bluuebunny/crossref_metadata_2025 huggingface dataset:
Outcomes of continent catheterizable stomas for urinary and fecal incontinence: comparison among different tissue options
Authors: Castellan Miguel A. , Gosalbez Rafael , Labbie Andrew , Ibrahim Emad , Disandro Michael
Published: April 2005

OBJECTIVE

To retrospectively review the outcome of appendix, transverse tubularized intestine segments, caecal flap, gastric tube and others tissue options used as a continent stoma for urinary and fecal incontinence.

PATIENTS AND METHODS

Between January 1993 and January 2003 we created 179 continent stomas to treat urinary and fecal incontinence in 135 patients (81 females and 54 males; mean age at surgery 13 years, 118, 87%, aged <17 years). We used either appendix (112), a short segment of bowel following the Yang‐Monti technique (49), gastric augment single pedicle tube (eight), caecal flap (seven), Casale continent vesicostomy (two) and Meckel's diverticulum (one). Thirty‐six patients had both urinary and fecal continent stomas created.

RESULTS

The mean follow‐up for the appendix group was 46 months for the urinary stoma and 23 months for the Malone antegrade continent enema (MACE) stoma. Stoma‐related complications occurred in 24 of 112 (21%) patients; there was complete channel fibrosis in five (4%). The mean follow‐up for the Yang‐Monti group was 38 months for the urinary and 59.2 months for the MACE stoma. There were stoma‐related problems in 11 of 49 (22%) patients, with complete channel fibrosis in three (6%). Overall, in the long‐term follow‐up, there were stoma‐related complications in 42 of 179 (23.5%) procedures.

CONCLUSIONS

Continent catheterizable stomas are a feasible and reliable method for treating urinary and fecal incontinence. Long‐term success can be accomplished with appendix, transverse tubularized intestinal segments and caecal flaps, with similar complication rates in all groups. Surgeon preference and individual patient status should determine the surgical technique to be used.
Enuresis in childhood, and urinary and fecal incontinence in adult life: do they share a common cause?
Authors: Gurbuz Ayse , Karateke Ates , Kabaca Canan
Published: April 2005

OBJECTIVE

To investigate whether there is any association between urinary or fecal incontinence and childhood bedwetting, and given such a relationship, to detect which type of urinary incontinence (UI) is associated with childhood bedwetting.

PATIENTS AND METHODS

In all, 1021 patients who were admitted to the outpatient gynaecology clinics of the authors’ institution for an annual gynaecological examination were included in this descriptive clinical study. A simple multi‐choice screening questionnaire was used to collect data for analysis.

RESULTS

There was a history of bedwetting in childhood in 181 (21.1%) of women without and in 48 (29.6%) of those with UI; the difference was significant (chi‐square, P < 0.05). Women with stress UI had significantly higher rates of enuresis in childhood (35.4%) than those without UI (21.1%; P = 0.003). Of women who had a history of bedwetting in childhood, 12.2% had stress UI, but only 6.4% of those with no such history had stress UI. Fecal incontinence was significantly more common in women with a history of bedwetting in childhood (P < 0.05).

CONCLUSION

A history of childhood bedwetting seems to increase the risk of having UI, stress UI and fecal incontinence. Being aware of this association may provide an opportunity to avoid exposing these women to additional risk factors for these condition.
Colpo‐wrap: a new continence procedure
Authors: Boemers Thomas M. , Schimke Christa M.
Published: April 2005

OBJECTIVE

To present a new surgical method to increase bladder outlet resistance for the treatment of urinary incontinence in girls and women.

PATIENTS AND METHODS

Six patients (mean age 9.6 years), with urinary incontinence were operated using the new technique within the last 3 years. The principle of the procedure is tightening of the bladder neck by mobilizing the anterior vaginal wall and wrapping it around the bladder neck and proximal urethra, in the sense of a vaginoplication (colpoplication). The underlying conditions and causes for urinary incontinence was neurogenic bladder‐sphincter dysfunction caused by myelodysplasia in three girls and anorectal malformation combined with a tethered spinal cord in one. In one case incontinence was caused by a cloacal anomaly and one girl had intrinsic sphincter insufficiency after repetitive Otis urethrotomies. The colpo‐ wrap was combined with a bladder augmentation and Mitrofanoff in three patients, the three other girls undergoing isolated procedures.

RESULTS

The result of the method is a constant increase in outlet resistance and coaptation of the urethra, comparable with the effect of a vaginal sling procedure. Five patients are completely dry after surgery, one girl with cloaca needed an additional bladder neck injection with hyaluranon/dextranomer copolymer. Transurethral catheterization was possible after surgery with no problems in all patients who required intermittent catheterization.

CONCLUSION

Considering the feasibility of this technique the colpo‐wrap is a reasonable alternative for treating urinary incontinence in females.
Changes in bone structure after augmentation cystoplasty in chronic uraemic rats
Authors: Brkovic Drasko , Linke Joachim , Jakse Gerhard , Bauss Frieder
Published: April 2005

OBJECTIVE

To investigate the effect of urinary diversion using several types of intestinal segments on cortical and cancellous bone structure of growing rats with renal insufficiency.

