Development and validation of a simple NAFLD clinical scoring system for identifying patients without advanced disease

BACKGROUND

Clinical predictors of advanced non-alcoholic liver disease (NAFLD) are needed to guide diagnostic evaluation and treatment.

METHODS

To better understand the demographics of NAFLD and risk factors for advanced disease, this study analysed 827 patients with NAFLD at two geographically separate tertiary medical centres.

RESULTS

The cohort was 51% female and had a median body mass index (BMI) of 33 kg/m(2); 3% had a normal BMI. Common co-morbidities included hypertension (60%) and diabetes (35%); insulin resistance was present in 91% and advanced fibrosis in 24% of patients. When comparing patients with no fibrosis or mild fibrosis to those with advanced fibrosis, BMI > or = 28 kg/m(2), age > 50 years, and aspartate transaminase/alanine aminotransferase (AST/ALT) ratio > or = 0.8, a quantitative assessment check index (QUICKI) score < 0.294 (equivalent to homeostasis model assessment (HOMA) > 6.2) and the presence of diabetes mellitus (DM) were individually associated by univariate analysis with odds ratios (ORs) of > or = 2.4 for advanced fibrosis. Based on the results of forced entry logistic regression analysis, three variables were combined in a weighted sum (BMI > or = 28 = 1 point, AAR of > or = 0.8 = 2 points, DM = 1 point) to form an easily calculated composite score for predicting advanced fibrosis called the BARD score. A score of 2-4 was associated with an OR for advanced fibrosis of 17 (confidence interval 9.2 to 31.9) and a negative predictive value of 96%.

CONCLUSIONS

Insulin resistance and its co-morbidities are often present in patients with NAFLD. An easily calculated score based on readily available clinical data can reliably exclude the presence of advanced fibrosis in these patients, particularly among non-diabetics.

Development and evaluation of evidence based risk assessment tool (STRATIFY) to predict which elderly inpatients will fall: case-control and cohort studies

OBJECTIVES

To identify clinical characteristics of elderly inpatients that predict their chance of falling (phase 1) and to use these characteristics to derive a risk assessment tool and to evaluate its power in predicting falls (phases 2 and 3).

DESIGN

Phase 1: a prospective case-control study. Phases 2 and 3: prospective evaluations of the derived risk assessment tool in predicting falls in two cohorts.

SETTING

Elderly care units of St Thomas's Hospital (phase 1 and 2) and Kent and Canterbury Hospital (phase 3).

SUBJECTS

Elderly hospital inpatients (aged > or = 65 years): 116 cases and 116 controls in phase 1,217 patients in phase 2, and 331 in phase 3.

MAIN OUTCOME MEASURES

21 separate clinical characteristics were assessed in phase 1, including the abbreviated mental test score, modified Barthel index, a transfer and mobility score obtained by combining the transfer and mobility sections of the Barthel index, and several nursing judgements.

RESULTS

In phase 1 five factors were independently associated with a higher risk of falls: fall as a presenting complaint (odds ratio 4.64 (95% confidence interval 2.59 to 8.33); a transfer and mobility score of 3 or 4 (2.10 (1.22 to 3.61)); and primary nurses' judgment that a patient was agitated (20.9 (9.62 to 45.62)), needed frequent toileting (2.48 (1.08 to 5.70)), and was visually impaired (3.56 (1.26 to 10.05)). A risk assessment score (range 0-5) was derived by scoring one point for each of these five factors. In phases 2 and 3 a risk assessment score > 2 was used to define high risk: the sensitivity and specificity of the score to predict falls during the following week was 93% and 88% respectively in phase 2 and 92% and 68% respectively in phase 3.

CONCLUSION

This simple risk assessment tool predicted with clinically useful sensitivity and specificity a high percentage of falls among elderly hospital inpatients.

PIP2 and PIP as determinants for ATP inhibition of KATP channels

Adenosine triphosphate (ATP)-sensitive potassium (KATP) channels couple electrical activity to cellular metabolism through their inhibition by intracellular ATP. ATP inhibition of KATP channels varies among tissues and is affected by the metabolic and regulatory state of individual cells, suggesting involvement of endogenous factors. It is reported here that phosphatidylinositol-4, 5-bisphosphate (PIP2) and phosphatidylinositol-4-phosphate (PIP) controlled ATP inhibition of cloned KATP channels (Kir6.2 and SUR1). These phospholipids acted on the Kir6.2 subunit and shifted ATP sensitivity by several orders of magnitude. Receptor-mediated activation of phospholipase C resulted in inhibition of KATP-mediated currents. These results represent a mechanism for control of excitability through phospholipids.

