bluuebunny/crossref_metadata_2025 huggingface dataset:
Allometric scaling of the maximum metabolic rate of mammals: oxygen transport from the lungs to the heart is a limiting step
Authors: Painter Page R
Published: August 2005

Background

The maximum metabolic rate (MMR) of mammals is approximately proportional to M

0.9
, where M is the mammal's body weight. Therefore, MMR increases with body weight faster than does the basal metabolic rate (BMR), which is approximately proportional to M

0.7
. MMR is strongly associated with the capacity of the cardiovascular system to deliver blood to capillaries in the systemic circulation, but properties of this vascular system have not produced an explanation for the scaling of MMR.

Results

Here we focus on the pulmonary circulation where resistance to blood flow (impedance) places a limit on the rate that blood can be pumped through the lungs before pulmonary edema occurs. The maximum pressure gradient that does not produce edema determines the maximum rate that blood can flow through the pulmonary veins without compromising the diffusing capacity of oxygen. We show that modeling the pulmonary venous tree as a fractal-like vascular network leads to a scaling equation for maximum cardiac output that predicts MMR as a function of M as well as the conventional power function aM

b
does and that least-squares regression estimates of the equation's slope-determining parameter correspond closely to the value of the parameter calculated directly from Murray's law.

Conclusion

The assumption that cardiac output at the MMR is limited by pulmonary capillary pressures that produce edema leads to a model that is in agreement with experimental measurements of MMR scaling, and the rate of blood flow in pulmonary veins may be rate-limiting for the pathway of oxygen.
Illegal births and legal abortions – the case of China
Authors: Hemminki Elina , Wu Zhuochun , Cao Guiying , Viisainen Kirsi
Published: August 2005

Background

China has a national policy regulating the number of children that a woman is allowed to have. The central concept at the individual level application is "illegal pregnancy". The purpose of this article is to describe and problematicize the concept of illegal pregnancy and its use in practice.

Methods

Original texts and previous published and unpublished reports and statistics were used.

Results

By 1979 the Chinese population policy was clearly a policy of controlling population growth. For a pregnancy to be legal, it has to be defined as such according to the family-level eligibility rules, and in some places it has to be within the local quota. Enforcement of the policy has been pursued via the State Family Planning (FP) Commission and the Communist Party (CP), both of which have a functioning vertical structure down to the lowest administrative units. There are various incentives and disincentives for families to follow the policy. An extensive system has been created to keep the contraceptive use and pregnancy status of all married women at reproductive age under constant surveillance. In the early 1990s FP and CP officials were made personally responsible for meeting population targets. Since 1979, abortion has been available on request, and the ratio of legal abortions to birth increased in the 1980s and declined in the 1990s. Similar to what happens in other Asian countries with low fertility rates and higher esteem for boys, both national- and local-level data show that an unnaturally greater number of boys than girls are registered as having been born.

Conclusion

Defining a pregnancy as "illegal" and carrying out the surveillance of individual women are phenomena unique in China, but this does not apply to other features of the policy. The moral judgment concerning the policy depends on the basic question of whether reproduction should be considered as an individual or social decision.
Stride-to-stride variability while backward counting among healthy young adults
Authors: Beauchet Olivier , Dubost Véronique , Herrmann François R , Kressig Reto W
Published: August 2005

Background

Little information exists about the involvement of attention in the control of gait rhythmicity. Variability of both stride time and stride length is closely related to the control of the rhythmic stepping mechanism. We sought 1) to determine whether backward counting while walking could provoke significant gait changes in mean values and coefficients of variation of stride velocity, stride time and stride length among healthy young adults; and 2) to establish whether change in stride-to-stride variability could be related to dual-task related stride velocity change, attention, or both.

Methods

Mean values and coefficients of variation of stride velocity, stride time and stride length were recorded using the Physilog®-system, at a self-selected walking speed in 49 healthy young adults (mean age 24.1 ± 2.8 years, women 49%) while walking alone and walking with simultaneous backward counting. Performance on backward counting was evaluated by recording the number of figures counted while sitting alone and while walking.

Results

Compared with walking alone, a significant dual-task-related decrease was found for the mean values of stride velocity (p < 0.001), along with a small but significant increase for the mean values and coefficients of variation of stride time (p < 0.001 and p = 0.015, respectively). Stride length parameters did not change significantly between both walking conditions. Dual-task-related increase of coefficient of variation of stride time was explained by changing stride velocity and variability between subjects but not by backward counting. The number of figures counted while walking decreased significantly compared to backward counting alone. Further, the dual-task related decrease of the number of enumerated figures was significantly higher than the dual-task related decrease of stride velocity (p = 0.013).