MATERIAL AND METHODS

In all, 110 female Sprague‐Dawley rats (8 weeks old) had either a two‐stage subtotal nephrectomy by removing five‐sixths of the renal mass, or a sham operation. Except for a uraemic control group, all uraemic rats then had an enterocystoplasty using stomach, ileum or colon (20 animals per group). An additional group with colic augmentation received the bisphosphonate ibandronate. After 12 weeks, the left tibia was assessed using peripheral quantitative computed tomography and bone histomorphometry.

RESULTS

After subtotal nephrectomy all groups had ≈ 30% less endogenous creatinine clearance. Renal failure alone or in association with gastric or colic augmentation induced only negligible changes in the mass and structure of cortical and cancellous tibial bone. In contrast, rats after ileal augmentation and renal failure had a significant reduction in cancellous bone mineral density (P < 0.05) whereas the reduction in trabecular bone area and volume was not statistically significant. Furthermore, ileocystoplasty caused a decrease in trabecular number and perimeter, increased trabecular separation and enlarged bone marrow space, whereas ileocystoplasty had no effect on cortical bone. The changes were not associated with alterations in serum pH. Ibandronate treatment in the colonic cystoplasty group increased trabecular bone mass and structural variables over the untreated colonic cystoplasty group.

CONCLUSIONS

These results suggest that cystoplasty using an ileal segment causes a decrease in bone mass and architecture in growing rats with mild uraemia. It remains open to question whether the results obtained from experimental animals can be directly extrapolated to the clinical situation.
Effects of TAK‐802, a novel acetylcholinesterase inhibitor, and tamsulosin, an α1‐adrenoceptor antagonist, and their synergistic effects on the urodynamic characteristics in a guinea‐pig model of functional bladder outlet obstruction
Authors: Nagabukuro Hiroshi , Hashimoto Tadatoshi , Iwata Masashi , Doi Takayuki
Published: April 2005

OBJECTIVE

To investigate the effects of TAK‐802, a potent acetylcholinesterase inhibitor, and tamsulosin, an α1‐adrenoceptor antagonist, and their concomitant administration on the urodynamic characteristics in a guinea‐pig model of functional bladder outlet obstruction.

MATERIALS AND METHODS

Cystometry was performed in urethane‐anaesthetized guinea pigs, and various urodynamic variables, including the maximum flow rate (Qmax), voiding efficiency, maximum intravesical pressure (Pvesmax) and intravesical pressure at Qmax (PvesQmax), were measured before and after administration of the drugs in combination and alone.

RESULTS

Continuous intravenous infusion of phenylephrine, an α1‐adrenoceptor agonist (1–6 µg/animal/min), dose‐dependently decreased the Qmax and voiding efficiency, and increased the Pvesmax and PvesQmax, possibly by constricting urethral smooth muscle. In this functional urethral constriction model, both TAK‐802 at 1 and 10 µg/kg and tamsulosin at 3 and 10 µg/kg (intravenously) caused increasing effects on the Qmax and voiding efficiency. The effects were more apparent with combined exposure. Although the Pvesmax was dose‐dependently increased by TAK‐802 alone, the effects were completely abolished by concomitant treatment with tamsulosin.

CONCLUSION

These results suggest that TAK‐802 and tamsulosin have synergistic effects in increasing the Qmax and voiding efficiency, and TAK‐802 does not inhibit the decreasing effect of tamsulosin on urethral resistance. That TAK‐802 increased Pves when administered alone implies that monotherapy using an acetylcholinesterase inhibitor should be withheld in patients with voiding dysfunction caused by obvious bladder outlet obstruction with benign prostatic hyperplasia, to avoid disorders of the upper urinary tracts, and it should be used with an α1‐adrenoceptor antagonist. Whether TAK‐802 combined with an α1‐adrenoceptor antagonist confers additional clinical benefit is not yet known.
The use of a newly designed nonabsorbable polymeric stent in reconstructing the vas deferens: a feasibility study in New Zealand white rabbits
Authors: Vrijhof Eric J. , De Bruine Adriaan , Zwinderman Aeilko H. , Lycklama À Nijeholt August A.B. , Koole Leo H.
Published: April 2005

OBJECTIVES

To investigate the use of a newly designed stent in the reconstruction of the vas deferens.

MATERIALS AND METHODS

In 26 New Zealand White rabbits, 13 conventional one‐layer microscopic reconstructions were compared with 13 stented reconstructions of the vas deferens. The newly designed nonabsorbable polymeric stent was shaped to facilitate the rejoining of the two loose ends of the vas deferens, using a central ridge to prevent migration. Semen was collected before and after surgery, using an artificial vaginal system (26 samples before and 115 after surgery). The individual and average total sperm count, motility and progressive motile sperm density (PMSD), were compared after surgery for both groups. After the final semen analysis, rabbits were killed and patency was assessed histologically at the site of the anastomosis.

RESULTS

After an initial decline the mean total sperm count increased in both groups. The increase was significantly larger (P = 0.05) in the stented rabbits. The mean motility and PMSD showed no significant differences between both groups (P = 0.11 and 0.71, respectively). Histological examination of the anastomosed area showed partial obstruction (>50% narrowing of the original lumen) in five of the 13 conventionally treated rabbits, with no strictures in the stented group. Despite the narrowing in the conventional group the patency rates were not affected. The mean (range) operating time for the conventional and stented groups was 132 (99–168) and 98 (62–113) min, respectively (P < 0.001).

