Measuring diet cost at the individual level: a comparison of three methods

Background/objectives:

Household-level food spending data are not suitable for population-based studies of the economics of nutrition. This study compared three methods of deriving diet cost at the individual level.

Subjects/methods:

Adult men and women (n=164) completed 4-day diet diaries and a food frequency questionnaire (FFQ). Food expenditures over 4 weeks and supermarket prices for 384 foods were obtained. Diet costs (US$/day) were estimated using: (1) diet diaries and expenditures; (2) diet diaries and supermarket prices; and (3) FFQs and supermarket prices. Agreement between the three methods was assessed on the basis of Pearson correlations and limits of agreement. Income-related differences in diet costs were estimated using general linear models.

Results:

Diet diaries yielded mean (s.d.) diet costs of $10.04 (4.27) based on Method 1 and $8.28 (2.32) based on Method 2. FFQs yielded mean diet costs of $7.66 (2.72) based on Method 3. Correlations between energy intakes and costs were highest for Method 3 (r²=0.66), lower for Method 2 (r²=0.24) and lowest for Method 1 (r²=0.06). Cost estimates were significantly associated with household incomes.

Conclusion:

The weak association between food expenditures and food intake using Method 1 makes it least suitable for diet and health research. However, merging supermarket food prices with standard dietary assessment tools can provide estimates of individual diet cost that are more closely associated with food consumed. The derivation of individual diet cost can provide insights into some of the economic determinants of food choice, diet quality and health.

Cryopreservation of Greenshell™ mussel (Perna canaliculus) trochophore larvae

The Greenshell™ mussel (Perna canaliculus) is the main shellfish species farmed in New Zealand. The aim of this study was to evaluate the effects of cryoprotectant concentration, loading and unloading strategy as well as freezing and thawing method in order to develop a protocol for cryopreservation of trochophore larvae (16-20 h old). Toxicity tests showed that levels of 10-15% ethylene glycol (EG) were not toxic to larvae and could be loaded and unloaded in a single step. Through cryopreservation experiments, we designed a cryopreservation protocol that enabled 40-60% of trochophores to develop to D-larvae when normalized to controls. The protocol involved: holding at 0 °C for 5 min, then cooling at 1 °C min⁻¹ to -10 °C, holding for a further 5 min, then cooling at 0.5 °C min⁻¹ to -35 °C followed by a 5 min hold and then plunging into liquid nitrogen. A final larval rearing experiment of 18 days was conducted to assess the ability of these frozen larvae to develop further. Results showed that only 2.8% of the frozen trochophores were able to develop to competent pediveligers.

Cholesterol addition and removal in pacific oyster oocytes does not improve cryopreservation success

The optimal cholesterol content in cells could provide the benefit of lowering or eliminating the lipid phase transition temperature, while maintaining membrane fluidity and strength; thus, making cells less sensitive to chilling injury and more amenable to cryopreservation. Such effects were shown in some gametes and embryos of certain mammalian species, however, some other cell types, benefited from cholesterol removal. The experiments developed in this study aimed to determine the effect of incubating Pacific oyster (Crassostrea gigas) oocytes in cholesterol-addition or removal solutions prior to cryopreservation on their post-thaw fertilization ability. The results showed a positive association of cholesterol with the oocytes when assessed by fluorescent microscopy. However, this uptake was not reflected by an increase in cholesterol as determined by colorimetric analysis or in the post-thaw fertilization rate of treated oocytes. It is presumed either that oyster oocytes already contain a substantial amount of cholesterol or other lipids in their plasma membranes and do not benefit from any additional cholesterol or there is no lipid phase transition temperature in oyster oocytes.

Survival of Pacific oyster, Crassostrea gigas, oocytes in relation to intracellular ice formation

The effect of IIF in Pacific oyster oocytes was studied using cryo and transmission electron microscopy (TEM). The viability of oocytes at each step of a published cryopreservation protocol was assessed in an initial experiment. Two major viability losses were identified; one when oocytes were cooled to -35 degrees C and the other when oocytes were plunged in liquid nitrogen. Although the cryomicroscope showed no evidence of IIF in oocytes cooled with this protocol, TEM revealed that these oocytes contained ice crystals and were at two developmental stages when frozen, prophase and metaphase I. To reduce IIF, the effect of seven cooling programmes involving cooling to -35 or -60 degrees C at 0.1 or 0.3 degrees C min(-1) and holding for 0 or 30 min at -35 or -60 degrees C was evaluated on post-thaw fertilization rate of oocytes. Regardless of the cooling rate or holding time, the fertilization rate of oocytes cooled to -60 degrees C was significantly lower than that of oocytes cooled to -35 degrees C. The overall results indicated that observations of IIF obtained from cryomicroscopy are limited to detection of larger amounts of ice within the cells. Although the amount of cellular ice may have been reduced by one of the programmes, fertilization was reduced significantly; suggesting that there is no correlation between the presence of intracellular ice and post-thaw fertilization rate. Therefore, oyster oocytes may be more susceptible to the effect of high solute concentrations and cell shrinkage than intracellular ice under the studied conditions.

Successful cryopreservation of Pacific oyster (Crassostrea gigas) oocytes

Protocols for cryopreservation of sperm and oocytes would provide the ultimate control over parental crosses in selective breeding programmes. Sperm freezing is routine for many species, but oocyte freezing remains problematic, with virtually zero success in aquatic species to date. This paper describes the development of a successful protocol for cryopreserving high concentrations of Pacific oyster (Crassostrea gigas) oocytes. Ethylene glycol (10%) and dimethyl sulfoxide (15%) were found to be the most effective cryoprotectants resulting in post-thaw fertilization rates of 51.0+/-8.0 and 45.1+/-8.3%, respectively. Propylene glycol was less effective and methanol resulted in zero fertilization post-thaw. The use of Milli-Q water rather than seawater as a base medium significantly improved fertilization (20.4+/-3.0 and 8.7+/-2.2%, respectively) as did the inclusion of a 5 min isothermal hold at -10 or -12 degrees C (35.9+/-5.0 and 31.9+/-4.6%, respectively). The optimal cooling rate post-hold was 0.3 degrees C min(-1), with virtually zero post-thaw fertilization with cooling rates of 3 and 6 degrees C min(-1). Using an optimized protocol, post-thaw fertilization rates for oocytes from eight individual females ranged from 0.8 to 74.5% and D-larval yields from 0.1 to 30.1%. For three individuals, larvae were reared through to spat. Development of D-larvae to eyed larvae and spat was similar for larvae produced from unfrozen (24.8+/-4.1% developed to eyed larvae and 16.5+/-3.2% to spat) and cryopreserved (28.4+/-0.6 and 18.7+/-0.5%, respectively) oocytes. The ability to cryopreserve large quantities of oyster oocytes represents a major advance in cryobiology and selective breeding.