Conclusion

The observed performance-changes in gait and backward counting while dual tasking confirm that certain aspects of walking are attention-demanding in young adults. In the tested group of 49 young volunteers, dual tasking caused a small decrease in stride velocity and a slight increase in the stride-to-stride variability of stride time, while stride velocity variability was not affected by the attention-demanding task. The increase in stride time variability was apparently the result of a change in gait speed, but not a result of dual tasking. This suggests that young adults require minimal attention for the control of the rhythmic stepping mechanism while walking.
Clarifying the role of three-dimensional transvaginal sonography in reproductive medicine: an evidenced-based appraisal
Authors: Raine-Fenning Nick , Fleischer Arthur C
Published: August 2005

This overview describes and illustrates the clinical applications of three-dimensional transvaginal sonography in reproductive medicine. Its main applications include assessment of uterine anomalies, intrauterine pathology, tubal patency, polycystic ovaries, ovarian follicular monitoring and endometrial receptivity. It is also useful for detailed evaluation of failed and/or ectopic pregnancy. Three-dimensional color Doppler sonography provides enhanced depiction of uterine, endometrial, and ovarian vascularity.
Perinatal Glucocorticoid Treatment Produces Molecular, Functional, and Morphological Changes in the Anterior Pituitary Gland of the Adult Male Rat
Authors: Theogaraj E. , John C. D. , Christian H. C. , Morris J. F. , Smith S. F. , Buckingham J. C.
Published: August 2005

Stress or glucocorticoid (GC) treatment in perinatal life can induce long-term changes in the sensitivity of the hypothalamo-pituitary-adrenocortical axis to the feedback actions of GCs and, hence, in GC secretion. These changes have been ascribed largely to changes in the sensitivity of the limbic system, and possibly the hypothalamus, to GCs. Surprisingly, the possibility that early life stress/GC treatment may also exert irreversible effects at the pituitary level has scarcely been addressed. Accordingly, we have examined the effects of pre- and neonatal dexamethasone treatment on the adult male pituitary gland, focusing on the following: 1) the integrity of the acute annexin 1 (ANXA1)-dependent inhibitory actions of GCs on ACTH secretion, a process requiring ANXA1 release from folliculostellate (FS) cells; and 2) the morphology of FS cells and corticotrophs. Dexamethasone was given to pregnant (d 16–19) or lactating (d 1–7 postpartum) rats via the drinking water (1 μg/ml); controls received normal drinking water. Pituitary tissue from the offspring was examined ex vivo at d 90. Both treatment regimens reduced ANXA1 expression, as assessed by Western blotting and quantitative immunogold labeling. In particular, the amount of ANXA1 located on the outer surface of the FS cells was reduced. By contrast, IL-6 expression was increased, particularly by the prenatal treatment. Pituitary tissue from untreated control rats responded to dexamethasone with an increase in cell surface ANXA1 and a reduction in forskolin-induced ACTH release. In contrast, pituitary tissue from rats treated prenatally or neonatally with dexamethasone was unresponsive to the steroid, although, like control tissue, it responded readily to ANXA1, which readily inhibited forskolin-driven ACTH release. Prenatal dexamethasone treatment reduced the size but not the number of FS cells. It also caused a marked reduction in corticotroph number and impaired granule margination without affecting other aspects of corticotroph morphology. Similar but less marked effects on pituitary cell morphology and number were evident in tissue from neonatally treated rats. Our study shows that, when administered by a noninvasive process, perinatal GC treatment exerts profound effects on the adult pituitary gland, impairing the ANXA1-dependent GC regulation of ACTH release and altering the cell profile and morphology.
A Mouse Model of Albright Hereditary Osteodystrophy Generated by Targeted Disruption of Exon 1 of the Gnas Gene
Authors: Germain-Lee Emily L. , Schwindinger William , Crane Janet L. , Zewdu Rediet , Zweifel Larry S. , Wand Gary , Huso David L. , Saji Motoyasu , Ringel Matthew D. , Levine Michael A.
Published: August 2005

Albright hereditary osteodystrophy is caused by heterozygous inactivating mutations in GNAS, a gene that encodes not only the α-chain of Gs (Gαs), but also NESP55 and XLαs through use of alternative first exons. Patients with GNAS mutations on maternally inherited alleles are resistant to multiple hormones such as PTH, TSH, LH/FSH, GHRH, and glucagon, whose receptors are coupled to Gs. This variant of Albright hereditary osteodystrophy is termed pseudohypoparathyroidism type 1a and is due to presumed tissue-specific paternal imprinting of Gαs. Previous studies have shown that mice heterozygous for a targeted disruption of exon 2 of Gnas, the murine homolog of GNAS, showed unique phenotypes dependent on the parent of origin of the mutated allele. However, hormone resistance occurred only when the disrupted gene was maternally inherited. Because disruption of exon 2 is predicted to inactivate Gαs as well as NESP55 and XLαs, we created transgenic mice with disruption of exon 1 to investigate the effects of isolated loss of Gαs. Heterozygous mice that inherited the disruption maternally (−m/+) exhibited PTH and TSH resistance, whereas those with paternal inheritance (+/−p) had normal hormone responsiveness. Heterozygous mice were shorter and, when the disrupted allele was inherited maternally, weighed more than wild-type littermates. Gαs protein and mRNA expression was consistent with paternal imprinting in the renal cortex and thyroid, but there was no imprinting in renal medulla, heart, or adipose. These findings confirm the tissue-specific paternal imprinting of GNAS and demonstrate that Gαs deficiency alone is sufficient to account for the hormone resistance of pseudohypoparathyroidism type 1a.
β-Catenin-dependent Wnt signalling controls the epithelial organisation of somites through the activation ofparaxis
Authors: Linker Claudia , Lesbros Cynthia , Gros Jérôme , Burrus Laura W. , Rawls Alan , Marcelle Christophe
Published: August 2005

