Accelerated long-term forgetting in patients with acquired brain injury.

OBJECTIVE: Recent research suggests that patients with neurological disorders without overt seizures may also experience accelerated long-term forgetting (ALF). This term describes unimpaired learning and memory performance after standard retention intervals, but an excessive rate of forgetting over delays of days or weeks. The objective of this retrospective study was to investigate ALF in patients with an acquired brain injury (ABI) and to associate memory performance with executive functions. METHODS: Verbal memory performance (short-term recall, 30-min recall, 1-week recall) was assessed in 34 adult patients with ABI and compared to a healthy control group (n = 54) using an auditory word learning and memory test. RESULTS: Repeated measure analysis showed significant effects of time and group as well as interaction effects between time and group regarding recall and recognition performance. Patients with ABI had a significantly impaired 1-week recall and recognition performance compared to the healthy control group. Correlations between recall performance and executive functions were nonsignificant. DISCUSSION: Our results demonstrate that non-epileptic patients with ABI, especially patients with frontal and fronto-temporal lesions, are prone to ALF. Additionally, our data support the assumption that ALF results from a consolidation impairment since verbal recall and recognition were impaired in patients with ABI.

Scanning laser optical tomography in a neuropathic mouse model : Visualization of structural changes.

BACKGROUND: In the field of hearing research a variety of imaging techniques are available to study molecular and cellular structures of the cochlea. Most of them are based on decalcifying, embedding, and cutting of the cochlea. By means of scanning laser optical tomography (SLOT), the complete cochlea can be visualized without cutting. The Cav1.3-/- mice have already been extensively characterized and show structural changes in the inner ear. Therefore, they were used in this study as a model to investigate whether SLOT can detect structural differences in the murine cochlea. MATERIALS AND METHODS: Whole undissected cochleae from Cav1.3-/- and wild-type mice of various postnatal stages were immunostained and analyzed by SLOT. The results were compared to cochlea preparations that were immunostained and analyzed by fluorescence microscopy. In addition, cochlea preparations were stained with osmium tetraoxide. RESULTS: Visualization by SLOT showed that the staining of nerve fibers at P27 in Cav1.3-/- mice was almost absent compared to wild-type mice and earlier timepoints (P9). The analysis of cochlea preparations confirmed a reduction of the radial nerve fibers. In addition, a significantly reduced number of ribbon synapses per inner hair cell (IHC) at P20 and P27 in the apical part of the cochlea of Cav1.3-/- mice was detected. CONCLUSION: The visualization of whole non-dissected cochleae by SLOT is a suitable tool for the analysis of gross phenotypic changes, as demonstrated by means of the Cav1.3-/- mouse model. For the analysis of finer structures of the cochlea, however, further methods must be used.

[Scanning laser optical tomography in a neuropathic mouse model : Visualization of structural changes. German version]. / Scannende laseroptische Tomographie in einem neuropathischen Mausmodell : Visualisierung von strukturellen Veränderungen.

BACKGROUND: In the field of hearing research a variety of imaging techniques are available to study molecular and cellular structures of the cochlea. Most of them are based on decalcifying, embedding, and cutting of the cochlea. By means of scanning laser optical tomography (SLOT), the complete cochlea can be visualized without cutting. The Cav1.3-/- mice have already been extensively characterized and show structural changes in the inner ear. Therefore, they were used in this study as a model to investigate whether SLOT can detect structural differences in the murine cochlea. MATERIALS AND METHODS: Whole undissected cochleae from Cav1.3-/- and wildtype mice of various postnatal stages were immunostained and analyzed by SLOT. The results were compared to cochlea preparations that were immunostained and analyzed by fluorescence microscopy. In addition, cochlea preparations were stained with osmium tetraoxide. RESULTS: Visualization by SLOT showed that the staining of nerve fibers at P27 in Cav1.3-/- mice was almost absent compared to wildtype mice and earlier timepoints (P9). The analysis of cochlea preparations confirmed a reduction of the radial nerve fibers. In addition, a significantly reduced number of ribbon synapses per inner hair cell (IHC) at P20 and P27 in the apical part of the cochlea of Cav1.3-/- mice was detected. CONCLUSION: The visualization of whole non-dissected cochleae by SLOT is a suitable tool for the analysis of gross phenotypic changes, as demonstrated by means of the Cav1.3-/- mouse model. For the analysis of finer structures of the cochlea, however, further methods must be used.

Delivery of proteins to mammalian cells via gold nanoparticle mediated laser transfection.