Smad-Runx interactions during chondrocyte maturation

BACKGROUND

Intracellular signaling triggered by bone morphogenetic proteins (BMPs) results in activated Smad complexes that regulate transcription of BMP-responsive genes. However, the low specificity of Smad binding to regulatory sequences implies that additional tissue-specific transcription factors are also needed. Runx2 (Cbfal) is a transcription factor required for bone formation. We have examined the role of Smads and Runx2 in BMP induction of type X collagen, which is a marker of chondrocyte hypertrophy leading to endochondral bone formation.

METHODS

Pre-hypertrophic chondrocytes from the cephalic portion of the chick embryo sternum were placed in culture in the presence or absence of rhBMP-2. Cultures were transiently transfected with DNA containing the BMP-responsive type X collagen promoter upstream of the luciferase gene. The cultures were also transfected with plasmids, causing over-expression of Smads or Runx2, or both. After 24-48 hours, cell extracts were examined for levels of luciferase expression.

RESULTS

In the presence of BMP-2, chondrocytes over-expressing BMP-activated Smadl or Smad5 showed significant enhancement of luciferase production compared with that seen with BMP alone. This enhancement was not observed with over-expression of Smad2, a transforming growth factor beta (TGF-beta)-activated Smad. Overexpression of Runx2 in BMP-treated cultures increased transcriptional activity to levels similar to those seen with Smads 1 or 5. When chondrocytes were simultaneously transfected with both Runx2 and Smad 1 or 5, promoter activity was further increased, indicating that BMP-stimulated Smad activity can be augmented by increasing the levels of Runx2.

CONCLUSIONS

These results implicate the skeletal tissue transcription factor Runx2 in regulation of chondrocyte hypertrophy and suggest that maximal transcription of the type X collagen gene in pre-hypertrophic chondrocytes involves interaction of BMP-stimulated Smads with Runx2.

CLINICAL RELEVANCE

Many skeletal abnormalities are associated with impaired regulation of chondrocyte hypertrophy in growth plates. These studies demonstrate that both BMP-activated Smads and Runx2 levels can modulate chondrocyte transition to hypertrophy.

Transient chondrogenic phase in the intramembranous pathway during normal skeletal development

Calvarial and facial bones form by intramembranous ossification, in which bone cells arise directly from mesenchyme without an intermediate cartilage anlage. However, a number of studies have reported the emergence of chondrocytes from in vitro calvarial cell or organ cultures and the expression of type II collagen, a cartilage-characteristic marker, in developing calvarial bones. Based on these findings we hypothesized that a covert chondrogenic phase may be an integral part of the normal intramembranous pathway. To test this hypothesis, we analyzed the temporal and spatial expression patterns of cartilage characteristic genes in normal membranous bones from chick embryos at various developmental stages (days 12, 15 and 19). Northern and RNAse protection analyses revealed that embryonic frontal bones expressed not only the type I collagen gene but also a subset of cartilage characteristic genes, types IIA and XI collagen and aggrecan, thus resembling a phenotype of prechondrogenic-condensing mesenchyme. The expression of cartilage-characteristic genes decreased with the progression of bone maturation. Immunohistochemical analyses of developing embryonic chick heads indicated that type II collagen and aggrecan were produced by alkaline phosphatase activity positive cells engaged in early stages of osteogenic differentiation, such as cells in preosteogenic-condensing mesenchyme, the cambium layer of periosteum, the advancing osteogenic front, and osteoid bone. Type IIB and X collagen messenger RNAs (mRNA), markers for mature chondrocytes, were also detected at low levels in calvarial bone but not until late embryonic stages (day 19), indicating that some calvarial cells may undergo overt chondrogenesis. On the basis of our findings, we propose that the normal intramembranous pathway in chicks includes a previously unrecognized transient chondrogenic phase similar to prechondrogenic mesenchyme, and that the cells in this phase retain chondrogenic potential that can be expressed in specific in vitro and in vivo microenvironments.

The internal chondrocyte-specific promoter of the chick type III collagen gene is activated by AP1 and is repressed in fibroblasts by a complex containing an LBP1-related protein

The chick type III collagen gene contains an internal promoter in intron 23 in addition to the promoter preceding exon 1. The internal promoter, which is used preferentially in cultured chondrocytes, directs production of an alternative transcript that cannot encode type III collagen. This promoter is used ineffic-iently in skin fibroblasts, which transcribe the gene from the upstream promoter. We show below that the internal promoter is regulated by an activation element containing a potential activator protein 1 (AP1) site and a repressor element containing a potential binding site for leader binding protein 1 (LBP1). Electro-phoretic mobility shift assays indicate that the activation and repressor elements are bound by AP1 and an LBP1-related protein, respectively. Replacement of the AP1 site resulted in substantially decreased promoter activity in both chondrocytes and fibroblasts, indicating that this site is required for promoter function, but the low level of promoter activity in fibro-blasts is not due to loss of functional AP1. In contrast, replacement of the LBP1-like site increased activity only in fibroblasts, suggesting that this site is responsible in part for repression of promoter activity in fibroblasts.

Legionella: a new millennium bug

With the expanding elderly and immunocompromised populations and with creation of new ecological niches for the organism, the clinical laboratory scientist can expect to encounter Legionella in the twenty-first century. Inability to detect this pathogen with routine culture and staining techniques presents an ongoing problem. Clinical laboratory scientists need to consider implementation of special culture protocols and urinary antigen procedures. Prompt recognition of Legionella leads to the initiation of effective antimicrobial therapy. This is one area where clinical microbiology can directly affect patient outcome.

