bluuebunny/crossref_metadata_2025 huggingface dataset:
CYP7B1‐mediated metabolism of dehydroepiandrosterone and 5α‐androstane‐3β,17β‐diol – potential role(s) for estrogen signaling
Authors: Pettersson Hanna , Holmberg Lisa , Axelson Magnus , Norlin Maria
Published: March 2008

CYP7B1, a cytochrome P450 enzyme, metabolizes several steroids involved in hormonal signaling including 5α‐androstane‐3β,17β‐diol (3β‐Adiol), an estrogen receptor agonist, and dehydroepiandrosterone, a precursor for sex hormones. Previous studies have suggested that CYP7B1‐dependent metabolism involving dehydroepiandrosterone or 3β‐Adiol may play an important role for estrogen receptor β‐mediated signaling. However, conflicting data are reported regarding the influence of different CYP7B1‐related steroids on estrogen receptor β activation. In the present study, we investigated CYP7B1‐mediated conversions of dehydroepiandrosterone and 3β‐Adiol in porcine microsomes and human kidney cells. As part of these studies, we compared the effects of 3β‐Adiol (a CYP7B1 substrate) and 7α‐hydroxy‐dehydroepiandrosterone (a CYP7B1 product) on estrogen receptor β activation. The data obtained indicated that 3β‐Adiol is a more efficient activator, thus lending support to the notion that CYP7B1 catalysis may decrease estrogen receptor β activation. Our data on metabolism indicate that the efficiencies of CYP7B1‐mediated hydroxylations of dehydroepiandrosterone and 3β‐Adiol are very similar. The enzyme catalyzed both reactions at a similar rate and the Kcat/Km values were in the same order of magnitude. A high dehydroepiandrosterone/3β‐Adiol ratio in the incubation mixtures, similar to the ratio of these steroids in many human tissues, strongly suppressed CYP7B1‐mediated 3β‐Adiol metabolism. As the efficiencies of CYP7B1‐mediated hydroxylation of dehydroepiandrosterone and 3β‐Adiol are similar, we propose that varying steroid concentrations may be the most important factor determining the rate of CYP7B1‐mediated metabolism of dehydroepiandrosterone or 3β‐Adiol. Consequently, tissue‐specific steroid concentrations may have a strong impact on CYP7B1‐dependent catalysis and thus on the levels of different CYP7B1‐related steroids that can influence estrogen receptor β signaling.
Nursing Diagnosis: Is It Time for a New Definition?
Authors: Herdman T. Heather
Published: March 2008

PURPOSE.  The Diagnosis Development Committee (DDC) of NANDA International frequently receives proposed “physiologic” and “surveillance diagnosis” submissions that may not meet the current definition of nursing diagnosis (NANDA, 2007, p. 332). There has been a request for a vote on newly proposed definitions of nursing diagnosis, risk diagnosis, and syndromes. The purpose of this article is to provide information which enables members and interested nurses to continue the dialogue and to share their thoughts and also to consider the thoughts and information generated by the participants in the NANDA‐I interest survey on the definition of nursing diagnoses.

DATA SOURCES.  An electronic survey of the current NANDA‐I definitions, and potential changes to those definitions, was distributed via the NANDA‐I Web site. This article summarizes the overall findings of that survey and provides an overview of commentary received from the 269 participants.

CONCLUSIONS.  It is necessary to continue the dialogue on this important decision and to provide a mechanism for input from members and interested nurses before reaching any conclusions on this subject.

NURSING IMPLICATIONS.  NANDA‐I has been recognized as the leader in the development and implementation of nursing diagnoses and must act responsibly in assessing the changing and emerging trends in nursing practice and in responding to these trends.
The Need for International Nursing Diagnosis Research and a Theoretical Framework
Authors: Lunney Margaret
Published: March 2008

PURPOSE.  To describe the need for nursing diagnosis research and a theoretical framework for such research.

DATA SOURCES.  A linguistics theory served as the foundation for the theoretical framework.

DATA SYNTHESIS.  Reasons for additional nursing diagnosis research are: (a) file names are needed for implementation of electronic health records, (b) international consensus is needed for an international classification, and (c) continuous changes occur in clinical practice. A theoretical framework used by the author is explained.

CONCLUSIONS.  Theoretical frameworks provide support for nursing diagnosis research. Linguistics theory served as an appropriate exemplar theory to support nursing research.

