bluuebunny/crossref_metadata_2025 huggingface dataset:
Achieving Higher Pathological Complete Response Rates in HER-2–Positive Patients With Induction Chemotherapy Without Trastuzumab in Operable Breast Cancer
Authors: Penault-Llorca Frédérique , Abrial Catherine , Mouret-Reynier Marie-Ange , Raoelfils Inès , Durando Xavier , Leheurteur Marianne , Gimbergues Pierre , Tortochaux Jacques , Curé Hervé , Chollet Philippe
Published: April 2007

Recent trials of induction chemotherapy in bulky operable breast cancer have shown much higher pathological complete response (pCR) rates with trastuzumab-driven combinations. However, it is useful to take into account the specific chemosensitivity of HER-2–positive tumors. The aim of this study was to assess the pCR rate according to HER-2 status in response to chemotherapy, without an anti–HER-2 specific biological agent, in 710 operable breast cancer patients. Since 1982, these patients have been treated with several different neoadjuvant chemotherapy combinations. During this period, HER-2 overexpression was most often not assessed. Subsequently, we assessed HER-2 expression using archival paraffin-embedded tissue. A technically usable specimen was available for 413 of the 710 patients. Before treatment, 51 patients were HER-2 positive, 287 patients were HER-2 negative, and the results were inconclusive for 75 patients. Of these patients, a pCR in breast and nodes was obtained in 94 patients (14.3%), but this event was threefold more frequent for HER-2–positive patients (23.5%) than for HER-2–negative patients (7%).

The overall survival (OS) and disease-free survival (DFS) rates at 10 years were 66.6% and 57.4%, respectively. The DFS rate was, as expected, better for HER-2–negative patients, with HER-2 status assessed before as well as after chemotherapy. A significant difference was found for OS in favor of HER-2–negative patients only with postchemotherapy assessment of HER-2, a fact similar to our previous findings. Finally, there was a tendency toward a higher DFS rate for HER-2–positive patients who achieved a pCR compared with HER-2–positive patients who did not.
Neutropenic Events in Community Practices Reduced by First and Subsequent Cycle Pegfilgrastim Use
Authors: Ozer Howard , Mirtsching Barry , Rader Michael , Luedke Susan , Noga Stephen J. , Ding Beiying , Dreiling Lyndah
Published: April 2007

Learning Objectives

After completing this course, the reader will be able to: Describe the incidence of neutropenia-related endpoints when pegfilgrastim was administered in the first and subsequent chemotherapy cycles.Compare results with data reflecting current practice standards.Discuss the relevance of pegfilgrastim use beginning in the first cycle of chemotherapy.

CME Access and take the CME test online and receive 1 AMA PRA Category 1 Credit™ at CME.TheOncologist.com
Assessing Responsiveness of Cancer-Related Fatigue Instruments: Distribution-Based and Individual Anchor-Based Methods
Authors: Shun Shiow-Ching , Beck Susan L. , Pett Marjorie A. , Richardson Stephanie J.
Published: April 2007

Background.

The aims of the study were to examine the responsiveness of Chinese versions of the Cancer Fatigue Scale (C-CFS), the Schwartz Cancer Fatigue Scale-revised (C-SCFS-r), and the Fatigue Symptom Inventory (C-FSI) based on effect sizes and patient perceptions of change.

Method.

Convenience sampling was used to recruit subjects at a chemotherapy treatment center for outpatients in Taiwan. Data were collected twice: on the day cancer patients were receiving chemotherapy treatment (T1) and 2 days post-treatment (T2).

Results.

Questionnaires were complete at T2 by 148 subjects (60.9%). The differences between T1 and T2 were statistically significant for all three scales. The effect sizes, ranging from a medium to a large change for the C-CFS, C-SCFS-r, and C-FSI were reported based on four groups (self-reported no increase, small increase, moderate increase, and large increase). Generalized estimating equations were used to compare the fatigue scores based on the four groups by controlling for the fatigue level at baseline and the time effect. The results indicate that the fatigue scores after 2 days of treatment in the three “change” groups were statistically significantly larger than in the “no increase” group. In addition, the pretreatment fatigue level in the “large increase” group was significantly higher than in the other three groups.

Conclusion.

Results indicate that the three scales are sensitive to change over 2 days. However, the three scales may not effectively discriminate between a moderate and large change. Therefore, further testing on cancer patients with severe fatigue to examine responsiveness to detect minimal important differences for the three scales is recommended.
Local cytokine levels associated with delayed-type hypersensitivity responses: modulation by gender, ovariectomy, and estrogen replacement
Authors: Ma Lisa J , Guzmán Esther A , DeGuzman Ariel , Muller H Konrad , Walker Ameae M , Owen Laurie B
Published: April 2007

It is well established that females mount stronger immune responses than males, but only very little is understood about the underlying mechanisms. We have analyzed local cytokine differences among intact females, those that had been ovariectomized (OVX), those receiving estrogen replacement after OVX, and males, both before and after production of delayed-type hypersensitivity (DTH) responses. We report confirmation of a much larger DTH response in females versus males. However, OVX resulted in an even larger response, while estrogen replacement resulted in a smaller response when compared with intact females. In animals exposed for the first time to an antigen (without a DTH response), OVX increased interleukin-6 (IL-6) and estrogen replacement after OVX suppressed IL-6. Of the cytokines that differed between males and females exposed for the first time to an antigen, only IL-6 was higher in females versus males when exposure to antigen occurred for the second time (when the DTH response occurs). Analysis of cytokines with OVX and estrogen replacement after a second exposure to antigen showed that IL-6 did not significantly change. Levels of IL-4; Regulated upon Activation, Normal T-cell Expressed; and Secreted; and thrombopoietin, however, correlated with the DTH response, suggesting direct or indirect positive regulation by estrogen. These results suggest an important role for both IL-6 and IL-4 in determining the degree of DTH response, with IL-6 (which appears negatively regulated by estrogen) increasing and IL-4 (which appears positively regulated by estrogen) decreasing the response. The results further suggest that IL-6 may play a role in predisposing to a larger DTH response, while IL-4 levels seem more important during an active response.
The emerging role of FOXO transcription factors in pancreatic β cells
Authors: Glauser Dominique A , Schlegel Werner
Published: April 2007