Retinoid signaling is required for chondrocyte maturation and endochondral bone formation during limb skeletogenesis

Retinoids have long been known to influence skeletogenesis but the specific roles played by these effectors and their nuclear receptors remain unclear. Thus, it is not known whether endogenous retinoids are present in developing skeletal elements, whether expression of the retinoic acid receptor (RAR) genes alpha, beta, and gamma changes during chondrocyte maturation, or how interference with retinoid signaling affects skeletogenesis. We found that immature chondrocytes present in stage 27 (Day 5.5) chick embryo humerus exhibited low and diffuse expression of RARalpha and gamma, while RARbeta expression was strong in perichondrium. Emergence of hypertrophic chondrocytes in Day 8-10 embryo limbs was accompanied by a marked and selective up-regulation of RARgamma gene expression. The RARgamma-rich type X collagen-expressing hypertrophic chondrocytes lay below metaphyseal prehypertrophic chondrocytes expressing Indian hedgehog (Ihh) and were followed by mineralizing chondrocytes undergoing endochondral ossification. Bioassays revealed that cartilaginous elements in Day 5.5, 8.5, and 10 chick embryo limbs all contained endogenous retinoids; strikingly, the perichondrial tissues surrounding the cartilages contained very large amounts of retinoids. Implantation of beads filled with retinoid antagonist Ro 41-5253 or AGN 193109 near the humeral anlagens in stage 21 (Day 3.5) or stage 27 chick embryos severely affected humerus development. In comparison to their normal counterparts, antagonist-treated humeri in Day 8.5-10 chick embryos were significantly shorter and abnormally bent; their diaphyseal chondrocytes had remained prehypertrophic Ihh-expressing cells, did not express RARgamma, and were not undergoing endochondral ossification. Interestingly, formation of an intramembranous bony collar around the diaphysis was not affected by antagonist treatment. Using chondrocyte cultures, we found that the antagonists effectively interfered with the ability of all-trans-retinoic acid to induce terminal cell maturation. The results provide clear evidence that retinoid-dependent and RAR-mediated mechanisms are required for completion of the chondrocyte maturation process and endochondral ossification in the developing limb. These mechanisms may be positively influenced by cooperative interactions between the chondrocytes and their retinoid-rich perichondrial tissues.

Evaluation and conservative management of chronic lower extremity arterial disease

Aging of the population has made atherosclerotic cardiovascular disease one of the most significant health problems in the United States. Primary care providers are often the first contact for persons presenting with symptoms of chronic lower extremity arterial disease. Accurate assessment can prevent erroneous referrals, unnecessary diagnostic studies, and added time and medical expense for patients. Understanding of the natural history and risk factors associated with chronic lower extremity arterial disease provides the foundation for developing a knowledgeable, comprehensive plan of care for patients. Through multidisciplinary collaboration and a strong commitment to patient education and support, care providers can enhance the quality of life for individuals with chronic lower extremity arterial disease.

Predicting patient satisfaction: a study of two emergency departments

To identify perceptions that predict overall patient (dis)satisfaction with Emergency Department (ED) care, we studied responses to a survey mailed to all discharged patients over a 6-month period (Academic Hospital), and to a telephone interview of a random sample of discharged patients over a 1-year period (Community Hospital). The survey and interview both assessed overall satisfaction, as well as satisfaction with perceived waiting times, information delivery, and expressive quality of physicians, nurses, and staff. Data for 1176 patients (training sample) and 1101 patients (holdout sample) who rated overall satisfaction as either "very good" or "very poor" (Academic Hospital), and for 856 patients (training sample) and 431 patients (holdout sample) who rated overall satisfaction as either "excellent" or "poor" (Community Hospital), were retained for analysis. For both hospitals, nonlinear tree models efficiently achieved overall classification accuracy exceeding 98% in training analysis and 95% in holdout analysis (all p < .0001). The findings suggest that overall patient (dis)satisfaction with care received in the ED is nearly perfectly predictable on the basis of patient-rated expressive qualities of ED staff, particularly physicians and nurses. Interventions designed to reinforce positive (and extinguish negative) expressive health-care provider behaviors may cut the number of extremely dissatisfied patients in half.

Ambulatory blood pressure and Holter monitoring of emergency physicians before, during, and after a night shift

BACKGROUND

Occupational stress may affect measured hemodynamic and electrocardiographic variables. Data describing the physiologic effects of work on the emergency physician (EP) are sparse.

OBJECTIVE

To determine whether blood pressure (BP) and heart rate variability (HRV) of the EP are affected during a night shift in the ED.

METHODS

This prospective study evaluated BP and HRV in attending EPs at an urban academic medical center for a 24-hour period during which a night shift was scheduled. Participants were fitted with an oscillometric ambulatory BP device and a Holter monitor at 1500 hours on the day of a night shift. The monitors were worn continuously before, during, and after a night shift (2300-0700) in the ED and were removed at 1500. Systolic BP (SBP), diastolic BP (DBP), mean arterial pressure (MAP), heart rate (HR), measures of HRV, and occurrence of cardiac dysrhythmias were evaluated. Comparisons were made for ED and non-ED awake periods and non-ED sleep periods.

RESULTS

Twelve participants completed the study. Eight (67%) subjects were men and 4 (33%) were women. Age ranged from 28 to 40 years (mean 34.1+/-4.1). Results were analyzed using repeated-measures ANOVA. An elevation of mean DBP (5.5 mm Hg+/-4.37; p < 0.05; 95% CI 1-10) during night shift activity was seen. A trend toward elevation of SBP, MAP, and HR was discernible. HRV measures indicated a significant relative increase in sympathetic vs parasympathetic tone and an increase in HR of prework and work compared with postwork. Dysrhythmias observed included sinus tachycardia, sinus bradycardia, sinus pause, atrial premature beats, atrial couplets and triplets, supraventricular tachycardia, and premature ventricular contractions.

CONCLUSIONS

The elevation of DBP during a night shift suggests that these patterns of BP variability are activity- or stress-related rather than a result of a true diurnal variation. HRV analysis suggests that sympathetic tone is heightened both before work and during work. The implications of such findings to the health of the EP warrant further investigation.

Dichotomous effects of beta-chemokines on HIV replication in monocytes and monocyte-derived macrophages

The role of beta-chemokines in the pathogenesis of HIV disease remains undefined. Given the potent capacities of these proteins to attract mononuclear cells to inflammatory sites, such as lymph nodes of patients with HIV disease, the effects of exposure of monocytes and monocyte-derived macrophages to beta-chemokines before HIV infection were compared with their effects when added either simultaneously with or after HIV infection. In this system, HIV replication was substantially increased in cells that had been exposed to beta-chemokines before HIV infection. These effects were pertussis toxin sensitive. By contrast, HIV replication was inhibited in cells that had been exposed to beta-chemokines either simultaneously with or after HIV infection. These effects were not pertussis toxin sensitive. In view of this potent capacity of beta-chemokines to stimulate HIV replication, treatment approaches for HIV disease based on the apparent inhibitory activity of these proteins on viral replication should be undertaken with caution.