CONCLUSIONS

The total sperm counts, motility and PMSD showed no or little difference after surgery between the conventional and stented rabbits. The stented reconstruction was easy, had no secondary stricturing and reduced the operating time.
Angiotropism of human prostate cancer cells: implications for extravascular migratory metastasis
Authors: Lugassy Claire , Vernon Stephen E. , Warner John W. , Le Carter Q. , Manyak Michael , Patierno Stephen R. , Barnhill Raymond L.
Published: April 2005

OBJECTIVES

To report several samples of invasive human prostate cancer showing angiotropism, and to use human prostate cancer cells stably expressing green fluorescence protein (GFP) in in vitro and in vivo models to assess the dissemination pathway of prostate cancer cells.

MATERIALS AND METHODS

Malignant melanoma and prostate carcinoma cells can migrate along anatomical structures such as nerves; previous studies showed that melanoma cells can be perivascular, on the outside of the endothelium, i.e. they are angiotropic, which suggests the hypothesis that melanoma cells also may migrate along vascular channels, termed ‘extravascular migratory metastasis’ (EVMM). Thus we examined histologically 10 human prostatic carcinoma specimens for the presence of angiotropism. In vitro, the PC‐3 prostate cancer cells were co‐cultures with capillary‐like structures. In vivo, PC‐3 cells were implanted on the chick chorio‐allantoic membrane (CAM).

RESULTS

Histologically, in all 10 cases, angiotropism was detected at least focally within the tumour or at the advancing front of the tumour. In vitro, the PC‐3 cells spread along the external surface of the vascular tubules; in vivo, PC‐3 cells formed a cuff around some vessels a few millimetres beyond the tumour, showing angiotropism. Histopathology of the CAM confirmed the perivascular location of tumour cells and the absence of tumour cells within the vessel lumina.

CONCLUSION

The presence of angiotropic tumour cells in human invasive prostate cancers, associated with the angiotropism of GFP prostate cancer cells cultivated in vitro and in vivo in angiogenic models, raises the possibility that some prostate tumour cells may migrate along the external surface of vessels as a mechanism of spread, i.e. EVMM.
Young Children's Prosocial and Aggressive Behaviors and Their Experiences of Being Targeted for Similar Behaviors by Peers
Authors: Persson Gun E. B.
Published: April 2005

Children's target experiences (as recipients of prosocial peer acts and victims of peer aggression) were investigated for their concurrent and longitudinal associations with prosocial and aggressive behavior. Forty‐four children (initially 22–40 months) were observed in naturalistic interactions with peers during a two‐month period for each of three consecutive years. Results revealed no consistency over time in children's experiences as targets for aggressive or prosocial peer acts, although there was some indication that altruistic target experiences may be stable from the end of the preschool period. Early behavior appeared to affect the way children were later treated by peers, but no support was found for the idea that early target experiences influence later behavior. Prosocial behavior was concurrently and longitudinally associated with prosocial target experiences. Aggressive behavior reduced the likelihood of children being targets of prosocial peer behavior and, over time, also of their being targets of peers’ aggression.
The Relationship Between Indirect and Physical Aggression on Television and in Real Life
Authors: Coyne Sarah M. , Archer John
Published: April 2005

Viewing indirect aggression on television has been shown to have negative short‐term effects on a viewer's subsequent aggressive behavior; however, the longer term relationship between viewing indirect aggression on television and in real life has not yet been examined. Three hundred and forty‐seven adolescents, aged 11–14, were asked to list their five favorite television programs. These programs were analyzed for the amount and type of aggression they contained. Peer‐nominated indirect aggression was predicted by other aggressive behavior, sex, and televised indirect aggression. In particular, indirectly aggressive girls viewed more indirect aggression on television than any other group. Peer‐nominated physical aggression was predicted by other aggressive behavior and sex, but not by televised physical or indirect aggression. This study provides a starting point for future long‐term research on the effect of viewing indirect aggression in the media.
Mothers’ Typical and Event‐Specific Positive Expressions Influence Children's Memory for Events
Authors: Dunsmore Julie C. , Halberstadt Amy G. , Eaton Kimberly L. , Robinson Megan L.
Published: April 2005

Mothers (N=67) taught their preschool children crafts while varying emotional expressions (delight, irritation). Mothers’ typical expressive styles were assessed by questionnaire. After three weeks, children's memory was assessed with a free‐recall interview followed by re‐enactment of craft‐making with an interviewer. Children of mothers high in positive expressiveness had more elaborate recall when mothers expressed delight rather than irritation. Children of mothers low in positive expressiveness re‐enacted more event details when their mothers were less varied in expression rather than expressive of emotion in general or delight in particular, and had more elaborate recall when their mothers expressed irritation rather than delight. Findings suggest that children remember more when their mother's emotional expressions during an event fit her typical style.
Evolution of Migraine Diagnoses in Adolescents: A 3-Year Annual Survey
Authors: Wang S-J , Fuh J-L , Juang K-D , Lu S-R , Hsu L-C , Chen W-T , Pwu R-F
Published: April 2005