FOXO transcription factors critically control fundamental cellular processes, including metabolism, cell differentiation, cell cycle arrest, DNA repair, and other reactions to cellular stress. FOXO factors sense the balance between stimuli promoting growth and differentiation versus stress stimuli signaling damage. Integrated through the FOXO system, these divergent stimuli decide on cell fate, a choice between proliferation, differentiation, or apoptosis. In pancreatic β cells, most recent evidence highlights complex FOXO-dependent responses to glucose, insulin, or other growth factors, which include regulatory feedback. In the short term, FOXO-dependent mechanisms help β cells to accomplish their endocrine function, and may increase their resistance to oxidative stress due to transient hyperglycemia. In the long term, FOXO-dependent responses lead to the adaptation of β cell mass, conditioning the future ability of the organism to produce insulin and cope with changes in fuel abundance. FOXO emerges as a key factor for the maintenance of a functional endocrine pancreas and represents an interesting element in the development of therapeutic approaches to treat diabetes. This review on the role of FOXO transcription factors in pancreatic β cells has three parts. In Part I, FOXO transcription factors will be presented in general: structure, molecular mechanisms of regulation, cellular functions, and physiological roles. Part II will focus on specific data about FOXO factors in pancreatic β cells. Lastly in Part III, it will be attempted to combine general and β cell-specific knowledge with the aim to envisage globally the role of FOXO factors in β cell-linked physiology and disease.
Aggregate size and behaviour of self-compacting concrete
Authors: Shobha M. , Harish Mohan D. , Raju P. S. N.
Published: April 2007

One reason why concrete is a successful and commonly used building material is that it can be cast into any structural form required, taking advantage of its fluid behaviour at early ages. However, there is a limit to the fluid behaviour of normal fresh concrete, which cannot, on its own, flow past obstructions, through nooks or into corners. Thorough compaction, using vibration, is normally essential for achieving the required strength and durability of concrete. As concrete is produced and placed at construction sites, under conditions far from ideal, it often ends up with unpleasant results such as rock pockets, sand streaks, and a host of workmanship-related problems. The costs of remediation and making good may be high, or the durability may be compromised. Self-compacting concrete (SCC) may provide a solution to these problems. As the name signifies, it is able to compact itself without any additional vibrations or compactive effort. Consequently the danger of vibration- and noise-related health issues is minimised, and the construction process is safer and more productive. There have been several studies of SCC and the use of admixtures in it. Of these, the partial replacement of sand with ground granulated blastfurnace slag has gained considerable impetus. The main objective of this paper is to investigate the effect of maximum size of aggregate on the fresh and hardened properties of SCC. The behaviour of various mix proportions of SCC was investigated, and the variations in the compressive strength and split tensile strength of standard cubes and cylinders were studied. Ultrasonic pulse velocity was also studied to assess the quality of SCC with different maximum sizes of aggregates.
Use of sewage sludge ash as mineral admixture in mortars
Authors: Coutand M. , Cyr M. , Clastres P.
Published: April 2007

This paper presents the physical, chemical and mechanical characteristics of sewage sludge ash (SSA), in order to compare its properties with the standard requirements for coal fly ash (FA). It also provides an evaluation of its environmental behaviour when used as a mineral admixture in cement-based materials. Results show that, compared with FA, SSA has a high amount of calcium and phosphorus but a relatively low fraction of silica. SSA is composed of irregular grains having a high specific surface area and thus leading to a high water demand. The high water absorption of SSA requires an increase of the water–binder ratio of mortars, or the use of a water-reducing admixture. The strength activity index (25% replacement of cement) reaches more than 90% after 28 days, showing a long-term positive effect, which might be related to the pozzolanic activity. The amount of leached elements of SSA mortars is slightly higher than for the reference mortar without residue, but it remains within the same order of magnitude. The comparison of the characteristics of SSA with the FA specifications given by American and European standards shows that SSA does not satisfy the requirements to be directly considered as a mineral admixture. Nevertheless, these preliminary results show that SSA could be classified between filler and pozzolanic admixtures. Thus SSA may not necessarily be excluded from use in cement-based materials.
Periopathogenic Bacteria in Persistent Periapical Lesions: An In Vivo Prospective Study
Authors: Lin Shaul , Sela Galit , Sprecher Hannah
Published: April 2007

Background: The aim of this in vivo prospective study was to detect the presence of periopathogenic bacteria in persistent periapical lesions and to compare the reliability of two different methods: anaerobic culture and the DNA hybridization technique.

Methods: Samples were obtained from 24 patients with persistent periapical lesions referred for surgical endodontic treatment. A sterile paper point was inserted into the periapical lesion for 10 seconds. The point was stored in sterile transfer tubes and analyzed by DNA hybridization. Tissue samples were transported in transfer medium and analyzed further using anaerobic culture.