The gene encoding the elongation factor P protein is essential for viability and is required for protein synthesis

Elongation factor P (EFP) is a protein that stimulates the peptidyltransferase activity of fully assembled 70 S prokaryotic ribosomes and enhances the synthesis of certain dipeptides initiated by N-formylmethionine. This reaction appears conserved throughout species and is promoted in eukaryotic cells by a homologous protein, eIF5A. Here we ask whether the Escherichia coli gene encoding EFP is essential for cell viability. A kanamycin resistance (KanR) gene was inserted near the N-terminal end of the efp gene and was cloned into a plasmid, pMAK705, that has a temperature-sensitive origin of replication. After transformation into a recA+ E. coli strain, temperature-sensitive mutants were isolated, and their chromosomal DNA was sequenced. Mutants containing the efp-KanR gene in the chromosome grew at 33 degrees C only in the presence of the wild-type copy of the efp gene in the pMAK705 plasmid and were unable to grow at 44 degrees C. Incorporation of various isotopes in vivo suggests that translation is impaired in the efp mutant at 44 degrees C. At 44 degrees C, mutant cells are severely defective in peptide-bond formation. We conclude that the efp gene is essential for cell viability and is required for protein synthesis.

T-cell response to HIV in natural infection: optimized culture conditions for detecting responses to gag peptides

The proliferative responses to four gag peptides were examined in 24 HIV-seropositive patients whose CD4 counts ranged between 500 and 1400 cells/mm3. To overcome some of the limitations imposed by HIV infection on the T-cell proliferative assay, recombinant interleukin 2 (rIL-2) was added to the cultures, and the culture time of the cells was increased from the standard 6 to 8 or 10 days. Four of 24 patients responded to one or more core peptides, aa180-194, 208-217, 267-286, and 287-306 by the standard 6-day culture: this increased to 13 of 24 using the optimized culture approach. The greatest number and magnitude of responses occurred after cells were in culture for 8 days. Eight patients responded to gag 180-194, which has not been identified previously as a TH epitope in humans but has considerable homology with a TH epitope recognized by cloned T cells from macaques immunized with simian immunodeficiency virus (SIV). We have identified four T-cell epitopes on the HIV core protein p24, using synthetic peptides as immunogens. Three of the peptides would not have been considered immunogenic had the standard assay system been used to detect T-cell responsiveness. We have also shown that a region of the core protein encompassed by aa180-194 is recognized by TH cells in humans.

Role of nuclear cardiology in the evaluation of acute coronary syndromes

Over the last 20 years, nuclear cardiology has become a mainstay in the evaluation of ischemic heart disease. In the setting of acute coronary syndromes (myocardial infarction or unstable angina), myocardial perfusion imaging has emerged as an important tool in assessing the functional significance of angiographic coronary stenoses, evaluating the efficacy of therapeutic interventions, and risk-stratifying patients in the postinfarction period. Recent literature has demonstrated the diagnostic and prognostic value, as well as the cost-effectiveness, of perfusion imaging in acute chest pain syndromes and the diagnostic superiority of perfusion imaging compared with two-dimensional echocardiography. Acute perfusion imaging is now being included in the algorithm for the triage and management of acute chest pain syndromes. Emergency physicians are increasingly using nuclear cardiac imaging modalities for aid in the evaluation of patients who present with chest pain of uncertain origin.

The chick type III collagen gene contains two promoters that are preferentially expressed in different cell types and are separated by over 20 kb of DNA containing 23 exons

Type III collagen is present in prechondrogenic mesenchyme, but not in cartilages formed during endochondral ossification. However, cultured chick chondrocytes contain an unusual transcript of the type III collagen gene in which exons 1-23 are replaced with a previously undescribed exon, 23A; this alternative transcript does not encode type III collagen. This observation suggested that, although production of type III collagen mRNA is repressed in chondrocytes, transcription of the type III collagen gene may continue from an alternative promoter. To test this prediction, we isolated and characterized both the upstream and internal promoters of this gene and tested their ability to direct transcription in chondrocytes and skin fibroblasts. The upstream promoter is active in fibroblasts, but inactive in chondrocytes, indicating that repression of type III collagen synthesis during chondrogenesis is transcriptionally mediated. Additionally, sequences in intron 23, preceding exon 23A, function as a highly active promoter in chondrocytes; transcription from this promoter is repressed in fibroblasts. Thus transcriptional control of the type III collagen gene is highly complex, with two promoters separated by at least 20 kb of DNA that are preferentially expressed in different cell types and give rise to RNAs with different structures and functions.

Annexin V-mediated calcium flux across membranes is dependent on the lipid composition: implications for cartilage mineralization

Annexin V is a major component of matrix vesicles and has a role in mediating the influx of Ca2+ into these vesicles, thus promoting the initiation of hypertrophic cartilage matrix mineralization. However, the mechanisms and factors regulating annexin V-mediated Ca2+ influx into these vesicles are not well understood. Since the lipid composition of matrix vesicles differs from that of the plasma membrane of chondrocytes and is rich in phosphatidylserine, we asked whether the lipid composition may regulate annexin V function. We prepared liposomes containing different concentrations of phosphatidylserine and determined how the lipid composition affected (a) the interactions between annexin V and liposomes and (b) annexin V-mediated Ca2+ influx into the liposomes. We found that annexin V was able to bind to every liposome tested. However, we observed the most prominent increases in tryptophan 187 emission intensity, a measure of the degree of interactions between annexin V and lipid bilayers, only with liposomes containing a high concentration of phosphatidylserine. In addition, a significant fraction of annexin V associated with phosphatidylserine-rich liposomes was not extractable by EDTA treatment but required a detergent, indicating that annexin V inserts into bilayers of these liposomes. Chemical cross-linking analysis revealed that matrix vesicles and phosphatidylserine-rich liposomes induced the formation of the annexin V hexamer. Interestingly, a significant Ca2+ influx in the presence of annexin V occurred only in liposomes containing a high phosphatidylserine content. Moreover, annexin V-mediated Ca2+ influx into these liposomes was inhibited (i) by anti-annexin V antibodies and (ii) by treatment with zinc and cadmium, indicating the essential role of the protein in Ca2+ influx. The results of this study indicate that phosphatidylserine-rich bilayers induce the formation of a hexameric annexin V, possibly leading to a Ca2+-dependent insertion of annexin V into the bilayer and establishment of annexin V-mediated Ca2+ influx into matrix vesicles or liposomes. The phosphatidylserine-rich membrane of matrix vesicles in vivo may thus offer an ideal specialized environment in which the biological function of annexin V is optimized, leading to rapid Ca2+ influx, intralumenal crystal growth, and cartilage matrix mineralization.