The regulation of cell adhesion in epithelia is a fundamental process governing morphogenesis in embryos and a key step in the progression of invasive cancers. Here, we have analysed the molecular pathways controlling the epithelial organisation of somites. Somites are mesodermal epithelial structures of vertebrate embryos that undergo several changes in cell adhesion during early embryonic life. We show that Wnt6 in the ectoderm overlaying the somites, but not Wnt1 in the neighbouring neural tube, is the most likely candidate molecule responsible for the maintenance of the epithelial structure of the dorsal compartment of the somite: the dermomyotome. We characterised the signalling pathway that mediates Wnt6 activity. Our experiments suggest that the Wnt receptor molecule Frizzled7 probably transduces the Wnt6 signal. Intracellularly, this leads to the activation of theβ-catenin/LEF1-dependent pathway. Finally, we demonstrate that the bHLH transcription factor paraxis, which was previously shown to be a major player in the epithelial organisation of somites, is a target of theβ-catenin signal. We conclude that β-catenin activity, initiated by Wnt6 and mediated by paraxis, is required for the maintenance of the epithelial structure of somites.
Predictors of young dating adults' inclination to engage in extradyadic sexual activities: A multi‐perspective study
Authors: McAlister Anna , Pachana Nancy , Jackson Chris J.
Published: August 2005

Using a multi‐perspective vignette design, we explored predictors of young peoples' (N=119) propensity to engage in unfaithful activities while dating. Demographic measures, a datding investment model, and measures of functional and dysfunctional impulsivity were used to predict inclination to engage in each of two extradyadic activities (kissing and sexual activity). The results of moderated multiple regression analyses revealed that a respondent's number of sexual partners, level of dysfunctional impulsivity, satisfaction with current relationship, and quality of relationship alternatives significantly predicted inclination to engage in both of the extradyadic activities. Consistent with previous findings, gender only showed significant predictive value in relation to extradyadic sex inclination. Moreover, the association between sex, love, and marriage interacted with gender in the prediction of both extradyadic activities and interacted with commitment in the prediction of extradyadic sex inclination. Suggestions for future research in this area are offered in light of these new findings.
Perceived discrimination of international visitors to universities in Germany and the UK
Authors: Krahé Barbara , Abraham Charles , Felber Juliane , Helbig Muriel K.
Published: August 2005

The extent to which international students and academics feel discriminated against in the host country was explored in three samples from two countries: students in Germany (N=161), students in the UK (N=139), and academics in Germany (N=79). Respondents completed a measure of perceived discrimination of increasing severity, comprising antilocution (verbal derogation), avoidance, behavioural discrimination, and physical assault. Physical discernibility as foreigner, quality of private contacts with host nationals, and language proficiency were explored as predictors of perceived discrimination. Across the three samples, respondents who were identifiable as foreigners by their appearance reported more discrimination. Positive contacts with host nationals were associated with lower levels of perceived discrimination. Language proficiency predicted perceived antilocution in the two German samples. All samples perceived their personal level of discrimination to be lower than that of their respective in‐groups (international students/academics), but the tendency was moderated by visibility and contact quality.
Nazi cruelties: Are they literally hard to imagine?
Authors: Rassin Eric , van Rootselaar Anne‐Fleur , van der Heiden Simone , Ugahary Airthana , Wagener Stephanie
Published: August 2005

In four experiments, the characteristics of participants' mental imagery of World War II were investigated. In the first experiment, mental images of WWII were found to lack clarity compared to mental images of a Medieval war. In a second experiment, the association between the lack of clarity of WWII mental images, and the underestimation of Nazi cruelties was explored. In line with the expectation based on source monitoring theory, participants whose mental imagery was less clear more readily endorsed an item modelling denial of Nazi cruelties. In a third experiment, these findings were replicated. In experiment 4, participants' WWII mental images were manipulated by means of film footage. Ultimately, it is argued that viewing film footage of poor quality results in unclear mental images of WWII, and that lack of clarity of WWII imagery is associated with a tendency to Nazi cruelties.
Real-Time PCR Assays Targeting a Unique Chromosomal Sequence of Yersinia pestis
Authors: Chase Catherine J , Ulrich Melanie P , Wasieloski Leonard P , Kondig John P , Garrison Jeffrey , Lindler Luther E , Kulesh David A
Published: August 2005

Background: Yersinia pestis, the causative agent of the zoonotic infection plague, is a major concern as a potential bioweapon. Current real-time PCR assays used for Y. pestis detection are based on plasmid targets, some of which may generate false-positive results.

Methods: Using the yp48 gene of Y. pestis, we designed and tested 2 real-time TaqMan® minor groove binder (MGB) assays that allowed us to use chromosomal genes as both confirmatory and differential targets for Y. pestis. We also designed several additional assays using both Simple-Probe® and MGB Eclipse™ probe technologies for the selective differentiation of Yersinia pseudotuberculosis from Y. pestis. These assays were designed around a 25-bp insertion site recently identified within the yp48 gene of Y. pseudotuberculosis.

Results: The Y. pestis-specific assay distinguished this bacterium from other Yersinia species but had unacceptable low-level detection of Y. pseudotuberculosis, a closely related species. Simple-Probe and MGB Eclipse probes specific for the 25-bp insertion detected only Y. pseudotuberculosis DNA. Probes that spanned the deletion site detected both Y. pestis and Y. pseudotuberculosis DNA, and the 2 species were clearly differentiated by a post-PCR melting temperature (Tm) analysis. The Simple-Probe assay produced an almost 7 °C Tm difference and the MGB Eclipse probe a slightly more than 4 °C difference.