Results: At least one periodontal pathogenic bacterium was found in seven of 24 cases. Bacterial species present were Treponema denticola (three cases), Porphyromonas gingivalis (three cases), Tannerella forsythensis (four cases), Prevotella intermedia (one case), and Actinobacillus actinomycetemcomitans (three cases). No particular signs or symptoms were associated with the presence of these bacterial species. Anaerobic culture failed to identify any of the periopathogenic bacteria.

Conclusions: Periodontal pathogenic bacterial DNA can be detected in persistent periapical lesions. Anaerobic cultures failed to detect the periodontal pathogenic bacteria in positive hybridization assays, suggesting that standard culture methods lack sensitivity or that hybridization assays are flawed with low specificity. The clinical significance of the presence of bacterial DNA in persistent periapical lesions remains to be determined.
Influence of Different Implant Surfaces on Peri‐Implant Osteogenesis: Histomorphometric Analysis in Sheep
Authors: Franchi Marco , Bacchelli Beatrice , Giavaresi Gianluca , De Pasquale Viviana , Martini Désirée , Fini Milena , Giardino Roberto , Ruggeri Alessandro
Published: April 2007

Background: The present study investigated peri‐implant osteogenesis and implant biologic fixation in different zirconia sandblasted endosseous titanium surfaces (SLA‐60 and SLA‐120) and a turned titanium surface (T) 2 and 4 weeks after surgery.

Methods: Seventy‐two implant screws were implanted in tibia of six sheep. Histologic sections of implants (2 and 4 weeks after surgery) were analyzed with light microscopy for histomorphometric analysis of bone‐to‐implant contact (BIC), bone ingrowth (BI), and bone surface (BS/BV). Histologic blocks were used to perform bone microhardness studies next to the implants. Some implants were also observed with scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

Results: In general, the highest values of BIC, BI, BS/BV, and Vickers hardness number (HV) were measured in SLA‐60 samples, followed by SLA‐120 and T implants. Two weeks after surgery, all the implants appeared biologically fixed by a newly formed woven bone arranged in thin bone trabeculae and filling the gap between implant and host bone. Four weeks after implantation, the thickness of the woven bone trabeculae had increased, especially around the SLA‐60 and SLA‐120 implants by a gradual deposition of parallel‐fiber bone.

Conclusions: Our results suggest that, in the early period of peri‐implant healing, the implant surface morphology that seemed to influence the increase of peri‐implant osteogenesis, bone turnover, and peri‐implant bone maturation was SLA‐60. We suggest that this surface, characterized by moderately deep titanium cavities very similar to the osteocyte lacunae, could act as a microscopic scaffold for mesenchymal and/or osteoblast‐like cells adhesion.
Evaluation of the Incidence of Preterm Low Birth Weight in Patients Undergoing Periodontal Therapy
Authors: Gazolla Catia M. , Ribeiro Adair , Moysés Marcos R. , Oliveira Luiz A.M. , Pereira Luciano J. , Sallum Antônio W.
Published: April 2007

Background: Preterm low birth weight was reported to be related to periodontal infections that might influence the fetus–placenta complex. The aim of this study was to provide periodontal treatment for pregnant women and to evaluate if this treatment can interfere with pregnancy duration and weight of the newborn.

Methods: The sample consisted of 450 pregnant women who were under prenatal care at a polyclinic in Três Corações, Brazil. Women with risk factors, such as systemic alterations (ischemic cardiopathy, hypertension, tuberculosis, diabetes, cancer, anemia, seizure, psychopathology, urinary tract infection, sexually transmitted diseases, asthma, and human immunodeficiency virus), and/or users of alcohol, tobacco, and drugs were excluded from the study. Data related to age, socioeconomic level, race, marital status, number of previous pregnancies, and previous preterm delivery also were evaluated. Initially, the sample was divided into two groups: 122 healthy patients (group 1) and 328 patients with periodontal disease (group 2). In group 2, 266 patients underwent treatment and 62 patients dropped out. After mothers gave birth, pregnancy duration and the weight of all infants were analyzed and recorded.

Results: There was no statistical difference between the healthy and treated groups. However, there was a difference in the non‐treated group, with a 79% incidence of preterm low birth weight. Educational level, previous preterm birth, and periodontal disease were related significantly to preterm delivery (P <0.001).

Conclusion: Periodontal disease was related significantly to preterm low birth weight.
Combined Use of Platelet‐Rich Plasma and Bone Grafting With or Without Guided Tissue Regeneration in the Treatment of Anterior Interproximal Defects
Authors: Yassibag‐Berkman Zeynep , Tuncer Ozen , Subasioglu Turkan , Kantarci Alpdogan
Published: April 2007

Background: The aim of periodontal therapy is to prevent tissue destruction while achieving the regeneration of damaged tissues. Platelet‐rich plasma (PRP) is used to generate new bone, periodontal ligament, and new attachment with a strategy based on the modulation and enhancement of wound healing through an autologous source for growth factors obtained from the patient's own blood. The purpose of the present study was to evaluate the efficacy of PRP when used in combination with β‐tricalcium phosphate (β‐TCP) alloplastic graft material and collagen barrier membrane in the treatment of anterior interproximal intrabony defects.

Methods: Thirty interproximal intrabony defects in 25 systemically healthy patients were selected for the study. Defects were distributed randomly and equally into three groups: graft alone (β‐TCP), graft + PRP, and graft + PRP + membrane. The plaque index, gingival index, periodontal probing depth, relative attachment level, transgingival probing measurement, and radiographic analyses were performed at baseline and repeated after 6, 9, and 12 months.

