bluuebunny/crossref_metadata_2025_split huggingface dataset:
Concentric Cylinder Bioreactor for Production of Tissue Engineered Cartilage: Effect of Seeding Density and Hydrodynamic Loading on Construct Development
Authors: Saini Sunil , Wick Timothy M. 
Published: April 2003

AbstractA concentric cylinder bioreactor has been developed to culture tissue engineered cartilage constructs under hydrodynamic loading. This bioreactor operates in a low shear stress environment, has a large growth area for construct production, allows for dynamic seeding of constructs, and provides for a uniform loading environment. Porous poly‐lactic acid constructs, seeded dynamically in the bioreactor using isolated bovine chondrocytes, were cultured for 4 weeks at three seeding densities (60, 80, 100 × 106 cells per bioreactor) and three different shear stresses (imposed at 19, 38, and 76 rpm) to characterize the effect of chondrocyte density and hydrodynamic loading on construct growth. Construct seeding efficiency with chondrocytes is greater than 95% within 24 h. Extensive chondrocyte proliferation and matrix deposition are achieved so that after 28 days in culture, constructs from bioreactors seeded at the highest cell densities contain up to 15 × 106 cells, 2 mg GAG, and 3.5 mg collagen per construct and exhibit morphology similar to that of native cartilage. Bioreactors seeded with 60 million chondrocytes do not exhibit robust proliferation or matrix deposition and do not achieve morphology similar to that of native cartilage. In cultures under different steady hydrodynamic loading, the data demonstrate that higher shear stress suppresses matrix GAG deposition and encourages collagen incorporation. In contrast, under dynamic hydrodynamic loading conditions, cartilage constructs exhibit robust matrix collagen and GAG deposition. The data demonstrate that the concentric cylinder bioreactor provides a favorable hydrodynamic environment for cartilage construct growth and differentiation. Notably, construct matrix accumulation can be manipulated by hydrodynamic loading. This bioreactor is useful for fundamental studies of construct growth and to assess the significance of cell density, nutrients, and hydrodynamic loading on cartilage development. In addition, studies of cartilage tissue engineering in the well‐characterized, uniform environment of the concentric cylinder bioreactor will develop important knowledge of bioprocessing parameters critical for large‐scale production of engineered tissues.
Application of Multivariate Analysis to Optimize Function of Cultured Hepatocytes
Authors: Chan Christina , Hwang Daehee , Stephanopoulos Gregory N. , Yarmush Martin L. , Stephanopoulos George 
Published: April 2003

AbstractUnderstanding the metabolic and regulatory pathways of hepatocytes is important for biotechnological applications involving liver cells, including the development of bioartificial liver (BAL) devices. To characterize intermediary metabolism in the hepatocytes, metabolic flux analysis (MFA) was applied to elucidate the changes in intracellular pathway fluxes of primary rat hepatocytes exposed to human plasma and to provide a comprehensive snapshot of the hepatic metabolic profile. In the current study, the combination of preconditioning and plasma supplementation produced distinct metabolic states. Combining the metabolic flux distribution obtained by MFA with methodologies such as Fisher discriminant analysis (FDA) and partial least squares or projection to latent structures (PLS) provided insights into the underlying structure and causal relationship within the data. With the aid of these analyses, patterns in the cellular response of the hepatocytes that contributed to the separation of the different hepatic states were identified. Of particular interest was the recognition of distal pathways that strongly correlated with a particular hepatic function. The hepatic functions investigated were intracellular triglyceride accumulation and urea production. This study illustrates a framework for optimizing hepatic function and a possibility of identifying potential targets for improving hepatic functions.
Highly Efficient “Tight Fit” Immobilization of α‐Chymotrypsin in Mesoporous MCM‐41: A Novel Approach Using Precursor Immobilization and Activation
Authors: Fadnavis Nitin. W. , Bhaskar Veldurthy , Kantam Mannepalli Lakshmi , Choudary Boyapati Manoranjan 
Published: April 2003

