, decrements in muscular endurance and range of motion, which may lead to decreased quality of life. The purpose of this investigation was to determine the effects of walking pole use on shoulder function in female breast cancer survivors. Participants had previously been treated with 1 or a combination of the following: mastectomy, breast conservation therapy, axillary lymph node dissection, chemotherapy, or radiation. Participants were randomly placed in experimental (n = 6) and control (n = 6) groups and met with a cancer exercise specialist 2 times each week for 8 weeks. The experimental group used walking poles during the 20-minute aerobic portion of their workout, whereas the control group did not use walking poles but performed 20 minutes of aerobic exercise per workout session. Both groups participated in similar resistance training programs. Testing was done pre- and postexercise intervention to determine upper body muscular endurance and active range of motion at the glenohumeral joint. Repeated-measures analysis of variance (ANOVA) revealed significant improvements in muscular endurance as measured by the bench press (P = .046) and lat pull down (P = .013) in the walking pole group. No within-group improvements were found in the group that did not use walking poles. The data suggest that using a walking pole exercise routine for 8 weeks significantly improved muscular endurance of the upper body, which would clearly be beneficial in helping breast cancer survivors perform activities of daily living and regain an independent lifestyle.

Activities of Daily Living↗

PubMed2004

The solar photon thruster as a terrestrial pole sitter.

Geosynchronous satellites are invisible at high latitudes. A pole-sitting spacecraft would have communication, climate-studies, and near-polar Earth observation applications. We present a pole-sitter based on the solar photon thruster (SPT), a two-sail variant of the solar sail using a large curved collector sail (always normal to the Sun) to direct sunlight against a much smaller thruster. Thrust decreases slower for an SPT than for a conventional sail arrangement as the angle between sunlight and the collector normal increases. An SPT pole-sitter is offset from the terrestrial pole so that a component of Earth gravity balances the solar radiation-pressure component pushing the SPT off station. The component of gravitational attraction of the Earth pulling the spacecraft towards Earth is also balanced by a solar radiation-pressure component. Results are presented for 80-100% collector/thruster reflectivities. For a spacecraft areal mass thickness of 0.002 kg/m(2), collector and thruster reflectivities of 0.9, the SPT can be situated above latitude 45 degrees at a distance of approximately 60 Earth radii. An SPT pole sitter would be affected by lunar perturbation, which can be compensated for by an on-board rocket thruster producing 2 x 10(-6) g acceleration, a second SPT thruster sail thrusting against the influence of the Moon, or by directing a microwave beam against the spacecraft. Since an SPT pole sitter is in a position rather than an orbit, the effect of terrestrial gravitation limits the size and design of the payload package, which limits terrestrial target resolution.

Journal Article↗

PubMed1989

Restoration of pole-cell-forming ability to u.v.-irradiated Drosophila embryos by injection of mitochondrial lrRNA.

Screening a cDNA library generated from poly(A) +RNA of Drosophila cleavage embryos, we selected a cDNA clone (pDE20.6). The cDNA hybridized specifically with a poly(A) +RNA that is capable of restoring embryos from u.v.-caused inability of pole cell formation. The RNA hybrid-selected by pDE20.6 was also able to induce pole cells in the anterior region of embryos, if it was coinjected with u.v.-irradiated polar plasm, although the RNA or irradiated polar plasm alone was not effective. Pole cells thus formed in the anterior or in the u.v.-irradiated posterior region were identified by polar granules and nuclear bodies, morphological markers for normal pole cells. Furthermore, the RNA-induced pole cells were able to migrate into gonadal rudiments. The nucleotide sequence of pDE20.6 cDNA insert was highly homologous with the mitochondrial large rRNA (lrRNA) gene, but not with any nuclear DNA sequences. Using pDE20.6 as a primer, a full-length cDNA of mitochondrial lrRNA was generated and cloned. The RNA transcribed in vitro from the cDNA was able to restore pole cell formation. The cDNA hybridized only with a 1.5 kb poly(A) +RNA on a Northern blot. The 1.5 kb RNA sedimented more with the post-mitochondrial (P3) fraction than with the mitochondrial (P2) fraction, while the majority of transcripts from another mitochondrial gene was detected in the P2 fraction.

Animals↗

PubMed1994

Localization of vasa protein to the Drosophila pole plasm is independent of its RNA-binding and helicase activities.

