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Biomedical subjects

Michael Simon

Publications and source records attributed to Michael Simon.

17 recordsLinked to original sources
PubMed2007

Back or neck-pain-related disability of nursing staff in hospitals, nursing homes and home care in seven countries--results from the European NEXT-Study.

BACKGROUND: Musculoskeletal disorders are a widespread affliction in the nursing profession. Back or neck-pain-related disability of nursing staff is mainly attributed to physical and psychosocial risk factors. OBJECTIVES: To investigate which-and to what extent-physical and psychosocial risk factors are associated with neck/back-pain-related disability in nursing, and to assess the role of the type of health care institution (hospitals, nursing homes and home care institutions) within different countries in this problem. DESIGN: Cross-sectional secondary analysis of multinational data of nurses and auxiliary staff in hospitals (n=16,770), nursing homes (n=2140) and home care institutions (n=2606) in seven countries from the European NEXT-Study. METHODS: Multinomial logistic regression analysis with raw models for each factor and mutually adjusted with all analysed variables. RESULTS: Analysis of the pooled data revealed effort-reward imbalance as the predominant risk factor for disability in all settings (odds ratios for high disability by effort-reward ratio: hospital 5.05 [4.30-5.93]; nursing home 6.52 [4.04-10.52] and home care 6.4 [3.83-10.70] [after mutual adjustment of psychosocial and physical risk factors]). In contrast, physical exposure to lifting and bending showed only limited associations with odds ratios below 1.6; the availability and use of lifting aids was-after mutual adjustment-not or only marginally associated with disability. These findings were basically confirmed in separate analyses for all seven countries and types of institutions. CONCLUSIONS: The findings show a pronounced association between psychosocial factors and back or neck-pain-related disability. Further research should consider psychosocial factors and should take the setting where nurses work into account.

Adolescent↗
PubMed2006

Dietary fat reduction and breast cancer outcome: interim efficacy results from the Women's Intervention Nutrition Study.

BACKGROUND: Preclinical and observational studies suggest a relationship between dietary fat intake and breast cancer, but the association remains controversial. We carried out a randomized, prospective, multicenter clinical trial to test the effect of a dietary intervention designed to reduce fat intake in women with resected, early-stage breast cancer receiving conventional cancer management. METHODS: A total of 2437 women were randomly assigned between February 1994 and January 2001 in a ratio of 40:60 to dietary intervention (n = 975) or control (n = 1462) groups. An interim analysis was performed after a median follow-up of 60 months when funding for the intervention ceased. Mean differences between dietary intervention and control groups in nutrient intakes and anthropometric variables were compared with t tests. Relapse-free survival was examined using Kaplan-Meier analysis, stratified log-rank tests, and Cox proportional hazards models. Statistical tests were two-sided. RESULTS: Dietary fat intake was lower in the intervention than in the control group (fat grams/day at 12 months, 33.3 [95% confidence interval {CI} = 32.2 to 34.5] versus 51.3 [95% CI = 50.0 to 52.7], respectively; P<.001), corresponding to a statistically significant (P = .005), 6-pound lower mean body weight in the intervention group. A total of 277 relapse events (local, regional, distant, or ipsilateral breast cancer recurrence or new contralateral breast cancer) have been reported in 96 of 975 (9.8%) women in the dietary group and 181 of 1462 (12.4%) women in the control group. The hazard ratio of relapse events in the intervention group compared with the control group was 0.76 (95% CI = 0.60 to 0.98, P = .077 for stratified log rank and P = .034 for adjusted Cox model analysis). Exploratory analyses suggested a differential effect of the dietary intervention based on hormonal receptor status. CONCLUSIONS: A lifestyle intervention reducing dietary fat intake, with modest influence on body weight, may improve relapse-free survival of breast cancer patients receiving conventional cancer management. Longer, ongoing nonintervention follow-up will address original protocol design plans, which called for 3 years of follow-up after completion of recruitment.

