bluuebunny/crossref_metadata_2025 huggingface dataset:
Biochemical and Clinical Evidence for Uremic Toxicity
Authors: Bouré Tony , Vanholder Raymond
Published: March 2004

Abstract:  The uremic syndrome is a mix of clinical features resulting from multiple organ dysfunctions which develop when kidney failure progresses, and is attributed to the retention of solutes, which under normal conditions are excreted by the healthy kidneys into the urine. The most practical classification of uremic solutes is based on their physicochemical characteristics that influence their dialytic removal, in (1) small water soluble compounds, (2) the larger “middle molecules,” and (3) the protein bound compounds. Hence, uremic retention is much more complex than originally believed. Among the small water soluble compounds, urea exerts not much toxic activity and is not very representative in its kinetic behavior for many other uremic solutes. Among the middle molecules, many have been recognized to exert biological activity and hence to contribute to the uremic syndrome. Specific dialysis strategies apply large pore membranes to remove those middle molecules and have a beneficial impact on uremic morbidity and mortality. A substantial number of uremic solutes are protein bound. Only recently, a relation between their concentration and clinical status could be demonstrated. Likewise, it was only recently possible to demonstrate more than standard removal with super‐flux dialysis membranes. To further improve characterization of uremic solutes and to develop directed therapeutic approaches, further concerted action among various groups of researchers  will  be needed.
Improving The Analysis of Esophageal Acid Exposure by A New Parameter: Area Under H+
Authors: Rebecchi Fabrizio , Di Francia Italo , Giaccone Claudio , Morino Mario
Published: March 2004

ABSTRACT

OBJECTIVES:

We aimed to compare the data provided by 24-h continuous esophageal pH monitoring in a group of patients with gastroesophageal reflux disease (GERD) to those from a group of healthy volunteers using both conventional parameters and calculated area under the curve of hydrogen ion activity (AUH+), a new value that describes the true acid exposure, through both duration and depth of acidity changes.

METHODS:

Thirty healthy controls and 60 patients with GERD (30 symptomatic patients without endoscopic esophagitis or nonerosive GERD and 30 symptomatic patients with Savary I–IV endoscopic esophagitis or erosive GERD) were enrolled in a study based on 24-h pH monitoring to compare reference values by means of receiver operating characteristic (ROC) discriminant analysis.

RESULTS:

The best ROC cutoff value for nonerosive GERD patients was AUH+ = 103.7 (mmol/L) × min with sensitivity of 76.7% and specificity of 93.3%. The best ROC cutoff value for erosive GERD patients was AUH+ = 114.1 (mmol/L) × min with sensitivity of 100% and specificity of 96.7%. These cutoff values increase the sensitivity by 16.7% for nonerosive GERD patients and 10% for erosive GERD patients when compared to a common parameter such as the percentage of total time pH is <4 with a limit of 4.2%.

CONCLUSIONS:

AUH+ is a valid quantitative parameter to measure 24-h esophageal acid exposure. It may be a reliable and significant clinical aid because it is a more sensitive test in discriminating negative or positive adult patients with or without esophagitis who are submitted to 24-h esophageal pH monitoring.
Intestinal Metaplasia of The Gastric Cardia: A Prospective Study With Enhanced Magnification Endoscopy
Authors: Guelrud Moises , Herrera Idamys , Essenfeld Harold , Castro Julio , Antonioli Donald A
Published: March 2004

ABSTRACT

OBJECTIVE:

There are no endoscopic features that distinguish intestinal metaplasia of the cardia (CIM) from the normal cardia. Biopsy specimens are therefore randomly obtained from normal-appearing mucosa with significant potential sampling errors. Enhanced magnification endoscopy involves the combined use of magnification endoscopy with acetic acid instillation. This study assessed the value of enhanced magnification endoscopy in detecting CIM.

METHODS:

Patients undergoing elective upper endoscopy were invited to participate in the study. Patients were included if the squamocolumnar junction and the esophagogastric junction were judged to be at the same level. Enhanced magnification endoscopy was performed with 3% acetic acid instillation. Standard endoscopy was followed by magnification endoscopy and repeated after acetic acid spraying. Surface patterns were characterized before and after acetic acid spraying. The observed surface patterns were compared with histological results obtained from a single targeted biopsy specimen of each pattern.

RESULTS:

The overall prevalence of CIM was 34.8% (86/247 patients). After excluding 52 patients because of endoscopic evidence of Barrett's esophagus, 195 patients were eligible for participation in the study. In the study group, CIM was detected in 86 patients (44.1%) in targeted biopsy samples. No dysplasia was identified. Enhanced magnification endoscopy detected four different patterns of the mucosal surface: I) round pits, II) reticular, III) villous, and IV) ridged. The yields of detection of intestinal metaplasia according to endoscopic patterns were I) 0%, II) 5.3% (odds ratio = 0.05), III) 57.7% (odds ratio = 7.5, p = 0.0001), and IV) 95.8% (odds ratio = 42.8, p = 0.0001).

CONCLUSIONS:

CIM is more common than previously reported. Enhanced magnification endoscopy identifies two characteristic endoscopic patterns, villous (pattern III) and ridged (pattern IV), with outstanding clarity and resolution that correlate with histological identification of CIM with a single targeted biopsy sample. Enhanced magnification endoscopy will permit longitudinal studies of an entity that can be identified endoscopically.
Upper Gi Malignancy, Uncomplicated Dyspepsia, and The Age Threshold for Early Endoscopy
Authors: Canga Cristino , Vakil Nimish
Published: March 2004

ABSTRACT

OBJECTIVES:

We sought to determine the frequency with which patients with upper GI malignancies present with uncomplicated dyspepsia and to determine the impact of changing the threshold for early endoscopy from 45 to 55 yr, as has recently been recommended in European studies.