Nanoparticle laser interactions are in widespread use in cell manipulation. In particular, molecular medicine needs techniques for the directed delivery of molecules into mammalian cells. Proteins are the final mediator of most cellular cascades. However, despite several methodical approaches, the efficient delivery of proteins to cells remains challenging. This paper presents a new protein transfection technique via laser scanning of cells previously incubated with gold nanoparticles. The laser-induced plasmonic effects on the gold nanoparticles cause a transient permeabilization of the cellular membrane, allowing proteins to enter the cell. Applying this technique, it was possible to deliver green fluorescent protein into mammalian cells with an efficiency of 43%, maintaining a high level of cell viability. Furthermore, a functional delivery of Caspase 3, an apoptosis mediating protein, was demonstrated and evaluated in several cellular assays. Compared to conventional protein transfection techniques such as microinjection, the methodical approach presented here enables high-throughput transfection of about 10 000 cells per second. Moreover, a well-defined point in time of delivery is guaranteed by gold nanoparticle mediated laser transfection, allowing the detailed temporal analysis of cellular pathways and protein trafficking.

Coexpression of osteogenic and adipogenic differentiation markers in selected subpopulations of primary human mesenchymal progenitor cells.

Knowledge of the basic mechanisms controlling osteogenesis and adipogenesis might provide new insights into the prevention of osteoporosis and age-related osteopenia. With the help of magnetic cell sorting and fluorescence activated cell sorting (FACS), osteoblastic subpopulations of mesenchymal progenitor cells were characterized. Alkaline phosphatase (AP) negative cells expressed low levels of osteoblastic and adipocytic markers. AP positive cells expressed adipocytic markers more strongly than the AP negative cell populations, thus suggesting that committed osteoblasts exhibit a greater adipogenic potential. AP negative cells differentiated to the mature osteoblastic phenotype, as demonstrated by increased AP-activity and osteocalcin secretion under standard osteogenic culture conditions. Surprisingly, this was accompanied by increased expression of adipocytic gene markers such as peroxisome proliferator-activated receptor-gamma2, lipoprotein lipase and fatty acid binding protein. The induction of adipogenic markers was suppressed by transforming growth factor-beta1 (TGF-beta1) and promoted by bone morphogenetic protein 2 (BMP-2). Osteogenic culture conditions including BMP-2 induced both the formation of mineralized nodules and cytoplasmic lipid vacuoles. Upon immunogold electron microscopic analysis, osteoblastic and adipogenic marker proteins were detectable in the same cell. Our results suggest that osteogenic and adipogenic differentiation in human mesenchymal progenitor cells might not be exclusively reciprocal, but rather, a parallel event until late during osteoblast development.

Epileptic activity influences the speech organization in medial temporal lobe epilepsy.

Factors influencing atypical speech lateralization have theoretical importance in understanding the organization and reorganization of higher cognitive functions, as well as having practical implications, especially in brain surgery and neurorehabilitation. Atypical (right-sided or bilateral) language representation is more frequent in focal epilepsy than in healthy people. This difference is thought to be related to early childhood brain injuries localized in the neighbourhood of speech centres. The effect of epileptic activity on speech lateralization has not been investigated, although much data suggest that epileptic activity may interfere with higher brain functions. It can only be evaluated in a homogeneous human population with epilepsy having the same lesion type in the same localization. For these reasons, we investigated 184 patients with medial temporal lobe epilepsy (MTLE) due to unilateral hippocampal sclerosis (HS), but without other epileptogenic lesions. All patients underwent comprehensive presurgical evaluation. In MTLE, the influence of age at the time of brain damage, i.e. the initial precipitating injury (IPI), could be evaluated separately from the other timing factors. Of 100 patients in whom a Wada test was performed, left-sided speech occurred in 76% of the left-sided and in 100% of the right-sided MTLE patients (P < 0.05). For further evaluation, we included only the 83 left-sided MTLE patients. The mean age at seizure onset was 10.1 +/- 7.8 years (range 1-37 years); the mean age at evaluation was 35.7 +/- 9.8 years. Based on the Wada test, left-sided speech was present in 63 patients, while in 20 (24%) patients the Wada test revealed atypical speech dominance. We found that atypical speech representation in left MTLE was associated with higher spiking frequency (P < 0.05) and with sensory auras representing an ictal involvement of the lateral temporal structures (P < 0.01). Psychic auras suggesting limbic seizure spread showed a significant association with left-sided speech dominance in left MTLE (P < 0.05). Neither age at epilepsy onset, nor age at IPI was associated with atypical speech in left MTLE. Conclusively, we found that in patients with focal epilepsy, not only the known factors, i.e. the age at which the brain injury occurred and its localization, but also the epileptic activity itself, i.e. interictal discharges and seizure spread, may influence speech reorganization. Our findings also suggest that not only structural elements but also functional factors have an effect on the language organization of the brain.