Adult↗
PubMed2006

Nanosized insulin-complexes based on biodegradable amine-modified graft polyesters poly[vinyl-3-(diethylamino)-propylcarbamate-co-(vinyl acetate)-co-(vinyl alcohol)]-graft-poly(L-lactic acid): protection against enzymatic degradation, interaction with Caco-2 cell monolayers, peptide transport and cytotoxicity.

Non-parenteral insulin delivery by the oral route is limited by epithelial barriers and enzymatic degradation. Nanosized insulin-complexes based on amine modified comb-like polyesters were designed to overcome these barriers. Protection of insulin in nanocomplexes (NC) from enzymatic degradation was investigated. The interaction with enterocyte-like Caco-2 cells in terms of cytotoxicity, transport through and uptake in the cell layers was evaluated by measuring transepithelial electrical resistance (TEER), release of lactate dehydrogenase (LDH) and insulin transport. The protection capacity of NC and their interaction with Caco-2 cells varied strongly as a function of lactide-grafting (hydrophobicity). With increasing lactide-grafting (P(26) < or = P(26)-1(LL) < or = P(26)-2(LL)) NC protected up to 95% of the insulin against degradation by trypsin. Transport and uptake into cell monolayers increased with higher l-lactid grafting. About 25% of a 1.25mg/ml TRITC-insulin NC dispersion with P(26)-2(LL) was recovered in Caco-2 cells after 90 min. A concentration dependent cytotoxicity profile was observed showing elevated LDH release and decreased TEER values. The cytotoxicity correlates with the surfactant like character of the polymers, decreasing the surface tension to 46 mN/m for the amphiphilic P(26)-2(LL). The observed TEER decrease was reversible after 20 h, suggesting that the biodegradable comb-polyesters offer a promising approach to overcome mucosal barriers.

Caco-2 Cells↗
PubMed2006

The impact of detrusor overactivity on the management of stress urinary incontinence in women.

The presence of overactive bladder symptoms, urodynamic detrusor overactivity, and urge incontinence can complicate the diagnosis and management of stress urinary incontinence in women. The exact pathophysiology of mixed incontinence is not well characterized; in some patients, the stress and urge etiology may be pathologically linked. The role of urodynamics in evaluating patients with mixed incontinence remains controversial. Conservative therapies, such as bladder training, pelvic floor exercise, biofeedback, and electrical stimulation, offer moderate success in women with mixed incontinence. Surgery (colposuspension, bladder neck pubovaginal slings, and midurethral slings) offers excellent subjective and objective cure rates in patients with mixed incontinence. Preoperative detrusor overactivity is cured consistently 50%of the time with colposuspension and slings. Overall, the presence of preoperative detrusor overactivity does not appear to significantly worsen the outcome of conservative and surgical treatments for stress urinary incontinence in women.

Female↗
PubMed2006

A phase II study of docetaxel, doxorubicin, and infusional 5-fluorouracil in the treatment of patients with locally advanced breast cancer.

OBJECTIVE: The primary aim of this study was to estimate the rate of clinical and pathologic response to preoperative docetaxel, doxorubicin, and infusional 5-fluorouracil in patients with locally advanced breast cancer. Secondary objective included the determination of toxicity profile. PATIENTS AND METHODS: Thirty-nine patients (median age 49 years) with histologically confirmed locally advanced breast cancer (stage IIIA or IIIB) were studied. Patients received 4 courses of chemotherapy with docetaxel (75 mg/m2 iv over 1 hour), doxorubicin (50 mg/m2 iv bolus), and 5-fluorouracil (300 mg/m2/d as continuous iv infusion on days 1-5). Treatment cycles were repeated every 21 days. Prophylactic filgastrim 5 microg/kg s/c QD was administered to all patients. Definitive surgery was performed after the completion of 4 cycles of therapy. Pathologic complete response was defined as the absence of invasive cancer in both the breast and ipsilateral axillary lymph nodes. RESULTS: The clinical objective response rate (partial plus complete) was 87% (95% confidence interval [CI]: 76-98%). Three patients (8%) had complete pathologic response. Two patients progressed preoperatively. Thirteen patients (33%) developed neutropenic fever. Fifty-three percent of the patients were hospitalized for treatment related complications. No cardiotoxicity or treatment related deaths were observed. CONCLUSIONS: Triple cytotoxic therapy based on concurrent doxorubicin and docetaxel with infusional 5-flourouracil (5-FU) does not appear to significantly improve the pathologic response in patients with locally advanced breast cancer.