IMPLICATION.  Additional nursing diagnosis studies based upon a theoretical framework are needed and linguistics theory can provide an appropriate structure for this research.
Relation Between Flow and Temporal Variations of Nitrate and Pesticides in Two Karst Springs in Northern Alabama1
Authors: Kingsbury James A.
Published: March 2008

Abstract:  Two karst springs in the Mississippian Carbonate Aquifer of northern Alabama were sampled between March 1999 and March 2001 to characterize the variability in concentration of nitrate, pesticides, selected pesticide degradates, water temperature, and inorganic constituents. Water temperature and inorganic ion data for McGeehee Spring indicate that this spring represents a shallow flow system with a relatively short average ground‐water residence time. Water issuing from the larger of the two springs, Meridianville Spring, maintained a constant temperature, and inorganic ion data indicate that this water represents a deeper flow system having a longer average ground‐water residence time than McGeehee Spring. Although water‐quality data indicate differing short‐term responses to rainfall at the two springs, the seasonal variation of nitrate and pesticide concentrations generally is similar for the two springs. With the exception of pesticides detected at low concentrations, the coefficient of variation for most constituent concentrations was less than that of flow at both springs, with greater variability in concentration at McGeehee Spring. Degradates of the herbicides atrazine and fluometuron were detected at concentrations comparable to or greater than the parent pesticides. Decreases in concentration of the principal degradate of fluometuron from about July to November indicate that the degradation rate may decrease as fluometuron (demethylfluometuron) moves deeper into the soil after application. Data collected during the study show that from about November to March when recharge rates increase, nitrate and residual pesticides in the soil, unsaturated zone, and storage within the aquifer are transported to the spring discharges. Because of the increase in recharge, fluometuron loads discharged from the springs during the winter were comparable to loads discharged at the springs during the growing season.
FTABLE Generation Method Effects on Instream Fecal Bacteria Concentrations Simulated With HSPF1
Authors: Hall Kyle M. , Zeckoski Rebecca W. , Brannan Kevin M. , Benham Brian L.
Published: March 2008

Abstract:  Computer simulation models are used extensively for the development of total maximum daily loads (TMDLs). Specifically, the Hydrological Simulation Program‐FORTRAN (HSPF) is used in Virginia for the development of TMDLs for bacteria impairments. HSPF estimates discharge from a reach using function tables (FTABLES). The FTABLE relates stream stage, surface area, and volume to discharge from a reach. In this study, five FTABLE estimation methods were assessed by comparing their effect on various simulation outputs. Four “field‐based” methods used detailed cross‐sectional data collected via site surveys. A fifth “digital‐based” method used digital elevation data in combination with the Natural Resources Conservation Service Regional Hydraulic Geometry Curves. Sets of FTABLEs created using each method were used in simulations of instream bacteria concentration for a Virginia watershed. Several statistics relating to instream bacteria including long‐term average concentration, die‐off, and the violation rate of Virginia’s bacteria criterion were compared. The pair‐wise Student’s t‐test was used for the comparison. The HSPF simulations that used FTABLES estimated from digitally based data consistently produced significantly higher long‐term average instream fecal bacteria concentrations, significantly lower instream fecal bacteria die‐off, which is related to differences in residence time in the streams, and significantly higher water quality criterion violation rates.
Predicting Root Density in Streambanks1
Authors: Piercy Candice , Wynn Theresa
Published: March 2008

Abstract:  Roots of riparian vegetation increase streambank erosion resistance and structural stability; therefore, knowledge of root density and distribution in streambanks is useful for stream management and restoration. The objective of this study was to compare streambank root distributions for herbaceous and woody vegetation and to develop empirical models to predict root density. Root length density, root volume ratio, soil physical and chemical properties, and above‐ground vegetation densities were measured at 25 sites on six streams in southwestern Virginia. The Mann‐Whitney test was used to determine differences in root density along stream segments dominated by either woody or herbaceous vegetation. Multiple linear regression was used to develop relationships between root density and site characteristics. Study results showed that roots were evenly distributed across the bank face with the majority of roots having diameters less than 2 mm. Soil bulk density and above‐ground vegetation were key factors influencing root density. While significant relationships were developed to predict root density, the predictive capabilities of the equations was low. Because of the highly variable nature of soil and vegetation properties, it is recommended at this time that soil erodibility and root density be measured in the field for design and modeling purposes, rather than estimated based on empirical relationships.
Differences in Evaporation Between a Floating Pan and Class A Pan on Land1
Authors: Masoner Jason R. , Stannard David I. , Christenson Scott C.
Published: March 2008

Abstract:  Research was conducted to develop a method for obtaining floating pan evaporation rates in a small (less than 10,000 m2) wetland, lagoon, or pond. Floating pan and land pan evaporation data were collected from March 1 to August 31, 2005, at a small natural wetland located in the alluvium of the Canadian River near Norman, Oklahoma, at the U.S. Geological Survey Norman Landfill Toxic Substances Hydrology Research Site. Floating pan evaporation rates were compared with evaporation rates from a nearby standard Class A evaporation pan on land. Floating pan evaporation rates were significantly less than land pan evaporation rates for the entire period and on a monthly basis. Results indicated that the use of a floating evaporation pan in a small free‐water surface better simulates actual physical conditions on the water surface that control evaporation. Floating pan to land pan ratios were 0.82 for March, 0.87 for April, 0.85 for May, 0.85 for June, 0.79 for July, and 0.69 for August.
Effect of Mutans Streptococcal Colonization on Plaque Formation and Regrowth in Young Children – A Brief Communication
Authors: Lee Christian , Tinanoff Norman , Minah Glenn , Romberg Elaine
Published: March 2008

