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Biomedical subjects

C Meyer

Publications and source records attributed to C Meyer.

At least 127 records · Page 7Linked to original sources
PubMed2001

Analysis of allelic imbalance in patients with colorectal cancer according to stage and presence of synchronous liver metastases.

OBJECTIVE: To investigate the relationship between number and location of allelic imbalances (AI) and local tumor progression according to Astler-Coller classification. SUMMARY BACKGROUND DATA: Spontaneous errors in DNA replication (i.e., allelic imbalance or microsatellite instability) have been suggested to play an important role in carcinomatous transformation as reflecting alterations of gene function. METHODS: One hundred two consecutive patients with colorectal carcinoma undergoing surgical resection were included in this study. Patients were distributed according to the Astler-Coller classification as stages A (n = 7), B1 (n = 15), B2 (n = 24), C (n = 31), and D (n = 25). Fluorescent polymerase chain reaction was performed on frozen tumor, normal colon mucosa, and blood DNA at 35 microsatellite markers. Allelic imbalance frequency was compared with tumor staging. RESULTS: The percentage of AI was significantly higher in stage D than in A/B1 and B2. In addition, the percentage of AI was significantly higher in 10 synchronous colorectal liver metastases than in stage A/B1 and B2 tumors. However, the allelotyping revealed a subgroup of A/B1 tumors with a high AI frequency. Statistical analysis showed that the presence of AI at microsatellites D1S305, D2S138, D3S1282, D17S790, and D22S928 presented a significantly positive correlation with stages. CONCLUSION: The frequency of AI significantly correlates with tumor progression of colorectal cancer. Primary tumors with synchronous colorectal liver metastases showed a higher percentage of AI, suggesting that a frequency of AI greater than 35% with this selection of markers indicates a high risk of local progression and of development of metastases.

Adult↗
PubMed2001

Social convergence of disturbed eating attitudes in young adult women.

It has been suggested that a broad range of social factors influence disturbed eating attitudes, but there has been relatively little investigation of the role of peer influence. Drawing from social identity theory, this longitudinal study of a nonclinical group of women examined whether social proximity results in a convergence of eating psychopathology over time. Forty-one nonclinical women (living in 11 communal apartments) completed the Eating Disorders Inventory (EDI) at three time points (1 week after moving in, 10 weeks later, and a further 14 weeks later). The women's eating and related attitudes were compared across the three time points. Then divergence scores were calculated (showing the spread of EDI scores within each apartment) and compared across the three time points. The spread of scores within the apartments changed significantly, indicating some convergence in those attitudes that are socially valued (restrictive attitudes; body concerns) and divergence in those attitudes that are not socially valued (bulimia). There was also an increase in convergence of levels of perfectionism. The findings support the suggestion that social proximity promotes convergence of socially valued eating characteristics but divergence of socially stigmatised characteristics. Further research is suggested to establish the generalizability of these findings and to identify those who are most at risk of such social effects on eating disturbance.

Adult↗
PubMed2001

The psychopathology of bulimic women who report childhood sexual abuse: the mediating role of core beliefs.

Although reported sexual abuse in childhood is associated with bulimic behaviors, less is known about the cognitive factors that explain this association. This study examined the potential role of core beliefs as a mediator in the abuse-bulimia link. Sixty-one bulimic women were interviewed regarding any history of childhood sexual abuse and completed measures of bulimic behaviors, dissociation, depression, and core beliefs. The 21 women who reported a history of childhood sexual abuse had significantly higher levels of several core beliefs and greater levels of psychopathology. Different core beliefs acted as mediators in the relationships between sexual abuse and individual symptoms. The findings support the suggestion that schema-focused cognitive therapy may be useful in working with bulimics, particularly if they have been sexually abused in childhood. Further research is needed to determine the role of core beliefs in mediating the impact of other forms of trauma and how traumas relate to other "escape" behaviors.

Adult↗
PubMed2001

Mu 1A deficiency induces a profound increase in MPR300/IGF-II receptor internalization rate.