Adult↗
PubMed2005

Evaluation of different strategies for real-time RT-PCR expression analysis of corticotropin-releasing hormone and related proteins in human gestational tissues.

In this article real-time quantitative RT-PCR strategies for investigation of mRNA distribution in stress-related corticotropin-releasing hormone (CRH), CRH-binding protein (CRH-BP), and CRH receptors (CRH-R1, CRH-R2) in human gestational tissues are described. The effect of sample and RNA preparation, reverse transcription, and the quantitation strategy were investigated. Both thawing of the sample before homogenization and the RT reaction were identified as critical steps. In contrast, the time-lag from the biopsy until snap-freezing and the homogenization procedure had little effect. The "housekeeping" gene cyclophilin was found to be differently expressed in gestational tissues, compromising its use as internal reference. For relative quantitation of mRNA levels by TaqMan PCR the standard curve method and the comparative C (T) method (DeltaDeltaC (T) or DeltaC (T)' method) were compared. Both calculation strategies delivered similar relative mRNA amounts in identifying the placenta as the main source of CRH and CRH-BP mRNA compared with myometrium and decidua. Consistent results were also obtained for CRH-R1 and CRH-R2 by both methods of calculation. We conclude that the simpler comparative C (T) method is adequate for assessing the mRNA levels of CRH, CRH-BP, and CRH receptors in human gestational tissues.

Algorithms↗
PubMed2005

Insulin containing nanocomplexes formed by self-assembly from biodegradable amine-modified poly(vinyl alcohol)-graft-poly(L-lactide): bioavailability and nasal tolerability in rats.

PURPOSE: The bioavailability and local tolerability of insulin containing nanocomplexes from amine-modified poly(vinyl alcohol)-graft-poly(L-lactide) were studied in rats. Histology of the nasal epithelium was studied to document integrity of the mucosa. METHODS: Nanocomplexes (NC) were prepared by spontaneous self-assembly of insulin and the water-soluble amphiphilic polymer. Changes in blood glucose and insulin blood concentration were monitored in anesthetized rats using a glucose meter and enzyme-linked immunosorbent assay, respectively. Histological sections of the nasal cavity were examined after H&E staining by light microscopy. RESULTS: NC reduced blood glucose level in fasted healthy rats by 20% after 50-80 min and in streptozotocin induced diabetic rats by 30% within 75-95 min compared to basal levels. In both animal models significant concentrations of human insulin were detected, with relative bioavailabilities F(rel) of 2.8 up to 8.3%. The more hydrophobic, lactic acid grafted polyester were more effective at a threefold higher polymer concentration, increasing the relative bioavailability F(rel) of a 5 IU/kg dose from 2.8 to 5.7%. Histological examination of the nasal mucosa after 4 h showed no signs of toxicity at the site of nasal administration. CONCLUSIONS: These results demonstrate that the NC significantly enhanced insulin absorption, suggesting that amphiphilic biodegradable comb-polymers offer a promising approach for nasal peptide delivery.

Administration, Intranasal↗
PubMed2005

Corrosion resistance and biocompatibility of a new porous surface for titanium implants.