Clinical use of the patellar-pubic percussion sign in hip trauma

To assess the reliability and validity of osteophony (patellar-pubic percussion [PPP] test) as a physical diagnostic sign in the evaluation of hip trauma, a prospective study was undertaken of 41 consecutive patients presenting to the emergency department with a history of hip trauma necessitating radiographic examination. Fifteen of 19 (78.9%) patients who presented with a history of hip trauma and a fracture on radiograph were found to have had an abnormal PPP sign by at least one of two raters (P < .0001). Only 1 of 22 (4.6%) patients without evidence of fracture (eg, contusion) had an abnormal PPP sign. This patient had diffuse Paget's disease. Nine of 10 (90%) patients who had trochanteric fractures had an abnormal PPP sign (P < .02). Overall reliability of the PPP sign based on two observers was 90.2% (P < .0001). In those patients with radiographic evidence of fracture, interrater reliability was 84.2% (P < .0001). For patients in whom physicians agreed on the PPP sign, the PPP test resulted in a 0% false-positive error and a 25% false-negative error. For patients in whom either physician noted an abnormal PPP sign, the PPP test resulted in a 4.6% false-positive error and a 21.1% false-negative error. The presence of an abnormal PPP sign in the evaluation of hip trauma is associated with evidence of fracture or other bony abnormality on radiograph.

Molecular characterization of the prokaryotic efp gene product involved in a peptidyltransferase reaction

The translation factor EF-P is required for efficient prokaryotic peptide bond synthesis on 70S ribosomes from fMet-tRNAfMet. This protein has been purified from Escherichia coli cells and the gene, efp, encoding it has been cloned and sequenced. We have isolated recombinant clones which overexpress a protein that co-migrates with purified EF-P upon SDS-PAGE analysis. Using these clones, we report the purification, crystallization and initial characterization of the efp gene product. The mechanism by which EF-P stimulates peptide-bond synthesis was studied using several antibiotics that inhibit translocation, peptide-bond synthesis and decoding. The stimulation of peptidyltransferase by EF-P was not inhibited by antibiotics that affect translocation and occupation of the A site (in the elongation state), ie thiostrepton, viomycin, neomycin and fusidic acid but was inhibited by streptomycin as well as by inhibitors of peptidyltransferase, chloramphenicol and lincomycin. This observation and the requirement for L16 but not for the L7/L12 nor L6 or L11 r-proteins suggest that the binding site for EF-P may overlap the peptidyltransferase center of the ribosome.

Effects of actual waiting time, perceived waiting time, information delivery, and expressive quality on patient satisfaction in the emergency department

STUDY OBJECTIVE

To determine the effects of actual waiting time, perception of waiting time, information delivery, and expressive quality on patient satisfaction.

METHODS

During a 12-month study period, a questionnaire was administered by telephone to a random sample of patients who had presented to a suburban community hospital emergency department during the preceding 2 to 4 weeks. Respondents were asked several questions concerning waiting times (ie, time from triage until examination by the emergency physician and time from triage until discharge from the ED), information delivery (eg, explanations of procedures and delays), expressive quality (eg, courteousness, friendliness), and overall patient satisfaction.

RESULTS

There were 1,631 respondents. The perception that waiting times were less than expected was associated with a positive overall satisfaction rating for the ED encounter (P < .001). Satisfaction with information delivery and with ED staff expressive quality were also positively associated with overall satisfaction during the ED encounter (P < .001). Actual waiting times were not predictive of overall patient satisfaction (P = NS).

CONCLUSION

Perceptions regarding waiting time, information delivery, and expressive quality predict overall patient satisfaction, but actual waiting times do not. Providing information, projecting expressive quality, and managing waiting time perceptions and expectations may be a more effective strategy to achieve improved patient satisfaction in the ED than decreasing actual waiting time.

How accurate are waiting time perceptions of patients in the emergency department?

STUDY OBJECTIVE

To assess the ability of patients to accurately estimate specific waiting times in the emergency department.

METHODS

A questionnaire was administered by telephone to a random sample of 776 patients (or parents or responsible caretakers, if appropriate) who had been treated within the previous 2 to 4 weeks in the ED of a suburban hospital. Respondents were asked their perceptions of two particular time frames: (1) the time elapsed from triage until initial examination by the emergency physician (physician waiting time [PWT]), and (2) the time elapsed from triage until departure from the ED (total waiting time [TWT]). Corresponding actual times were extracted from a computerized database. Time frames were divided into discrete periods for comparison. The correspondence between actual and perceived times was assessed by optimal data analysis.

RESULTS

Only 22.3% of the respondents accurately estimated PWT. Although this level of accuracy is statistically significant (P < .0001), it reflects only 11% of the theoretically possible improvement in accuracy beyond chance. More respondents overestimated than underestimated PWT (49.9% versus 27.8%, respectively). In contrast, TWT was accurately estimated by 36.6% of the respondents (P < .0001), reflecting 18% of the theoretically possible improvement in accuracy beyond chance. Fewer respondents overestimated than underestimated TWT (24.5% versus 38.9%, respectively).

CONCLUSION

Patients are not very accurate in their estimation of actual waiting times. Although fewer than one fourth of the respondents overestimated the TWT spent in the ED, almost half the respondents overestimated the PWT.