AbstractThe zymogen α‐chymotrypsinogen A is bound to mesoporous silica MCM‐41 with a protein loading of 170 mg/g solid (MCM‐Z) by a simple stirring in aqueous tris‐HCl buffer (pH 7.2). The bound zymogen is then activated with trypsin to obtain α‐chymotrypsin immobilized on MCM‐41 (MCM‐E.I) that displays an effective enzyme activity corresponding to 65 mg protein/g of solid support (3250 BTEE units/g). A direct immobilization of commercially available α‐chymotrypsin (MCM‐E.II) gives lower loading (1250 BTEE units/g). Protein content of the solid support after immobilization is confirmed by thermogravimetric analysis (TGA). The enzyme is tightly bound to the support and can be used over 100 recycles over 1 week in aqueous as well as reverse micellar media. The immobilized enzyme (MCM‐E.I) has been used for resolution of N‐acetyl‐dl‐amino acid esters and racemic trans‐4‐methoxy‐3‐phenylglycidic acid (PGA) methyl ester.
Comparative Genomic Analysis of dha Regulon and Related Genes for Anaerobic Glycerol Metabolism in Bacteria
Authors: Sun Jibin , van den Heuvel Joop , Soucaille Philippe , Qu Yinbo , Zeng An‐Ping 
Published: April 2003

AbstractThe dihydroxyacetone ( dha) regulon of bacteria encodes genes for the anaerobic metabolism of glycerol. In this work, genomic data are used to analyze and compare the dha regulon and related genes in different organisms in silico with respect to gene organization, sequence similarity, and possible functions. Database searches showed that among the organisms, the genomes of which have been sequenced so far, only two, i.e., Klebsiella pneumoniaeMGH 78578 and Clostridium perfringens contain a complete dha regulon bearing all known enzymes. The components and their organization in the dha regulon of these two organisms differ considerably from each other and also from the previously partially sequenced dha regulons in Citrobacter freundii, Clostridium pasteurianum, and Clostridium butyricum. Unlike all of the other organisms, genes for the oxidative and reductive pathways of anaerobic glycerol metabolism in C. perfringens are located in two separate organization units on the chromosome. Comparisons of deduced protein sequences of genes with similar functions showed that the dha regulon components in K. pneumoniae and C. freundii have high similarities (80–95%) but lower similarities to those of the Clostridium species (30–80%). Interestingly, the protein sequence similarities among the dha genes of the Clostridium species are in many cases even lower than those between the Clostridium species and K. pneumoniae or C. freundii, suggesting two different types of dharegulon in the Clostridium species studied. The in silico reconstruction and comparison of dha regulons revealed several new genes in the microorganisms studied. In particular, a novel dha kinase that is phosphoenolpyruvate‐dependent is identified and experimentally confirmed for K. pneumoniaein addition to the known ATP‐dependent dha kinase. This finding gives new insights into the regulation of glycerol metabolism in K. pneumoniaeand explains some hitherto not well understood experimental observations.
Gender Differences in Problem Drinking and Depression: Different “Vulnerabilities?”
Authors: Skaff Marilyn McKean , Finney John W. , Moos Rudolf H. 
Published: April 2003

AbstractThis study examines the relationship between stressors and resources and the functioning of a sample of 515 men and women who had a drinking problem. At a one‐year follow‐up, both women and men had improved on three functioning measures: alcohol consumption, days intoxicated, and depression. There were no gender differences at Time 2 on alcohol consumption, but men had more days intoxicated and women had more symptoms of depression. The impact of stressors and resources varied by life domain, functioning criterion, and gender. Although the predictors varied, the amount of variance in depression accounted for was the same for women and men. The most striking gender difference was the stronger impact of friendships for women on all aspects of functioning. This study provides support for reconsideration of the stress vulnerability of women and men.
A Simple, Unified Approach to Bayesian Risk Calculations
Authors: Hodge Susan E. 
Published: April 2003