Results: At the end of 12 months, relative attachment gain was 2.4, 2.1, and 2.5 mm in the three treatment groups, respectively. No statistically significant differences in clinical and radiographic measurements were observed among the groups.

Conclusions: All options were effective in the treatment of anterior interproximal intrabony defects. The results also suggested that PRP added no clinical benefit to β‐TCP alloplastic graft material used alone or in combination with GTR.
Therapeutic Efficacy of Cold Therapy After Intraoral Surgical Procedures: A Literature Review
Authors: Greenstein Gary
Published: April 2007

Background: Cryotherapy (e.g., ice pack) is prescribed commonly after oral surgery to inhibit swelling and discomfort. However, there is a dearth of data concerning various aspects of cold therapy: optimal delivery mode, best interval for application (time on/time off), and total duration of treatment to attain desired clinical outcomes.

Methods: The literature was searched for clinical trials that assessed the benefits of cryotherapy after oral surgical procedures. In addition, other studies were reviewed that evaluated physiological responses to cold therapy.

Results: To inhibit signs of inflammation and achieve beneficial results with cryotherapy, skin temperature (normally 33°C) needs to be reduced to 10°C to 15°C. Cold therapy usually decreased skin temperature to 10°C to 15°C within 10 to 20 minutes. Physiological studies indicated cryotherapy resulted in vasoconstriction, reduction of edema, and diminished pain perception. Various methods can be used to lower tissue temperature. Ice or gel packs are easy and efficient techniques to cool tissues. Seven studies published in English were found that addressed the use of cryotherapy after oral surgical procedures. Five investigations demonstrated no clinical benefits from cold therapy, and two studies indicated that cryotherapy reduced post‐surgical edema and pain. The time interval for cold applications varied in different studies (10 minutes to continuous for hours). There seemed to be consensus among clinicians that cryotherapy should be applied for 10 to 20 minutes followed by a rest period. The duration of therapy ranged from 2 to 72 hours. No clinical trials were conducted to determine the optimal interval of cold application (time on/off) or extended duration of cryotherapy after surgical procedures to attain the best therapeutic benefits.

Conclusions: Ice applied after surgical procedures may reduce swelling and discomfort. However, data from studies regarding the benefits of ice therapy after oral surgery are inconclusive. To resolve this ambiguity, additional clinical trials need to be conducted.
Socioeconomic and Sociodemographic Variables Associated With Oral Hygiene Status in Mexican Schoolchildren Aged 6 to 12 Years
Authors: Villalobos‐Rodelo Juan J. , Medina‐Solís Carlo E. , Maupomé Gerardo , Vallejos‐Sánchez Ana A. , Lau‐Rojo Laura , de León‐Viedas Marco V. Ponce
Published: April 2007

Background: The purpose of this study was to identify the socioeconomic and sociodemographic variables associated with oral hygiene status in schoolchildren aged 6 to 12 years in Navolato, Sinaloa, Mexico.

Methods: A cross‐sectional study was carried out in 3,048 schoolchildren. A questionnaire was used to determine socioeconomic and sociodemographic variables, and a clinical oral examination was carried out to establish oral hygiene status. The “plaque” component of the simplified oral hygiene index (S‐OHI) was the criterion used to determine oral hygiene status in children. Using principal component analysis, five socioeconomic factors were streamlined to one principal component to determine the individual socioeconomic level. Data were analyzed with non‐parametric tests and multivariable logistic regression.

Results: The population included 1,456 boys and 1,592 girls. The mean value for S‐OHI was 1.10 ± 0.34. The largest percentage (50.8%) of the S‐OHI scores ranged between 0 and 1. In the multivariate model, younger age, male gender, and lower toothbrushing frequency (P <0.05) were associated with poor oral hygiene. Children with better socioeconomic status had better oral hygiene (P <0.05).

Conclusions: Most children (∼60%) had an acceptable level of oral hygiene. Diverse variables were associated with oral hygiene in these Mexican children, highlighting a gradient distribution throughout the socioeconomic spectrum. It is necessary to implement strategies that would help to diminish the disparities observed across diverse socioeconomic groups.
Genetic Influences of Adiponectin on Insulin Resistance, Type 2 Diabetes, and Cardiovascular Disease
Authors: Menzaghi Claudia , Trischitta Vincenzo , Doria Alessandro
Published: April 2007

Recent evidence points to molecules secreted by the adipose tissue, or adipokines, as possible links between increased adipose mass and metabolic abnormalities. Among these molecules, adiponectin has drawn much attention because of its insulin-sensitizing and antiatherogenic actions, suggesting that genetic deficits in its production or action may contribute to insulin resistance and coronary artery disease (CAD). A meta-analysis of the data published to date supports this hypothesis. Two independent effects, corresponding to the two linkage disequilibrium blocks that can be identified at the adiponectin locus, appear to be present. In the 5′ block, the g.−11391G→A variant has a modest but significant effect on adiponectinemia, with a mean difference between genotypes of 1.64 ng/ml (95% CI 0.88–2.41). In the 3′ block, the g.+276G→T variant is a strong determinant of insulin resistance and CAD, with minor allele homozygotes having a lower homeostasis model assessment of insulin resistance (HOMAIR) index (−0.36 units, 95% CI 0.24–0.47) and a lower cardiovascular risk (odds ratio 0.55, 95% CI 0.38–0.80) than carriers of other genotypes. No consistent effect on BMI or risk of type 2 diabetes is evident. Polymorphisms in the genes coding for the adiponectin receptors may also influence the risk of insulin resistance and CAD, but data on these genes are still too sparse to draw firm conclusions. In summary, the studies published to date indicate that polymorphisms at the adiponectin locus are indeed predictors of circulating adiponectin levels, insulin sensitivity, and atherosclerosis, highlighting the pivotal role of this adipokine in the modulation of metabolism and atherogenesis.
Variants in ARHGEF11, a Candidate Gene for the Linkage to Type 2 Diabetes on Chromosome 1q, Are Nominally Associated With Insulin Resistance and Type 2 Diabetes in Pima Indians
Authors: Ma Lijun , Hanson Robert L. , Que Lorem N. , Cali Anna M.G. , Fu Mao , Mack Janel L. , Infante Aniello M. , Kobes Sayuko ,   the International Type 2 Diabetes 1q Consortium, Bogardus Clifton , Shuldiner Alan R. , Baier Leslie J.
Published: April 2007