We conducted a 3-year annual questionnaire survey of the International Headache Society (IHS) migraine diagnoses among 2414 adolescents aged 13. For those with migraine without aura (IHS 1.1) at the baseline survey ( n = 89), 28% and 24% retained the IHS 1.1 diagnosis at the 2nd and 3rd surveys. Only 0.5% of adolescents had a persistent IHS 1.1 diagnosis for 3 years. Of those with IHS 1.1 or migrainous disorder (IHS 1.7) ( n = 449), 43% and 48% retained the IHS 1.1 or IHS 1.7 diagnosis at the 2nd and 3rd surveys. Conversion between IHS 1.1 and IHS 1.7 was common. About 5.6% of the adolescents suffered from IHS 1.1 or IHS 1.7 for all 3 years. Independent predictors for persistent IHS 1.1 or IHS 1.7 diagnosis included frequent headache (> 5 days/month) (relative risk (RR) = 1.8) and pulsatile headache (RR = 1.5). The diagnosis of IHS 1.1 in adolescents was quite unstable. Conversion between IHS 1.1 and IHS 1.7 was an important cause. Factoring IHS 1.7 into the spectrum of migraine diagnoses during epidemiological surveys provides a realistic impression of the disease burden in this age group.
Critical Flicker Frequency in Migraine. A Controlled Study in Patients without Prophylactic Therapy
Authors: Kowacs PA , Piovesan EJ , Werneck LC , Fameli H , Zani AC , da Silva HP
Published: April 2005

The critical flicker frequencies (CFF) of individuals with migraine with and without aura were determined and compared to those of normal controls. Twenty-six migraine patients, 12 with aura and 14 without aura and 30 healthy controls were included. Migraineurs were tested during a migraine-free period, through both the continuous flicker method (CFM) and the forced choice method (FCM). Migraineurs presented a mean flickering fusion threshold lower than healthy controls with the CFM (40.45 vs. 44.33, respectively; P = 0.019) and with the FCM (34.16 Hz vs. 38.5 Hz, respectively, P = 0.019). Both groups of migraineurs had significantly lower thresholds as compared to controls, migraineurs with aura presenting the lowest thresholds for the fusion of flickering ( P = 0.008 and P = 0.0001 with the CFM and the FCM, respectively). Results confirmed and extended previous observations of abnormal flicker fusion thresholds in migraineurs. We hypothesize that this finding might be related to a shorter cortical stimulation silent period.
Platelet Membrane Fluidity and Peroxynitrite Levels in Migraine Patients during Headache-Free Periods
Authors: Taffi R , Vignini A , Lanciotti C , Luconi R , Nanetti L , Mazzanti L , Provinciali L , Silvestrini M , Bartolini M
Published: April 2005

Previous investigations have suggested that changes in platelet activity may play a key role in the pathophysiology of migraine via mechanisms involving the nitric oxide (NO) pathway. Changes in platelet response and nitrite levels have recently been demonstrated during migraine attacks, while there is considerable uncertainty about NO activity in headache-free periods. A reactive oxidant produced from NO and superoxide anion at the site of inflammation, peroxynitrite (ONOO-) has effects including changes in membrane activity and fluidity. The aim of the present study was to determine ONOO- levels in the platelets of patients suffering from migraine during the headache-free period. Nitric oxide synthase (eNOS and iNOS) expression in platelets and the effects of ONOO- on membrane Na+/K+-ATPase activity and membrane fluidity were also evaluated. Subjects were 57 patients suffering from migraine without aura and 35 controls. Blood samples were collected in the headache-free period. Platelet ONOO- levels were determined using dichlorofluorescein acetate with steady-state fluorescence. Platelets were then probed for induction of eNOS and iNOS expression by western immunoblotting. Membrane Na+/K+-ATPase activity and fluidity were determined with the fluorescent probes TMA-DPH and DPH. In the presence of extracellular L-arginine(100 μmol/l), ONOO- production was significantly greater in patients' platelets than in those of controls ( P < 0.001). Western immunoblotting of platelet proteins evidenced higher iNOS expression in patients than in controls. In addition, platelet membrane Na+/K+-ATPase activity and membrane fluidity evaluated by TMA-DPH were significantly lower in patients ( P < 0.001). In conclusion, migraine patients show intercritic changes in platelet membrane fluidity and activity that may be related to the oxidative stress caused by increased ONOO- levels.
Placebo Response in a Patient with Chronic Migraine and Ergotic Overuse
Authors: Pascual-Lozano AM , Chamarro-Lazáro R , Láinez MJA
Published: April 2005

Facilitation of nociceptive systems has been implicated in Chronic-Migraine pathogenesis. Daily consumption of medication may be a contributing factor. The patient was male, aged 76 years, with history of migraine without aura. Six years ago, he presented with a mild-moderate daily pulsating headache. He was overusing analgesics and ergotamine. After withdrawing, the patient started a non-pulsating headache, diffuse and constant. During follow up, he was refractive to several symptomatic and prophylactic treatments. When we treated him with placebo capsules, the headache responded very well. At first, pain-relief occurred for 6 h and progressively, extended. Two years later, when our patient started to use transdermal patches of fentanyl for treatment of a complex regional pain syndrome type 1, his headache did not improve. Patient has maintained prolonged response to placebo. Actually, he is pain-free for 2-3 days with 1 placebo capsule. We discuss mechanisms of chronic-migraine, drug-overuse, drug-induced headache and placebo addiction. Powerful psychological mechanisms could determine response to placebo in this patient.
POVERTY INDICES AND POLICY ANALYSIS
Authors: Myles John , Picot Garnett
Published: April 2005