METHODS:

Three hundred forty-one patients with upper GI malignancies at two Milwaukee teaching hospitals were identified from electronic databases. Trained physician-investigators reviewed the charts using a specifically designed questionnaire. Staging of GI cancers was performed using the TNM classification to determine operability. Uncomplicated dyspepsia was defined as dyspepsia without alarm symptoms/signs (dysphagia, vomiting, weight loss, early satiety, GI bleeding, or anemia).

RESULTS:

There were 341 patients with upper GI malignancies with a mean age of 68 yr (range = 22–94). Twenty-one patients were younger than 45 and 65 were under 55. Uncomplicated dyspepsia was the presenting symptom in five of 65 (7.7%) patients younger than 55 and one of 21 (4.8%) patients under 45 (p = 0.99). Five patients 55 or younger presented with uncomplicated dyspepsia. All had advanced, inoperable disease (stage III or higher).

CONCLUSIONS:

1) In a racially diverse United States population, upper GI malignancy presenting without alarm symptoms is uncommon. 2) Raising the threshold for immediate endoscopy in uncomplicated dyspepsia from age 45 to 55 increases the risk of missing an underlying malignancy but may not affect outcome, as incurable disease was present at diagnosis within a few weeks of the onset of symptoms.
Octreotide Relaxes The Hypertensive Sphincter of Oddi: Pathophysiological and Therapeutic Implications
Authors: Fazel Ali , Li Spencer C , Burton Frank R
Published: March 2004

ABSTRACT

OBJECTIVES:

As our understanding of the pathophysiology of sphincter of Oddi dysfunction (SOD) expands, new avenues arise for pharmacological intervention. Recent evidence suggests that SOD results from a loss of myenteric plexus inhibitory neurons resulting in unopposed cholinergic tone. Octreotide inhibits postganglionic cholinergic neurons, and thus we hypothesize that administration of octreotide will decrease sphincteric pressure in individuals with SOD.

METHODS:

Thirty-eight patients presenting with recurrent abdominal pain and SOD (basal pressure > 40 mm Hg) were studied. The study was prospective, placebo controlled, and blinded. Patient allocation was consecutive. Sphincter of Oddi manometry was performed in standard fashion. The test group (n = 19) received octreotide acetate (100 μg i.v.), and the control group (n = 19) received i.v. saline. Basal, phasic, and duct pressures as well as phasic amplitude and frequency were recorded before and 3 min after the i.v. infusion. Changes in these parameters before and after i.v. infusions were compared.

RESULTS:

Octreotide caused a statistically significant reduction in peak and basal sphincter of Oddi pressures relative to saline (p < 0.01 and p < 0.001). Octreotide did not significantly affect wave amplitude, wave frequency, or duct pressure.

CONCLUSIONS:

Octreotide has the potential to be a valuable addition to the armamentarium for the medical management of SOD.
Budesonide and Mesalazine in Active Crohn's Disease: A Comparison of The Effects on Quality of Life
Authors: Thomsen Ole Ø , Cortot Antoine , Jewell Derek , Wright John P , Winter Trevor , Veloso Fernando T , Vatn Morten , Persson Tore , Pettersson Eva
Published: March 2004

ABSTRACT

OBJECTIVES:

Controlled ileal release budesonide and slow release mesalazine are both used to treat mild to moderate active Crohn's disease, although data show that budesonide is more effective in inducing remission. When comparing different treatment options, the effects of agents on health-related quality of life must be considered as well as efficacy. In this study, we sought to compare the effects of budesonide and mesalazine on the health-related quality of life of patients with active Crohn's disease.

METHODS:

The study included 182 patients with Crohn's Disease Activity Index scores between 200 and 400. Patients were randomized in a double blind, double dummy, multicenter study to receive 9 mg of budesonide, once daily (n = 93), or 2 g of mesalazine, b.i.d. (n = 89), for 16 wk. Quality of life was assessed at baseline and after 2, 4, 8, 12, and 16 wk of treatment using the Psychological General Well-Being index. In addition, a physician's global evaluation was used to assess how symptoms affected patients' normal activities.

RESULTS:

Patients treated with budesonide experienced significantly greater improvement in Psychological General Well-Being scores than the group treated with mesalazine after 2, 8, 12, and 16 wk. All components of this index showed greater improvements in the budesonide-treated group than in the mesalazine group at 12 and 16 wk. The physician's global evaluation showed significantly greater improvements in the budesonide group than in the mesalazine group at all visits.

CONCLUSION:

Budesonide (9 mg once daily) improves health-related quality of life to a greater extent than mesalazine (2 g b.i.d.) in patients with mild to moderate active Crohn's disease.
Central Processing of Rectal Pain in Patients With Irritable Bowel Syndrome: An Fmri Study
Authors: Bonaz B , Baciu M , Papillon E , Bost R , Gueddah N , Le Bas J-F , Fournet J , Segebarth C
Published: March 2004

ABSTRACT

OBJECTIVES:

In healthy subjects, the neural correlates of visceral pain bear much similarity with the correlates of somatic pain. In patients with irritable bowel syndrome, the central nervous system is believed to play a strong modulatory or etiological role in the pathophysiology of the disease. We hypothesize that this role must be reflected in aberrations of central functional responses to noxious visceral stimulation in these patients. To verify this hypothesis, we have induced transient rectal pain in patients and assessed the functional responses of the brain by means of functional magnetic resonance imaging.