The mannose-6-phosphate/IGF-II receptor MPR300 mediates sorting of lysosomal enzymes from the trans-Golgi network to endosomes and endocytosis of hormones, for example, of IGF-II. We analyzed transport of MPR300 in mu1A-adaptin-deficient fibroblasts, which lack a functional AP-1 clathrin adaptor complex. In mu1A-adaptin-deficient fibroblasts, the homologous MPR46 accumulates in endosomes due to a block in retrograde transport to the trans-Golgi network. The MPR300-mediated endocytosis is markedly enhanced. We demonstrate that the seven-fold increase in endocytosis is not associated with an increased steady-state concentration of receptors at the plasma membrane, but with an increased internalization rate of MPR300. Internalization of other receptors that are also endocytosed by AP-2 is not affected. More MPR300 receptors are found in clathrin-coated pits of the plasma membrane, whereas outside coated-areas, more MPR300 are concentrated in clusters and all intracellular receptors reside in endosomes, which are in equilibrium with the plasma membrane. Thus AP-1-mediated transport of MPR300 from endosomes to the TGN controls indirectly the recycling rate of the receptor between the plasma membrane and endosomes.

Adaptor Protein Complex 1↗
PubMed2001

The utility of dimensional and categorical approaches to understanding dissociation in the eating disorders.

OBJECTIVE: The present study compared levels of dissociation across groups of eating-disordered women, investigating the utility of dimensional and categorical measures of dissociation in understanding diagnoses and behaviours in the eating disorders. METHODS: The Dissociative Experiences Scale (DES-II) was completed by 170 eating-disordered women (drawn from out-patient assessment clinics) and 203 nonclinical women. The clinical group also supplied information regarding eating behaviours and related features (alcohol abuse, reported history of sexual abuse). The DES-II and a subset of its items (DES-Taxon) were used as dimensional and categorical discriminators of the groups and of the presence/absence of specific features and symptoms. RESULTS: When treated as dimensional measures, the DES-II and DES-Taxon had similar levels of clinical utility (particularly discriminating the binge-purge anorexics from the other clinical groups). However, the DES-Taxon was a superior categorical measure, discriminating groups more clearly and predicting the presence of many symptoms and features much more powerfully. CONCLUSIONS: The DES-Taxon is a potentially valuable self-report measure for indicating the level and presence of dissociative psychopathology in the eating disorders. As well as being convenient to administer and score, it has the clinical and research value of indicating those patients in whom treatment might need to include addressing pathological dissociation.

Depersonalization↗
PubMed2001

Effect of diode laser irradiation on the attachment rate of periodontal ligament cells: an in vitro study.

BACKGROUND: The present study is part of a basic research program investigating the cellular effects of an 810 nm GaAlAs-diode laser on human periodontal tissues. The aim of the investigation was to evaluate the effects of laser treatment of root surface specimens on the attachment of periodontal ligament (PDL) cells in vitro. METHODS: Root specimens were prepared from periodontally diseased teeth. PDL cells were obtained from human third molar ligaments. Cells were cultured under simple, standardized, and reproducible experimental conditions. One hundred fifty root specimens were scaled and root planed with curets followed by air-powder abrasive treatment; 75 were then lased and 75 served as controls. The irradiation time was 20 seconds at a power output of 1 W. The root segments were placed into culture dishes, covered with a solution of PDL cells, and incubated for 72 hours. The specimens were then washed with phosphate buffer to remove cells not attached to the surface, and the adherent cells were stained with methylene blue. Cells were counted using a reflected light microscope and the cell density per mm2 was calculated. RESULTS: The analysis of 150 specimens revealed no significant differences between the groups (P = 0.347, Wilcoxon test). The cell numbers, however, were slightly higher on laser specimens. The mean was 66 cells/mm2 in the laser group and 63.7 cells/mm2 in the control group. CONCLUSIONS: The application of the diode laser at the parameters used did not have a substantially positive effect on the new attachment of PDL cells on the tooth specimens. It remains to be investigated whether the difference detected is really clinically relevant.

Aluminum↗
PubMed2001

Renal gluconeogenesis: its importance in human glucose homeostasis.

Studies conducted over the last 60 years in animals and in vitro have provided considerable evidence that the mammalian kidney can make glucose and release it under various conditions. Until quite recently however, it was generally believed that the human kidney was not an important source of glucose except during acidosis and after prolonged fasting. This review will summarize early work in animals and humans, discuss methodological problems in assessing renal glucose release in vivo, and present results of recent human studies that provide evidence that the kidney may play a significant role in carbohydrate metabolism under both physiological and pathological conditions.

Animals↗
PubMed2001

Swarm intelligence. A whole new way to think about business.