Conclusions: Our method clearly discriminates Y. pestis DNA from all other Yersinia species tested and from the closely related Y. pseudotuberculosis. These chromosomal assays are important both to verify the presence of Y. pestis based on a chromosomal target and to easily distinguish it from Y. pseudotuberculosis.
Diagnostic Considerations in the Measurement of Human Chorionic Gonadotropin in Aging Women
Authors: Snyder Jennifer A , Haymond Shannon , Parvin Curtis A , Gronowski Ann M , Grenache David G
Published: August 2005

Background: Human chorionic gondadotropin (hCG) screening tests are performed on nearly all female patients of childbearing age before any medical intervention. Although older women usually have negative hCG test results, positive results do occur and may cause clinical confusion. We examined changes with age in serum hCG concentrations in nonpregnant women and investigated the use of serum follicle-stimulating hormone (FSH) measurements as an aid to interpreting higher than expected (“positive”) hCG results.

Methods: We used 240 serum specimens for each of 4 female cohorts: pregnant, ≥18 years; nonpregnant, 18–40 years (premenopausal); nonpregnant, 41–55 years (perimenopausal); and nonpregnant, >55 years (postmenopausal). Patients were excluded if they had an ectopic pregnancy, a history of trophoblastic disease or a germ-cell tumor, or if no chart was available for review. Quantitative hCG and FSH tests were performed on each specimen.

Results: Serum hCG concentrations in nonpregnant women increased with the age of the women. hCG results were higher and significantly different (P <0.0001) for nonpregnant women >55 years (<2.0 to 13.1 IU/L) compared with nonpregnant women 18–40 years (<2.0 to 4.6 IU/L) and 41–55 years (<2.0 to 7.7 IU/L). Nineteen nonpregnant women >40 years of age had hCG concentrations ≥5.0 IU/L, all with an FSH concentration >32.4 IU/L. The highest FSH concentration in pregnancy was 7.3 IU/L.

Conclusions: Serum hCG increases with age in nonpregnant women. A cutoff of 14.0 IU/L should be used when interpreting hCG results in women >55 years of age. Pregnancy is unlikely in perimenopausal women 41–55 years of age with an hCG between 5.0 and 14.0 IU/L if serum FSH is >20.0 IU/L.
The Prophylactic and Therapeutic Effects of Cholinolytics on Perfluoroisobutylene Inhalation Induced Acute Lung Injury
Authors: Zhang Tianhong , Zhang Xigang , Shao Zhihua , Ding Rigao , Yang Shunjiang , Ruan Jinxiu , Sun Xiaohong , Xu Jin , Huang Chunqian , Hu Zuliang , Zhang Xianchang
Published: August 2005

The Prophylactic and Therapeutic Effects of Cholinolytics on Perfluoroisobutylene Inhalation Induced Acute Lung Injury: Tianhong Zhang, et al. Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, P. R. China— Perfluoroisobutylene (PFIB) is a kind of fluoro‐olefin that is ten times more toxic than phosgene. The mechanisms of the acute lung injury (ALI) induced by PFIB inhalation remain unclear. To find possible pharmacological interventions, mice and rats were exposed to PFIB, and the prophylactic or therapeutic effects of 3‐quinuclidinyl benzilate (QNB) and anisodamine were studied and confirmed. It was observed that the wet lung/body weight and the dry lung/body weight ratios at 24 h after PFIB exposure (130 mg/m3 for 5 min) were significantly decreased when a single dose of QNB (5 mg/kg) was administered intraperitoneally either 30 min before exposure or 10 h after exposure. Anisodamine was without any prophylactic or therapeutic effects at single doses below 30 mg/kg. The effects of QNB against PFIB inhalation induced ALI were well evidenced by the significantly decreased mice mortality at 72 h, the total protein concentration in bronchoalveolar lavage fluid at 24 h after the PFIB exposure, as well as the ultrastructural observations. The analysis of the time courses of lung sulfhydryl concentration, myeloperoxidase (MPO) activity and hemorheology assay showed that the toxicity of PFIB may be due to consumption of lung protein sulfhydryl, influx of polymorphonuclear leukocytes (PMNs) into the lung, and increased peripheral blood viscosity at a low shear rate, all of which were partially blocked by QNB intervention except for PMN influx. The results suggest that cholinolytics might have prophylactic and therapeutic roles in PFIB inhalation induced ALI.
Prevalence and Psychosocial Risk Factors of Upper Extremity Musculoskeletal Pain in Industries of Taiwan: A Nationwide Study
Authors: Lee Hsin‐Yi , Yeh Wen‐Yu , Chen Chun‐Wan , Wang Jung‐Der
Published: August 2005

Prevalence and Psychosocial Risk Factors of Upper Extremity Musculoskeletal Pain in Industries of Taiwan: A Nationwide Study: Hsin‐Yi Lee, et al. Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Taiwan—Prevalence of upper extremity disorders and their associations with psychosocial factors in the workplace have received more attention recently. A national survey of cross‐sectional design was performed to determine the prevalence rates of upper extremity disorders among different industries. Trained interviewers administered questionnaires to 17,669 workers and data on musculoskeletal complaints were obtained along with information on risk factors. Overall the 1‐year prevalence of neck (14.8%), shoulder (16.6%), and hand (12.4%) disorders were higher than those of the upper back (7.1%) and elbow (8.3%) among those who sought medical treatment due to the complaint. Workers in construction and agriculture‐related industries showed a higher prevalence of upper extremity disorders. After multiple logistic regression adjusted for age, education, and employment duration, we found job content, physical working condition, a harmonious interpersonal relationship at the workplace and organizational problems were significant determinants of upper extremity disorders in manufacturing and service industries. Male workers in manufacturing industries showed more concern about physical working conditions while female workers in public administration emphasized problems of job content and interpersonal relationships. We concluded that these factors were major job stressors contributing to musculoskeletal pain of the upper extremity.
Relationship between Turnover and Periodic Health Check‐Up Data among Japanese Hospital Nurses: A Three‐Year Follow‐Up Study
Authors: Shimizu Takashi , Eto Risa , Horiguchi Itsuko , Obata Yasuko , Feng Qiaolian , Nagata Shoji
Published: August 2005