METHODS:

Twelve right-handed patients (11 female) were examined. Functional imaging (1.5 T) was performed following a block paradigm, alternating epochs with and without noxious stimulation of the rectum. Rectal pain was induced by inflating a latex balloon. Whole-brain coverage was achieved by means of echo-planar magnetic resonance acquisition.

RESULTS:

A strong variability of the individual responses to rectal pain was found in patients with irritable bowel syndrome. Significant activations were found in only two patients, and group analysis did not reveal significant activations. In contrast, all patients exhibited significant deactivations. Group analysis revealed significant deactivations within the right insula, the right amygdala, and the right striatum.

CONCLUSIONS:

This study reveals aberrant functional responses to noxious rectal stimulation in patients with irritable bowel syndrome. Those results add grounds to the hypothesis that the central nervous system plays a significant role in the pathophysiology of this syndrome.
Outcome of Patients With Radiation Enteritis Treated With Home Parenteral Nutrition
Authors: Scolapio James S , Ukleja Andrzej , Burnes Jan U , Kelly Darlene G
Published: March 2004

ABSTRACT

OBJECTIVES:

Intestinal failure requiring either surgery or home parenteral nutrition (HPN) develops in approximately 5% of patients treated with radiation. The aim of the study was to determine survival, duration of HPN, and complications associated with HPN in patients with intestinal failure after radiation therapy.

METHODS:

Fifty-four patients with radiation enteritis who received HPN were studied (39 women and 15 men with a mean age of 57.9 yr). Retrospective data were collected from the patients' medical records dated between 1975 and 1999. The probability of survival was calculated by the Kaplan-Meier method.

RESULTS:

HPN was initiated a median of 20 months (range = 2–432) from the start of radiation therapy. The mean number of intestinal operations for radiation-related complications was 2.2/patient (range = 0–6). The causes of intestinal failure resulting from radiation therapy were intestinal obstruction (27 patients), short bowel (17), malabsorption (five), fistula (three), and dysmotility (two). The mean duration of HPN was 20.4 months (range = 2–108). At last follow-up, 37 patients (68%) were dead, most as a result of recurrent cancer. One patient died of catheter sepsis, and no other deaths were directly related to HPN. The overall estimated 5-yr probability of survival on HPN calculated by Kaplan-Meier analysis was 64%.

CONCLUSIONS:

HPN is a reasonable treatment option in patients with intestinal failure as a result of radiation enteritis. Survival and complications associated with HPN in patients with radiation enteritis seem to be similar to those in other HPN-treated groups.
Low Free and Total Insulinlike Growth Factor I (Igf-I) and Igf Binding Protein-3 Levels in Chronic Inflammatory Bowel Disease: Partial Normalization During Prednisolone Treatment
Authors: Grønbæk H , Thøgersen T , Frystyk J , Vilstrup H , Flyvbjerg A , Dahlerup J F
Published: March 2004

ABSTRACT

OBJECTIVES:

Catabolism and growth impairment are well known complications of chronic inflammatory bowel disease (CIBD). This may be caused by disease activity itself and/or the medical treatment, which may lead to changes in the growth hormone and insulinlike growth factor I (IGF-I) axis. Interest has focused on corticosteroids, as they are known to influence the growth hormone/IGF-I axis.

METHODS:

The aim of the present study was to examine changes in total and free IGF-I, IGF binding proteins (IGFBPs), and IGFBP-3 protease activity in 10 patients with severe acute activity in colon CIBD before and during high dose prednisolone treatment (1 wk) and 3 months tapering. Eight healthy subjects served as controls.

RESULTS:

Total and free IGF-I were significantly reduced by 35% and 53%, respectively, before prednisolone treatment (p < 0.05), and free IGF-I remained reduced even by the end of the study period relative to controls (p < 0.05). IGFBP-3 was reduced by 16% before (p < 0.05), with normalization during prednisolone treatment and tapering relative to controls. There was no evidence of increase in IGFBP-3 protease activity. IGFBP-1 was increased before and tended also to be increased during prednisolone treatment and tapering.

CONCLUSIONS:

Marked changes in serum total and free IGF-I and IGFBPs were demonstrated in patients with severe exacerbation of CIBD without complete normalization during high dose prednisolone treatment and tapering. These changes may partly be involved in the catabolism of active CIBD patients.
Awareness of Genetic Testing for Colorectal Cancer Predisposition Among Specialists in Gastroenterology
Authors: Batra Shivani , Valdimarsdottir Heiddis , McGovern Margaret , Itzkowitz Steven , Brown Karen
Published: March 2004

ABSTRACT

OBJECTIVES:

Adult gastroenterologists practicing in New York State were surveyed to determine their practice with regard to identifying family histories consistent with inherited forms of colorectal cancer, and to assess their awareness of cancer genetic counseling and molecular genetic testing for familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer (HNPCC).

METHODS:

A closed-ended questionnaire was mailed to 815 gastroenterologists identified through the membership Directory of the American Gastroenterological Association (1998). Two mailings resulted in a response rate of 35%.