What do ants and bees have to do with business? A great deal, it turns out. Individually, social insects are only minimally intelligent, and their work together is largely self-organized and unsupervised. Yet collectively they're capable of finding highly efficient solutions to difficult problems and can adapt automatically to changing environments. Over the past 20 years, the authors and other researchers have developed rigorous mathematical models to describe this phenomenon, which has been dubbed "swarm intelligence," and they are now applying them to business. Their research has already helped several companies develop more efficient ways to schedule factory equipment, divide tasks among workers, organize people, and even plot strategy. Emulating the way ants find the shortest path to a new food supply, for example, has led researchers at Hewlett-Packard to develop software programs that can find the most efficient way to route phone traffic over a telecommunications network. South-west Airlines has used a similar model to efficiently route cargo. To allocate labor, honeybees appear to follow one simple but powerful rule--they seem to specialize in a particular activity unless they perceive an important need to perform another function. Using that model, researchers at Northwestern University have devised a system for painting trucks that can automatically adapt to changing conditions. In the future, the authors speculate, a company might structure its entire business using the principles of swarm intelligence. The result, they believe, would be the ultimate self-organizing enterprise--one that could adapt quickly and instinctively to fast-changing markets.

Commerce↗
PubMed2001

Three-year follow up assessment of Class II restorations in primary molars with a polyacid-modified composite resin and a hybrid composite.

PURPOSE: To evaluate the 3-year success rate of Class II restorations in primary molars performed with Compoglass, a polyacid-modified resin-based composite (compomer) and TPH-Spectrum, a hybrid resin-based composite. MATERIAL AND METHODS: In a dental practice, in each of 52 children at least two primary molars were restored. 96 primary molars were restored with TPH-Spectrum using the total-etching-technique and 94 with Compoglass without acid etching prior to application of the bonding adhesive. The restorations were assessed at baseline (1996) and after 1 and 2 yrs according to the Ryge criteria. After 3 yrs the restorations (46 Compoglass, 46 TPH-Spectrum) of 35 children were re-evaluated. RESULTS: After 3 yrs the cumulative success rate according to the Kaplan-Meier-estimation was 79.5% for the Compoglass and 85.8% for the TPH-Spectrum restorations. No significant differences were observed between the two materials with respect to color matching, cavosurface discoloration, anatomic form, margin integrity and caries assessment. The present investigation revealed that TPH-Spectrum and Compoglass are suitable materials for restoring primary molars. CLINICAL SIGNIFICANCE: After an observation period of 3 years, both TPH-Spectrum and Compoglass demonstrated acceptable clinical results.

Acid Etching, Dental↗
PubMed2001

[Psychiatric illness from a multi-generational perspective: results of a longitudinal study with children and grandchildren of hospitalized depressed patients].

In a longitudinal empirical study data from three generations were gathered: Generation 1: formerly depressive patients, who had been treated as inpatients; generation 2: children of these patients; generation 3: grandchildren of the former patients. The first investigation of the children was carried out in the seventies, the follow-up-assessment of children and grandchildren was done in 1996. In the follow-up-study the meanwhile grown-up children of the depressive patients showed to a high degree psychic disturbances and were in treatment because of these problems. The majority of the grandchildren showed no relevant deviations. The severity of the depressive illness (in generation 1) and the psychopathological status of the former inpatient's spouse proved to be relevant prognostic factors with regard to the long-term development and resilience of children and grandchildren.

Adolescent↗
PubMed2001

Myocardial blood flow and flow reserve in response to short-term cyclical hormone replacement therapy in postmenopausal women.

OBJECTIVES: To measure the effects of combined cyclical hormone replacement therapy (HRT) on myocardial blood flow (MBF) in postmenopausal women at high risk for coronary heart disease (CHD) and in women with documented CHD. BACKGROUND: Estrogen restores endothelium-dependent vasodilation in response to acetylcholine in postmenopausal women, and it has a direct, endothelium-independent vasodilatory effect on coronary arteries. METHODS: To determine whether coronary microcirculation can be affected by short-term, combined HRT, we performed positron emission tomography (PET) in two groups of women without previous HRT. Group I (n = 10) had one or more risk factors for CHD; group II (n = 8) had documented CHD and previous myocardial infarction. Group II was older (54 +/- 4 vs 59 +/- 5 y, P = .03) and had lower total cholesterol levels at baseline because of lipid-lowering therapy (244 +/- 31 vs 203 +/- 40 mg/dL, P = .03). Patients underwent baseline dynamic PET with N-13 ammonia at rest and during maximal adenosine-induced hyperemia to assess MBF. Each then began taking HRT (conjugated equine estrogen alone or with medroxyprogesterone acetate (MPA), administered in cyclical fashion), and returned for follow-up PET 46 +/- 12 days later. RESULTS: There was no difference in resting MBF between groups I and II prior to starting therapy or at follow-up. Stress MBF and flow reserve (FR) tended to be higher in group I patients at baseline. MBF values remained unchanged at follow-up and resulted in similar FR values at baseline and during HRT for both groups. Women using only estrogen (n = 6) tended to show higher FR values after estrogen therapy, however. CONCLUSIONS: Short-term HRT in postmenopausal women did not lead to improvements in MBF or FR. Combined cyclical HRT may not exert measurable effects on coronary microcirculation. MPA may attenuate estrogen effects on the coronaries, which may be largely endothelium-dependent.