AbstractA simple, unified approach for calculating Bayesian risks is presented and illustrated with examples. Although new genetic tools have reduced the need for these risk calculations, situations still exist in which consultands need to know these kinds of risks (for example, when no direct test is available for a particular deleterious mutation, or when a consultand wants to know his/her risk before deciding whether to undergo a direct test). The “Unified Approach” presented here is straightforward and ensures calculating the correct risks. It can be applied to a wide variety of genetic counseling situations, including but not limited to: calculating recurrence or carrier risks for dominant and recessive diseases; incorporating false‐positive and false‐negative rates on genetic tests into risk calculations; and determining the probability that an isolated case in a family represents a new mutation. The method is based on basic principles of probability and likelihood theory but can be used without sophisticated knowledge of this theory. The method relies on two rules, the “Rule of All Configurations” and the “Rule of Fundamental Probabilities,” which are explained and illustrated. The Unified Approach does not represent new or original mathematics but should make it easier for users to calculate risks accurately. A warning is included that complex calculations should always be independently verified by another individual.
The mental health of crime victims: Impact of legal intervention
Authors: Herman Judith Lewis 
Published: April 2003

AbstractIn the aftermath of crime, victims must decide whether to seek justice. An encounter with the legal system offers major potential benefits to crime victims, but also exposes them to significant risks. Victims who file civil or criminal complaints are subject to the rules and procedures of a complex legal system, where their mental health and safety may be of marginal concern, and where the potential for retraumatization may be high. This paper reviews the social and psychological barriers that discourage victim participation in the legal system, and existing studies that document the impact of participation on victims' mental health. Prospective longitudinal research focusing on victims in the legal system is recommended.
Cancer Risk Assessment and Genetic Counseling in an Academic Medical Center: Consultands' Satisfaction, Knowledge, and Behavior in the First Year
Authors: Penles Stadler Mona , Mulvihill John J. 
Published: April 2003

AbstractIn 1995, we formally established a multifaceted cancer genetics program of clinical services, research, and education at a general academic medical center. In the first year, 58 families, mostly physician referred, received cancer risk assessment and genetic counseling for a family and/or medical history of cancer. The primary reasons for seeking consultation were to determine their risk or their offspring's risk for developing certain cancers and to inquire about the availability of DNA testing for predisposition to breast, ovarian, or colon cancers. To assess the level of satisfaction with program services, 51 consultands (22% with a personal history of cancer) were interviewed independently by telephone 3–12 months after the session. One goal of the survey was to improve program service. Ninety percent of respondents reported that the consultation was worth their time and money. Forty‐two percent stated that their anxiety related to their cancer risk had decreased following counseling and 56% indicated no change. Recall of exact numerical risk was poor and one‐third could not remember hearing any risk estimate. More respondents would recommend the service to friends (90%) than to family members (75%). Overall, the service was positively received by the majority of patients.
Multiple Mediators of the Effects of Acculturation Status on Delinquency for Mexican American Adolescents
Authors: Samaniego Roxana Y. , Gonzales Nancy A. 
Published: April 2003

AbstractResearch has shown that more acculturated Latino adolescents are at increased risk for delinquent behavior relative to their less acculturated counterparts. The present study examined the mediating effects of seven variables hypothesized to account for the empirical link between acculturation status and delinquent activity for a sample of Mexican American adolescents. Mediational analyses provided support for four of the putative mediators which included family conflict, maternal monitoring, inconsistent discipline, and negative peer hassles. Examined together, these variables totally mediated the effect of acculturation status on delinquent behavior. In addition, family conflict and maternal monitoring uniquely accounted for a significant proportion of the mediated variance above that explained by the other variables in the model. Adolescent's cultural identity, perceived discrimination, and maternal acceptance were not supported as mediators.
The Influence of American Urban Culture on the Development of Normative Beliefs About Aggression in Middle‐Eastern Immigrants
Authors: Souweidane Violet , Huesmann L. Rowell 
Published: April 2003

AbstractThe effects of a community's culture on children's and adolescents' normative beliefs about the appropriateness of aggression were examined. One hundred forty‐seven high school students and 103 fourth graders participated in a survey of normative beliefs; 69 high school and 44 elementary school students were of Middle‐Eastern background. Although there were no differences in the beliefs of immigrant and nonimmigrant fourth graders, adolescents born in the United States were more accepting of aggression than those who immigrated from the Middle East. Moreover, adolescents who immigrated to the U.S. at age 12 or later were less accepting of aggression than those who immigrated prior to age 12.
Legal interventions for child victims
Authors: Whitcomb Debra 
Published: April 2003