The Drosophila gene vasa encodes a DEAD-box protein, which is localized during early oogenesis to the perinuclear region of the nurse cells and later to the pole plasm at the posterior end of the oocyte. Posterior localization of vasa protein depends upon the functions of four genes: capu, spir, osk and stau. We have found that localization of vasa to the perinuclear nuage is abolished in most vas alleles, but is unaffected by mutations in four genes required upstream for its pole plasm localization. Thus localization of vasa to the nuage particles is independent of the pole plasm assembly pathway. Furthermore, electron-dense nuage particles are less abundant in the cytoplasm of nurse cells from vas mutants that fail to exhibit perinuclear localization, suggesting that the formation of the nuage depends upon vas function. Eight of nine vas point mutations cause codon substitutions in a region conserved among DEAD-box genes. The proteins from two mutant alleles that retain the capacity to localize to the posterior pole of the oocyte, vasO14 and vasO11, are both severely reduced in RNA-binding and -unwinding activity as compared to the wild-type protein on a variety of RNA substrates including in vitro synthesized pole plasm RNAs. Initial recruitment of vasa to the pole plasm must consequently depend upon protein-protein interactions but, once localized, vasa must bind to RNA to mediate germ cell formation.

Adenosine Triphosphate↗

PubMed1994

Drosophila virilis oskar transgenes direct body patterning but not pole cell formation or maintenance of mRNA localization in D. melanogaster.

The Drosophila melanogaster gene oskar is required for both posterior body patterning and germline formation in the early embryo; precisely how oskar functions is unknown. The oskar transcript is localized to the posterior pole of the developing oocyte, and oskar mRNA and protein are maintained at the pole through early embryogenesis. The posterior maintenance of oskar mRNA is dependent upon the presence of oskar protein. We have cloned and characterized the Drosophila virilis oskar homologue, virosk, and examined its activity as a transgene in Drosophila melanogaster flies. We find that the cis-acting mRNA localization signals are conserved, although the virosk transcript also transiently accumulates at novel intermediate sites. The virosk protein, however, shows substantial differences from oskar: while virosk is able to rescue body patterning in a D. melanogaster oskar- background, it is impaired in both mRNA maintenance and pole cell formation. Furthermore, virosk induces a dominant maternal-effect lethality when introduced into a wild-type background, and interferes with the posterior maintenance of the endogenous oskar transcript in early embryogenesis. Our data suggest that virosk protein is unable to anchor at the posterior pole of the early embryo; this defect could account for all of the characteristics of virosk mentioned above. Our observations support a model in which oskar protein functions both by nucleating the factors necessary for the activation of the posterior body patterning determinant and the germ cell determinant, and by anchoring these factors to the posterior pole of the embryo. While the posterior body patterning determinant need not be correctly localized to provide body patterning activity, the germ cell determinant may need to be highly concentrated adjacent to the cortex in order to direct pole cell formation.

Amino Acid Sequence↗

PubMed1999

Induction of indora expression in pole cells by the mesoderm is required for female germ-line development in Drosophila melanogaster.

In many animal groups, the interaction between germ and somatic line is required for germ-line development. In Drosophila, the germ-line precursors (pole cells) formed at the posterior tip of the embryos migrate toward the mesodermal layer where they adhere to the dorsolateral mesoderm, which ensheaths the pole cells to form the embryonic gonads. These mesodermal cells may control the expression of genes that function in pole cells for their development into germ cells. However, such downstream genes have not been isolated. In this study, we identify a novel transcript, indora (idr), which is expressed only in pole cells within the gonads. Reduction of idr transcripts by an antisense idr expression caused the failure of pole cells to produce functional germ cells in females. Furthermore, we demonstrate that idr expression depends on the presence of the dorsolateral mesoderm, but it does not necessarily require its specification as the gonadal mesoderm. Our findings suggest that the induction of idr in pole cells by the mesodermal cells is required for germ-line development.

Amino Acid Sequence↗

PubMed1998

Focusing on spindle poles.