Objectives: Visible plaque on the maxillary anterior teeth of young children has been identified as a risk indicator for early childhood caries. The present study examined whether this plaque is related to the colonization of children's teeth with Mutans streptococci (MS) or toothbrushing frequency. Methods: Thirty‐nine children, aged 12 to 36 months, had plaque scores, and plaque samples were taken from the labial surfaces of the maxillary incisors at baseline and repeated 3 days after suspended oral hygiene (plaque regrowth). Results: A positive correlation was found between the baseline percent MS and regrowth plaque score and between baseline and regrowth plaque scores. Plaque scores of those that brushed zero to one time a day were not different from those who brushed two or more times a day. Conclusions: This study suggests that the presence of plaque on the anterior teeth of young children is consistent and related to MS colonization.
Oral Health Disparities in Children of Immigrants: Dental Caries Experience at Enrollment and during Follow‐Up in the New England Children's Amalgam Trial
Authors: Maserejian Nancy Nairi , Trachtenberg Felicia , Hayes Catherine , Tavares Mary
Published: March 2008

Objectives: Previous research shows increased dental decay among immigrants, but little is known about the oral health of the growing population of children of immigrants. We compared the children of immigrants to the children of US‐born caregivers in their caries experience at enrollment and their new caries increments during the 5‐year New England Children's Amalgam Trial (NECAT).

Methods: NECAT recruited 283 Boston‐area children aged 6 to 10 with untreated caries and offered free semiannual preventive and restorative dental care during the trial. Sociodemographic factors and caregiver immigrant status were assessed through interviews. Multivariate negative binomial models evaluated the association between caregiver immigrant status and clinically assessed carious surfaces.

Results: Forty percent of these Boston‐area children had immigrant caregivers. At baseline, the children of immigrants had more carious surfaces (11.5 versus 9.4, adjusted for race/ethnicity, age, gender, and caregiver smoking status). Caregiver language preference explained some of this association. Immigrant status and language preference were not associated with 5‐year caries increments.

Conclusions: Prevalent disparities in the unmet dental needs of the immigrants' children were quickly ameliorated during participation in NECAT. Dental initiatives that target neighborhoods and are sensitive to acculturation levels may help improve and maintain the oral health of immigrant families.
Integrating human resource planning with strategic planning
Authors: McQueen Jennifer
Published: March 2008

Abstract: Human resource management, directly linked to operational and environmental forecasts, is a critical tool for public administrators as they respond to current difficult economic conditions. This paper describes new developments within the public service of Canada to improve the quality of human resource planning and to ensure its complete integration into the corporate planning system.

Planning for human resources must start at the top when the major objectives of the organization are set. These objectives establish the framework within which the strategic plan and the operational plans must fit. The author describes the factors which contribute to the complexity of developing and administering human resource planning in the public service and the principal elements of the Policy and Expenditure Management System (PEMS). Then, a new system is described which is proposed to be introduced in the federal public service in 1985. Its purpose is the integration of human resource planning, including career planning, training and development, hiring and action to redress under‐representation, with operational and strategic planning. Its tools include attrition forecasting, environmental scanning, models of the organization under varying circumstances, occupational analysis and job definition, and it must be supported by data bases of considerable quality.

In the Canadian public service it has become evident that the roles of the manager and personnel specialist must change if human resource planning is to work. Managers must be trained and able to foresee the human resource implications of their strategic and operational plans. The specialist must be able to provide information and analytical support needed to turn implications into valid, realistic long‐ and short‐term plans for the achievement of corporate goals through development and appointment of appropriate resources. Human resource plans must emanate from the basic objective of the organization set by the Chief Executive Officer and the executive team; they will succeed in direct proportion to the level of commitment and support awarded to them by Chief Executive Officers and the extent to which managers are held accountable for them.
The public service of Canada: the case for political neutrality
Authors: D'Aquino Thomas
Published: March 2008

Abstract: Change is in the wind. There is an expectation that when the present leadership of the governing Liberal party passes from the scene and a transition to a Progressive Conservative or newly led Liberal government follows, sweeping changes at the top of the public service dl be the order of the day. The author welcomes a healthy dose of change — but change that is carefully thought through and orderly.

He defends the concept of a permanent, professional, non‐partisan public service and points out how the doctrine of political neutrality has been eroded. He argues for a return to a stricter adherence to the anonymity principle and to a reaffirmation of merit as the benchmark of appointments.

In seeking to strengthen the accountability of the public service to the executive, the author rejects partisan appointments to the public service in favour of appointed senior policy advisors. He proposes buttressing the role of individual advisors with a partisan research and policy analysis unit of some ten to fifteen people reporting directly to the Prime Minister and the cabinet as a whole. He suggests the upgrading of the research apparatuses of political parties themselves. Finally, he underscores the vital role that Parliament could play in exacting public service accountability.

The author concludes that the federal public service in its central characteristics should be preserved, and that changes should be aimed inure in the direction of the restoration of the basic principles that have guided it in the past.
Phases of recognition and management of financial crisis in public organizations
Authors: Jones L. R.
Published: March 2008

Abstract: This article provides a model of the manner in which public organizations recognize and attempt to manage financial crises and prolonged financial stress. It presents some cutback management options and provides an approach for assessing the severity of financial crises. Issues and management approaches discussed include program reduction and termination costs and benefits, organizational planning, evaluation and decision participation, centralization of decision‐making and improvement of public sector marketing.