Relationship between Turnover and Periodic Health Check‐Up Data among Japanese Hospital Nurses: A Three‐year Follow‐Up Study: Takashi Shimizu, et al. University of Occupational and Environmental Health—The present study explored the relationship between turnover and periodic health check‐up data among Japanese hospital nurses. The subjects were 379 registered nurses in a Japanese hospital and the duration of our study period was three years. By the proportional hazard model, we investigated the relative risks (RRs) of the turnover rate associated with the following: lifestyles (irregularity of meals, taking breakfast), work environment (working hours, work schedule), and health status (body mass index [BMI], serum total cholesterol [T‐cho], taking medication, sleep disturbance). We obtained the data on turnover from October, 1997 to September, 2000. During the observed period we were able to follow up on 363 female nurses (96%) and the turnover total amongst them was 100. We divided the subjects into a younger (21–25‐yr‐old) and an older (>25‐yr‐old) group because of the interaction between age and turnover. In the younger group, we found that sleep disturbance influenced turnover significantly. On the other hand, in the older nurses, BMI and T‐cho contributed to turnover significantly. Our results imply the possibility of a partial association between turnover and periodic health check‐up data among the nurses.
Serum Biomarkers for Identifying Acute Chest Syndrome Among Patients Who Have Sickle Cell Disease and Present to the Emergency Department
Authors: Naprawa James T. , Bonsu Bema K. , Goodman Deborah G. , Ranalli Mark A.
Published: August 2005

Objective. To compare the accuracy of biomarkers for identifying acute chest syndrome (ACS) in patients with sickle cell disease presenting to a pediatric emergency department (ED).

Methods. We conducted a 13-month-long (2002–2003) cohort study with nested case-control in patients with sickle cell disease presenting to the pediatric ED with vaso-occlusive crises or fever in which we compared levels of secretory phospholipase A2 (sPLA2), endothelin-1, interleukin-6 (IL-6), and peripheral white blood cell count (WBC) in cases that were complicated by ACS and in control subjects with uncomplicated illnesses. For diagnosis, a test was considered to be accurate when the area under its receiver operator characteristic curve (AUC) was >0.70. Laboratory tests with AUC values ≥0.70 were entered into a binary recursive partitioning model for diagnosis.

Results. For the period of study, samples from 72 visits were obtained from 51 patients who presented with vaso-occlusive crises (range: 1–4 visits per patient; 15 were enrolled more than once). ACS complicated 19 of 72 visits (26%, 95% confidence interval: 17%–38%). At an AUC value of 0.79, only the sPLA2 test was accurate for diagnosing ACS. AUC values for peripheral WBC, endothelin-1, and IL-6 were 0.68, 0.51, and 0.52, respectively. Binary recursive partitioning retained only sPLA2 at a cutoff of 13.7 ng/mL to be accurate for diagnosis. This cutoff had a sensitivity of 74% (14 of 19), a specificity of 87% (46 of 53), a positive likelihood ratio of 5.6, and a negative likelihood ratio of 0.18.

Conclusions. Secretory phospholipase A2 but not endothelin-1, IL-6, or WBC is an accurate test for identifying present or incipient ACS in young patients who present to the ED with sickle cell pain crises.
Asymptomatic Inflammatory Bowel Disease Presenting With Mucocutaneous Findings
Authors: Galbraith Sheila S. , Drolet Beth A. , Kugathasan Subra , Paller Amy S. , Esterly Nancy B.
Published: August 2005

Although inflammatory bowel disease (IBD) typically presents with gastrointestinal complaints, mucocutaneous lesions are commonly associated and can precede gastrointestinal symptoms, thereby alerting the clinician to the diagnosis of IBD before the onset of gastrointestinal symptoms. Nine children are reported who had no gastrointestinal symptoms suggestive of IBD but presented with mucocutaneous findings of IBD and were subsequently diagnosed with Crohn's disease or ulcerative colitis based on characteristic features on gastrointestinal endoscopy and/or biopsies. The majority of the patients had oral and perianal lesions. We believe that IBD is a common etiology for persistent oral lesions in the pediatric population. In addition to a good history, children with unexplained oral mucous membrane lesions should have an examination of the rectal and genital mucosa as well as tests for complete blood count, iron levels, sedimentation rate, albumin, and occult blood in the stool with endoscopy and biopsies to rule out IBD if indicated.
High Barrier Effects of (0001)|(0001) Zinc Oxide Bicrystals: Implication for Varistor Ceramics with Inversion Boundaries
Authors: Lee Jong-Sook , Maier Joachim
Published: August 2005