SecA protein hydrolyzes ATP and is an essential component of the protein translocation ATPase of Escherichia coli

Bacterial protein export requires two forms of energy input, ATP and the membrane electrochemical potential. Using an in vitro reaction reconstituted with purified soluble and peripheral membrane components, we can now directly measure the translocation-coupled hydrolysis of ATP. This translocation ATPase requires inner membrane vesicles, SecA protein and translocation-competent proOmpA. The stimulatory activity of membrane vesicles can be blocked by either antibody to the SecY protein or by preparing the membranes from a secY-thermosensitive strain which had been incubated at the non-permissive temperature in vivo. The SecA protein itself has more than one ATP binding site. 8-azido-ATP inactivates SecA for proOmpA translocation and for translocation ATPase, yet does not inhibit a low level of ATP hydrolysis inherent in the isolated SecA protein. These data show that the SecA protein has a central role in coupling the hydrolysis of ATP to the transfer of pre-secretory proteins across the membrane.

Intracellular anions as the voltage sensor of prestin, the outer hair cell motor protein

Outer hair cells (OHCs) of the mammalian cochlea actively change their cell length in response to changes in membrane potential. This electromotility, thought to be the basis of cochlear amplification, is mediated by a voltage-sensitive motor molecule recently identified as the membrane protein prestin. Here, we show that voltage sensitivity is conferred to prestin by the intracellular anions chloride and bicarbonate. Removal of these anions abolished fast voltage-dependent motility, as well as the characteristic nonlinear charge movement ("gating currents") driving the underlying structural rearrangements of the protein. The results support a model in which anions act as extrinsic voltage sensors, which bind to the prestin molecule and thus trigger the conformational changes required for motility of OHCs.

Identifying predictors of high quality care in English general practice: observational study

OBJECTIVES

To assess variation in the quality of care in general practice and identify factors associated with high quality care.

DESIGN

Observational study.

SETTING

Stratified random sample of 60 general practices in six areas of England.

OUTCOME MEASURES

Quality of management of chronic disease (angina, asthma in adults, and type 2 diabetes) and preventive care (rates of uptake for immunisation and cervical smear), access to care, continuity of care, and interpersonal care (general practice assessment survey). Multiple logistic regression with multilevel modelling was used to relate each of the outcome variables to practice size, routine booking interval for consultations, socioeconomic deprivation, and team climate.

RESULTS

Quality of clinical care varied substantially, and access to care, continuity of care, and interpersonal care varied moderately. Scores for asthma, diabetes, and angina were 67%, 21%, and 17% higher in practices with 10 minute booking intervals for consultations compared with practices with five minute booking intervals. Diabetes care was better in larger practices and in practices where staff reported better team climate. Access to care was better in small practices. Preventive care was worse in practices located in socioeconomically deprived areas. Scores for satisfaction, continuity of care, and access to care were higher in practices where staff reported better team climate.

CONCLUSIONS

Longer consultation times are essential for providing high quality clinical care. Good teamworking is a key part of providing high quality care across a range of areas and may need specific support if quality of care is to be improved. Additional support is needed to provide preventive care to deprived populations. No single type of practice has a monopoly on high quality care: different types of practice may have different strengths.

Acquired cystic disease of the kidneys: a hazard of long-term intermittent maintenance haemodialysis

In the period 1968-76, necropsies were carried out on 30 patients who had been treated by long-term intermittent maintenance haemodialysis. Fourteen of these patients developed bilateral cystic disease of the kidney. Clinical, pathological, and radiological investigation of these patients when they first presented did not reveal any evidence of renal cystic change. The main complications of this condition are haemorrhage and tumour formation. Six patients developed renal tumours, and in five cases these were multiple. The histological appearance of these neoplasms gave no indication as to whether they would behave in an aggressive manner. One patient died of metastatic carcinomatosis from a renal primary. The condition of acquired cystic disease of the kidney should be suspected if patients on maintenance haemodialysis suffer from recurrent haematuria or are found to have enlarging kidneys.