Adenosine↗
PubMed2001

Teaching an online course.

An online pharmacology course was developed for nursing students in the associate degree program at Delaware County Community College, Media, PA. The course was a response to an expressed need from students for more pharmacology content in their curriculum and as part of an articulation agreement with Widener University School of Nursing, Chester, PA, registered nurse to a masters of science in nursing program. Course design was a team effort among faculty and instructional technology specialists. Faculty developed a list of features the course needed to deliver the content as well as instructional activities designed to help learning to occur. Instructional technology specialists designed the course layout, chose the appropriate software needed to support the course design, and developed original programming as necessary. These elements were woven into a course that is tailored to our instructional design. In the years since the course was first offered, changes have been made to increase interaction between students and to provide all aspects of the course online, including testing. Teaching online challenges faculty to learn new technical skills as well as to think about new ways of teaching.

Attitude of Health Personnel↗
PubMed2000

Maturation and pro-peptide cleavage of beta-secretase.

Amyloid beta-peptide is generated by two sequential proteolytic cleavages mediated by beta-secretase (BACE) and gamma-secretase. BACE was recently identified as a membrane-associated aspartyl protease. We have now analyzed the maturation and pro-peptide cleavage of BACE. Pulse-chase experiments revealed that BACE is post-translationally modified during transport to the cell surface, which can be monitored by a significant increase in the molecular mass. The increase in molecular mass is caused by complex N-glycosylation. Treatment with tunicamycin and N-glycosidase F led to a BACE derivative with a molecular weight corresponding to an unmodified version. In contrast, the mature form of BACE was resistant to endoglycosidase H treatment. The cytoplasmic tail of BACE was required for efficient maturation and trafficking through the Golgi; a BACE variant lacking the cytoplasmic tail undergoes inefficient maturation. In contrast a soluble BACE variant that does not contain a membrane anchor matured more rapidly than full-length BACE. Pro-BACE was predominantly located within the endoplasmic reticulum. Pro-peptide cleavage occurred immediately before full maturation and trafficking through the Golgi.

Amidohydrolases↗
PubMed2000

Structural requirements for the stabilization of metarhodopsin II by the C terminus of the alpha subunit of transducin.

The retinal receptor rhodopsin undergoes a conformational change upon light excitation to form metarhodopsin II (Meta II), which allows interaction and activation of its cognate G protein, transducin (G(t)). A C-terminal 11-amino acid peptide from transducin, G(talpha)-(340-350), has been shown to both bind and stabilize the Meta II conformation, mimicking heterotrimeric G(t). Using a combinatorial library we identified analogs of G(talpha)-(340-350) that bound light-activated rhodopsin with high affinity (Martin, E. L., Rens-Domiano, S., Schatz, P. J., and Hamm, H. E. (1996) J. Biol. Chem. 271, 361-366). We have made peptides with key substitutions either on the background of the native G(talpha)-(340-350) sequence or on the high affinity sequences and used the stabilization of Meta II as a tool to determine which amino acids are critical in G protein-rhodopsin interaction. Removal of the positive charge at the N termini by acylation or delocalization of the charge by K to R substitution enhances the affinity of the G(talpha)-(340-350) peptides for Meta II, whereas a decrease was observed following C-terminal amidation. Cys-347, a residue conserved in pertussis toxin-sensitive G proteins, was shown to interact with a hydrophobic site in Meta II. These studies provide further insight into the mechanism of interaction between the G(talpha) C terminus and light-activated rhodopsin.

Amino Acid Sequence↗