Alterations of the commercially pure titanium (cpTi) surface may be undertaken to improve its biological properties. The aim of this study was to investigate the biocompatibility of cpTi when submitted to a new, porous titanium, surface treatment (porous Ti). Five types of surface treatments, namely sintered microspheres porous titanium (porous Ti), titanium plasma spray (TPS), hydroxyapatite (HA), sandblasted and acid etched (SBAE), and resorbable blast medium, sandblasted with hydroxyapatite (RBM) were made. In the experimental methods, the corrosion potentials were measured over time, and then a linear sweep voltammetric analysis measured the polarization resistances and corrosion currents. For biocompatibility evaluation, MG63 osteoblast-like cells were used. Cell morphology, cell proliferation, total protein content, and alkaline phosphatase (ALP) activity were evaluated after 2 h, and after 2, 4 and 7 d. Porous Ti and SBAE showed a better corrosion resistance, with a weak corrosion current and a high polarization resistance, than the other surfaces. Cell attachment, cell morphology, cell proliferation, and ALP synthesis were influenced by the surface treatments, with a significant increase observed of the activity of osteoblast cells on the porous coating (porous Ti). Based on these results, it is suggested that the porous Ti surface has a significantly better biocompatibility than the other surface treatments and an excellent electrochemical performance.

Analysis of Variance↗
PubMed2004

The depolymerization of chitosan: effects on physicochemical and biological properties.

Chitosan has been extensively used as an absorption enhancer for macromolecules and as gene delivery vehicle. Both properties are molecular weight (MW) dependent. Here, we investigate factors affecting the oxidative depolymerization of chitosan and physicochemical properties of the resulting polymer fractions including their cytotoxicity. The molecular weight of the depolymerized chitosan was influenced by the initial concentration and the source of chitosan. At constant initial concentrations, the molecular weight decreased linearly with the chitosan/NaNO2 ratio and was a function of logarithm of the reaction time. Chitosan with larger molecular weight was more sensitive to depolymerization. No structural change was observed during the depolymerization process by infrared and proton nuclear magnetic resonance spectroscopy. In addition, thermal properties of chitosan fragments were studied by thermal gravimetric analysis and it was found that the decomposition temperature was molecular weight dependent. Furthermore, the solubility of different molecular weight chitosan was assayed as a function of pH and it increased with decreasing molecular weight. The cytotoxicity of chitosan was concentration dependent but almost molecular weight independent according to MTT assay using L929 cell line recommended by USP26. In summary, low molecular weight fractions of chitosan may potentially useful for the design of drug delivery systems due to the improved solubility properties.

Biocompatible Materials↗
PubMed2004

Special populations recruitment for the Women's Health Initiative: successes and limitations.

The Women's Health Initiative (WHI) is a study designed to examine the major causes of death and disability in women. This multi-arm, randomized, controlled trial of over 160,000 post-menopausal women of varying ethnic and socioeconomic backgrounds and a goal of 20% of the study participants from minority populations is perhaps one of the most challenging recruitment efforts ever undertaken. Of the two main study arms, the Clinical Trial (CT) and the Observational Study (OS), the CT arm recruitment goal was to randomize 64,500 postmenopausal women 50-79 years of age. Women enrolled in the study will be followed for a period of 8-12 years. Ten clinical centers, out of a total of 40 throughout the United States, were selected as minority recruitment centers on the basis of their history of interaction with and access to large numbers of women from certain population subgroups. WHI enrollment began in September 1993 and ended in December 1998, resulting in the randomization and enrollment of a total of 161,856 (17.5% minority) women participants (68,135 (18.5% minority) in the CT and 93,721 (16.7%) in the OS). Within the CT arm, WHI achieved 101.7% of the goal of 48,000 participants in the Dietary Modification (DM) component, and 99.4% of the goal of 27,500 in the hormone-replacement component (HRT), with 11.8% overlap between DM and HRT. Of those who expressed initial interest in WHI, African Americans had the highest randomization yields in the DM component and Hispanics had the highest in the HRT component (15.2% and 10.2%, respectively). Overall, mass mailing was the greatest source of randomized participants. In addition, minority clinics found community outreach, personal referrals, and culturally appropriate recruitment materials particularly effective recruitment tools. For minority recruitment, our findings suggest that the key to high yield is reaching the target population through appropriate recruitment strategies and study information that get their attention. Also, once minority subjects are reached, they tend to participate.