Among the conclusions drawn are that (a) greater investment in market research and marketing is needed in the public sector; (b) management of financial crises must take into account the rigidities arid constraints which characterize bureaucratic organizations; and (c) inability to adapt to environmental change aid new social conditions reduces the probability of survival for public agencies.

Sommaire: Cet article fournit un modèle de la façon dont les organismes publics admettent l'esistence de crises financières oil de contraitites inonétaires prolongées et essaierit d'y faire face. Il présente certaines options de retranchement ainsi qu'une approche permettant d'évaiuer la gravité des crises financières. Les problèmes et les concepts de gestion envisagés incluent l'analyse coût‐bénéfice de la réduction et de l'annulation des programmes, la planification organisationnelle, l'évaluation et la décision participative, la centralisation de la prise de décision et l'amélioration du marketing.

Parmi les conclusions qu'en tire l'auteur, citons le hesoin d'un plus grand investissement dans la recherche et le marketing pour le secteur public, la nécessité de traiter et de gérer les crises financières en fonction des rigidités et des contraintes qui caractérisent les organisations bureaucratiques et, finalement, la conscience que l'incapacitéà s'adapter aux changements de l'environnement et aux nouvelles conditions sociales réduit les chances de survie de ces organismes publics
The ombudsman in France
Authors: Rowat Donald C.
Published: March 2008

Abstract: Though France and the United Kingdom are the most populous countries with a legislative ombudsman at the national level, little has been written in English ahout the French plan. Created in 1973, it resembles the British scheme for the central administration, in that coinplaints must he forwarded to the ombudsman (Médiateur) by members of Parliament. The French plan has been more successful than the British one, and hence ought to lw studied by other populous countries considering such a plan. It differs from the British scheme in several important respects, three of its unique features being its political nature. its decentralization and its reform orientation. However, a comparison of the total number of coinplaints received by the plan in France with that in countries where complaints are made directly‐ indicates that, as in the United Kingdom, the requirement for complaints to be made through legislators has been a serious restriction, and has prevented the plan from meeting a large part of the need.

Sommaire: Bien que la France et le Royaume‐Uni soient les pays les plus peuplés àêtre dotés d'um médiateur législatif (ombudsman) au niveau national, le système françis n'a pas suscité heaucoup de commentaires de la part des auteurs anglophones. Créé en 1973. ce systéme ressemble à celui instauné au Royaume‐Uni pour l'administration centrale en ce que les plaintes doivent être transmises au médiateur par l'intermédiaire des députés. Le système français a connu plus de succès que le Lritannique et mérite par conéquent d'être étudié par d'autres pays à haute derisité démographique qui envisageraient un tel systéme. Il differe du inodèle britannique par certains aspects importants, ses trois caractéristiques particulières étant sa nature politique. sa décentralisation et son orientation réformatrice. Toutefois, une comparaison entre le nombre total de plaintes enregistrées dans Ic cadre du système fiançais et le nombre de plaintes déposées dans les pays où l'on a adopté la façon directe de procéder démontre que comme au Royaume‐Unit, l'intermédiaire qu'est le député constitue un obstacle important qui empêche le système fraiçais de répidre à une grande partie des hesoins.
Books Reviewed Comptes Rendu
Authors: Sheridan William , Laponce J. A.
Published: March 2008

Book reviewed in this article:

Not for Export By GLEN WILLIAMS

Threshold Firms By GUY STEED

The Language of the Skies: the Bilingual Air Traffic Control Conflict in Canada, By SANDFORD F. BORINS
Virtual microscopy as a practical alternative to conventional microscopy in pathology education
Authors: Kim Min Hyung , Park Youngwoon , Seo Donghee , Lim Yu Jin , Kim Dong‐Il , Kim Chul Woo , Kim Woo Ho
Published: March 2008

Background and aims: Laboratory education on pathology for undergraduate medical student has traditionally been conducted by using analog microscopy on glass slides with standard pathological cases. Virtual microscopy was recently introduced as an alternative to conventional microscopy, but there are issues surrounding its in the educational context. Methods: We introduced virtual microscopy in a pathology laboratory class, as an addition to analog microscopy. One hundred and sixty first year‐medical students were surveyed using preformed or free questions after use of both virtual and conventional microscopy. Results: Many advantages were noticed and students strongly favored virtual microscopy. Most students reported that use of the virtual microscope can significantly improve performance and learning efficiency. The three most significant advantages of virtual microscopy were freedom from optical stress, better image quality and time saving. Less advantageous points were inconvenient slide selection, less vivid feeling of examining and that the technique was not useful for finding artifacts such as foreign bodies. Although they could save time by using virtual microscopy, more students remained longer in the laboratory room when they used virtual microscopy. Conclusion: Virtual microscopy was accepted by students as an excellent tool to facilitate learning. We believe that virtual microscope is an excellent tool for pathology laboratory education.
Rabies in a Puppy Imported from India to the USA, March 2007
Authors: Castrodale L. , Walker V. , Baldwin J. , Hofmann J. , Hanlon C.
Published: March 2008