Inversion boundaries (IBs) of a head-to-head or (0001)|(0001) (C+|C+) configuration bisect virtually every grain in typical commercial ZnO varistor ceramics. They are most often considered electrically inactive, and the effect on the grain growth behavior has been recently addressed. In this work, various configurations of ZnO bicrystals were prepared using different source crystals and strong barrier effects were observed in some (0001)|(0001) (C−|C−) bicrystals using crystals with higher impurity contents. The crystallographic polarity and impurity effects were systematically examined by doping C+|C+ and C−|C− bicrystals with single and double additives of Mn, Co, Ni, and Bi. Varying degrees of barrier effects including varistor-like behaviors were observed in C−|C− bicrystals depending on dopants, while C+|C+ bicrystals consistently exhibited negligible effects. Because the IBs in ZnO varistor ceramics preferentially expose C− surfaces in the grain boundaries, the superior property of commercial ZnO varistor ceramics is suggested to be assisted by the presence of IBs.
Mg–Ca–Zn Bulk Metallic Glasses with High Strength and Significant Ductility
Authors: Gu X. , Shiflet G.J. , Guo F.Q. , Poon S.J.
Published: August 2005

The development of Mg–Ca–Zn metallic glasses with improved bulk glass forming ability, high strength, and significant ductility is reported. A typical size of at least 3–4 mm amorphous samples can be prepared using conventional casting techniques. By varying the composition, the mass density of these light metal based bulk amorphous alloys ranges from 2.0 to 3.0 g/cm3. The typical measured microhardness is 2.16 GPa, corresponding to a fracture strength of about 700 MPa and specific strength of around 250–300 MPa cm3/g. Unlike other Mg- or Ca-based metallic glasses, the present Mg–Ca–Zn amorphous alloys show significant ductility.
Correlation Between Chemical Reaction and Brittle Fracture Found in Electroless Ni(P)/immersion gold–solder Interconnection
Authors: Sohn Yoon-Chul , Yu Jin
Published: August 2005

Occurrence of brittle interfacial fracture at an electroless Ni(P)/immersion gold–solder joint has long been a serious problem not yet fully understood. In our previous report on the electroless Ni(P) [J. Mater. Res.19,2428 (2004)], it was shown that crystallization of the Ni(P) film and growth of the Ni3SnP layer were accelerated after the intermetallic compound (IMC) spalling, and accurate failure locus of the brittle fracture due to so-called “IMC spalling induced microstructure degradation of the Ni(P) film” is presented for the first time in this communication. For Sn–3.0Ag–0.5Cu solder joints, (Ni,Cu)3Sn4and/or (Cu,Ni)6Sn5ternary IMCs formed at the interface, and neither spalling nor interfacial fracture was observed. For Sn–3.5Ag joints, Ni3Sn4compound formed, and the brittle fracture occurred through the Ni3SnP layer in the solder pads where Ni3Sn4had spalled. Since the Ni3SnP layer is getting thicker during or after Ni3Sn4spalling, control of IMC spalling is crucial to ensure the reliability of Ni(P)/solder system.
Simulated Soft Tissue Nanoindentation: A Finite Element Study
Authors: Gupta Shikha , Carrillo Fernando , Balooch Medhi , Pruitt Lisa , Puttlitz Christian
Published: August 2005

To address the growing interest in nanoindentation for biomaterials, the following finite element study investigated the influence of indentation testing protocol and substrate geometry on quasi-static and dynamic load-displacement behavior of linear viscoelastic materials. For a standard linear solid, the conventional quasi-static indentation modulus, EQS, fell between the instantaneous and equilibrium modulus of the model. EQS approached the equilibrium modulus only for indentation unloading times 1000 times greater than the characteristic relaxation time of the model. It was nearly insensitive to other changes in the indentation testing protocol, such as tip radius and penetration depth, exhibiting variations of only 5–10%. Dynamic nanoindentation provided a quantitatively accurate assessment of the complex dynamic modulus (within ±12%) for a range material of parameters at physiologically relevant testing parameters. Both quasi-static and dynamic moduli calculated from the irregular surfaces varied with the size and shape of the irregularities but were still within 10% of the smooth surface values for penetration depths larger than the dimensions of the surface irregularities.
Investigation of the Crystallization Mechanisms in Indium Molybdenum Oxide Films by Vacuum Annealing
Authors: Sun Shi-Yao , Huang Jow-Lay , Lii Ding-Fwu
Published: August 2005

The crystallization mechanisms for potentially high mobility molybdenum-indium-oxide (IMO) film were studied. The crystalline IMO films were deposited on unheated glass substrates via high-density plasma evaporation, and subsequent vacuum annealing was performed at 150, 200, and 250 °C for 30 min. The results of x-ray diffraction and x-ray photoelectron spectroscopy and electrical properties suggested that the room-temperature crystallization was induced from the highest compressive strain, caused by the charged clusters and oxygen vacancies. The highest mobility of 75.8 cm2/Vs obtained at 250 °C was due to the charged In–Mo+6–O clusters and strain relaxation with (222)/(440) orientation change.
Electromigration Studies of Sn(Cu) and Sn(Ni) Alloy Stripes
Authors: Wei C.C. , Liu C.Y.
Published: August 2005