RESULTS:

In all, 99% of the gastroenterologists obtained a family history from their patients, and 95% were aware of cancer genetic counseling. However, only 51% would routinely refer patients for genetic counseling before providing cancer predisposition testing. In addition, only 52% were aware of the availability of genetic tests for FAP and 34% for HNPCC. Presented with a family history consistent with HNPCC, 79% could identify the syndrome, 26% recommended genetic counseling for the consultand, and 16% advised appropriate screening, according to current recommendations.

CONCLUSIONS:

The majority of gastroenterologists do obtain a family history on their patients. However, there is a need for physician education regarding the recognition of pedigrees consistent with inherited colorectal cancer, the genetic counseling process, and the availability of mutation testing for FAP and HNPCC.
Semiannual and Annual Surveillance of Cirrhotic Patients for Hepatocellular Carcinoma: Effects on Cancer Stage and Patient Survival (Italian Experience)
Authors: Trevisani Franco , De Notariis Stefania , Rapaccini Gianludovico , Farinati Fabio , Benvegnù Luisa , Zoli Marco , Grazi Gian Luca , Del Poggio Paolo , Di Nolfo Maria Anna , Bernardi Mauro
Published: March 2004

ABSTRACT

OBJECTIVES:

Surveillance of cirrhotic patients for early detection of hepatocellular carcinoma, based on ultrasonography and α1-fetoprotein determination, is a recommended practice. However, it has not been proved that this procedure can improve patient survival.

METHODS:

We conducted a multicenter retrospective study on 1051 consecutive patients with hepatocellular carcinoma. The criteria for eligibility were presence of underlying cirrhosis, and description of cancer stage and modalities of its diagnosis. Among 821 patients fulfilling these criteria, the tumor was detected during semiannual surveillance in 215 individuals (group 1), during annual surveillance in 155 (group 2), and as a result of symptoms or incidentally in 451 (group 3). Survival of patients under surveillance was corrected for lead time.

RESULTS:

Cancer stage was similar in groups 1 and 2 and was less advanced than in group 3 (p < 0.001). The frequency of ablative treatments or chemoembolization was similar in groups 1 and 2 and was greater than in group 3 (p < 0.001). Both surveillance programs doubled the prevalence of potential candidates for liver transplantation (68.5% and 62.5%) with respect to group 3 (32.3%, p < 0.001). However, only 15 patients underwent transplantation. In groups 1 and 2, the 5-yr survival was equivalent and was greater than in group 3 (p < 0.001). By segregating patients according to severity of cirrhosis, the benefit was confined to compensated cirrhosis (adjusted relative risk of death for patients under surveillance: 0.59 [95% CI = 0.45–0.78]).

CONCLUSIONS:

Semiannual and annual surveillance equally improve the survival of cirrhotic patients with hepatocellular carcinoma and greatly increase the amenability rate to liver transplantation. When access to liver transplantation is limited, this benefit is restricted to patients with a good cirrhosis-related prognosis.
Selenoprotein Levels in Patients With Colorectal Adenomas and Cancer
Authors: Early Dayna S , Hill Kristina , Burk Raymond , Palmer Ivan
Published: March 2004

ABSTRACT

OBJECTIVES:

Selenium is a trace mineral that, as a constituent of certain selenoproteins, acts as an antioxidant. Results of studies addressing a cancer protective effect of selenium have been controversial. The present study measured selenoprotein-P, extracellular glutathione peroxidase, and plasma selenium in patients with colon cancer and adenomatous colon polyps to determine whether patients who develop colorectal adenomas or cancer are selenium deficient.

METHODS:

Patients who presented to an endoscopy center for colonoscopy or who were referred to our institution with a newly diagnosed colorectal cancer were offered enrollment in the trial. Each patient underwent phlebotomy, usually immediately after colonoscopy. In all, 103 patients were enrolled in the study. Of these, 33 patients were found to have colorectal cancer, 35 adenomatous colon polyps, and 17 normal examinations. A total of 18 patients had other diagnoses and were not included in the study group.

RESULTS:

The mean age for the colorectal cancer group was 69 yr, for the adenomatous colon polyp group 62 yr, and for the normal group was 56 yr. The adenomatous colon polyp and normal groups were predominantly female. Based on one way analysis of variance tests, there was no significant difference in selenoprotein-P or plasma selenium levels or extracellular glutathione peroxidase activity among the three groups (p = 0.28, 0.098, and 0.35 respectively).

CONCLUSIONS:

The present data suggest that patients with adenomatous colon polyps and those with colorectal cancer are not selenium deficient.
High Prevalence of Undetected Ulcerative Colitis: Data From The Nottingham Fecal Occult Blood Screening Trial
Authors: Howarth G F , Robinson M H E , Jenkins D , Hardcastle J D , Logan R F A
Published: March 2004

ABSTRACT

OBJECTIVES:

Inflammatory bowel disease (IBD) is usually diagnosed as a result of symptoms but occasionally is found during investigation for other conditions. An earlier report from Nottingham had found a high prevalence of previously undetected “asymptomatic” IBD detected as a result of colorectal cancer screening, and the aim of this study was to reassess the prevalence, symptoms, and outcome in these patients.

METHODS:

We investigated subjects found to be fecal occult blood (FOB) positive in a randomized trial of FOB screening for colorectal cancer. All FOB-positive subjects were investigated by colonoscopy or flexible sigmoidoscopy and barium enema. Subjects with IBD were referred back to their general practitioner for any further investigation and treatment.