The chick alpha2(I) collagen gene contains two functional promoters, and its expression in chondrocytes is regulated at both transcriptional and post-transcriptional levels

Embryonic chick cartilages contain transcripts derived from the alpha2(I) collagen gene, although type I collagen is not normally found in these tissues; most of these RNAs are alternative transcripts initiating within intron 2. Use of the internal start site results in replacement of exons 1 and 2 with a previously undescribed exon and a change in the translational reading frame; thus, the alternative transcript cannot encode alpha2(I) collagen. We have demonstrated that production of the alternative transcript is due to activation of an internal promoter in chondrocytes and have identified a 179-base pair domain that is required for its activity. Furthermore, we have shown that the alternative transcript resulting from activation of the internal promoter turns over relatively rapidly; thus, the steady-state level of this transcript is less than predicted based on the transcription rate. The upstream promoter is only partially repressed in chondrocytes, suggesting that the lack of authentic alpha2(I) collagen mRNA may also be due in part to decreased mRNA stability. Thus, repression of alpha2(I) collagen synthesis in cartilage involves both transcriptional and post-transcriptional mechanisms. In contrast, repression of alpha1(I) collagen synthesis appears to be mediated primarily at the level of transcription.

A prospective study of in-line skating: observational series and survey of active in-line skaters--injuries, protective equipment, and training

OBJECTIVES

1) To assess the relationship between types of injuries incurred and training and protective equipment worn by adults injured while in-line skating; 2) to observe the type and amount of protective equipment worn by in-line skaters while skating; and 3) to survey active in-line skaters about formal training, protective equipment, and history of injuries incurred, and the effect of such injuries on the protective equipment subsequently worn.

METHODS

A prospective study of consecutive adult patients presenting to the ED for evaluation of in-line skating injuries; a consecutive-series observational study of active in-line skaters to assess protective equipment worn; and a survey of selected active in-line skaters. Eighty-five adult patients were included who presented with a history of injury related to in-line skating to the EDs of an urban academic medical center, a suburban academic-affiliated hospital, and a community hospital. Four hundred eleven active in-line skaters on the Chicago lakefront were observed for protective equipment worn, 91 of whom participated in the survey.

RESULTS

Of those presenting to the ED with injuries, only 15% indicated that they had received formal in-line skating instruction. Of the ED patients, 50% wore no protective equipment; overall, 6% wore a helmet; 44%, wrist protection; 23%, knee protection; and 19%, elbow protection. Only 2% wore all of the above equipment. The primary mechanism of injury reported was a loss of balance (58%); others included collision with objects (25%), collision with bicycles (11%), and collision with cars (5%). Fractures or dislocations occurred in 48% of the patients; 6% had head injuries necessitating CT scans. Those who wore no protective gear were more likely to require hospital admission (p < 0.05). Of the 411 in-line skaters observed, 157 (38%) wore no protective equipment. Compared with the injured group presenting to the ED, fewer observed participants were without protection (p < 0.05). Among those surveyed, prior injury was not associated with the subsequent use of protective gear.

CONCLUSION

Patients who present to the ED for evaluation of in-line skating injuries have a high incidence of fractures/dislocations. Few injured or surveyed in-line skaters had formal training. Use of protective equipment by injured skaters was associated with a decreased likelihood of hospitalization. Observed in-line skaters more commonly wore protective gear than did those who presented to the ED with injuries.

The full moon and ED patient volumes: unearthing a myth

To determine if there is any effect of the full moon on emergency department (ED) patient volume, ambulance runs, admissions, or admissions to a monitored unit, a retrospective analysis of the hospital electronic records of all patients seen in an ED during a 4-year period was conducted in an ED of a suburban community hospital. A full moon occurred 49 times during the study period. There were 150,999 patient visits to the ED during the study period, of which 34,649 patients arrived by ambulance. A total of 35,087 patients was admitted to the hospital and 11,278 patients were admitted to a monitored unit. No significant differences were found in total patient visits, ambulance runs, admissions to the hospital, or admissions to a monitored unit on days of the full moon. The occurrence of a full moon has no effect on ED patient volume, ambulance runs, admissions, or admissions to a monitored unit.

Inability to follow up ED patients by telephone: there must be 50 ways to leave your number

OBJECTIVE

To determine the ability to complete follow-up home telephone calls to ED patients.

METHODS

A retrospective review of the ability to reach 4,741 patients called during a posttreatment patient satisfaction survey of visits to a suburban community hospital ED.

RESULTS

Only 54.9% of all patients called could be contacted after three or fewer phone calls. Of the 2,139 (45.1%) who could not be reached, there was no answer for 1,260 (58.9%), despite three telephone calls to a number currently in service. A significant minority (21.1%) had given nonworking numbers. Another 12.4% indicated that no one by the name of the patient lived at the number called and 2.9% of the respondents alleged that the patient was deceased.

CONCLUSIONS

Almost half of the patients who present to the ED and supply home telephone numbers give telephone numbers at which they cannot be reached in follow-up. Using telephone follow-up alone to reach patients seen in the ED may be an unreliable method of communication.

Injury with spontaneous deployment of an automobile air bag

We report a case of significant injury to an automobile driver due to spontaneous air bag deployment not associated with a collision or application of external force to the automobile.

Carbon dioxide exchange of lettuce plants under hypobaric conditions

Growth of plants in a Controlled Ecological Life Support System (CELSS) may involve the use of hypobaric pressures enabling lower mass requirements for atmospheres and possible enhancement of crop productivity. A controlled environment plant growth chamber with hypobaric capability designed and built at Ames Research Center was used to determine if reduced pressures influence the rates of photosynthesis (Ps) and dark respiration (DR) of hydroponically grown lettuce plants. The chamber, referred to as a plant volatiles chamber (PVC), has a growing area of about 0.2 m2, a total gas volume of about 0.7 m3, and a leak rate at 50 kPa of <0.1%/day. When the pressure in the chamber was reduced from ambient to 51 kPa, the rate of net Ps increased by 25% and the rate of DR decreased by 40%. The rate of Ps increased linearly with decreasing pressure. There was a greater effect of reduced pressure at 41 Pa CO2 than at 81 Pa CO2. This is consistent with reports showing greater inhibition of photorespiration (Pr) in reduced O2 at low CO2 concentrations. When the partial pressure of O2 was held constant but the total pressure was varied between 51 and 101 kPa, the rate of CO2 uptake was nearly constant, suggesting that low pressure enhancement of Ps may be mainly attributable to lowered partial pressure of O2 and the accompanying reduction in Pr. The effects of lowered partial pressure of O2 on Ps and DR could result in substantial increases in the rates of biomass production, enabling rapid throughput of crops or allowing flexibility in the use of mass and energy resources for a CELSS.