Hemispheric asymmetry in visuospatial attention assessed with transcranial magnetic stimulation.

Transcranial magnetic stimulation (TMS) was used to study visuospatial attention processing in ten healthy volunteers. In a forced choice recognition task the subjects were confronted with two symbols simultaneously presented during 120 ms at random positions, one in the left and the other in the right visual field. The subject had to identify the presented pattern out of four possible combinations and to press the corresponding response key within 2 s. Double-pulse TMS (dTMS) with a 100-ms interstimulus interval (ISI) and an intensity of 80% of the stimulator output (corresponding to 110-120% of the motor threshold) was applied by a non-focal coil over the right or left posterior parietal cortex (PPC, corresponding to P3/P4 of the international 10-20 system) at different time intervals after onset of the visual stimulus (starting at 120 ms, 270 ms and 520 ms). Double-pulse TMS over the right PPC starting at 270 ms led to a significant increase in percentage of errors in the contralateral, left visual field (median: 23% with TMS vs 13% without TMS, P=0.0025). TMS applied earlier or later showed no effect. Furthermore, no significant increase in contra- or ipsilateral percentage of errors was found when the left parietal cortex was stimulated with the same timing. These data indicate that: (1) parietal influence on visuospatial attention is mainly controlled by the right lobe since the same stimulation over the left parietal cortex had no significant effect, and (2) there is a vulnerable time window to disturb this cortical process, since dTMS had a significant effect on the percentage of errors in the contralateral visual hemifield only when applied 270 ms after visual stimulus presentation.

Biomaterial properties and biocompatibility in cell culture of a novel self-inflating hydrogel tissue expander.

The aim of this study was to investigate the swelling properties and the biocompatibility of a novel tissue expander material. The self-inflating material is a hydrogel consisting of a modified copolymer of methylmethacrylate and N-vinyl-2-pyrrolidone, which takes up water by osmosis. To increase the swelling volume, the primarily neutral gel material was modified by converting it into an ionized gel. To study the swelling and pressure behavior of the material, the anhydrous gel cylinders were equilibrated in distilled water, saline, and sugar solutions. The biocompatibility was investigated in cell culture. We tested the hydrogel eluate after swelling for cytotoxicity and mutagenicity using the cell lines MRC-5 and P3X63 Ag8 653 (Ag8). Furthermore, particles of the material were added to cell cultures to induce foreign body reactions and to verify its influence on monocyte differentiation. The material has a swelling capacity (Q = maximum swelling volume/anhydrous volume) of 5 to 50 depending on the degree of ionization of the polymer network. In this study, two polymer modifications with a swelling equilibrium of Q = 11.1 and 30 in water were tested. The swelling ratio also depends on concentration and ion content of the equilibration medium. The highest swelling capacity was found in water, the lowest in Ringer's solution. The swelling of the anhydrous material with the swelling capacity of Q = 11.1 fits best the average purpose of material properties for tissue expansion and generates a maximal hydrostatic pressure of approximately 235 mmHg. Effects on cell proliferation were detected only at the highest eluate concentration tested (i.e., eluate: culture medium = 1:1), which was far beyond physiological values, whereas mutagenicity was absent. Monocytes neither migrated nor tightly attached to the hydrogel. They neither phagocytose the material nor did they show any sign of a foreign body reaction, e.g., formation of multinucleated giant cells or monocyte proliferation. In the presence of hydrogel material, the differentiation processes of monocytes to macrophages or dendritic cells, respectively, were found to be undisturbed. From these results, we conclude that there is a high biocompatibility of the expander material, which may be a favorable and interesting candidate for further clinical applications.

Alkaline phosphatase expression during monocyte differentiation. Overlapping markers as a link between monocytic cells, dendritic cells, osteoclasts and osteoblasts.