Mutations that alter the signal sequence of alkaline phosphatase in Escherichia coli

A phoA-lacZ gene fusion was used to isolate mutants altered in the alkaline phosphatase signal sequence. This was done by selecting Lac+ mutants from a phoA-lacZ fusion strain that produces a membrane-bound hybrid protein and is unable to grow on lactose. Two such mutant derivatives were characterized. The mutations lie within the phoA portion of the fused gene and cause internalization of the hybrid protein. When the mutations were genetically recombined into an otherwise wild-type phoA gene, they interfered with export of alkaline phosphatase to the periplasm. The mutant alkaline phosphatase protein was found instead in the cytoplasm in precursor form. DNA sequence analysis demonstrated that both mutations lead to amino acid alterations in the signal sequence of alkaline phosphatase.

Gating of Ca2+-activated K+ channels controls fast inhibitory synaptic transmission at auditory outer hair cells

Fast inhibitory synaptic transmission in the central nervous system is mediated by ionotropic GABA or glycine receptors. Auditory outer hair cells present a unique inhibitory synapse that uses a Ca2+-permeable excitatory acetylcholine receptor to activate a hyperpolarizing potassium current mediated by small conductance calcium-activated potassium (SK) channels. It is shown here that unitary inhibitory postsynaptic currents at this synapse are mediated by SK2 channels and occur rapidly, with rise and decay time constants of approximately 6 ms and approximately 30 ms, respectively. This time course is determined by the Ca2+ gating of SK channels rather than by the changes in intracellular Ca2+. The results demonstrate fast coupling between an excitatory ionotropic neurotransmitter receptor and an inhibitory ion channel and imply rapid, localized changes in subsynaptic calcium levels.

Serum aminotransferase levels and platelet counts as predictors of degree of fibrosis in chronic hepatitis C virus infection

OBJECTIVE

In patients with chronic hepatitis C virus (HCV) infection, liver fibrosis stage is a prognostic factor for therapy outcome. So far, a liver biopsy is necessary to determine disease stage accurately. We sought to develop a simple, noninvasive method of accurately predicting the degree of liver fibrosis in chronic HCV infection.

METHODS

We retrospectively studied 211 consecutive patients with chronic HCV, who received a liver biopsy at the Liver Center of the University of California, San Diego. A total of 58 of these patients had a positive history of alcohol abuse, and we analyzed them separately in a sensitivity analysis. AST/ALT ratio and platelet counts were determined in all patients. Fibrosis was staged using the METAVIR score.

RESULTS

Both AST/ALT ratio and platelet counts correlated significantly with the disease stage (r = 0.190, p = 0.006, and r = -0.543, p < 0.00, respectively). In a sensitivity analysis, there was no correlation between AST/ALT ratio and disease stage for patients with a history of alcohol abuse. For patients without history of alcohol abuse, the correlation between disease stage, AST/ALT ratio, and platelet counts was r = 0.297, p < 0.00, and r = 0.560, p < 0.00, respectively. In these patients, AST/ALT ratio > or =1 in combination with a platelet count of <150,000/mm3 can identify patients with severe fibrosis or cirrhosis (stages 3 and 4) with a positive predictive value of 93.1%. Sensitivity, specificity, and negative predictive value were 41.2%, 99.1%, and 85.0%, respectively. In patients with ALT/AST ratio of <1 or platelet counts of >150,000/mm3, these laboratory parameters cannot predict liver fibrosis stage.

CONCLUSION

AST/ALT ratio in combination with platelet counts may obviate a liver biopsy for fibrosis staging in some patients with chronic HCV infection.

Deconstructing Vulnerability for Psychosis: Meta-Analysis of Environmental Risk Factors for Psychosis in Subjects at Ultra High-Risk

Background

Subjects at ultra high-risk (UHR) for psychosis have an enhanced vulnerability to develop the disorder but the risk factors accounting for this accrued risk are undetermined.

Method

Systematic review of associations between genetic or environmental risk factors for psychosis that are widely established in the literature and UHR state, based on comparisons to controls.