Our aim in this paper is to show how recent developments in the theory and methods of poverty measurement can be applied to provide more accurate descriptions of poverty trends to the typical consumers of these statistics—policy analysts, policy‐makers and their critics. Since Amartya Sen's (1976) classic critique of the “headcount” approach to poverty measurement, considerable progress has been made in constructing axiomatically‐driven measures of “poverty intensity.” These measures have had little influence outside the small world of experts who devised them largely because their mathematical representation has made their meaning obscure to potential users. We focus on the Sen‐Shorrocks‐Thon (SST) index and its elaboration by Osberg and Xu which provides the information contained in the index in a format that is easily accessible within traditional categories of poverty analysis. The SST index and its decomposition provide an analytical framework for discussing the underlying components of aggregate trends that allows for unambiguous answers to the usual policy‐related questions concerning the components of change as well as their magnitude and direction.
RELATIVE OR ABSOLUTE POVERTY LINES: A NEW APPROACH
Authors: Madden David
Published: April 2005

When measuring poverty over time analysts must choose the value of the income elasticity of the poverty line, which essentially determines whether an absolute or relative poverty line is being used. The choice of this parameter is ultimately a value judgement, but this paper suggests an approach which has some empirical basis. Borrowing from the life‐style and deprivation approach to poverty, various dimensions of poverty and deprivation are identified and the income elasticity of these items is used as the income elasticity of the poverty line. Data from the 1987 and 1994 Irish Household Budget Surveys suggest an upper bound of 0.7 for this parameter. Poverty measures using a number of values of the income elasticity of the poverty line are presented and test statistics are presented to determine whether observed differences in poverty measures are statistically significant.
HIGH AND LOW EARNINGS JOBS: THE FORTUNES OF EMPLOYERS AND WORKERS
Authors: Theeuwes Jules , Lane Julia , Stevens David
Published: April 2005

The focus of the literature on the effect of job changes has been on the consequences of job destruction on the individual worker. In this paper we analyze the impact on the earnings distribution of both job creation and job destruction. We establish a link between job reallocation and the movement of workers into and out of the tails of the earnings distribution. Both job creating and job destroying employers shed jobs mostly from the middle and lower tails of the earnings distribution, although this is cyclically very sensitive. Labor mobility (triggered by job reallocation) is risky: mobile workers will generally end up in the upper or lower tail of the distribution rather than in the middle. If workers move across industry boundaries, they typically move to the lower tails of the distribution. In sum, the fortunes of workers depend on the fortunes of their employers.
Efficiency and total factor productivity in Ukrainian agriculture in transition
Authors: Lissitsa Alexej , Odening Martin
Published: April 2005

This article analyzes efficiency and total factor productivity (TFP) change of large agricultural enterprises during their transition to a market economy in Ukraine. Efficiency is calculated by Data Envelopment Analysis and productivity change is measured by the Malmquist Productivity Change Index in the period between 1990 and 1999. On average, TFP declined by 6% annually, dropping a total 42%. The main reason for the observed TFP decline is a decrease in technical efficiency, which is found to be remarkably significant. At the same time there is a high variation among individual enterprises: the distribution of efficiency scores widens, which indicates that the farms diverge with respect to their economic performance. A Tobit regression analysis is conducted in which efficiency scores are related to factors such as farm type, farm size, initial conditions, and legal form.
Cost‐effective nitrogen leaching reduction as influenced by linkages between farm‐level decisions
Authors: Ekman Sone
Published: April 2005

This article focuses on how the linkages between various farm‐level decisions affect the choice of measures to reduce nitrogen leaching from crop production. A mathematical programming model is developed. The model considers not only management decisions that affect nitrogen leaching directly, but also other decision variables such as scheduling of field operations and machinery investments. A simplified analysis that ignores the latter management decisions, and the linkages between the various decisions, may result in abatement policies that are not cost‐effective because the policies will have other effects than expected. As an example, the empirical results show that subsidies to catch crops and spring ploughing may contribute to increased nitrogen load, quite contrary to the purpose of these subsidies. Further, it is noted that the characteristics of the production system make it costly to change land use, tillage practices, or fertilizer use drastically. Instead, cost‐effective nitrogen abatement includes a mix of various adjustments of farm‐level production practices. The EU set‐aside payment appears to reduce abatement costs.
Technical and scale efficiency of crop and livestock farms in Poland: does specialization matter?
Authors: Latruffe Laure , Balcombe Kelvin , Davidova Sophia , Zawalinska Katarzyna
Published: April 2005

The technical and scale efficiency of Polish farms is analyzed using data envelopment analysis. Efficiency differences are measured according to farm specialization, in crop or livestock, at two points in time during transition, 1996 and 2000. The efficiency results are reviewed in light of confidence intervals provided by bootstrapping. Livestock farms are found to be, on average, more technically and scale efficient than crop farms. Scale efficiency is high for both specializations. Technical inefficiency appears mostly to be due to “pure technical” rather than “scale” inefficiency, and thus attributable to inefficient management practices. The evidence suggests that the low‐educational attainment of people engaged in agriculture is one important reason for these inefficient practices. In 2000, 64% of livestock farms and 86% of crop farms were operating under increasing returns to scale. Improvements in the land lease legislation and changes to the policy support to farmers' pensions could stimulate the land market and remove the incentives to keep a fragmented operational structure.
The demand for selected nutrients by Greek households: an empirical analysis with quantile regressions
Authors: Fousekis Panos , Lazaridis Panagiotis
Published: April 2005