Human monocytes (Mo) in culture can be differentiated into macrophages (M phi), dendritic cells (DC) and osteoclasts. In addition, we have established a Mo-derived in vitro granuloma model which here was compared with ex-vivo isolated foreign body granuloma cells. In these models overlapping phenotypes developed between monocyte-derived dendritic cells (MoDC), osteoclasts, M phi, and osteoblasts. In Mo cultures granulomas were induced by immobilized particulate material. AP activity (osteoblast marker) was found to be co-expressed with cytoplasmic tartrate resistant acid phosphatase (TRAP) as a marker of osteoclasts. While proliferating, the number of AP+ cells decreased, being replaced by cells co-expressing the osteoclast markers vitronectin receptor (VNR) and TRAP. Coexpression of the Mo/M phi marker CD68 with AP or VNR confirmed the monocytic origin of the cells. When Mo were treated with interleukin-4 (IL-4), the number of AP+ cells markedly increased and remained stably expressed over 12 days. In explants from ex vivo granulomas obtained from endoprosthetic revisions the major cell type was the AP+ cell co-expressing CD68. The bone-specific alkaline phosphatase (BAP) as a marker of osteoblasts was detected by FACS analysis in the ex vivo granuloma cells. By RT-PCR the mRNA for osteocalcin, which is a highly specific marker for osteoblasts, was detected. From our results we conclude an ontogenetic relationship between macrophages, DC and osteoclasts. Furthermore, the data suggest a transdifferentiation between Mo and osteoblasts.

Osteoporosis. An overview of the National Osteoporosis Foundation clinical practice guide.

During the past decade, numerous organizations and associations have published recommendations for the prevention and treatment of osteoporosis. For the primary care physician, the most applicable of these--due to its reliance on clinical trial data and its scope--is the clinical guide published by the National Osteoporosis Foundation. The guide addresses risk assessment, bone mineral density testing, diagnosis, nutritional supplementation, and pharmacologic therapy, including consideration of the newer agents used to slow or manage osteoporosis progression. Reflecting one of the key deficiencies in the clinical trial data, the guide applies predominantly to a patient population of postmenopausal white females. The refined design of new osteoporosis studies will in time allow for recommendations that apply to a more diverse patient population.

Human osteoblast-like cells phagocytose metal particles and express the macrophage marker CD68 in vitro.

Periprosthetic osteolysis is a major cause of aseptic loosening in artificial joint replacement. It is assumed to occur in conjunction with the activation of macrophages. We have shown in vitro that human osteoblast-like cells, isolated from bone specimens obtained from patients undergoing hip replacement, phagocytose fine particles of titanium alloy (TiAlV). The human osteoblast-like cells were identified immunocytochemically by the presence of bone-specific alkaline phosphatase (BAP). With increasing duration of culture, a variable number of the osteoblastic cells became positive for the macrophage marker CD68, independent of the phagocytosis of particles, with a fine granular cytoplasmic staining which was coexpressed with BAP as revealed by immunodoublestaining. The metal particles were not toxic to the osteoblastic cells since even in culture for up to four weeks massively laden cells were vital and had a characteristic morphology. Cells of the human osteosarcoma cell line (HOS 58) were also able to phagocytose metal particles but had only a low expression of the CD68 antigen. Fluorescence-activated cell scanning confirmed our immunocytochemical results. Additionally, the cells were found to be negative for the major histocompatibility complex-II (MHC-II) which is a marker for macrophages and other antigen-presenting cells. Negative results of histochemical tests for tartrate-resistant acid phosphatase excluded the contamination by osteoclasts or macrophages in culture. Our observations suggest that the osteoblast can either change to a phagocytosing cell or that the phagocytosis is an underestimated property of the osteoblast. The detection of the CD68 antigen is insufficient to prove the monocytic lineage. In order to discriminate between macrophages and osteoblasts additional markers should be used. To our knowledge, this is the first demonstration of cells of an osteoblastic origin which have acquired a mixed phenotype of both osteoblasts and macrophages.

A human in vitro granuloma model using heat killed Candida albicans cells immobilized on plastic culture wells.

A new model for studying the initial events of granuloma formation in vitro is presented using heat killed Candida albicans immobilized on the surface of plastic culture wells. Human monocytes were induced to accumulate and to proliferate, forming multinucleated giant cells (MGC) and epitheloid cells within 4 days of culture. Tumour necrosis factor-alpha (TNF-alpha), interleukin (IL)-1 beta and IL-6 were detected in culture supernatants. These monokines, and additionally macrophage colony stimulating factor (M-CSF), were also detected immunocytochemically. The granuloma formation was inhibited by Dexamethasone (Dex), Pentoxifylline (POF), or interferon-gamma (IFN-gamma) in a dose-dependent manner. Antibodies to M-CSF reduced the granuloma formation to a great extent with a striking reduction of monocyte proliferation. Using antibodies to TNF-alpha the authors found a complete inhibition of the granuloma including MGC formation and monocyte proliferation.