Results

Forty-four studies encompassing 170 independent datasets and 54 risk factors were included. There were no studies on association between genetic or epigenetic risk factors and the UHR state that met the inclusion criteria. UHR subjects were more likely to show obstetric complications, tobacco use, physical inactivity, childhood trauma/emotional abuse/physical neglect, high perceived stress, childhood and adolescent low functioning, affective comorbidities, male gender, single status, unemployment and low educational level as compared to controls.

Conclusions

The increased vulnerability of UHR subjects can be related to environmental risk factors like childhood trauma, adverse life events and affective dysfunction. The role of genetic and epigenetic risk factors awaits clarification.

Control of electrical activity in central neurons by modulating the gating of small conductance Ca2+-activated K+ channels

In most central neurons, action potentials are followed by an afterhyperpolarization (AHP) that controls firing pattern and excitability. The medium and slow components of the AHP have been ascribed to the activation of small conductance Ca(2+)-activated potassium (SK) channels. Cloned SK channels are heteromeric complexes of SK alpha-subunits and calmodulin. The channels are activated by Ca(2+) binding to calmodulin that induces conformational changes resulting in channel opening, and channel deactivation is the reverse process brought about by dissociation of Ca(2+) from calmodulin. Here we show that SK channel gating is effectively modulated by 1-ethyl-2-benzimidazolinone (EBIO). Application of EBIO to cloned SK channels shifts the Ca(2+) concentration-response relation into the lower nanomolar range and slows channel deactivation by almost 10-fold. In hippocampal CA1 neurons, EBIO increased both the medium and slow AHP, strongly reducing electrical activity. Moreover, EBIO suppressed the hyperexcitability induced by low Mg(2+) in cultured cortical neurons. These results underscore the importance of SK channels for shaping the electrical response patterns of central neurons and suggest that modulating SK channel gating is a potent mechanism for controlling excitability in the central nervous system.

Two distinct ATP-binding domains are needed to promote protein export by Escherichia coli SecA ATPase

Six putative ATP-binding motifs of SecA protein were altered by oligonucleotide-directed mutagenesis to try to define the ATP-binding regions of this multifunctional protein. The effects of the mutations were analysed by genetic and biochemical assays. The results show that SecA contains two essential ATP-binding domains. One domain is responsible for high-affinity ATP binding and contains motifs A0 and B0, located at amino acid residues 102-109 and 198-210, respectively. A second domain is responsible for low-affinity ATP binding and contains motifs A3 and a predicted B motif located at amino acid residues 503-511 and 631-653, respectively. The ATP-binding properties of both domains were essential for SecA-dependent translocation ATPase and in vitro protein translocation activities. The significance of these findings for the mechanism of SecA-dependent protein translocation is discussed.

Outcome in patients on continuous ambulatory peritoneal dialysis and haemodialysis: 4-year analysis of a prospective multicentre study

In a study in seven large renal units in England, the morbidity and mortality of all patients starting continuous ambulatory peritoneal dialysis (CAPD) and haemodialysis during 1983-85 were monitored prospectively over a 4-year period and related to reasons for choice of therapy and potential risk factors. 610 new patients (median age 52 years, range 3-80 years) started CAPD; 16% had diabetes mellitus and 21% cerebrovascular or cardiovascular disease. 329 patients (median age 48 years, range 5-77 years) started haemodialysis; 7% had diabetes mellitus and 17% cerebrovascular or cardiovascular disease. The Kaplan-Meier patient survival estimates at 4 years were 74% for haemodialysis and 62% for CAPD; technique survival figures for the same period were 91% for haemodialysis and 61% for CAPD. Cox's proportional hazards regression analysis showed that cerebrovascular/cardiovascular disease, age over 60 years, and diabetes mellitus were important predictors for survival in CAPD patients; there were no risk factors associated with permanent change to haemodialysis. In the haemodialysis group early change to CAPD was associated with presence of cerebrovascular or cardiovascular disease. The major cause of drop-out in both groups was transplantation. The mean length of hospital admission was 14.8 days per patient-year for CAPD and 12.4 days per patient-year for haemodialysis.