In March 2007, a puppy that was recently imported from India into the United States was found to be positive for rabies by the Alaska Department of Health and Social Services. This case report highlights several important public health issues. First, recognizing that humans and animals are part of a global community with frequent travel and translocation, the risks of disease introduction, particularly with sub‐clinical or incubating animals, are real and present. Animal‐importation regulations, policies and practices are intended to minimize these risks and should be routinely evaluated and updated as needed in response to occurrences such as detailed in this communication. Second, veterinarians play key roles in safeguarding the public’s health with regard to monitoring the movement of animals and diagnosing zoonoses. Third, investigating rabies cases that involve multiple jurisdictions are labour‐intensive and require significant resources to ensure that all potentially exposed persons are identified and receive the appropriate rabies post‐exposure prophylaxis.
Feeding Supplemental Dried Distiller’s Grains Increases Faecal Shedding of Escherichia coli O157 in Experimentally Inoculated Calves
Authors: Jacob M. E. , Parsons G. L. , Shelor M. K. , Fox J. T. , Drouillard J. S. , Thomson D. U. , Renter D. G. , Nagaraja T. G.
Published: March 2008

Escherichia coli O157 is an important foodborne pathogen and asymptomatic cattle serve as major reservoirs for human infection. We have shown a positive association between feeding distiller’s grains and E. coli O157 prevalence in feedlot cattle. The objective of this study was to determine the effect of feeding dried distiller’s grain (DDG) on faecal shedding of E. coli O157 in calves experimentally inoculated with E. coli O157. Holstein calves (five per treatment group), fed steam‐flaked corn‐based high‐grain diets supplemented with 0% (control) or 25% DDG, were orally inoculated with a five‐strain mixture (6 × 109 CFU/calf) of nalidixic acid‐resistant (NalR) E. coli O157. Faecal samples were taken three times per week for 6 weeks to determine the prevalence and concentration of NalRE. coli O157. At the end of the study (day 43), calves were euthanized and necropsied. Ruminal, caecum, colon, and rectal contents, and rectoanal mucosal swab (RAMS) samples were collected at necropsy to determine NalRE. coli O157 concentration. There was a trend for an interaction between treatment and faecal sampling day. The concentration of NalRE. coli O157 in the faeces was significantly higher in faecal samples from calves fed DDG compared with control calves on days 35, 37, 39 and 42. At necropsy, the concentration of NalRE. coli O157 was higher in the caecum (P = 0.01), colon (P = 0.03) and rectum (P = 0.01) from calves fed DDG compared with control animals. The number of sites at necropsy positive for NalRE. coli O157 was higher in calves fed DDG compared with calves in the control treatment (P < 0.001). Our results indicate that E. coli O157 gut persistence and faecal prevalence increased in calves fed DDG, which potentially have important implications for food safety.
Repeated inspiratory occlusions acutely impair myocardial function in rats
Authors: Simpson Jeremy A. , Brunt Keith R. , Iscoe Steve
Published: March 2008

Repeated episodes of hypoxia and sympathetic activation during obstructive sleep apnoea are implicated in the initiation and progression of cardiovascular diseases, but the acute effects are unknown. We hypothesized that repeated inspiratory occlusions cause acute myocardial dysfunction and injury. In 22 spontaneously breathing pentobarbital‐anaesthetized rats, inspiration was occluded for 30 s every 2 min for 3 h. After ∼1.5 h, mean arterial pressure started to fall; heart rate between occlusions was stable throughout, consistent with only transient increases in sympathetic activity during each occlusion. Three hours of occlusions resulted in ventricular diastolic dysfunction (reduced peak rate of change of ventricular pressure and slower relaxation). Post‐occlusions, the left ventricular contractile response to dobutamine was blunted. After 1 h of recovery, left ventricular pressure generation had returned to values no different from those in sham animals in 5 of 9 of the animals. Cardiac myofibrils from rats subjected to occlusions had depressed calcium‐activated myosin ATPase activity, indicating myofilament contractile dysfunction that was not due to breakdown of contractile proteins. Haematoxylin and eosin‐stained cross‐sections revealed multifocal areas of necrosis within the septum and both ventricles. Repeated inspiratory occlusions, analogous to moderately severe obstructive sleep apnoea, acutely cause global cardiac dysfunction with multifocal myocardial infarcts.
Experimental Study and Model on Critical Heat Flux of Refrigerant-123 and Water in Microchannels
Authors: Kuan Wai Keat , Kandlikar Satish G.
Published: March 2008