Collaboration in research: testing the PIPC model on clinical and nonclinical outcomes.

This outcomes research used a collaborative framework between a college of nursing and a medical center to test the effects of the Partners in Patient Care delivery model (PIPC) on clinical and nonclinical outcomes. An experimental pretest-postest design was used to compare selected nonclinical outcomes and clinical outcomes of care in two patient units. Results showed that there were significant differences between units in the nonclinical outcomes of nurse satisfaction, salary costs, supply costs, and productivity as measured by documentation time. In addition, there were significant differences in the clinical outcomes of care in terms of patient satisfaction. No significant differences were found in number of falls, medication errors, and intravenous infections; however, when ratios of these indicators were examined in relation to patient days, significant differences in the medication error ratio and the fall ratio were revealed. The results indicate that the PIPC delivery model did have positive effects on patient satisfaction and nurse satisfaction but that there were increased costs and increased time spent in documentation on the pilot unit.

The use of focus groups to assist in the design and implementation of a new nursing practice model.

Focus groups facilitate change in healthcare institutions by providing comparative perceptions of all levels of healthcare staff in the environment, obtaining impressions of new options for healthcare delivery for which no information is available, and stimulating new ideas to improve cost-effective quality care. The authors discuss their experience using this data gathering and evaluation approach during the planning and implementation of a new nursing practice model. Factors to consider when using focus groups are offered, and lessons learned from the experience are presented.

Improving nursing practice with staff education: the challenges of dysphagia.

The 15 million Americans who experience some degree of dysphagia risk choking, airway obstruction, aspiration-related pulmonary disease, and/or death. These complications increase mortality, morbidity, length of hospitalization, and healthcare costs, but may be preventable through nursing intervention. Fifty-four nursing care workers (NCWs) from medical/surgical units in two acute care hospitals were assigned by convenience to two experimental groups and a control group. Experimental groups A and B participated in an educational program on dysphagia designed to increase their knowledge of dysphagia, knowledge attention, and the number of dysphagic patients identified and referred. Group B received deliberate reinforcement of program content over a 1-month period. The educational intervention had a significant effect on knowledge level and knowledge retention, immediately and at 1-month posttest in both experimental groups. NCWs applied what they learned to clinical practice as evidenced by an increase in the number of patients identified as being at risk for or experiencing dysphagia. Reinforcement of program content did not affect the outcomes. The study has implications for staff educators and nursing personnel who care for persons at risk for dysphagia.

Partners in patient care: measuring the effects on patient satisfaction and other quality indicators.

An experimental pretest/posttest design compared pilot and control nursing units in a medical center in Southwest Florida to assess the effects of a Partners in Patient Care (PIPC) nursing care delivery model on selected quality of care outcomes-patient satisfaction, patient medication errors, falls, and IV infections. There were no significant differences between units in the number of falls, medication errors, and IV infections. When the ratios of these events to patient days were examined, there was a significant difference between the pilot and control units in the medication error ratio and the fall ratio. The results indicate that the PIPC nursing model had a positive effect on patient satisfaction.

Effects of the PIPC model on outcome measures of productivity and costs.

The purpose of this experimental research was to determine the effects of the Partners in Care Practice Model (PIPC) on the outcomes of productivity and costs. Over an 18-month study period, no significant differences were found in costs per patient day between the pilot and control units; however, significant differences were found in actual salaries, amount of time spent in documentation, and supply costs. Differences in costs and productivity reflected increased training costs and costs for additional supplies on the pilot unit.

Team-building process in launching a practice model.

With the growing use of multiple types of nurse extenders in new patient care-delivery models, there is a need not only for outcome research on their design and use but for identification and discussion of effective team-building processes necessary to implementing these models. This article presents an analysis of the interdisciplinary team process and the levels of team building and processes needed at each level to test a new nursing practice model. The team processes included not only those within the medical center but included the collaborative process established between the college of nursing and medical center. Both of these were crucial to a successful change in nursing practice.

Effects of the partners in care practice model on nursing outcomes.

The purpose of this study was to identify the effects of an empirically-designed nursing practice model on the outcome variables of job satisfaction, autonomy, and retention/turnover of nursing staff. After 6 months significant differences were found on the experimental unit in overall job satisfaction, and on the subscales of job satisfaction in task requirements and perception of pay. Significant differences were found between the control and experimental unit on the Job Satisfaction Index subscales of interaction, task requirements, and autonomy. No significant differences were found in retention/turnover of staff between the experimental and control unit.