A modified procedure for fractionating histones

A method is described, which is capable of fractionating histones obtained from any animal source into five major groups. Although the method is based on procedures initially developed by E. W. Johns (1964), involving differential solubility in solutions of acids and of ethanol, it gives a cleaner separation and possesses the considerable advantage that the starting material is whole histone rather than a nucleoprotein preparation.

SecA protein, a peripheral protein of the Escherichia coli plasma membrane, is essential for the functional binding and translocation of proOmpA

We have reconstituted protein translocation across plasma membrane vesicles of Escherichia coli using purified proOmpA and trigger factor, a 63 kd soluble protein. Treatment of membrane vesicles with urea inactivates them for translocation unless a factor present in cytoplasmic extracts is added during the translocation reaction. Sedimentation analysis showed that the stimulatory activity is of distinctly higher mol. wt than trigger factor. Cytoplasmic extracts from a strain that greatly overproduces the SecA protein are highly enriched in the stimulatory activity for untreated membranes and restore translocation to urea-treated membranes, suggesting that this protein is the stimulatory factor. This assay was used to monitor the isolation of SecA protein from the overproducing strain. The purified protein is soluble, yet binds peripherally to membranes with high affinity and supports translocation. Using pure proOmpA, SecA protein, trigger factor and urea-treated membranes, the protein export process was resolved into binding and translocation steps. We find that proOmpA binds to membrane vesicles with or without SecA protein, but that translocation only occurs when SecA was bound prior to proOmpA.

Falls in English and Welsh hospitals: a national observational study based on retrospective analysis of 12 months of patient safety incident reports

INTRODUCTION

Falls in hospital inpatients are common, with reported rates ranging from 3 to 14 per 1,000 bed days. They cause physical and psychological harm, are associated with impaired rehabilitation, increased length of stay and excess cost, and lead to complaints and litigation, making them a crucial area for risk management. A National Reporting and Learning System (NRLS) for patient safety incidents in England and Wales was utilised to examine frequency of falls in hospitals specialising in acute care, rehabilitation and mental health; related harm; timing; age and gender of patients who fell; and to draw general lessons from this which might inform fall-prevention strategies.

METHODS

The NRLS database was searched retrospectively for slips, trips and falls occurring between 1 September 2005 and 31 August 2006. Organisations were classified as "regularly reporting" if they returned reports at least monthly and with at least 100 patient safety incidents per month for acute trusts and 50 per month for community and mental health trusts. Falls rates were standardised as number of falls per 1,000 occupied bed days. Reporting hospitals used standardised categories for degree of harm from incidents, and injury rates were calculated as the percentage of injuries by severity per fall. Key word searches combined with free text scrutiny were conducted to identify specific injuries. Specific falls rates for time of day, gender and age were also compared, with age and gender adjusted for bed occupancy rates from Hospital Episode Statistics (HES) data. Most data were used descriptively, though 95% confidence intervals were used to facilitate comparisons between groups and where samples are generalised to the data set as a whole.

RESULTS

Reports of 206,350 falls were received from a total of 472 organisations. Falls incidents accounted for 32.3% of all reported patient safety incidents. 152,069 (73.7%) reports were from acute hospitals, 28,198 (13.7%) from community hospitals, and 26,083 (12.6%) from mental health units. Only 102 of these could be classified as "regularly reporting" organisations, and in these the mean standardised rates of falls per 1,000 bed days were 4.8 in acute hospitals, 2.1 in mental health units and 8.4 in community hospitals. 133,417 falls (64.7%) resulted in "no harm," 64,144 (31.1%) in "low harm," 7,506 (3.6%) in "moderate harm," and 1230 (0.6%) in "severe harm," with 26 reported deaths. The proportions of falls resulting in some degree of harm varied significantly across the care settings: mental health units (44.5%; 95% CI 43.9 to 45.1), community hospitals (37.0%; 95% CI 36.4 to 37.6) and acute hospitals (33.4%; 95% CI 33.2 to 33.7). Patients aged 85-89 years had a higher-than-expected likelihood of falling relative to bed days. Males accounted for 50.8% (95% CI 50.5 to 51.1) of falls and females 49.2% (95% CI 48.9 to 49.5). (Occupied bed days were 45.5% male and 54.4% female.) The proportion of falls varied considerably with time, with a peak occurring between 10:00 and 11:59.