RESULTS:

Seventy-five thousand two hundred fifty-three subjects (aged 45–74) were sent FOB tests and 44,838 (60%) completed a series of tests on one or more occasions. Of 133,000 test series, 1.5% were positive. During investigation 53 cases of previously undetected IBD (52 of ulcerative colitis) were found; 52% (27/52) had proctosigmoiditis only, whereas 25% (13/52) had pancolitis. Only 17% (9/52) were completely asymptomatic, with a half or more reporting some rectal bleeding (54%) or diarrhea (50%). The overall prevalence of undetected ulcerative colitis was 69/105 (95% CI = 50–88/105) in people offered screening and 116/105 (95% CI = 85–147/105) in people accepting screening and was higher in men. Of 32 subjects followed up 2–12 yr after diagnosis, 91% (29) continued to have few or no symptoms, with only 12 currently receiving any treatment for their colitis.

CONCLUSIONS:

In comparison with detected disease, undetected ulcerative colitis is relatively common but does usually cause some symptoms. It generally appears to follow a benign course, but a significant proportion have extensive colitis and may therefore be at an increased risk of colorectal cancer.
A New Model for Boundary Layer Transition Using a Single-Point RANS Approach
Authors: Walters D. Keith , Leylek James H.
Published: March 2004

This paper presents the development and implementation of a new model for bypass and natural transition prediction using Reynolds-averaged Navier-Stokes computational fluid dynamics (CFD), based on modification of two-equation, linear eddy-viscosity turbulence models. The new model is developed herein based on considerations of the universal character of transitional boundary layers that have recently been documented in the open literature, and implemented into a popular commercial CFD code (FLUENT) in order to assess its performance. Two transitional test cases are presented: (1) a boundary layer developing on a flat heated wall, with free-stream turbulence intensity Tu∞ ranging from 0.2 to 6%; and (2) flow over a turbine stator vane, with chord Reynolds number 2.3×105, and Tu∞ from 0.6 to 20%. Results are presented in terms of Stanton number, and compared to experimental data for both cases. Results show good agreement with the test cases and suggest that the new approach has potential as a predictive tool.
Investigation of an Inversely Designed Centrifugal Compressor Stage—Part II: Experimental Investigations
Authors: Schleer M. , Hong S. S. , Zangeneh M. , Roduner C. , Ribi B. , Pløger F. , Abhari R. S.
Published: March 2004

This paper presents an experimental investigation of two centrifugal compressor stage configurations. The baseline configuration has been designed using conventional design engineering tools. The second configuration was designed using advanced inverse design rules as described in Part I. It is designed to match the choke flow as well as the best point of the conventionally designed stage. The experimental investigation is conducted in the industry-scale centrifugal compressor facility at the Turbomachinery Laboratory of the Swiss Federal Institute of Technology. Performance maps for both configurations at several speed lines are presented. These plots show the overall behavior of the stages designed using the different design approaches and their operating range. Time-resolved measurements show details of the unsteady flow field within the diffuser close to the impeller exit. The time-resolved data have been analyzed to assist the explanation of changes in the characteristics and associated efficiency penalties and gains. The processed data show the benefits of the new inverse design method with respect to an improvement of the compressor efficiency and the operating range. It is seen that the application of an inverse design method results in a more uniform flow into the diffuser.
Backward Traveling Rotating Stall Waves in Centrifugal Compressors
Authors: Spakovszky Z. S.
Published: March 2004

Rotating stall waves that travel against the direction of rotor rotation are reported for the first time and a new, low-order analytical approach to model centrifugal compressor stability is introduced. The model is capable of dealing with unsteady radially swirling flows and the dynamic effects of impeller-diffuser component interaction as it occurs in centrifugal compression systems. A simple coupling criterion is developed from first principles to explain the interaction mechanism important for system stability. The model findings together with experimental data explain the mechanism for first-ever observed backward traveling rotating stall in centrifugal compressors with vaned diffusers. Based on the low-order model predictions, an air injection scheme between the impeller and the vaned diffuser is designed for the NASA Glenn CC3 high-speed centrifugal compressor. The steady air injection experiments show an increase of 25% in surge-margin with an injection mass flow of 0.5% of the compressor mass flow. In addition, it is experimentally demonstrated that this injection scheme is robust to impeller tip-clearance effects and that a reduced number of injectors can be applied for similar gains in surge-margin. The results presented in this paper firmly establish the connection between the experimentally observed dynamic phenomena in the NASA CC3 centrifugal compressor and a first principles based coupling criterion. In addition, guidelines are given for the design of centrifugal compressors with enhanced stability.       Winner of the “Best Paper Award,” Turbomachinery Committee
Measurements and Predictions of Heat Transfer on Rotor Blades in a Transonic Turbine Cascade
Authors: Giel Paul W. , Boyle Robert J. , Bunker Ronald S.
Published: March 2004