AbstractMany commentators have expressed concern over the plight of children in the nation's court system, fearing that child victim/witnesses might suffer significant trauma. In efforts to alleviate this presumed trauma, new laws were passed and traditional procedures were modified. This paper synthesizes available research addressing 2 questions pertaining to the mental health needs of child victims: (1) To what extent are children traumatized by their involvement in the justice system, and (2) What interventions are effective in reducing children's trauma? The review concludes that most children can testify without suffering long‐term adverse effects. It also identifies elements of the justice system that appear to heighten stress for children. Finally, it suggests several strategies that might be effective in alleviating that stress.
Effect of Particles on the Recovery of
Cryptosporidium
Oocysts from Source Water Samples of Various Turbidities
Authors: Feng Yao Yu , Ong Say Leong , Hu Jiang Yong , Song Lian Fa , Tan Xiao Lan , Ng Wun Jern 
Published: April 2003

ABSTRACT

Cryptosporidium parvum
can be found in both source and drinking water and has been reported to cause serious waterborne outbreaks which threaten public health safety. The U.S. Environmental Protection Agency has developed method 1622 for detection of
Cryptosporidium
oocysts present in water. Method 1622 involves four key processing steps: filtration, immunomagnetic separation (IMS), fluorescent-antibody (FA) staining, and microscopic evaluation. The individual performance of each of these four steps was evaluated in this study. We found that the levels of recovery of
C. parvum
oocysts at the IMS-FA and FA staining stages were high, averaging more than 95%. In contrast, the level of recovery declined significantly, to 14.4%, when the filtration step was incorporated with tap water as a spiking medium. This observation suggested that a significant fraction of
C. parvum
oocysts was lost during the filtration step. When
C. parvum
oocysts were spiked into reclaimed water, tap water, microfiltration filtrate, and reservoir water, the highest mean level of recovery of (85.0% ± 5.2% [mean ± standard deviation]) was obtained for the relatively turbid reservoir water. Further studies indicated that it was the suspended particles present in the reservoir water that contributed to the enhanced
C. parvum
oocyst recovery. The levels of
C. parvum
oocyst recovery from spiked reservoir water with different turbidities indicated that particle size and concentration could affect oocyst recovery. Similar observations were also made when silica particles of different sizes and masses were added to seeded tap water. The optimal particle size was determined to be in the range from 5 to 40 μm, and the corresponding optimal concentration of suspended particles was 1.42 g for 10 liters of tap water.
Colonization of
Vitis vinifera
by a Green Fluorescence Protein-Labeled,
gfp
-Marked Strain of
Xylophilus ampelinus
, the Causal Agent of Bacterial Necrosis of Grapevine
Authors: Grall Sophie , Manceau Charles 
Published: April 2003

ABSTRACT

The dynamics of
Xylophilus ampelinus
were studied in
Vitis vinifera
cv. Ugni blanc using
gfp
-marked bacterial strains to evaluate the relative importance of epiphytic and endophytic phases of plant colonization in disease development. Currently, bacterial necrosis of grapevine is of economic importance in vineyards in three regions in France: the Cognac, Armagnac, and Die areas. This disease is responsible for progressive destruction of vine shoots, leading to their death. We constructed
gfp
-marked strains of the CFBP2098 strain of
X. ampelinus
for histological studies. We studied the colonization of young plants of
V. vinifera
cv. Ugni blanc by
X. ampelinus
after three types of artificial contamination in a growth chamber and in a greenhouse. (i) After wounding of the stem and inoculation, the bacteria progressed down to the crown through the xylem vessels, where they organized into biofilms. (ii) When the bacteria were forced into woody cuttings, they rarely colonized the emerging plantlets. Xylem vessels could play a key role in the multiplication and conservation of the bacteria, rather than being a route for plant colonization. (iii) When bacterial suspensions were sprayed onto the plants, bacteria progressed in two directions: both in emerging organs and down to the crown, thus displaying the importance of epiphytic colonization in disease development.
Nondigestible Oligosaccharides Enhance Bacterial Colonization Resistance against
Clostridium difficile
In Vitro
Authors: Hopkins Mark J. , Macfarlane George T. 
Published: April 2003