Spindle poles are discernible by light microscopy as the sites where microtubules converge at the ends of both mitotic and meiotic spindles. In most cell types centrosomes are present at spindle poles due to their dominant role in microtubule nucleation. However, in some specialized cell types microtubules converge into spindle poles in the absence of centrosomes. Thus, spindle poles in centrosomal and acentrosomal cell types are structurally different, and it is this structural dichotomy that has created confusion as to the mechanism by which microtubules are organized into spindle poles. This review summarizes a series of recent articles that begin to resolve this confusion by demonstrating that spindle poles are organized through a common mechanism by a conserved group of non-centrosomal proteins in the presence or absence of centrosomes.

Animals↗

PubMed2007

Effects of hiking downhill using trekking poles while carrying external loads.

UNLABELLED: Hiking is a recreational activity shown to offer significant positive effects on the human body. However, walking downhill and external load carriage have both been shown to increase the risk of musculoskeletal pain and injury. The use of hiking poles has been demonstrated to be successful in reducing forces placed on the lower extremities. However, whether these effects can be observed with load carriage has not been examined. PURPOSE: The purpose of this research was to examine the effectiveness of pole use in hiking downhill while carrying different external loads. METHODS: Fifteen experienced male hikers volunteered. Conditions included hiking with and without the use of hiking poles for each of three backpack conditions (no pack, day pack (15% BW), and large expedition pack (30% BW). Ten trials were completed for each condition, for a total of 60 trials per participant. All conditions were performed in a random order. The net joint moments and power at the ankle, knee, and hip, as well as the net joint forces at the knee were examined statistically using a 2 x 3 (poles x packs) repeated-measures ANOVA, with a family wise alpha level of 0.05. RESULTS: A significant reduction was observed for the sagittal plane moment at each of the joints in the lower extremity with pole use. Reductions were also observed in the peak power absorption for the ankle and knee. These results held true across pack conditions, as packs only resulted in a larger power generation at the hip. CONCLUSION: A reduction in the forces, moments, and power around the joint, with the use of poles, will help reduce the loading on the joints of the lower extremity.

Adult↗

PubMed2005

Time evolution of second-order nonlinear profiles induced within thermally poled silica samples.

The second-order nonlinear profile induced within thermally poled Infrasil silica samples is characterized as a function of the duration of the poling process. For poling durations shorter than 5 min the spatial distribution of the chi(2) susceptibility exhibits a triangular shape. This observation, as well as the maximum value of the electric field recorded during poling (1.9 x 10(9) V/m), is in excellent agreement with charge migration models that involve a single charge carrier. It is shown that for higher poling durations the nonlinear profiles tend to flatten; in that case the charge injection mechanisms cannot be neglected. For another point of view, the experimental method introduced herein has allowed us to determine the mobility of the rapid charge carrier involved in the poling process: micro = 1.5 x 10(-15) m2 V(-1) s(-1) at 250 degrees C.

Journal Article↗

PubMedDate not supplied

Occurrence of metals in soil and ground water near chromated copper arsenate-treated utility poles.

To thoroughly investigate the metal contamination around chromated copper arsenate (CCA)/polyethylene glycol (PEG)-treated utility poles, a total of 189 soil samples obtained from different depths and distances near six treated poles in the Montreal area (Canada) were analyzed for Cu, Cr, and As content. Various soil physicochemical properties were also determined. Ground water samples collected below the poles were analyzed for metals and bioassays with Daphnia magna were conducted. Generally, sandy soils had lower contaminant levels than clayey and organic soils. Copper concentrations in soil were highest followed by As and Cr. The highest Cu (1460 +/- 677 mg kg(-1)), As (410 +/- 150 mg kg(-1)), and Cr (287 +/- 32 mg kg(-1)) concentrations were found at the ground line and immediately adjacent to the pole. Contaminant levels then decreased with distance, approaching background levels within 0.1 m from the pole for Cr and 0.5 m for Cu and As. Chromium and Cu levels generally approached background levels at a depth of 0.5 m. Average As content near the pole on all study sites was three to eight times higher than Quebec's Level C criterion (50 mg kg(-1)), although it dropped to 31 mg kg(-1) at 0.1 m. Results also showed that As persisted up to 1 m in soil depth (17-54 mg kg(-1)). Copper and Cr concentrations in ground water samples were always <1.000 mg L(-1) and <0.05 mg L(-1), respectively and Cr(VI) was <0.02 mg L(-1). One sample contained an As concentration >0.025 mg L(-1) but bioassays showed that, overall, ground water had a low ecotoxic potential.

Aluminum Silicates↗