Detailed heat transfer measurements and predictions are given for a power generation turbine rotor with 127 deg of nominal turning and an axial chord of 130 mm. Data were obtained for a set of four exit Reynolds numbers comprised of the facility maximum point of 2.50×106, as well as conditions which represent 50%, 25%, and 15% of this maximum condition. Three ideal exit pressure ratios were examined including the design point of 1.443, as well as conditions which represent −25% and +20% of the design value. Three inlet flow angles were examined including the design point and ±5deg off-design angles. Measurements were made in a linear cascade with highly three-dimensional blade passage flows that resulted from the high flow turning and thick inlet boundary layers. Inlet turbulence was generated with a blown square bar grid. The purpose of the work is the extension of three-dimensional predictive modeling capability for airfoil external heat transfer to engine specific conditions including blade shape, Reynolds numbers, and Mach numbers. Data were obtained by a steady-state technique using a thin-foil heater wrapped around a low thermal conductivity blade. Surface temperatures were measured using calibrated liquid crystals. The results show the effects of strong secondary vortical flows, laminar-to-turbulent transition, and also show good detail in the stagnation region.
Effect of Blade Tip Geometry on Tip Flow and Heat Transfer for a Blade in a Low-Speed Cascade
Authors: Saxena Vikrant , Nasir Hasan , Ekkad Srinath V.
Published: March 2004

A comprehensive investigation of the effect of various tip sealing geometries is presented on the blade tip leakage flow and associated heat transfer of a scaled up HPT turbine blade in a low-speed wind tunnel facility. The linear cascade is made of four blades with the two corner blades acting as guides. The tip section of a HPT first stage rotor blade is used to fabricate the two-dimensional blade. The wind tunnel accommodates an 116 deg turn for the blade cascade. The mainstream Reynolds number based on the axial chord length at cascade exit is 4.83×105. The upstream wake effect is simulated with a spoked wheel wake generator placed upstream of the cascade. A turbulence grid placed even farther upstream generates the required freestream turbulence of 4.8%. The center blade has a tip clearance gap of 1.5625% with respect to the blade span. Static pressure measurements are obtained on the blade surface and the shroud. The effect of crosswise trip strips to reduce leakage flow and associated heat transfer is investigated with strips placed along the leakage flow direction, against the leakage flow and along the chord. Cylindrical pin fins and pitch variation of strips over the tip surface are also investigated. Detailed heat transfer measurements are obtained using a steady-state HSI-based liquid crystal technique. The effect of periodic unsteady wake effect is also investigated by varying the wake Strouhal number from 0. to 0.2, and to 0.4. Results show that the trip strips placed against the leakage flow produce the lowest heat transfer on the tips compared to all the other cases with a reduction between 10–15% compared to the plain tip. Results also show that the pitch of the strips has a small effect on the overall reduction. Cylindrical pins fins and strips along the leakage flow direction do not decrease the heat transfer coefficients and in some cases enhance the heat transfer coefficients by as much as 20%.
Active Flow Separation Control of a Stator Vane Using Embedded Injection in a Multistage Compressor Experiment
Authors: Culley Dennis E. , Bright Michelle M. , Prahst Patricia S. , Strazisar Anthony J.
Published: March 2004

Active flow control has been applied to the suction surface of stator vanes in a low speed axial compressor. Injection from the suction surface has been shown to reduce separation on vanes that were induced to separate by increasing the vane stagger angle by 3° deg. Various configurations were investigated including injector geometry (slots versus holes) and type of injection (steady versus unsteady). Unsteady injection was realized using two different approaches; external actuation through a high frequency valve and embedded actuation using a fluidic device internal to the vane. Using total pressure loss through the vane passage as a metric, reductions in area-averaged loss of 25% were achieved using injected mass flow rates on the order of 1% of compressor throughflow. The development of a tracking control algorithm was also explored for the purpose of closed-loop control. A reliable method of detecting surface separation was implemented using unsteady pressure measurements on the compressor casing near the vane suction surface.
Experimental and Numerical Study of Stall Flutter in a Transonic Low-Aspect Ratio Fan Blisk
Authors: Sanders A. J. , Hassan K. K. , Rabe D. C.
Published: March 2004

Experiments are performed on a modern design transonic shroudless low-aspect ratio fan blisk that experienced both subsonic/transonic and supersonic stall-side flutter. High-response flush mounted miniature pressure transducers are utilized to measure the unsteady aerodynamic loading distribution in the tip region of the fan for both flutter regimes, with strain gages utilized to measure the vibratory response at incipient and deep flutter operating conditions. Numerical simulations are performed and compared with the benchmark data using an unsteady three-dimensional nonlinear viscous computational fluid dynamic (CFD) analysis, with the effects of tip clearance, vibration amplitude, and the number of time steps-per-cycle investigated. The benchmark data are used to guide the validation of the code and establish best practices that ensure accurate flutter predictions.
Investigation of an Inversely Designed Centrifugal Compressor Stage—Part I: Design and Numerical Verification
Authors: Zangeneh M. , Schleer M. , Pløger F. , Hong S. S. , Roduner C. , Ribi B. , Abhari R. S.
Published: March 2004

In this paper the three-dimensional inverse design code TURBOdesign-1 is applied to the design of the blade geometry of a centrifugal compressor impeller with splitter blades. In the design of conventional impellers the splitter blades normally have the same geometry as the full blades and are placed at mid-pitch location between the two full blades, which can usually result in a mismatch between the flow angle and blade angles at the splitter leading edge. In the inverse design method the splitter and full blade geometry is computed independently for a specified distribution of blade loading on the splitter and full blades. In this paper the basic design methodology is outlined and then the flow in the conventional and inverse designed impeller is compared in detail by using computational fluid dynamics (CFD) code TASCflow. The CFD results confirm that the inverse design impeller has a more uniform exit flow, better control of tip leakage flow and higher efficiency than the conventional impeller. The results also show that the shape of the trailing edge geometry has a very appreciable effect on the impeller Euler head and this must be accurately modeled in all CFD computations to ensure closer match between CFD and experimental results. Detailed measurements are presented in part II of the paper.
Aerodynamic Blade Row Interactions in an Axial Compressor—Part II: Unsteady Profile Pressure Distribution and Blade Forces
Authors: Mailach Ronald , Vogeler Konrad
Published: March 2004