The present work is aimed toward understanding the effect of flow boiling stability on critical heat flux (CHF) with Refrigerant 123 (R-123) and water in microchannel passages. Experimental data and theoretical model to predict the CHF are the focus of this work. The experimental test section has six parallel microchannels, with each having a cross-sectional area of 1054×157μm2. The effect of flow instabilities in microchannels is investigated using flow restrictors at the inlet of each microchannel to stabilize the flow boiling process and avoid the backflow phenomena. This technique resulted in successfully stabilizing the flow boiling process. The present experimental CHF results are found to correlate best with existing correlations to overall mean absolute errors (MAEs) of 33.9% and 14.3% with R-123 and water, respectively, when using a macroscale rectangular equation by Katto (1981, “General Features of CHF of Forced Convection Boiling in Uniformly Heated Rectangular Channels,” Int. J. Heat Mass Transfer, 24, pp. 1413–1419). A theoretical analysis of flow boiling phenomena revealed that the ratio of evaporation momentum to surface tension forces is an important parameter. A theoretical CHF model is proposed using these underlying forces to represent CHF mechanism in microchannels, and its correlation agrees with the experimental data with MAE of 2.5%.
Experimental and Numerical Study of One, Two, and Three Embedded Needle Cryoprobes Simultaneously Operated by High Pressure Argon Gas
Authors: Magalov Z. , Shitzer A. , Degani D.
Published: March 2008

One, two, and three needle cryoprobes, 1.47mm outside diameter, simultaneously and uniformly operated by high pressure argon gas, were tested in a gel simulating the thermal properties of biological tissues. The probes were inserted into the same depth in the gel through two parallel templates with holes drilled on a 5×5mm2 mesh. The temperature of the active segment of the probe was monitored by a single soldered thermocouple (TC). Temperatures in the gel were monitored by K-type TC strings in the radial, and in the downward and upward axial directions. The phase-change problem in the gel was solved by ANSYS7.0, based on the enthalpy method. Calculated and measured results compared reasonably well with the most deviations observed in the upward axial direction. Results of this study may be summarized as follows: (a) Due to the cylindrical structure of the probe, the advancement of the frozen fronts was more pronounced in the upward axial and the radial directions than in the downward direction. (b) The farthest placement of the two probes (10mm) yielded the largest volumes enclosed by the isothermal contours. (c) In the tightest two placement configurations of the three probes, the −40°C fronts of all frozen lumps have joined together even after 1min of operation, while in the less tight configurations, joining occurred later. (d) In multiprobe applications and for a given duration of application, there exists a certain placement configuration that will produce the maximal volume of any temperature-specific frozen lump. The computational tool presented in this study could assist the surgeon in the preplanning of cryosurgical procedures and thus reduce uncertainties and enhance its success rate.
Heat
Transfer During Compression and Expansion of
Gas
Authors: Ota Masutaka , Haramura Yoshihiko
Published: March 2008

Heat transfer during compression and expansion of gas is investigated to obtain a correlation that is easy to use in the design of the reciprocating energy conversion machines. We carried out experiments to measure the heat transfer characteristics to̸from gas during compression and expansion to obtain the correlation. These measurements were performed using a piston-cylinder assembly over a range of volume ratios, frequencies, mean pressures, gases, and internal extended surface areas. The heat transfer was estimated thermodynamically from experimental pressure-volume data. Dimensionless groups for heat transfer are discussed in order to correlate the data. The product of the dimensionless heat transfer and specific heat ratio was found to be optimal and was correlated with only the Peclet number for a wide range of conditions, even for gases having different specific heat ratios. The temperature amplitude of the center of the test space was obtained, and it is found that the penetration depth reached the center when the Peclet number is in the range from 20 to 30.
Sheathless Mutant of Cyanobacterium
Gloeothece
sp. Strain PCC 6909 with Increased Capacity To Remove Copper Ions from Aqueous Solutions
Authors: Micheletti Ernesto , Pereira Sara , Mannelli Francesca , Moradas-Ferreira Pedro , Tamagnini Paula , De Philippis Roberto
Published: March 2008

The cyanobacterium
Gloeothece
sp. strain PCC 6909 and its sheathless mutant were tested for their abilities to remove copper ions from aqueous solutions, with the aim of defining the role of the various outermost polysaccharidic investments in the removal of the metal ions. Microscopy studies and chemical analyses revealed that, although the mutant does not possess a sheath, it releases large amounts of polysaccharidic material (released exocellular polysaccharides [RPS]) into the culture medium. The RPS of the wild type and the mutant are composed of the same 11 sugars, although they are present in different amounts, and the RPS of the mutant possesses a larger amount of acidic sugars and a smaller amount of deoxysugars than the wild type. Unexpectedly, whole cultures of the mutant were more effective in the removal of the heavy metal than the wild type (46.3 ± 3.1 and 26.7 ± 1.5 mg of Cu
2+
removed per g of dry weight, respectively). Moreover, we demonstrated that the contribution of the sheath to the metal-removal capacity of the wild type is scarce and that the RPS of the mutant is more efficient in removing copper. This suggests that the metal ions are preferably bound to the cell wall and to RPS functional groups rather than to the sheath. Therefore, the increased copper binding efficiency observed with the sheathless mutant can be attributed to the release of a polysaccharide containing larger amounts and/or more accessible functional groups (e.g., carboxyl and amide groups).
SalmonellaMichigan soft tissue infection in an immunocompromised child
Authors: Hames A , Mumford J , Hale J , Galloway A
Published: March 2008