Carbon dioxide exchange of lettuce plants under hypobaric conditions

Growth of plants in a Controlled Ecological Life Support System (CELSS) may involve the use of hypobaric pressures enabling lower mass requirements for atmospheres and possible enhancement of crop productivity. A controlled environment plant growth chamber with hypobaric capability designed and built at Ames Research Center was used to determine if reduced pressures influence the rates of photosynthesis (Ps) and dark respiration (DR) of hydroponically grown lettuce plants. The chamber, referred to as a plant volatiles chamber (PVC), has a growing area of about 0.2 m2, a total gas volume of about 0.7 m3, and a leak rate at 50 kPa of <0.1%/day. When the pressure in the chamber was reduced from ambient to 51 kPa, the rate of net Ps increased by 25% and the rate of DR decreased by 40%. The rate of Ps increased linearly with decreasing pressure. There was a greater effect of reduced pressure at 41 Pa CO2 than at 81 Pa CO2. This is consistent with reports showing greater inhibition of photorespiration (Pr) in reduced O2 at low CO2 concentrations. When the partial pressure of O2 was held constant but the total pressure was varied between 51 and 101 kPa, the rate of CO2 uptake was nearly constant, suggesting that low pressure enhancement of Ps may be mainly attributable to lowered partial pressure of O2 and the accompanying reduction in Pr. The effects of lowered partial pressure of O2 on Ps and DR could result in substantial increases in the rates of biomass production, enabling rapid throughput of crops or allowing flexibility in the use of mass and energy resources for a CELSS.

Prospective evaluation of emergency medicine instruction for rotating first-postgraduate-year residents

OBJECTIVE

To determine whether either bedside teaching alone (group A) or bedside teaching with written course materials (group B) improved written examination scores, satisfaction with the rotation, or clinical grades of rotating PGY1 residents.

METHODS

A prospective, controlled educational trial was conducted. Sixty-five PGY1 residents from diverse specialties rotated in the ED for one month over a ten-month study period, and were included in the study. The PGY1 residents were assigned to group by month of rotation. All the PGY1 residents received unstructured bedside teaching by emergency medicine (EM) residents and faculty. In addition, group B received written course materials on day 1.

RESULTS

Mean posttest scores were higher than mean pretest scores for the interns considered as a whole (p < 0.0001), but mean pretest, posttest, and clinical grades were comparable across instructional groups. Mean satisfaction ratings were higher for group A than for group B (p < 0.015). The interns specializing in EM achieved higher mean test scores (p < 0.013) and clinical grades (p < 0.003) than did the interns specializing in another medical specialty.

CONCLUSION

Both instructional methods were associated with improved written test performance. Written course materials did not augment bedside teaching in terms of test scores, clinical grades, or satisfaction with the rotation. At a university-based, high-volume ED, bedside teaching offers educational benefit to rotating PGY1 residents that may not be augmented by written course materials.

Detection of maternal cells in human umbilical cord blood using fluorescence in situ hybridization

Cord blood is a potential source of hematopoietic stem cells for transplantation and is being used on a growing number of patients. However, there are concerns that cord blood might be contaminated with maternal cells that could lead to graft-versus-host disease. To ascertain the extent to which maternal cell contamination of cord blood occurs, we examined 49 cord blood samples from male babies for maternal cells by fluorescence in situ hybridization using probes to the X and Y chromosomes. A minimum of 1,000 nuclei were scored from each sample, and maternal cells were found in 7 of the 49 cord bloods, at levels ranging from 0.04% to 1.0%. In addition, in 39 and 27 of the cord blood samples, respectively, we examined the CD8+ and CD34+ cell populations for maternal cells. Maternal cells were found in 5 of the 39 CD8 fractions and in 1 of the 27 CD34 fractions, at levels similar to that found in the unfractionated cord blood. In sum, maternal cells were found in either the unseparated mononuclear fraction or the CD8 or CD34 fractions in 10 of the 49 cord blood samples (20%). These results show that maternal cells are present in a substantial number of cord bloods, and that some of these maternal cells are T cells.

Human N-methyl-D-aspartate receptor modulatory subunit hNR3: cloning and sequencing of the cDNA and primary structure of the protein

Several cDNA clones encoding the human N-methyl-D-aspartate receptor modulatory subunit hNR3, were isolated from a human fetal brain library. The hNR3 cDNA demonstrated a 91.3-91.5% nucleotide (nt) identity with the rat NR2B and mouse epsilon 2 cDNAs. The nt sequence of hNR3 would encode a 1484 amino acid (aa) protein that has a 98.4-98.5% identity with the mouse epsilon 2 and rat NR2B subunits.

Retinoic acid is a major regulator of chondrocyte maturation and matrix mineralization

During the process of endochondral bone formation, chondrocytes undergo a series of complex maturational changes. Our recent studies indicate that this maturational process is influenced by the vitamin A derivative retinoic acid (RA). To learn how this agent regulates chondrocyte development, we characterized matrix gene expression during maturation of cartilage cells in chick sternum. RNAs were isolated from the cephalic portion of day 13, 14, 16, 18, and 20 chick embryo sternum and analyzed via northern blots. Type II collagen RNA levels remained fairly constant during this developmental period. In contrast, expression of type X collagen and alkaline phosphatase (APase) genes was first detected at day 16, followed by that of osteonectin (ON) and osteopontin (OP). To explore the mechanisms triggering these changes, chondrocytes were isolated from the cephalic portion of day 17-18 sternum (US cells) and grown in monolayer in standard serum-containing medium. After 3 weeks in culture, most of the cells enlarged and became type X collagen-positive, but they exhibited low APase activity and contained only trace amounts of ON and OP mRNAs. Treatment of parallel 3-week-old cultures with RA (10-100 nM) rapidly increased expression of the APase, ON, and OP genes severalfold. In concert with a significant increase in APase activity, there was abundant calcium accumulation in the RA-treated cultures. Electron microscopy confirmed the formation of large matrix-associated mineral crystals and the presence of numerous matrix vesicles. The effects of RA were also studied in cultures of immature chondrocytes isolated from the caudal portion of sternum (LS cells).(ABSTRACT TRUNCATED AT 250 WORDS)

Human N-methyl-D-aspartate receptor modulatory subunit hNR2A: cloning and sequencing of the cDNA and primary structure of the protein

Several cDNA clones encoding the human N-methyl-D-aspartate receptor modulatory subunit hNR2A, were isolated from human hippocampus and fetal brain libraries. DNA sequence analysis revealed overlapping clones permitting the reconstruction of full-length hNR2A cDNA. The hNR2A cDNA demonstrated an 88-89% nucleotide (nt) identity with the corresponding rodent cDNAs. The nt sequence of hNR2A would encode a 1464-aa protein that has a 95.2% identity with the rodent NR2A subunits.