A prior genome-wide linkage scan in Pima Indians indicated a young-onset (aged <45 years) type 2 diabetes susceptibility locus on chromosome 1q21-q23. ARHGEF11, which encodes the Rho guanine nucleotide exchange factor 11, was analyzed as a positional candidate gene for this linkage because this protein may stimulate Rho-dependent signals, such as the insulin signaling cascade. The ARHGEF11 gene, and two adjacent genes NTRK1 and INSRR, were sequenced in 24 Pima Indians who were not first-degree relatives. Sequencing of the coding regions, 5′ and 3′ untranslated regions and putative promoter regions of these genes, identified 28 variants in ARHGEF11, 11 variants in NTRK1, and 8 variants in INSSR. These 47 variants, as well as 84 additional public database variants within/between these genes, were genotyped for association analysis in the same group of Pima Indians who had participated in the linkage study (n = 1,228). An R1467H in ARHGEF11, and several additional noncoding variants that were in high linkage disequilibrium with this variant, were nominally associated with young-onset type 2 diabetes (P = 0.01; odds ratio 3.39) after adjusting for sex, family membership, and Pima heritage. The risk allele H had a frequency of 0.10. In a subgroup of 262 nondiabetic, full-heritage Pima Indians who had undergone detailed metabolic testing, the risk allele H also was associated with a lower mean insulin-mediated glucose disposal rate and a lower mean nonoxidative glucose storage rate after adjusting for age, sex, nuclear family membership, and percentage of body fat (P ≤ 0.01). These findings suggest that variation within ARHGEF11 nominally increases risk of type 2 diabetes, possibly as a result of increased insulin resistance.
Effects of Insulin Replacements, Inhibitors of Angiotensin, and PKCβ's Actions to Normalize Cardiac Gene Expression and Fuel Metabolism in Diabetic Rats
Authors: Arikawa Emi , Ma Ronald C.W. , Isshiki Keiji , Luptak Ivan , He Zhiheng , Yasuda Yutaka , Maeno Yasuhiro , Patti Mary Elizabeth , Weir Gordon C. , Harris Robert A. , Zammit Victor A. , Tian Rong , King George L.
Published: April 2007

High-density oligonucleotide arrays were used to compare gene expression of rat hearts from control, untreated diabetic, and diabetic groups treated with islet cell transplantation (ICT), protein kinase C (PKC)β inhibitor ruboxistaurin, or ACE inhibitor captopril. Among the 376 genes that were differentially expressed between untreated diabetic and control hearts included key metabolic enzymes that account for the decreased glucose and increased free fatty acid utilization in the diabetic heart. ICT or insulin replacements reversed these gene changes with normalization of hyperglycemia, dyslipidemia, and cardiac PKC activation in diabetic rats. Surprisingly, both ruboxistaurin and ACE inhibitors improved the metabolic gene profile (confirmed by real-time RT-PCR and protein analysis) and ameliorated PKC activity in diabetic hearts without altering circulating metabolites. Functional assessments using Langendorff preparations and 13C nuclear magnetic resonance spectroscopy showed a 36% decrease in glucose utilization and an impairment in diastolic function in diabetic rat hearts, which were normalized by all three treatments. In cardiomyocytes, PKC inhibition attenuated fatty acid–induced increases in the metabolic genes PDK4 and UCP3 and also prevented fatty acid–mediated inhibition of basal and insulin-stimulated glucose oxidation. Thus, PKCβ or ACE inhibitors may ameliorate cardiac metabolism and function in diabetes partly by normalization of fuel metabolic gene expression directly in the myocardium.
Dominant-Negative Effects of a Novel Mutated Ins2 Allele Causes Early-Onset Diabetes and Severe β-Cell Loss in Munich Ins2C95S Mutant Mice
Authors: Herbach Nadja , Rathkolb Birgit , Kemter Elisabeth , Pichl Lisa , Klaften Matthias , de Angelis Martin Hrabé , Halban Philippe A. , Wolf Eckhard , Aigner Bernhard , Wanke Ruediger
Published: April 2007