Using Blech’s structure, we studied the electromigration (EM) behaviors of four different Sn(Cu) and Sn(Ni) alloys, which are Sn, Sn0.7Cu, Sn3.0Cu, and Sn1Ni. The order of the EM rates was determined to be Sn0.7Cu > Sn > Sn3Cu > Sn1Ni. We believe that the lower yielding strength and higher grain boundary density of Sn0.7Cu were the main reasons that Sn0.7Cu had the fastest EM rate. Moreover, we found that the addition at Ni could effectively retard EM. The critical products of Sn, Sn0.7Cu, and Sn3.0Cu, which were determined to be 1500, 500, and 1580 A/cm, respectively. The diffuse-effective charge (DZ*) values of the solder stripes from this present work have same order magnitude of the reported values, which were measured by using actual solder bumps.
Density- and Hardness-optimized Pressureless Sintered and Post-hot Isostatic Pressed B4C
Authors: Cho Namtae , Bao Zhihao , Speyer Robert F.
Published: August 2005

Pressureless sintered B4C relative densities as high as 96.7% were obtained by optimizing the soak temperature, and holding at that temperature for the minimum time required to reach terminal density. Although the relative densities of pressureless sintered specimens were lower than that of commercially produced hot-pressed B4C, their (Vickers) hardness values were comparable. For 4.45-cm-diameter, 1.35-cm-high disk-shaped specimens, pressureless sintered to at least 93.0% relative density, post-hot isostatic pressing resulted in vast increases in relative densities (e.g., 100.0%) and hardness values significantly greater than that of commercially produced hot-pressed B4C.
Microstructural Evolution of an Ultrafine-grained Cryomilled Al 5083 Alloy During Thermomechanical Processing
Authors: Witkin David , Han Bing Q. , Lavernia Enrique J.
Published: August 2005

The microstructural changes in cryomilled and consolidated Al 5083 following compression testing at several temperatures are described. Prior to testing, the material had an average grain size of approximately 138 nm and exhibited a duplex microstructure, containing coarse grains between 500 and 2000 nm. After uniaxial compressive deformation at temperatures between 423 and 573 K (0.49–0.66 Tm), the average grain size increased to between 200 and 300 nm, consistent with the average grain size of extrusions formed from the same material at similar temperatures. The similarity in grain size distribution following uniaxial compression or extrusion despite differences in total strain and stress state imposed by each indicates that much of the deformation in the extrusion process occurs in coarse-grained regions.
Evidence for Extensive Grain Boundary Meander and Overgrowth of Substrate Grain Boundaries in High Critical Current Density ex Situ YBa2Cu3O7−x Coated Conductors
Authors: Feldmann D.M. , Larbalestier D.C. , Holesinger T. , Feenstra R. , Gapud A.A. , Specht E.D.
Published: August 2005

It has been generally accepted that YBa2Cu3O7−x (YBCO) films deposited on deformation textured polycrystalline metal tapes result in YBCO grain boundary (GB) networks that essentially replicate the GBs of the underlying substrate. Here we report that for thicker YBCO films produced by a BaF2 ex situ process, this is not true. Using electron backscatter diffraction combined with ion milling, we have been able to map the evolution of the YBCO grain structure and compare it to the underlying template in several coated conductors. For thin (≤0.5 μm) YBCO films deposited on rolling-assisted biaxially textured substrates (RABiTS), the YBCO GBs nearly directly overlap the substrate GBs. For 0.7–1.4 μm YBCO films, the GBs were found to meander along the substrate GBs and along the sample normal, with displacements several times the film thickness. In very thick films (2.5–2.9 μm), the YBCO grains can completely overgrow substrate grains and GBs, resulting in a substantial disconnection of the YBCO and substrate GB networks. Similar behavior is found for BaF2 ex situ YBCO films on ion-beam-assisted deposition-type templates. The ability of the YBCO to overgrow substrate grains and GBs is believed to be due to liquid-phase mediated laminar grain growth. Although the behavior of the YBCO GB networks changes with YBCO film thickness, the samples maintained high critical current density (Jc) values of >2 MA/cm2 for films up to 1.4 μm thick, and up to0.9 MA/cm2 for 2.5–2.9-μm-thick films.
Synthesis of Oriented BiFeO3Thin Films by Chemical Solution Deposition: Phase, Texture, and Microstructural Development
Authors: Tyholdt F. , Jørgensen S. , Fjellvåg H. , Gunnæs A.E.
Published: August 2005

Textured, thin films of BiFeO3(∼120 nm thickness) were synthesized by chemical solution deposition from a mixture of iron- and bismuth- 2-methoxyethoxides on Si(100)/SiO2/TiO2/Pt substrates. The use of alkoxides ensured good homogeneity and a low degree of organics that further facilitated low crystallization temperatures. Crystalline films were according to x-ray diffraction already obtained at 480 °C. Precursor characteristics were investigated using thermogravimetry and differential scanning calorimetry, whereas phase purity, microstructure and film topography were examined by x-ray diffraction, transmission electron microscopy, atomic force microscopy, and x-ray photoelectron spectroscopy. A small (10%) Bi excess was found necessary to obtain dense, pore-free films. Such additions also prevented decomposition of BiFeO3at high temperatures. The observed (012) texture is believed to originate from the growth mechanism as no relation to the substrate is found. This is also confirmed by observing (012) texture for films on glass substrates.
Nanotubes Patterned Thin Films of Barium-strontium Titanate
Authors: Wei Xuezheng , Vasiliev Alexander L. , Padture Nitin P.
Published: August 2005