The article uses information from the 1993–1994 Household Consumption Survey and the semiparametric quantile regression approach to analyze the demand for three macronutrients (carbohydrates, proteins, and fats) and three micronutrients (minerals, vitamins, and cholesterol) in Greece. According to the empirical results the age of the household head, the degree of urbanization, the percentage of food expenditure devoted to food away‐from‐home, and the per capita consumption expenditure affect the intakes of nutrients across all the five quantiles considered. The impact, however, of the household head's gender and the impact of his (her) educational achievement are located only at the lower and the higher quantiles, respectively. The expenditure elasticities are substantially lower than unity, suggesting inelastic responses of nutrient intakes to per capita consumption expenditure.
Acute dopamine/noradrenaline reuptake inhibition enhances human exercise performance in warm, but not temperate conditions
Authors: Watson Phillip , Hasegawa Hiroshi , Roelands Bart , Piacentini Maria Francesca , Looverie Roel , Meeusen Romain
Published: April 2005

Nine healthy endurance‐trained males were recruited to examine the effect of a dual dopamine/noradrenaline reuptake inhibitor on performance, thermoregulation and the hormonal responses to exercise. Subjects performed four trials, ingesting either a placebo (pla) or 2 × 300 mg bupropion (bup), prior to exercise in temperate (18°C) or warm (30°C) conditions. Trials consisted of 60 min cycle exercise at 55%Wmax immediately followed by a time trial (TT). TT performance in the heat was significantly improved by bupropion (pla: 39.8 ± 3.9 min, bup: 36.4 ± 5.7 min; P= 0.046), but no difference between treatments was apparent in temperate conditions (pla: 30.6 ± 2.2 min, bup: 30.6 ± 1.9 min; P= 0.954). While TT power output was consistently lower in the heat when compared to temperate conditions, this decrement was attenuated by bupropion. At the end of the TT in the heat, both core temperature (pla 39.7 ± 0.3°C, bup 40.0 ± 0.3°C; P= 0.017) and HR (pla 178 ± 7 beats min−1, bup 183 ± 12 beats min−1; P= 0.039), were higher in the bupropion trial than in the placebo. Circulating pituitary and adrenal hormone concentrations increased throughout exercise in all trials. Circulating serum prolactin was elevated above temperate levels during exercise in a warm environment (P < 0.001). These data indicate that performance in warm conditions is enhanced by acute administration of a dual dopamine/noradrenaline reuptake inhibitor. No such effect was apparent under temperate conditions. It appears that bupropion enabled subjects to maintain a greater TT power output in the heat with the same perception of effort and thermal stress reported during the placebo trial, despite the attainment of a higher core temperature.
Rapid protein kinase C‐dependent reduction of rat skeletal muscle voltage‐gated sodium channels by ciliary neurotrophic factor
Authors: Talon S. , Giroux‐Metges M.‐A. , Pennec J.‐P. , Guillet C. , Gascan H. , Gioux M.
Published: April 2005

The ciliary neurotrophic factor (CNTF), known to exert long‐term myotrophic effects, has not yet been shown to induce a rapid biological response in skeletal muscles. The present in vitro study gives rise to the possibility that CNTF could affect the sodium channel activity implied in the triggering of muscle fibre contraction. Therefore, we investigated the effects of an external CNTF application on macroscopic sodium current (INa) in rat native fast‐twitch skeletal muscle (flexor digitorum brevis, FDB) by using a cell‐attached patch‐clamp technique. The INa peak amplitude measured at a depolarizing pulse from −100 to −10 mV is rapidly reduced in a time‐ and dose‐dependent manner by CNTF (0.01–20 ng ml−1). The maximal decrease is 25% after 10 min incubation in 2 ng ml−1 CNTF. There was no alteration in activation or inactivation kinetics, or in activation curves constructed from current–voltage relationships in the presence of CNTF. In contrast, the relative INa inhibition induced by CNTF is accompanied by a hyperpolarizing shift in the midpoint of the inactivation curves: −6 and −10 mV for the steady‐state fast and slow inactivation, respectively. Furthermore, CNTF induces a 5 mV hyperpolarization of the resting membrane potential of the fibres. The effects of CNTF are similar to those of 1‐oleoyl‐2‐acetyl‐sn‐glycerol (OAG), a protein kinase C (PKC) activator, when no effect is observed in the presence of chelerythrine, a PKC inhibitor. These results suggest that, in skeletal muscle, CNTF can rapidly decrease sodium currents by altering inactivation gating, probably through an intracellular PKC‐dependent mechanism that could lead to decreased membrane excitability. The present study contributes to a better understanding of the physiological role of endogenous CNTF.
Differential effects of maurocalcine on Ca2+ release events and depolarization‐induced Ca2+ release in rat skeletal muscle
Authors: Szappanos Henrietta , Smida‐Rezgui Sophia , Cseri Julianna , Simut Cecilia , Sabatier Jean‐Marc , De Waard Michel , Kovács László , Csernoch László , Ronjat Michel
Published: April 2005