The novel diabetic mouse model Munich Ins2C95S was discovered within the Munich N-ethyl-N-nitrosourea mouse mutagenesis screen. These mice exhibit a T→A transversion in the insulin 2 (Ins2) gene at nucleotide position 1903 in exon 3, which leads to the amino acid exchange C95S and loss of the A6-A11 intrachain disulfide bond. From 1 month of age onwards, blood glucose levels of heterozygous Munich Ins2C95S mutant mice were significantly increased compared with controls. The fasted and postprandial serum insulin levels of the heterozygous mutants were indistinguishable from those of wild-type littermates. However, serum insulin levels after glucose challenge, pancreatic insulin content, and homeostasis model assessment (HOMA) β-cell indices of heterozygous mutants were significantly lower than those of wild-type littermates. The initial blood glucose decrease during an insulin tolerance test was lower and HOMA insulin resistance indices were significantly higher in mutant mice, indicating the development of insulin resistance in mutant mice. The total islet volume, the volume density of β-cells in the islets, and the total β-cell volume of heterozygous male mutants was significantly reduced compared with wild-type mice. Electron microscopy of the β-cells of male mutants showed virtually no secretory insulin granules, the endoplasmic reticulum was severely enlarged, and mitochondria appeared swollen. Thus, Munich Ins2C95S mutant mice are considered a valuable model to study the mechanisms of β-cell dysfunction and death during the development of diabetes.
Impaired Mitochondrial Substrate Oxidation in Muscle of Insulin-Resistant Offspring of Type 2 Diabetic Patients
Authors: Befroy Douglas E. , Petersen Kitt Falk , Dufour Sylvie , Mason Graeme F. , de Graaf Robin A. , Rothman Douglas L. , Shulman Gerald I.
Published: April 2007

Insulin resistance is the best predictor for the development of diabetes in offspring of type 2 diabetic patients, but the mechanism responsible for it remains unknown. Recent studies have demonstrated increased intramyocellular lipid, decreased mitochondrial ATP synthesis, and decreased mitochondrial density in the muscle of lean, insulin-resistant offspring of type 2 diabetic patients. These data suggest an important role for mitochondrial dysfunction in the pathogenesis of type 2 diabetes. To further explore this hypothesis, we assessed rates of substrate oxidation in the muscle of these same individuals using 13C magnetic resonance spectroscopy (MRS). Young, lean, insulin-resistant offspring of type 2 diabetic patients and insulin-sensitive control subjects underwent 13C MRS studies to noninvasively assess rates of substrate oxidation in muscle by monitoring the incorporation of 13C label into C4 glutamate during a [2-13C]acetate infusion. Using this approach, we found that rates of muscle mitochondrial substrate oxidation were decreased by 30% in lean, insulin-resistant offspring (59.8 ± 5.1 nmol · g−1 · min−1, P = 0.02) compared with insulin-sensitive control subjects (96.1 ± 16.3 nmol · g−1 · min−1). These data support the hypothesis that insulin resistance in skeletal muscle of insulin-resistant offspring is associated with dysregulation of intramyocellular fatty acid metabolism, possibly because of an inherited defect in the activity of mitochondrial oxidative phosphorylation.
Novel Insights Into the Regulation of the Bound and Diffusible Glucokinase in MIN6 β-Cells
Authors: Baltrusch Simone , Lenzen Sigurd
Published: April 2007

A stable MIN6 β-cell clone overexpressing glucokinase as an enhanced cyan fluorescent protein (ECFP) fusion construct was generated for analysis of glucokinase regulation in these glucose-responsive insulin-secreting cells. A higher glucokinase enzyme activity accompanied by an improved glucose-induced insulin secretion indicated the integration of ECFP-glucokinase into the functional pool of glucokinase protein in MIN6-ECFP-glucokinase cells. Fluorescence recovery after photobleaching experiments of MIN6-ECFP-glucokinase cells and photoactivation of a transiently transfected photoswitchable cyan fluorescent protein (PS-CFP)-glucokinase construct in MIN6 cells indicate a higher motility of the diffusible glucokinase fraction at high glucose concentrations. In agreement with previous studies, we observed significant binding of ECFP-glucokinase to insulin secretory granules. Using fluorescence lifetime imaging, we obtained evidence for an association between glucokinase and α-tubulin in MIN6-ECFP-glucokinase cells. Furthermore, immunohistochemistry and fluorescence resonance energy transfer analysis by acceptor photobleaching showed distinct association between endogenous glucokinase and α-tubulin as well as β-tubulin in MIN6 cells. Interestingly, glucokinase was also colocalized with kinesin, a motor protein involved in insulin secretory granule movement. Therefore, we suggest a role of a bound glucokinase protein fraction in the regulation of insulin granule movement along tubulin filaments.
Ca2+/Calmodulin-Dependent Protein Kinase Kinase-α Regulates Skeletal Muscle Glucose Uptake Independent of AMP-Activated Protein Kinase and Akt Activation
Authors: Witczak Carol A. , Fujii Nobuharu , Hirshman Michael F. , Goodyear Laurie J.
Published: April 2007