This two-part paper presents experimental investigations of unsteady aerodynamic blade row interactions in the first stage of the four-stage low-speed research compressor of Dresden. Both the unsteady boundary layer development and the unsteady pressure distribution of the stator blades are investigated for several operating points. The measurements were carried out on pressure side and suction side at midspan. In Part II of the paper the investigations of the unsteady pressure distribution on the stator blades are presented. The experiments were carried out using piezoresistive miniature pressure sensors, which are embedded into the pressure and suction side surface of a single blade. The unsteady pressure distribution on the blade is analyzed for the design point and an operating point near the stability limit. The investigations show that it is strongly influenced by both the incoming wakes and the potential flow field of the downstream rotor blade row. If a disturbance arrives the leading edge or the trailing edge of the blade the pressure changes nearly simultaneously along the blade chord. Thus the unsteady profile pressure distribution is independent of the wake propagation within the blade passage. A phase shift of the reaction on pressure and suction side is observed. The unsteady response of the boundary layer and the profile pressure distribution is compared. Based on the unsteady pressure distribution the unsteady pressure forces of the blades are calculated and discussed.
In Vitro Activities of Piperacillin against β-Lactamase-Negative Ampicillin-Resistant
Haemophilus influenzae
Authors: Morikawa Yoshiro , Kitazato Miyoshi , Mitsuyama Junichi , Mizunaga Shingo , Minami Shinzaburo , Watanabe Yasuo
Published: March 2004

The in vitro activities of piperacillin (PIP) against β-lactamase-negative ampicillin (AMP)-resistant (BLNAR)
Haemophilus influenzae
were compared with those of cefotaxime (CTX) and ceftriaxone (CRO), and the potency of PIP as therapy for meningitis caused by BLNAR is also discussed. PIP showed good activity (MIC at which 90% of strains are inhibited, 0.25 μg/ml) against 69 BLNAR strains, and its activity was comparable to that of CRO and superior to that of CTX. No significant correlation was observed between the MICs of PIP and CTX or CRO or AMP, whereas a high correlation was observed between the MICs of CTX and CRO. In the killing study, PIP showed potent bactericidal activity compared with those of CTX and CRO. By microscopic examination, PIP caused the formation of a spindle and short filamentous cells with bulges and induced cell lysis in BLNAR strains, while treatment with CTX and CRO resulted in the formation of large, spherical cells without any obvious lysis. The affinity of Bocillin FL, a fluorescent penicillin used for determination of the 50% inhibitory concentration (IC
50
s) for penicillin-binding proteins (PBPs), to PBPs 3a and 3b of BLNAR strains was drastically decreased compared with that to an AMP-susceptible strain (ATCC 33391). In the case of the BLNAR strains, the IC
50
s for PBPs 1a, 1b, and 2 were similar to those for the PBPs of ATCC 33391. Since the affinity of binding to PBPs 3a and 3b of the BLNAR strains decreased drastically, the second targets among the PBPs were PBP 2 for PIP, PBP1 (1a and 1b) for CTX and CRO. In conclusion, PIP showed excellent activities against BLNAR strains in a manner different from those of cephem antibiotics, suggesting that it could be a candidate therapeutic agent for the treatment of meningitis caused by BLNAR strains.
Activities of Newer Quinolones against
Escherichia coli
and
Klebsiella pneumoniae
Containing the Plasmid-Mediated Quinolone Resistance Determinant
qnr
Authors: Wang Minggui , Sahm Daniel F. , Jacoby George A. , Zhang Yingyuan , Hooper David C.
Published: March 2004

Seventeen
qnr
-containing transconjugants were constructed with azide-resistant
Escherichia coli
J53 as the recipient, and the MICs of 12 quinolones were tested by agar dilution methods. Sitafloxacin, BAYy3118, and premafloxacin had higher activity in vitro than ciprofloxacin against transconjugants and donors containing
qnr
. The donors had higher quinolone MICs than the transconjugants.
First-Choice Antibiotics at Subinhibitory Concentrations Induce Persistence of
Chlamydia pneumoniae
Authors: Gieffers Jens , Rupp Jan , Gebert Andreas , Solbach Werner , Klinger Matthias
Published: March 2004

Persistent growth forms of
Chlamydia pneumoniae
have been associated with chronic infections in vivo. We investigated the effects of first-line therapeutics on the induction of persistence by monitoring recoverable organisms, gene expression of membrane proteins, and morphology. We found that all of the antibiotics tested have distinct and subinhibitory concentrations at which they induce persistence.
Eradication of
Streptococcus pneumoniae
in the Nasopharyngeal Flora of Children with Acute Otitis Media after Amoxicillin-Clavulanate Therapy
Authors: Brook Itzhak , Gober Alan E.
Published: March 2004