Maurocalcine (MCa), a 33 amino acid toxin obtained from scorpion venom, has been shown to interact with the isolated skeletal‐type ryanodine receptor (RyR1) and to strongly modify its calcium channel gating. In this study, we explored the effects of MCa on RyR1 in situ to establish whether the functional interaction of RyR1 with the voltage‐sensing dihydropyridine receptor (DHPR) would modify the ability of MCa to interact with RyR1. In developing skeletal muscle cells the addition of MCa into the external medium induced a calcium transient resulting from RyR1 activation and strongly inhibited the effect of the RyR1 agonist chloro‐m‐cresol. In contrast, MCa failed to affect the depolarization‐induced Ca2+ release. In intact adult fibres MCa did not induce any change in the cytosolic Ca2+ concentration. However, when the surface membrane was permeabilized and calcium release events were readily observable, MCa had a time‐dependent dual effect: it first increased event frequency, from 0.060 ± 0.002 to 0.150 ± 0.007 sarcomere−1 s−1, and reduced the amplitude of individual events without modifying their spatial distribution. Later on it induced the appearance of long‐lasting events resembling the embers observed in control conditions but having a substantially longer duration. We propose that the functional coupling of DHPRs and RyR1s within a Ca2+ release unit prevents MCa from either reaching its binding site or from being able to modify the gating not only of the RyR1s physically coupled to DHPRs but all RyR1s within the Ca2+ release unit.
Electrophysiological differences between nociceptive and non‐nociceptive dorsal root ganglion neurones in the rat in vivo
Authors: Fang X. , McMullan S. , Lawson S. N. , Djouhri L.
Published: April 2005

Intracellular recordings were made from 1022 somatic lumbar dorsal root ganglion (DRG) neurones in anaesthetized adult rats, classified from dorsal root conduction velocities (CVs) as C, Aδ or Aα/β, and according to their responses to mechanical and thermal stimuli as nociceptive (including high‐threshold mechanoreceptive (HTM) units), and non‐nociceptive (including low‐threshold mechanoreceptive (LTM) and cooling units). Of these, 463 met electrophysiological criteria for analysis of action potentials (APs) evoked by dorsal root stimulation. These included 47 C‐, 71 Aδ‐ and 102 Aα/β‐nociceptive, 10 C‐, 8 Aδ− and 178 Aα/β‐LTM, 18 C‐ and 19 Aδ‐ unresponsive, and 4 C‐cooling units. Medians of AP and afterhyperpolarization (AHP) durations and AP overshoots were significantly greater for nociceptive than LTM units in all CV groups. AP overshoots and AHP durations were similar in nociceptors of all CV groups whereas AP durations were greater in slowly conducting, especially C‐fibre, nociceptors. C‐cooling units had faster CVs, smaller AP overshoots and shorter AP durations than C‐HTM units. A subgroup of Aα/β‐HTM, moderate pressure units, had faster CVs and AP kinetics than other Aα/β‐HTM units. Of the Aα/β‐LTM units, muscle spindle afferents had the fastest CV and AP kinetics, while rapidly adapting cutaneous units had the slowest AP kinetics. AP variables in unresponsive and nociceptive units were similar in both C‐ and Aδ‐fibre CV groups. The ability of fibres to follow rapid stimulus trains (fibre maximum following frequency) was correlated with CV but not sensory modality. These findings indicate both the usefulness and limitations of using electrophysiological criteria for identifying neurones acutely in vitro as nociceptive.
Partitioning oxidative fuels during cold exposure in humans: muscle glycogen becomes dominant as shivering intensifies
Authors: Haman François , Péronnet François , Kenny Glen P. , Massicotte Denis , Lavoie Carole , Weber Jean‐Michel
Published: April 2005

The effects of changes in shivering intensity on the relative contributions of plasma glucose, muscle glycogen, lipids and proteins to total heat production are unclear in humans. The goals of this study were: (1) to determine whether plasma glucose starts playing a more prominent role as shivering intensifies, (2) to quantify overall changes in fuel use in relation to the severity of cold exposure, and (3) to establish whether the fuel selection pattern of shivering is different from the classic fuel selection pattern of exercise. Using a combination of indirect calorimetry and stable isotope methodology, fuel metabolism was monitored in non‐acclimatized adult men exposed for 90 mins to 10°C (low‐intensity shivering (L)) or 5°C (moderate‐intensity shivering (M)). Results show that plasma glucose oxidation is strongly stimulated by moderate shivering (+122% from L to M), but the relative contribution of this pathway to total heat generation always remains minor (< 15% of total heat production). Instead, muscle glycogen is responsible for most of the increase in heat production between L and M. By itself, the increase in CHO oxidation is responsible for the 100 W increase in metabolic rate observed between L and M, because rates of lipid and protein oxidation remain constant. This high reliance on CHO is not compatible with the well known fuel selection pattern of exercise, when considering the relatively low metabolic rates elicited by shivering (∼30% for M). We conclude that shivering and exercise of similar energy requirements appear to be supported by different fuel mixtures. Investigating the physiological mechanisms underlying why a muscle producing only heat (shivering), or significant movement (exercise), shows a different pattern of fuel selection at the same power output strikes us as a fascinating area for future research.
Impaired voluntary running capacity of creatine kinase‐deficient mice
Authors: Momken Iman , Lechêne Patrick , Koulmann Nathalie , Fortin Dominique , Mateo Philippe , Doan Bich Thuy , Hoerter Jacqueline , Bigard Xavier , Veksler Vladimir , Ventura‐Clapier Renée
Published: April 2005