Aged↗
PubMed2004

Influence of donor storage time on corneal allograft survival.

PURPOSE: To investigate the influence of graft storage time on corneal allograft survival in high-risk and low-risk patients. DESIGN: Comparative retrospective nonrandomized clinical trial. PARTICIPANTS: Overall, 193 patients with 210 corneal allografts were classified as high risk or low risk for corneal allograft rejection on the basis of recipient corneal neovascularization and number of ipsilateral transplants. METHODS: Data from 3 groups were evaluated. The first group received fresh (no storage in culture medium) corneas, the second received corneas of donor storage time less than 7 days in minimum essential medium (MEM) at 37 degrees C, and the final group received corneas stored in MEM longer than 7 days. Recipients were analyzed for development of immune rejection according to storage time of the corneal tissue. Corneal allograft survival rate was determined with Kaplan-Meier survival analysis. The log-rank test was used to determine statistical significance. MAIN OUTCOME MEASURES: Risk of reversible and irreversible allograft rejection in corneas stored at various intervals in high-corneal and low-corneal transplant patients. RESULTS: High-risk corneal allograft recipients had a significantly prolonged allograft survival when the tissue was stored for 7 days or greater, compared with recipients receiving fresh tissues. Patients at low risk of corneal allograft rejection also showed a tendency for prolonged survival, although not statistically significant (P = 0.06). CONCLUSIONS: Storage of corneal tissue may reduce the frequency of allograft rejection, especially in high-risk patients.

Adolescent↗
PubMed2003

The effect of adding Pap smear information to a mammography reminder system in an HMO: results of randomized controlled trial.

BACKGROUND: While reminders can promote cancer screening in primary care, little is known about the potential interaction between multiple reminders. METHODS: We conducted a randomized controlled trial to compare the effect of combined Pap smear plus mammogram reminders and mammogram-only reminders among 2471 women 40 years of age or older enrolled in a health maintenance organization serving a predominantly Medicaid-eligible population. Reminders included both a mailed letter for the woman and a medical record prompt. RESULTS: Intervention assignment was unassociated with differences in rates of visitation to family medicine or internal medicine or completion of mammography during the study year. Compared to women assigned to mammogram-only reminder treatment, those assigned to the combined Pap smear plus mammogram reminder intervention were more likely to visit a gynecologist (34% compared to 29%, adjusted odds ratio = 1.33, 95% confidence interval 1.08-1.63) and to complete a Pap smear (30% compared to 23%, adjusted odds ratio = 1.39, 95% confidence interval 1.07-1.89). CONCLUSIONS: In the study setting, the addition of Pap smear to mammography reminders has a procedure-specific effect, increasing gynecology visits and Pap smear use while neither increasing nor decreasing other primary care visits or mammography. We find no evidence of reinforcement or competition between these reminders.

Adult↗
PubMedDate not supplied

Work-home conflict in the European nursing profession.

This study investigated predictors of the work-home conflict among registered nurses (n = 27,603) in eight European countries. Two scales were used to assess work-family conflict (WFC) and family-work conflict (FWC). Based on a distinction of time- and strain-based and individual factors for WFC, bivariate correlations and multiple linear regression analysis were computed. The relationship between WFC and intention to leave the nursing profession was also analyzed. Quantitative demands indicating intensity of work, regularity of working time, and being pressured to work overtime were the dominating predictors for WFC, explaining 13-23% of the observed variance. The association between WFC and intention to leave the nursing profession was pronounced in all countries except one. Most European countries lack qualified nurses. Attempts to retain nurses in their profession should take into consideration the WFC, the regularity of working time in particular, and overtime issues.

Adult↗