Effects of drugs on response duration differentiation. III. Acute variation of reinforced duration

Rats trained to hold a lever down for at least 1.0 s but less than 1.3 s could differentiate the reinforced response duration on about 50% of the trials. The response duration frequency distribution was a normal distribution with a peak near the minimum reinforced response duration. Dose-effect curves were determined for the effects of phencyclidine (PCP) and methamphetamine. Subsequently, rats continued to be trained for 3 days a week with responses between 1.0 and 1.3 s reinforced, but on days when injections were given either the maximum reinforced duration was increased to 2.3 s, or the minimum reinforced duration was lowered to 0.5. When the maximum duration was increased to 2.3 s, the percentage of reinforced responses increased to 60% and when the minimum reinforced duration was decreased to 0.5 s, the percentage of reinforced responses increased to 89%. Despite the increased percentage of reinforced responses when the time window was widened, the effects of PCP and methamphetamine were not changed. These data suggest that the effects of drugs on response duration differentiation are not greatly influenced by transient changes in reinforcement frequency.

An alternative transcript of the chick type III collagen gene that does not encode type III collagen

Type III collagen, a ubiquitous protein found in most connective tissues, is not present in hyaline cartilage. However, we have identified an alternative transcript of the type III collagen gene in cultured chondrocytes from several embryonic chick cartilages. This RNA contains exons 24-52, but exons 1-23 are replaced by 70 nucleotides of unique sequence, suggesting that transcription initiates at an alternative promoter. Two of the open reading frames in the alternative transcript are out of frame with the collagen coding sequence; a third open reading frame encodes the carboxyl-terminal two-thirds of the collagen sequence. Thus, this RNA cannot serve as a template for synthesis of normal type III collagen and may encode noncollagenous proteins and/or a truncated collagen. The alternative transcript has been detected as early as 2.5 days of embryogenesis and at later stages is present at low levels in many tissues, including limb mesenchyme and cartilage. These results, together with our previous identification of an alternative transcript of the chick alpha 2(I) collagen gene (Bennett, V. D., and Adams, S. L. (1990) J. Biol. Chem. 265, 2223-2230), suggest that some collagen genes may have alternative functions that are independent of their roles in collagen production.

Molecular characterization of the human EAA5 (GluR7) receptor: a high-affinity kainate receptor with novel potential RNA editing sites

Several cDNA clones encoding EAA5 receptor polypeptides were isolated from a human fetal brain library. The EAA5 cDNAs demonstrated an 88.7-90.1% nucleotide identity with rat GluR7 cDNAs. The nucleotide sequence of EAA5 would encode a 919-amino acid protein, that has a 97.7-98.9% identity with the rat GluR7 receptor. Two variation of the EAA5 cDNA were identified which result in amino acid substitutions in the predicted extracellular amino-terminal region; Ser310-->Ala and Arg352-->Gln. These variations can be attributed to RNA editing involving T-->G and G-->A substitutions. Both the location (with respect to glutamate receptors), and the nucleotides involved, in this putative RNA editing are novel and may therefore involve novel mechanisms. Ligand binding studies with membranes of transfected COS-1 cells expressing EAA5 polypeptides demonstrate a rank order of ligand affinity similar to that observed with the rat GluR7 receptor, and a dissociation constant for kainate (2.72 +/- 0.12 nM (n = 3)) that is approximately 20- to 30-fold higher than that observed for the rat GluR7 receptor. All of the ligands tested had a higher affinity for the human EAA5 receptor as compared to the rat GluR7 receptor. This report provides another example of pharmacological differences for similar receptors across species.

Retinoic acid induces rapid mineralization and expression of mineralization-related genes in chondrocytes

Numerous studies of experimental hypo- and hypervitaminosis A have long suggested that retinoic acid (RA) is involved in chondrocyte maturation during endochondral ossification and skeletogenesis. However, the specific and direct roles of RA in these complex processes remain unclear. Based on recent studies from our laboratories, we tested the hypothesis that RA induces the expression of genes associated with the terminal mineralization phase of chondrocyte maturation and promotes apatite deposition in the extracellular matrix. Cell populations containing chondrocytes at advanced stages of maturation were isolated from the upper portion of Day 18 chick embryo sterna and grown for 2 weeks in monolayer until confluent. The cells were then treated with low doses (10-100 nM) of RA for up to 6 days in the presence of a phosphate donor (beta-glycerophosphate) but in the absence of ascorbic acid. Within 4 days of treatment, RA dramatically induced expression of the alkaline phosphatase (APase), osteonectin, and osteopontin genes, caused a several-fold increase in APase activity, and provoked massive mineral formation while it left type X collagen gene expression largely unchanged. The mineral had a mean Ca/Pi molar ratio of 1.5; Fourier transform infrared spectra confirmed that it represented hydroxyapatite. Mineralization was completely abolished by treatment with parathyroid hormone; this profound effect confirmed that RA induced cell-mediated mineralization and not nonspecific precipitation. When cultures were treated with both RA and ascorbic acid, there was a slight further increase in APase activity and increased calcium accumulation. The effects of RA were also studied in cultures of immature chondrocytes isolated from the caudal portion of sternum; however, RA only had minimal effects on mineralization and gene expression in these cells. Thus, RA appears to be a rapid, potent, maturation-dependent, ascorbate-independent promoter of terminal maturation and matrix calcification in chondrocytes.

Late onset alcoholism: stress or structure

We studied 60 men (M age = 63.6 years) from six midwest treatment centers to determine whether stress resulting from loss of social-psychological structures was greater for later onset alcoholics. Each subject completed a modified Veteran's Alcoholism Screening Test (V.A.S.T.; Magruder-Habib, Harris, & Franker, 1982) and the Drinking Practices Survey (Adams, 1990). They were then identified as early onset (problem drinking before age 40) and later onset (problem drinking after age 40). Cross tabulations using the chi-square statistic showed that more early onset alcoholics were married than later onset alcoholics. Of the social-psychological structures, only marital status showed a significant relationship with alcoholism. This seemed to confirm that the onset of problem drinking has less to do with stress than with the loss of a spouse who may serve to regulate the older man's drinking.