Studies in nonmuscle cells have demonstrated that Ca2+/calmodulin-dependent protein kinase kinases (CaMKKs) are upstream regulators of AMP-activated protein kinase (AMPK) and Akt. In skeletal muscle, activation of AMPK and Akt has been implicated in the regulation of glucose uptake. The objective of this study was to determine whether CaMKKα regulates skeletal muscle glucose uptake, and whether it is dependent on AMPK and/or Akt activation. Expression vectors containing constitutively active CaMKKα (caCaMKKα) or empty vector were transfected into mouse muscles by in vivo electroporation. After 2 weeks, caCaMKKα was robustly expressed and increased CaMKI (Thr177/180) phosphorylation, a known CaMKK substrate. In muscles from wild-type mice, caCaMKKα increased in vivo [3H]-2-deoxyglucose uptake 2.5-fold and AMPKα1 and -α2 activities 2.5-fold. However, in muscles from AMPKα2 inactive mice (AMPKα2i), caCaMKKα did not increase AMPKα1 or -α2 activities, but it did increase glucose uptake 2.5-fold, demonstrating that caCaMKKα stimulates glucose uptake independent of AMPK. Akt (Thr308) phosphorylation was not altered by CaMKKα, and caCaMKKα plus insulin stimulation did not increase the insulin-induced phosphorylation of Akt (Thr308). These results suggest that caCaMKKα stimulates glucose uptake via insulin-independent signaling mechanisms. To assess the role of CaMKK in contraction-stimulated glucose uptake, isolated muscles were treated with or without the CaMKK inhibitor STO-609 and then electrically stimulated to contract. Contraction increased glucose uptake 3.5-fold in muscles from both wild-type and AMPKα2i mice, but STO-609 significantly decreased glucose uptake (∼24%) only in AMPKα2i mice. Collectively, these results implicate CaMKKα in the regulation of skeletal muscle glucose uptake independent of AMPK and Akt activation.
α1-Antitrypsin Protects β-Cells From Apoptosis
Authors: Zhang Bin , Lu Yuanqing , Campbell-Thompson Martha , Spencer Terry , Wasserfall Clive , Atkinson Mark , Song Sihong
Published: April 2007

β-Cell apoptosis appears to represent a key event in the pathogenesis of type 1 diabetes. Previous studies have demonstrated that administration of the serine proteinase inhibitor α1-antitrypsin (AAT) prevents type 1 diabetes development in NOD mice and prolongs islet allograft survival in rodents; yet the mechanisms underlying this therapeutic benefit remain largely unclear. Herein we describe novel findings indicating that AAT significantly reduces cytokine- and streptozotocin (STZ)-induced β-cell apoptosis. Specifically, strong antiapoptotic activities for AAT (Prolastin, human) were observed when murine insulinoma cells (MIN6) were exposed to tumor necrosis factor-α. In a second model system involving STZ-induced β-cell apoptosis, treatment of MIN6 cells with AAT similarly induced a significant increase in cellular viability and a reduction in apoptosis. Importantly, in both model systems, treatment with AAT completely abolished induced caspase-3 activity. In terms of its activities in vivo, treatment of C57BL/6 mice with AAT prevented STZ-induced diabetes and, in agreement with the in vitro analyses, supported the concept of a mechanism involving the disruption of β-cell apoptosis. These results propose a novel biological function for this molecule and suggest it may represent an effective candidate for attempts seeking to prevent or reverse type 1 diabetes.
Control of β-Cell Differentiation by the Pancreatic Mesenchyme
Authors: Attali Myriam , Stetsyuk Volodymyr , Basmaciogullari Annie , Aiello Virginie , Zanta-Boussif Maria A. , Duvillie Bertrand , Scharfmann Raphael
Published: April 2007

The importance of mesenchymal-epithelial interactions for normal development of the pancreas was recognized in the early 1960s, and mesenchymal signals have been shown to control the proliferation of early pancreatic progenitor cells. The mechanisms by which the mesenchyme coordinates cell proliferation and differentiation to produce the normal number of differentiated pancreatic cells are not fully understood. Here, we demonstrate that the mesenchyme positively controls the final number of β-cells that develop from early pancreatic progenitor cells. In vitro, the number of β-cells that developed from rat embryonic pancreatic epithelia was larger in cultures with mesenchyme than without mesenchyme. The effect of mesenchyme was not due to an increase in β-cell proliferation but was due to increased proliferation of early pancreatic duodenal homeobox-1 (PDX1)–positive progenitor cells, as confirmed by bromodeoxyuridine incorporation. Consequently, the window during which early PDX1+ pancreatic progenitor cells differentiated into endocrine progenitor cells expressing Ngn3 was extended. Fibroblast growth factor 10 mimicked mesenchyme effects on proliferation of early PDX1+ progenitor cells and induction of Ngn3 expression. Taken together, our results indicate that expansion of early PDX1+ pancreatic progenitor cells represents a way to increase the final number of β-cells developing from early embryonic pancreas.
Evidence That Rho Guanine Nucleotide Exchange Factor 11 (ARHGEF11) on 1q21 is a Type 2 Diabetes Susceptibility Gene in the Old Order Amish
Authors: Fu Mao , Sabra Mona M. , Damcott Coleen , Pollin Toni I. , Ma Lijun , Ott Sandra , Shelton John C. , Shi Xiaolian , Reinhart Laurie , O'Connell Jeffrey , Mitchell Braxton D. , Baier Leslie J. , Shuldiner Alan R.
Published: April 2007

Rho guanine nucleotide exchange factor 11 (ARHGEF11), located on chromosome 1q21, is involved in G protein signaling and is a pathway known to play a role in both insulin secretion and action. We genotyped 52 single nucleotide polymorphims (SNPs) in ARHGEF11 and compared the genotype frequencies of subjects with type 2 diabetes (n = 145) or type 2 diabetes/impaired glucose tolerance (IGT) (n = 293) with those of control subjects with normal glucose tolerance (NGT) (n = 358). Thirty SNPs, spanning the entire gene, were significantly associated with type 2 diabetes or type 2 diabetes/IGT. The most significantly associated SNP was rs6427340 (intron 2), in which the less common allele was the risk allele (odds ratio [OR] 1.82 [95% CI 1.20–2.70], P = 0.005 for type 2 diabetes vs. NGT and 1.79 [1.27–2.50], P = 0.0008 for type 2 diabetes/IGT vs. NGT). In an expanded set of nondiabetic subjects (n = 754), most of the type 2 diabetes–and IGT-associated SNPs were significantly associated with glucose levels during an oral glucose tolerance test, with the same SNP (rs6427340) showing the most significant associations (P = 0.007). All type 2 diabetes–and IGT-associated SNPs were in high linkage disequilibrium and constitute a single 133-kb haplotype block. These results, coupled with similar findings in Pima Indians, suggest that sequence variation in ARHGEF11 may influence risk of type 2 diabetes.
Glial Cell–Derived Cytokines Attenuate the Breakdown of Vascular Integrity in Diabetic Retinopathy
Authors: Nishikiori Nami , Osanai Makoto , Chiba Hideki , Kojima Takashi , Mitamura Yoshinori , Ohguro Hiroshi , Sawada Norimasa
Published: April 2007