A rare case of soft tissue infection due toSalmonellaMichigan in an immunocompromised child is reported. The same organism was isolated from a tortoise kept in the home. Immunocompromised patients are especially susceptible to reptile-associated salmonellosis and should be advised appropriately.
Prognostic and predictive factors in colorectal cancer
Authors: Zlobec I , Lugli A
Published: March 2008

Prognostication of newly diagnosed colorectal cancer (CRC) predominantly relies on stage as defined by the UICC-TNM and American Joint Committee on Cancer classifications. Tumour extent, lymph node status, tumour grade and the assessment of lymphatic and venous invasion are still the most important morphological prognostic factors. Evidence suggests that tumour budding and tumour border configuration are important, additional histological parameters but are not regarded as essential in prognosis. Although several molecular features, such as LOH18q and TP53 mutation analysis, have shown promising results in terms of their prognostic value, the American Society of Clinical Oncology Tumor Markers Expert Panel does not currently recommend their use in routine practice. cDNA-microarray, PCR and fluorescence in situ hybridisation are now frequently used to identity potential prognostic indicators in CRC, but the applicability of these methods in routine use is likely to have limited impact. Reliable prognostic markers identified by immunohistochemical protein profiling have yet to be established. Randomisation of data sets, assessment of interobserver variability for protein markers and scoring systems, as well as the use of receiver operating characteristic curve analysis in combination with multimarker-phenotype analysis of several different markers may be an effective tactical approach to increase the value of immunohistochemical findings. This article reviews the well established and additional prognostic factors in CRC and explores the contribution of molecular studies to the prognostication of patients with this disease. Additionally, an approach to improve the prognostic value of immunohistochemical protein markers is proposed.
Basal carcinoma of the breast revisited: an old entity with new interpretations
Authors: Korsching E , Jeffrey S S , Meinerz W , Decker T , Boecker W , Buerger H
Published: March 2008

The introduction of global gene expression analysis in breast cancer research has focused attention onto a repeatedly described subgroup of invasive breast cancer, the basal-like carcinomas. This subgroup is characterised by the expression of high-molecular weight cytokeratins 5, 14 and 17; using immunohistochemical diagnosis, it represents approximately 7–20% of invasive breast cancers. Some of these tumours fulfil the criteria of grade 3 invasive ductal carcinoma, the so-called triple negative carcinomas. However, other rare subgroups of metaplastic, medullary and myoepithelial carcinomas also belong to this entity. Even though the initial clinical prognostic relevance of basal-like breast cancers may have been overestimated, its distinctive biology generates many questions regarding the pathogenesis, chemosensitivity and optimal clinical management of this subgroup. Physiological progenitor cells within the normal female breast share essential immunohistochemical features with basal-like breast cancers. Although the exact relationship between subgroups of normal breast cells and their respective malignant counterparts is still under investigation, the major hallmarks of physiological progenitor cells are either maintained or reactivated by distinct genetic changes in basal breast cancer cells. This review will discuss the impact of these findings on our global understanding of breast cancer pathogenesis, especially from the perspective of its potential histogenesis. Clinical consequences and potential future research directions driven by the definition of basal breast cancers will also be discussed.
Contribution of the sympathetic hormone epinephrine to the sensitizing effect of ethanol on LPS-induced liver damage in mice
Authors: von Montfort Claudia , Beier Juliane I. , Guo Luping , Kaiser J. Phillip , Arteel Gavin E.
Published: March 2008

It is well known that ethanol preexposure sensitizes the liver to LPS hepatotoxicity. The mechanisms by which ethanol enhances LPS-induced liver injury are not completely elucidated but are known to involve an enhanced inflammatory response. Ethanol exposure also increases the metabolic rate of the liver, and this effect of ethanol on liver is mediated, at least in part, by the sympathetic hormone, epinephrine. However, whether or not the sympathetic nervous system also contributes to the sensitizing effect of ethanol preexposure on LPS-induced liver damage has not been determined. The purpose of this study was therefore to test the hypotheses that 1) epinephrine preexposure enhances LPS-induced liver damage (comparable to that of ethanol preexposure) and that 2) the sympathetic nervous system contributes to the sensitizing effect of ethanol. Accordingly, male C57BL/6J mice were administered epinephrine for 5 days (2 mg/kg per day) via osmotic pumps or bolus ethanol for 3 days (6 g/kg per day) by gavage. Twenty-four hours later, mice were injected with LPS (10 mg/kg ip). Both epinephrine and ethanol preexposure exacerbated LPS-induced liver damage and inflammation. Concomitant administration of propranolol with ethanol significantly attenuated the sensitizing effect of ethanol on LPS-induced liver damage. These data support the hypothesis that the sympathetic nervous system contributes, at least in part, to the mechanism of the sensitizing effect of ethanol. These results also suggest that sympathetic tone may contribute to the initiation and progression of alcoholic liver disease.
First-order approximation for the pressure-flow relationship of spontaneously contracting lymphangions
Authors: Quick Christopher M. , Venugopal Arun M. , Dongaonkar Ranjeet M. , Laine Glen A. , Stewart Randolph H.
Published: March 2008