The creatine kinase system (CK) is important for energy delivery in skeletal and cardiac muscles. The two main isoforms of this enzyme, cytosolic MM‐CK and mitochondrial mi‐CK, are expressed in a developmental and muscle‐type specific manner. Mice deficient in one or both of these isoforms are viable and fertile but exhibit profound functional, metabolic and structural muscle remodelling that primarily affects fast skeletal muscles, which show an increased contribution of oxidative metabolism to contractile function. However, the consequences of these alterations in terms of physical capabilities have not yet been characterized. Consequently, we compared the voluntary exercise capacity of 9‐month‐old male wild‐type (WT), M‐CK knockout (M‐CK−/−), and M‐CK and mi‐CK double knockout (CK−/−) mice, using cages equipped with running wheels. Exercise performance, calculated by total distance covered and by work done during the training period, was more than 10‐fold lower in CK−/− mice than controls, with M‐CK−/− mice exhibiting intermediate performance. Similarly, the mean distance run per activation was lower in M‐CK−/− and even lower in CK−/− mice. However, the maximal running speed (Vmax) was lower only for CK−/− mice. This was accompanied by severe skeletal muscle mass decrease in CK−/− mice, with signs of histological damage that included enlarged interstitial areas, aggregations of mononuclear cells in the interstitium, heterogeneity of myofibre size and the presence of very small fibres. No overt sign of cardiac dysfunction was observed by magnetic resonance imaging during dobutamine stimulation. These results show that metabolic failure induced by CK deficiency profoundly affects the ability of mice to engage in chronic bouts of endurance running exercise and that this decrease in performance is also associated with muscle wasting.
Direct-Transfer Preswirl System: A One-Dimensional Modular Characterization of the Flow
Authors: Dittmann M. , Dullenkopf K. , Wittig S.
Published: April 2005

In high-efficiency gas turbine engines, the cooling air for the high-pressure turbine stage is expanded through stationary preswirl nozzles, transferred through the preswirl chamber, and delivered to the blade feed holes of the rotor. By accelerating the cooling air in the direction of rotation, the total temperature relative to the rotor disk and the pressure losses occurring at the receiver hole inlet can be reduced. The discharge behavior of a direct-transfer preswirl system has been investigated experimentally for different number of receiver holes and different inlet geometries, varying axial gap widths between stator and rotor and for rotational Reynolds numbers up to Reϕ=2.3×10 6. The discharge coefficients of the preswirl nozzles are given in the absolute frame of reference while the definition of the discharge coefficients of the receiver holes is applied to the rotating system in order to consider the work done by the rotor. A momentum balance is used to evaluate the deflection of the preswirled air entering the receiver holes. The flow in the preswirl chamber is characterized by introducing an effective velocity of the cooling air upstream of the rotor disk. The influences of geometrical parameters and operating points are reported and discussed in this paper.
Aircraft Turbofan Engine Health Estimation Using Constrained Kalman Filtering
Authors: Simon Dan , Simon Donald L.
Published: April 2005

Kalman filters are often used to estimate the state variables of a dynamic system. However, in the application of Kalman filters some known signal information is often either ignored or dealt with heuristically. For instance, state-variable constraints (which may be based on physical considerations) are often neglected because they do not fit easily into the structure of the Kalman filter. This paper develops an analytic method of incorporating state-variable inequality constraints in the Kalman filter. The resultant filter is a combination of a standard Kalman filter and a quadratic programming problem. The incorporation of state-variable constraints increases the computational effort of the filter but significantly improves its estimation accuracy. The improvement is proven theoretically and shown via simulation results obtained from application to a turbofan engine model. This model contains 16 state variables, 12 measurements, and 8 component health parameters. It is shown that the new algorithms provide improved performance in this example over unconstrained Kalman filtering.
Resistance Reduction in Pulsating Turbulent Pipe Flows
Authors: Manna Marcello , Vacca Andrea
Published: April 2005

The paper describes the effects of forced harmonic oscillations of fixed frequency and amplitudes in the range Λ=Um/Ub=1-11 on the characteristics of a turbulent pipe flow with a bulk Reynolds number of 5900. The resulting Stokes layer δ is a fraction of the pipe radius χ=R/δ=53 so that the vorticity associated to the oscillating motion is generated in a small near wall region. The analysis is carried out processing a set of statistically independent samples obtained from wall-resolved large eddy simulations (LES); time and space averaged global quantities, extracted for the sake of comparison with recent experimental data, confirm the presence of a non-negligible drag reduction phenomenon. Phase averaged profiles of the Reynolds stress tensor components provide valuable material for the comprehension of the effects of the time varying mean shear upon the near wall turbulent flow structures. The large scales of motion are directly computed through numerical integration of the space filtered three-dimensional Navier-Stokes equations with a spectrally accurate code; the subgrid scale terms are parametrized with a dynamic procedure.
Experimental Study of Surface and Interior Combustion Using Composite Porous Inert Media
Authors: Marbach T. L. , Agrawal A. K.
Published: April 2005

Combustion using silicon carbide coated, carbon–carbon composite porous inert media (PIM) was investigated. Two combustion modes, surface and interior, depending upon the location of flame stabilization, were considered. Combustion performance was evaluated by measurements of pressure drop across the PIM, emissions of NOx and CO, and the lean blow-off limit. Data were obtained for the two combustion modes at identical conditions for a range of reactant flowrates, equivalence ratios, and pore sizes of the PIM. Results affirm PIM combustion as an effective method to extend the blow-off limit in lean premixed combustion.