Nasopharyngeal cultures were obtained from 60 children with acute otitis media before and after treatment with either 45 or 90 mg of amoxicillin (given as amoxicillin-clavulanate) per kg of body weight per day for 10 days. The number of
Streptococcus pneumoniae
isolates in the 45-mg/kg group was reduced from 12 to 6 and was reduced from 14 to 1 (
P
= 0.0261) in the 90-mg/kg group.
Antimicrobial Susceptibility and Mechanisms of Resistance to Quinolones and β-Lactams in
Acinetobacter
Genospecies 3
Authors: Ribera A. , Fernández-Cuenca F. , Beceiro A. , Bou G. , Martínez-Martínez L. , Pascual A. , Cisneros J. M. , Rodríguez-Baño J. , Pachón J. , Vila J.
Published: March 2004

Antimicrobial susceptibility was determined in 15 epidemiologically unrelated clinical isolates of
Acinetobacter
genospecies 3. Moreover, the mechanisms of resistance to some β-lactam antibiotics may be associated with the presence of a chromosomal cephalosporinase, AmpC, and the resistance to quinolones related to mutations in the
gyrA
and
parC
genes.
EBNA2 Amino Acids 3 to 30 Are Required for Induction of LMP-1 and Immortalization Maintenance
Authors: Gordadze Alexey V. , Onunwor Chisaroka W. , Peng RongSheng , Poston David , Kremmer Elisabeth , Ling Paul D.
Published: March 2004

Epstein-Barr virus (EBV) nuclear antigen 2 (EBNA2), a direct transcriptional activator of viral and cellular genes, is required for EBV-induced B-cell transformation. The functional role of conserved regions within the amino terminus of the protein preceding the poly-proline region has yet to be fully characterized. Thus, we tested whether the EBNA2 amino-terminal 30 amino acid residues, containing evolutionarily conserved region 1, are required for stimulating viral and cellular gene expression necessary for B-cell transformation in a viral transcomplementation assay. We found that these residues are required for its ability to induce LMP-1 expression in lymphoblastoid cell lines (LCLs), to stimulate LMP-1 promoter reporter plasmids in transient-cotransfection assays, and to rescue LCL growth following inactivation of endogenous wild-type EBNA2 protein. Deletion of amino acid residues 3 to 30 also impaired its ability to self-associate in coimmunoprecipitation assays. These data indicate that EBNA2 residues 3 to 30 comprise an essential domain required for induction of LMP-1 expression and, consequently, for maintenance of the immortalized phenotype of LCLs. The ability to self-associate into dimers or multimers conferred by this domain may be an important mechanism for these effects.
Human MxA Protein Inhibits the Replication of Crimean-Congo Hemorrhagic Fever Virus
Authors: Andersson Ida , Bladh Linda , Mousavi-Jazi Mehrdad , Magnusson Karl-Eric , Lundkvist Åke , Haller Otto , Mirazimi Ali
Published: March 2004

Crimean-Congo hemorrhagic fever virus
(CCHFV) belongs to the genus
Nairovirus
within the family
Bunyaviridae
and is the causative agent of severe hemorrhagic fever. Despite increasing knowledge about hemorrhagic fever viruses, the factors determining their pathogenicity are still poorly understood. The interferon-induced MxA protein has been shown to have an inhibitory effect on several members of the
Bunyaviridae
famil
y
, but the effect of MxA against CCHFV has not previously been studied. Here, we report that human MxA has antiviral activity against CCHFV. The yield of progeny virus in cells constitutively expressing MxA was reduced up to 1,000-fold compared with control cells, and accumulation of viral genomes was blocked. Confocal microscopy revealed that MxA colocalizes with the nucleocapsid protein (NP) of CCHFV in the perinuclear regions of infected cells. Furthermore, we found that MxA interacted with NP by using a coimmunoprecipitation assay. We also found that an amino acid substitution (E645R) within the C-terminal domain of MxA resulted in a loss of MxA antiviral activity and, concomitantly, in the capacity to interact with CCHFV NP. These results suggest that MxA, by interacting with a component of the nucleocapsid, prevents replication of CCHFV viral RNA and thereby inhibits the production of new infectious virus particles.
CD20 positive T cell lymphoma: is it a real entity?
Authors: Sun T , Akalin A , Rodacker M , Braun T
Published: March 2004

CD20+ T cell lymphoma is a rare condition that includes both precursor and peripheral T cell types. However, these cases may be mistaken for T cell marker positive B cell lymphoma, thus creating diagnostic problems with subsequent clinical implications. This report describes a unique case of nodal CD20+ T cell lymphoma with simultaneous cutaneous and subcutaneous involvement. Both nodal and cutaneous lymphomas demonstrated identical monoclonal bands in the T cell receptor rearrangement assay. However, no CD20 expression was demonstrated in the skin lesion. The instability of the CD20 antigen in this tumour may imply that CD20 is not an integral part of the tumour immunophenotype and probably plays no important role in its clinical course. Techniques to avoid misdiagnosis of this lymphoma are discussed.
Best Practice No 177
Authors: Galloway M J
Published: March 2004

This guideline reviews the introduction and development of business planning in the National Health Service. A guideline for writing a business case for service development that would form part of a pathology business plan has been developed. This guideline outlines six steps that are required in the preparation of a business case. The format of the guideline has been developed largely from other national guidelines that have been published for the development of capital projects. In view of the publication of these guidelines, the scope of this guideline excludes business cases for information, management, and technology projects and large capital projects.