DISCUSSION

This paper describes the largest retrospective study of hospital falls incidents and draws on data from almost 500 institutions of varying types. It describes wide variations in falls recording and reporting, and in recorded falls rates between institutions of different types and between institutions of ostensibly similar case-mix. As falls are the commonest reported patient safety incident, there is a pressing need for improvements in local reporting, recording and focused analysis of incident data, and for these data to be used at local and national level better to inform and target falls prevention, as well as to explore the reasons for large apparent differences in falls rates between institutions.

Multicenter seroepidemiologic study of the impact of cytomegalovirus infection on renal transplantation

The effects of cytomegalovirus (CMV) infection on patient and allograft survival were determined in 1245 renal transplant recipients from 46 transplant centers. When an antilymphocyte preparation was administered to cadaveric allograft recipients, those at risk for primary CMV had a worse outcome than similar patients treated with prednisone and azathioprine (53.1% alive at 6 months with a functioning allograft vs. 70.8%, P = .05) or patients at risk for reactivation CMV (53.1% vs. 71.1%, P = .035). Patients at risk for reactivation CMV had a better outcome if they received an antilymphocyte preparation (71.1% vs. 60.8%, P less than .01). The type of immunosuppression had no effect on patients without CMV. Living-related donor transplantation was not significantly influenced by CMV or type of immunosuppression. We conclude that CMV infection is strongly influenced by the form of immunosuppression employed, and that both are important determinants of the outcome of cadaveric renal transplantation.

The course of the terminal phase in patients with amyotrophic lateral sclerosis

The fear of "choking to death" is on the mind of most patients suffering from amyotrophic lateral sclerosis (ALS). So far, however, there have been no systematic surveys concerning the dying phase in a general ALS population. We therefore performed a structured telephone interview with the relatives of 121 patients who died from ALS and were followed by the Motor Neuron Outpatient Clinic of the Department of Neurology, University of Munich, Germany. These data are compared with those obtained by a retrospective analysis of medical records of 50 ALS patients who were followed by the Wisdom Hospice, Rochester, UK. The data show that most ALS patients (Germany 88%, UK 98%) died peacefully, and no patient "choked to death". The symptoms most frequently reported for the last 24 hours were dyspnoea, coughing, anxiety and restlessness. Around half (G 55%, UK 52%) of the patients died at home. The main palliative measures in place during the terminal phase were: home mechanical ventilation (G 21%, UK 0%), percutaneous endoscopic gastrostomy (G 27%, UK 14%), morphine (G 27%, UK 82%) and benzodiazepines (G 32%, UK 64%). The use of these palliative measures was judged to be beneficial by almost all relatives. These data support the hypothesis of a peaceful death process in ALS and should be communicated to patients and their relatives, at the latest after the onset of dyspnoea, to relieve unwarranted fears.

Brown-midrib maize (bm1)--a mutation affecting the cinnamyl alcohol dehydrogenase gene

Brown-midrib (bm) mutants of maize have modified lignin of reddish-brown colour. Although four independent bm loci are known, only one of the mutant genes has been previously identified. We report here that maize bm1, one of the less characterised mutants, shows severely reduced CAD activity in lignified tissues, resulting in the production of a modified lignin. Both the total lignin content and the structure of the polymer are altered by the mutation. We further describe the isolation and characterisation of the maize CAD cDNA and mapping of the CAD gene. CAD maps very closely to the known location of bm1 and co-segregates with the bm1 locus in two independent recombinant inbred populations. These data strongly support the premise that maize bm1 directly affects expression of the CAD gene.

SecA protein is exposed to the periplasmic surface of the E. coli inner membrane in its active state

E. coli cells harboring pCG169 containing the secD secF locus possessed SecA protein almost entirely in an integral membrane form in which it displayed normal protein translocation activity. These results imply that integral membrane SecA is the catalytically active form of this enzyme and that products of the secD secF locus regulate SecA association with the inner membrane. Protease and biotinylation accessibility studies of right side-out and inside-out membrane vesicles derived from this strain revealed that SecA was exposed to the periplasmic surface of the inner membrane. These studies suggest a model of bacterial protein secretion, whereby insertion of SecA into the inner membrane and its association with SecY/E/G promotes assembly of active protein-conducting channels comprised in part of integral membrane SecA protein, and products of the secD secF locus regulate the channel assembly-disassembly reaction by modulating the SecA insertion-deinsertion step.