A novel, low-temperature synthesis method for producing BaxSr(1−x)TiO3 (BST) thin films patterned in the form of nanotubes (“honeycomb”) on Ti substrates is reported. In this two-step method, the Ti substrate is first anodized to produce a surface layer (∼300 nm thickness) of amorphous titanium oxide nanotube (∼100 nm diameter) arrays. In the second step, the anodized substrate is subjected to hydrothermal treatment in aqueous Ba(OH)2 + Sr(OH)2 at 200 °C, where the nanotube arrays serve as templates for their topotactic (shape-preserving) hydrothermal conversion to polycrystalline BST nanotubes. A simple geometrical model is proposed to elucidate the mechanism of the hydrothermal growth of BST nanotubes. This opens the possibility of tailoring the titanium oxide nanotube arrays and of using various precursor solutions and their combinations in the hydrothermal bath to produce ordered, patterned thin-film structures of various Ti-containing ceramics. These could find use not only in a variety of electronic, optoelectronic, and sensor device applications but also in biomedical and catalysis applications, where patterned thin films are desirable.
Competing Fracture Modes in Brittle Materials Subject to Concentrated Cyclic Loading in Liquid Environments: Monoliths
Authors: Zhang Yu , Bhowmick Sanjit , Lawn Brian R.
Published: August 2005

The competition between fracture modes in monolithic brittle materials loaded in cyclic contact in aqueous environments with curved indenters is examined. Three main modes are identified: conventional outer cone cracks, which form outside the maximum contact; inner cone cracks, which form within the contact; and median–radial cracking, which form below the contact. Relations describing short-crack initiation and long-crack propagation stages as a function of number of cycles, based on slow crack growth within the Hertzian field, are presented. Superposed mechanical driving forces—hydraulic pumping in the case of inner cone cracks and quasiplasticity in the case of median–radials—are recognized as critically important modifying elements in the initial and intermediate crack growth. Ultimately, at large numbers of cycles, the cracks enter the far field and tend asymptotically to a simple, common relation for center-loaded pennylike configurations driven by slow crack growth. Crack growth data illustrating each mode are obtained for thick soda-lime glass plates indented with tungsten carbide spheres in cyclic loading in water, for a range of maximum contact loads and sphere radii. Generally in the glass, outer cone cracks form first but are subsequently outgrown in depth as cycling proceeds by inner cones and, especially, radial cracks. The latter two crack types are considered especially dangerous in biomechanical applications (dental crowns, hip replacements) where ceramic layers of finite thickness are used as load-bearing components. The roles of test variables (contact load, sphere radius) and material properties (hardness, modulus, toughness) in determining the relative importance of each fracture mode are discussed.
Hepatocyte Growth Factor Effects on Mesenchymal Stem Cells: Proliferation, Migration, and Differentiation
Authors: Forte Giancarlo , Minieri Marilena , Cossa Paolo , Antenucci Daniele , Sala Marilena , Gnocchi Viola , Fiaccavento Roberta , Carotenuto Felicia , De Vito Paolo , Baldini Patrizia Morena , Prat Maria , Di Nardo Paolo
Published: August 2005

Hepatocyte growth factor (HGF), a pleiotropic cytokine of mesenchymal origin promoting migration, proliferation, and survival in a wide spectrum of cells, can also modulate different biological responses in stem cells, but the mechanisms involved are not completely understood so far. In this context, we show that short-term exposure of mesenchymal stem cells (MSCs) to HGF can induce the activation of its cognate Met receptor and the downstream effectors ERK1/2, p38MAPK, and PI3K/Akt, while long-term exposure to HGF resulted in cytoskeletal rearrangement, cell migration, and marked inhibition of proliferation through the arrest in the G1-S checkpoint. When added to MSCs, the K252A tyrosine kinase inhibitor prevented HGF-induced responses. HGF's effect on MSC proliferation was reversed by p38 inhibitor SB203580, while the effects on cell migration were abrogated by PI3K inhibitor Wortmannin, suggesting that HGF acts through different pathways to determine its complex effects on MSCs. Prolonged treatment with HGF induced the expression of cardiac-specific markers (GATA-4, MEF2C, TEF1, desmin, α-MHC, β-MHC, and nestin) with the concomitant loss of the stem cell markers nucleostemin, c-kit, and CD105.
Unique Gene Expression Signature by Human Embryonic Stem Cells Cultured Under Serum-Free Conditions Correlates with Their Enhanced and Prolonged Growth in an Undifferentiated Stage
Authors: Skottman Heli , Strömberg Anne-Marie , Matilainen Eija , Inzunza Jose , Hovatta Outi , Lahesmaa Riitta
Published: August 2005

Understanding the interaction between human embryonic stem cells (hESCs) and their microenvironment is crucial for the propagation and the differentiation of hESCs for therapeutic applications. hESCs maintain their characteristics both in serum-containing and serum-replacement (SR) media. In this study, the effects of the serum-containing and SR culture media on the gene expression profiles of hESCs were examined. Although the expression of many known embryonic stem cell markers was similar in cells cultured in either media, surprisingly, 1,417 genes were found to be differentially expressed when hESCs cultured in serum-containing medium were compared with those cultured in SR medium. Several genes upregulated in cells cultured in SR medium suggested increased metabolism and proliferation rates in this medium, providing a possible explanation for the increased growth rate of nondifferentiated cells observed in SR culture conditions compared with that in serum medium. Several genes characteristic for cells with differentiated phenotype were expressed in cells cultured in serum-containing medium. Our data clearly indicate that the manipulation of hESC culture conditions causes phenotypic changes of the cells that were reflected also at the level of gene expression. Such changes may have fundamental importance for hESCs, and gene expression changes should be monitored as a part of cell culture optimization aiming at a clinical use of hESCs for cell transplantation.