The blood-retinal barrier (BRB) is a biological unit comprised of specialized capillary endothelial cells firmly connected by intercellular tight junctions and endothelium-surrounding glial cells. The BRB is essential for maintaining the retinal microenvironment and low permeability and is compromised in an early phase during the progression of diabetic retinopathy. Here, we demonstrate that retinoic acid receptor (RAR)α stimulants preferentially act on glial cells rather than endothelial cells, resulting in the enhanced expression of glial cell line–derived neurotrophic factor (GDNF) through recruitment of the RARα-driven trans-acting coactivator to the 5′-flanking region of the gene promoter. Conversely, RARα decreases expression of vascular endothelial growth factor (VEGF)/vascular permeability factor. These gene expression alterations causally limit vascular permeability by modulating the tight junction function of capillary endothelium in a paracrine manner in vitro. The phenotypic transformation of glial cells mediated by RARα is sufficient for significant reductions of vascular leakage in the diabetic retina, suggesting that RARα antagonizes the loss of tight junction integrity induced by diabetes. These findings reveal that glial cell–derived cytokines such as GDNF and VEGF regulate BRB function, implying that the glial cell can be a possible therapeutic target in diabetic retinopathy.
Genetic Deletion of Trb3, the Mammalian Drosophila tribbles Homolog, Displays Normal Hepatic Insulin Signaling and Glucose Homeostasis
Authors: Okamoto Haruka , Latres Esther , Liu Rong , Thabet Karen , Murphy Andrew , Valenzeula David , Yancopoulos George D. , Stitt Trevor N. , Glass David J. , Sleeman Mark W.
Published: April 2007

Trb3, a mammalian homolog of Drosophila tribbles, was proposed as a suppressor of Akt activity, predominantly in conditions of fasting and diabetes. Given these prior studies, we sought to determine whether Trb3 plays a major role in modulating hepatic insulin sensitivity. To answer this question, we produced mice in which a lacZ reporter was knocked into the locus containing the gene Trib3, resulting in a Trib3 null animal. Trib3 expression analyses demonstrated that the Trib3 is expressed in liver, adipose tissues, heart, kidney, lung, skin, small intestine, stomach, and denervated, but not normal, skeletal muscle. Trib3−/− mice are essentially identical to their wild-type littermates in overall appearance and body composition. Phenotypic analysis of Trib3−/− mice did not detect any alteration in serum glucose, insulin, or lipid levels; glucose or insulin tolerance; or energy metabolism. Studies in Trib3−/− hepatocytes revealed normal Akt and glycogen synthase kinase- 3β phosphorylation patterns, glycogen levels, and expressions of key regulatory gluconeogenic and glycolytic genes. These data demonstrate that deletion of Trib3 has minimal effect on insulin-induced Akt activation in hepatic tissue, and, as such, they question any nonredundant role for Trb3 in the maintenance of glucose and energy homeostasis in mice.
Glycoprotein Ibα Polymorphism T145M, Elevated Lipoprotein-Associated Phospholipase A2, and Hypertriglyceridemia Predict Risk for Recurrent Coronary Events in Diabetic Postinfarction Patients
Authors: Corsetti James P. , Ryan Dan , Moss Arthur J. , Rainwater David L. , Zareba Wojciech , Sparks Charles E.
Published: April 2007

To explore altered platelet function in recurrent coronary event risk among diabetic postinfarction patients, we investigated a function-altering genetic polymorphism (T145M) in the von Willebrand factor binding region of the platelet glycoprotein Ibα (GPIbα) subunit. The study comprised diabetic and nondiabetic patients of the Thrombogenic Factors and Recurrent Coronary Events postinfarction study. Cox proportional hazards multivariable modeling, adjusted for significant clinical covariates, was performed using the polymorphism and metabolic, inflammatory, and thrombogenic blood markers. Nondiabetic patients demonstrated risk for elevated lipoprotein-associated phospholipase A2 (Lp-PLA2). In contrast, diabetic patients demonstrated significant and independent risk for the M allele of the T145M polymorphism (MT plus MM versus TT, hazard ratio [HR] 3.73, 95% CI 1.90–7.33, P < 0.001), hypertriglyceridemia (2.91, 1.52–5.56, P = 0.001), and elevated Lp-PLA2 (2.78, 1.45–5.35, P = 0.002). Joint risk (one, two, or three risk factors) expressed as relative outcome rates (compared with no risk factors) were 2.4, 4.0, and 8.2, respectively. We conclude that the M allele of the T145M polymorphism of the GPIbα subunit predicts risk for recurrent coronary events in diabetic postinfarction patients, but not in nondiabetic postinfarction patients, supportive of an important role for platelet hyperactivation in diabetic coronary heart disease.