ABSTRACT

Clostridium difficile
is the principal etiologic agent of pseudomembranous colitis and is a major cause of nosocomial antibiotic-associated diarrhea. A limited degree of success in controlling
C. difficile
infection has been achieved by using probiotics; however, prebiotics can also be used to change bacterial community structure and metabolism in the large gut, although the effects of these carbohydrates on suppression of clostridial pathogens have not been well characterized. The aims of this study were to investigate the bifidogenicity of three nondigestible oligosaccharide (NDO) preparations in normal and antibiotic-treated fecal microbiotas in vitro and their abilities to increase barrier resistance against colonization by
C. difficile
by using cultural and molecular techniques. Fecal cultures from three healthy volunteers were challenged with a toxigenic strain of
C. difficile
, and molecular probes were used to monitor growth of the pathogen, together with growth of bifidobacterial and bacteroides populations, over a time course. Evidence of colonization resistance was assessed by determining viable bacterial counts, short-chain fatty acid formation, and cytotoxic activity. Chemostat studies were then performed to determine whether there was a direct correlation between bifidobacteria and
C. difficile
suppression. NDO were shown to stimulate bifidobacterial growth, and there were concomitant reductions in
C. difficile
populations. However, in the presence of clindamycin, activity against bifidobacteria was augmented in the presence of NDO, resulting in a further loss of colonization resistance. In the absence of clindamycin, NDO enhanced colonization resistance against
C. difficile
, although this could not be attributed to bifidobacterium-induced inhibitory phenomena.
Role of σBin Regulating the Compatible Solute Uptake Systems ofListeria monocytogenes: Osmotic Induction ofopuCIs σBDependent
Authors: Fraser Katy R. , Sue David , Wiedmann Martin , Boor Kathryn , O'Byrne Conor P. 
Published: April 2003

ABSTRACTThe regulation of the compatible solute transport systems inListeria monocytogenesby the stress-inducible sigma factor σBwas investigated. Using wild-type strain 10403S and an otherwise isogenic strain carrying an in-frame deletion insigB, we have examined the role of σBin regulating the ability of cells to utilize betaine and carnitine during growth under conditions of hyperosmotic stress. Cells lacking σBwere defective for the utilization of carnitine but retained the ability to utilize betaine as an osmoprotectant. When compatible solute transport studies were performed, the initial rates of uptake of both betaine and carnitine were found to be reduced in thesigBmutant; carnitine transport was almost abolished, whereas betaine transport was reduced to approximately 50% of that of the parent strain. Analysis of the cytoplasmic pools of compatible solutes during balanced growth revealed that both carnitine and betaine steady-state pools were reduced in thesigBmutant. Transcriptional reporter fusions to theopuC(which encodes an ABC carnitine transporter) andbetL(which encodes an a secondary betaine transporter) operons were generated by using a promoterless copy of thegusgene fromEscherichia coli. Measurement of β-glucuronidase activities directed byopuC-gusandbetL-gusrevealed that transcription ofopuCis largely σBdependent, consistent with the existence of a potential σBconsensus promoter motif upstream fromopuCA. The transcription ofbetLwas found to besigBindependent. Reverse transcriptase PCR experiments confirmed these data and indicated that the transcription of all three known compatible solute uptake systems (opuC,betL, andgbu), as well as a gene that is predicted to encode a compatible solute transporter subunit (lmo1421) is induced in response to elevated osmolarity. The osmotic induction ofopuCAandlmo1421 was found to be strongly σBdependent. Together these observations suggest that σBplays a major role in the regulation of carnitine utilization byL. monocytogenesbut is not essential for betaine utilization by this pathogen.