To return lymph to the great veins of the neck, it must be actively pumped against a pressure gradient. Mean lymph flow in a portion of a lymphatic network has been characterized by an empirical relationship (Pin − Pout = −Pp + RLQL), where Pin − Pout is the axial pressure gradient and QL is mean lymph flow. RL and Pp are empirical parameters characterizing the effective lymphatic resistance and pump pressure, respectively. The relation of these global empirical parameters to the properties of lymphangions, the segments of a lymphatic vessel bounded by valves, has been problematic. Lymphangions have a structure like blood vessels but cyclically contract like cardiac ventricles; they are characterized by a contraction frequency ( f) and the slopes of the end-diastolic pressure-volume relationship [minimum value of resulting elastance ( Emin)] and end-systolic pressure-volume relationship [maximum value of resulting elastance ( Emax)]. Poiseuille's law provides a first-order approximation relating the pressure-flow relationship to the fundamental properties of a blood vessel. No analogous formula exists for a pumping lymphangion. We therefore derived an algebraic formula predicting lymphangion flow from fundamental physical principles and known lymphangion properties. Quantitative analysis revealed that lymph inertia and resistance to lymph flow are negligible and that lymphangions act like a series of interconnected ventricles. For a single lymphangion, Pp = Pin ( Emax − Emin)/ Emin and RL = Emax/ f. The formula was tested against a validated, realistic mathematical model of a lymphangion and found to be accurate. Predicted flows were within the range of flows measured in vitro. The present work therefore provides a general solution that makes it possible to relate fundamental lymphangion properties to lymphatic system function.
Cerebral microvascular nNOS responds to lowered oxygen tension through a bumetanide-sensitive cotransporter and sodium-calcium exchanger
Authors: Bauser-Heaton Holly D. , Song Jin , Bohlen H. Glenn
Published: March 2008

Na+ cotransporters have a substantial role in neuronal damage during brain hypoxia. We proposed these cotransporters have beneficial roles in oxygen-sensing mechanisms that increase periarteriolar nitric oxide (NO) concentration ([NO]) during mild to moderate oxygen deprivation. Our prior studies have shown that cerebral neuronal NO synthase (nNOS) is essential for [NO] responses to decreased oxygen tension and that endothelial NO synthase (eNOS) is of little consequence. In this study, we explored the mechanisms of three specific cotransporters known to play a role in the hypoxic state: KB-R7943 for blockade of the Na+/Ca2+ exchanger, bumetanide for the Na+-K+-2Cl− cotransporter, and amiloride for Na+/H+ cotransporters. In vivo measurements of arteriolar diameter and [NO] at normal and locally reduced oxygen tension in the rat parietal cortex provided the functional analysis. As previously found for intestinal arterioles, bumetanide-sensitive cotransporters are primarily responsible for sensing reduced oxygen because the increased [NO] and dilation were suppressed. The Na+/Ca2+ exchanger facilitated increased NO formation because blockade also suppressed [NO] and dilatory responses to decreased oxygen. Amiloride-sensitive Na+/H+ cotransporters did not significantly contribute to the microvascular regulation. To confirm that nNOS rather than eNOS was primarily responsible for NO generation, eNOS was suppressed with the fusion protein cavtratin for the caveolae domain of eNOS. Although the resting [NO] decreased and arterioles constricted as eNOS was suppressed, most of the increased NO and dilatory response to oxygen were preserved because nNOS was functional. Therefore, nNOS activation secondary to Na+-K+-2Cl− cotransporter and Na+/Ca2+ exchanger functions are key to cerebral vascular oxygen responses.
Effects of elastic compression stockings on wall shear stress in deep and superficial veins of the calf
Authors: Downie Steven P. , Raynor Sheila M. , Firmin David N. , Wood Nigel B. , Thom Simon A. , Hughes Alun D. , Parker Kim H. , Wolfe John H. N. , Xu X. Yun
Published: March 2008

The purpose of this study was to estimate wall shear stress (WSS) in individual vessels of the venous circulation of the calf and quantify the effects of elastic compression based on change of vessel geometry and velocity waveform. The great saphenous vein and either a peroneal or posterior tibial vein have been imaged in four healthy subjects using magnetic resonance imaging, with and without the presence of a grade 1 medical stocking. Flow through image-based reconstructed geometries was numerically simulated for both a range of steady flow rates and ultrasound-derived transient velocity waveforms, scaled to give a standardized time averaged flow rate. For steady flow, the stocking produced an average percentage increase in mean WSS of ∼100% in the great saphenous vein across a range of 0.125–1.25 ml/s. The percentage increase in the peroneal/posterior tibial veins varied from 490 to 650% across a range of 0.5–5 ml/s. In addition, application of the stocking eliminated periods of very low or zero flow from the transient waveforms. The average minimum value of WSS in all vessels without the stocking was <0.1 Pa. With the stocking, this was increased to 0.7 Pa in the great saphenous and 0.9 Pa in the peroneal/posterior tibial veins. The pathophysiological effects of these changes are discussed. In conclusion, the flight stocking was effective in raising venous WSS levels in prone subjects, and this effect was much more pronounced in the deep vessels. The stocking also tended to prevent cessation of flow during periods of increased downstream pressure produced by respiration.