Do hospital fall prevention programs work? A systematic review

OBJECTIVES

To analyze published hospital fall prevention programs to determine whether there is any effect on fall rates. To review the methodological quality of those programs and the range of interventions used. To provide directions for further research.

DESIGN

Systematic review of published hospital fall prevention programs. Meta-analysis.

METHODS

Keyword searches of Medline, CINAHL, monographs, and secondary references. All papers were included that described fall rates before and during intervention. Risk ratios and 95% Confidence Intervals (95% CI) were estimated and random effects meta-analysis employed. Begg's test was applied to detect possible publication bias. Separate meta-analysis regressions were performed to determine whether individual components of multifaceted interventions were effective.

RESULTS

A total of 21 papers met the criteria (18 from North America), although only 10 contained sufficient data to allow calculation of confidence intervals. A rate ratio of <1 indicates a reduction in the fall rate, resulting from an intervention. Three were randomized controlled trials (pooled rate ratio 1.0 (CI 0.60, 1.68)), seven prospective studies with historical control (0.76 (CI 0.65, 0.88)). Pooled effect rate ratio from these 10 studies was 0.79 (CI 0.69, 0.89). The remaining 11 studies were prospective studies with historical control describing fall rates only. Individual components of interventions showed no significant benefit.

DISCUSSION

The pooled effect of about 25% reduction in the fall rate may be a result of intervention but may also be biased by studies that used historical controls not allowing for historical trends in the fall rate before and during the intervention. The randomized controlled trials apparent lack of effect might be due to a change in practice when patients and controls were in the same unit at the same time during a study. Studies did not analyze compliance with the intervention or opportunity costs resulting from the intervention. Research and clinical programs in hospital fall prevention should pay more attention to study design and the nature of interventions.

Reciprocal electromechanical properties of rat prestin: the motor molecule from rat outer hair cells

Cochlear outer hair cells (OHCs) are responsible for the exquisite sensitivity, dynamic range, and frequency-resolving capacity of the mammalian hearing organ. These unique cells respond to an electrical stimulus with a cycle-by-cycle change in cell length that is mediated by molecular motors in the cells' basolateral membrane. Recent work identified prestin, a protein with similarity to pendrin-related anion transporters, as the OHC motor molecule. Here we show that heterologously expressed prestin from rat OHCs (rprestin) exhibits reciprocal electromechanical properties as known for the OHC motor protein. Upon electrical stimulation in the microchamber configuration, rprestin generates mechanical force with constant amplitude and phase up to a stimulus frequency of at least 20 kHz. Mechanical stimulation of rprestin in excised outside-out patches shifts the voltage dependence of the nonlinear capacitance characterizing the electrical properties of the molecule. The results indicate that rprestin is a molecular motor that displays reciprocal electromechanical properties over the entire frequency range relevant for mammalian hearing.

Topology of the integral membrane form of Escherichia coli SecA protein reveals multiple periplasmically exposed regions and modulation by ATP binding

SecA insertion and integration into the Escherichia coli inner membrane is a critical step for the catalysis of protein translocation across this layer. To understand this step further, SecA topology was investigated. To determine which regions of SecA are periplasmically exposed, right-side out membrane vesicles were prepared from strains synthesizing monocysteine SecA variants produced by mutagenesis and probed with a membrane-impermeant sulfhydryl-labeling reagent. To determine which regions of SecA contain membrane-integration determinants, inverted inner membrane vesicles were subjected to proteolysis, and integral-membrane fragments of SecA were identified with region-specific antibodies. The membrane association properties of various truncated SecA species produced in vivo were also determined. Our analysis indicates that the membrane topology of SecA is complex with amino-terminal, central, and carboxyl-terminal regions of SecA integrated into the membrane where portions are periplasmically accessible. Furthermore, the insertion and penetration of the amino-terminal third of SecA, which includes the proposed preprotein-binding domain, is subject to modulation by ATP binding. The importance of these studies to the cycle of membrane insertion and de-insertion of SecA that promotes protein translocation and SecA's proximity to the preprotein channel are discussed.