A study of communication in the Cardiac Surgery Intensive Care Unit and its implications for automated briefing

We present a study of the information transferred among caregivers in the context of cardiac surgery and use the study to evaluate a system, MAGIC, that we are developing for automated generation of briefings. Our framework integrates cognitive and quantitative evaluation methods and features three standards that reflect current practice in the Cardiothoracic Intensive Care Unit (CTICU). Using experimental design to compare human-generated and machine-generated briefings, we show that MAGIC's current level of performance is useful. Moreover, MAGIC could help improve information flow in the CTICU by providing a consistent set of information earlier than in current practice. The separate standards are also consistent in suggesting specific modifications that may be necessary for iterative design and further system development.

Routine outcome monitoring in a public mental health system: the impact of patients who leave care

OBJECTIVE

An interest exists in using patient outcome data to evaluate the performance of publicly financed mental health organizations. Because patients leave these organizations at a high rate, the impact of patient attrition on routinely collected outcome data was examined.

METHODS

In one county mental health system, routinely collected data on a wide range of outcomes were examined, and a random sample of patients who left treatment was interviewed.

RESULTS

Of the 1,769 patients in ongoing treatment during a one-year period, 554 (31 percent) were lost to follow-up. Among a random sample of 102 patients who left treatment, two had died and 47 were interviewed. Compared with patients who left treatment, patients who stayed were older, more likely to have schizophrenia, less likely to be married, more likely to be living in an institution, more satisfied with their relationships with friends and family, and less likely to have legal problems. Average outcomes improved both for patients who stayed and for patients who left. Patients who left and could be located for follow-up were less severely ill and showed the greatest improvement and the best outcomes. Patients who left and could not be located may have been more severely ill at baseline.

CONCLUSIONS

Outcomes appear to vary substantially by whether patients stay in care and whether they can be located after leaving care. Public mental health systems that wish to evaluate treatment quality using outcome data should attend carefully to which patients are being assessed. Biases can result from convenience sampling and from patients leaving care.

Central control of the cardiovascular and respiratory systems and their interactions in vertebrates

This review explores the fundamental neuranatomical and functional bases for integration of the respiratory and cardiovascular systems in vertebrates and traces their evolution through the vertebrate groups, from primarily water-breathing fish and larval amphibians to facultative air-breathers such as lungfish and some adult amphibians and finally obligate air-breathers among the reptiles, birds, and mammals. A comparative account of respiratory rhythm generation leads to consideration of the changing roles in cardiorespiratory integration for central and peripheral chemoreceptors and mechanoreceptors and their central projections. We review evidence of a developing role in the control of cardiorespiratory interactions for the partial relocation from the dorsal motor nucleus of the vagus into the nucleus ambiguus of vagal preganglionic neurons, and in particular those innervating the heart, and for the existence of a functional topography of specific groups of sympathetic preganglionic neurons in the spinal cord. Finally, we consider the mechanisms generating temporal modulation of heart rate, vasomotor tone, and control of the airways in mammals; cardiorespiratory synchrony in fish; and integration of the cardiorespiratory system during intermittent breathing in amphibians, reptiles, and diving birds. Concluding comments suggest areas for further productive research.

Pre-slaughter control of Escherichia coli O157 in beef cattle: a simulation study

A stochastic simulation model was used to assess the benefit of measures implemented in the pre-slaughter period that are aimed at reducing the contamination of beef carcasses with Shiga-like-toxin-producing Escherichia coli O157. The scenario studied was based on an abattoir processing approximately 1000 head of lot-fed cattle per day. Input assumptions were described using probability distributions to reflect uncertainty in their true values. Control measures that were assessed were based on either a reduction in herd prevalence of infection, reduction in opportunity for cross-contamination in the processing plant by re-ordering of the slaughter queue, reduction of concentration of E. coli O157 in fresh faeces, or a reduction in the amount of faeces, mud and bedding ('tag') transferred from the hide to the carcass. Some control measures evaluated were hypothetical in nature and were included to assist with the planning of research priorities. Simulations suggested that the greatest potential impact is associated with vaccination and with an agent that reduces shedding E. coli O157 in faeces. Knowledge of herd-test results obtained by testing a sample of animals from the herd provides only a minor advantage in control programmes, although application of a rapid test to all animals in all lots might be of some benefit. Under most scenarios, there is ample opportunity for cross-contamination to occur within the slaughter plant as a result of early entry of cattle contaminated with E. coli O157. An industry-wide reduction in the amount of tag attached to hides and addition of a source of cattle having a prolonged average fasting time were not predicted to have a large impact on mean amount of carcass contamination with E. coli O157.

A simulation model for studying the role of pre-slaughter factors on the exposure of beef carcasses to human microbial hazards

A Monte Carlo simulation model was constructed for assessing the quantity of microbial hazards deposited on cattle carcasses under different pre-slaughter management regimens. The model permits comparison of industry-wide and abattoir-based mitigation strategies and is suitable for studying pathogens such as Escherichia coli O157:H7 and Salmonella spp. Simulations are based on a hierarchical model structure that mimics important aspects of the cattle population prior to slaughter. Stochastic inputs were included so that uncertainty about important input assumptions (such as prevalence of a human pathogen in the live cattle-population) would be reflected in model output. Control options were built into the model to assess the benefit of having prior knowledge of animal or herd-of-origin pathogen status (obtained from the use of a diagnostic test). Similarly, a facility was included for assessing the benefit of re-ordering the slaughter sequence based on the extent of external faecal contamination. Model outputs were designed to evaluate the performance of an abattoir in a 1-day period and included outcomes such as the proportion of carcasses contaminated with a pathogen, the daily mean and selected percentiles of pathogen counts per carcass, and the position of the first infected animal in the slaughter run. A measure of the time rate of introduction of pathogen into the abattoir was provided by assessing the median, 5th percentile, and 95th percentile cumulative pathogen counts at 10 equidistant points within the slaughter run. Outputs can be graphically displayed as frequency distributions, probability densities, cumulative distributions or x-y plots. The model shows promise as an inexpensive method for evaluating pathogen control strategies such as those forming part of a Hazard Analysis and Critical Control Point (HACCP) system.

Reliability of an ordinal rating system for assessing the amount of mud and feces (tag) on cattle hides at slaughter

A study was conducted to provide a quantitative description of the amount of tag (mud, soil, and bedding) adhered to the hides of feedlot beef cattle and to appraise the statistical reliability of a subjective rating system for assessing this trait. Initially, a single rater obtained baseline data by assessing 2,417 cattle for 1 month at an Ontario beef processing plant. Analysis revealed that there was a strong tendency for animals within sale-lots to have a similar total tag score (intralot correlation = 0.42). Baseline data were summarized by fitting a linear model describing an individual's total tag score as the sum of their lot mean tag score (LMTS) plus an amount representing normal variation within the lot. LMTSs predicted by the linear model were adequately described by a beta distribution with parameters nu = 3.12 and omega = 5.82 scaled to fit on the 0-to-9 interval. Five raters, trained in use of the tag scoring system, made 1,334 tag score observations in a commercial abattoir, allowing reliability to be assessed at the individual level and at the lot level. High values for reliability were obtained for individual total tag score (0.84) and lot total tag score (0.83); these values suggest that the tag scoring system could be used in the marketing and slaughter of Ontario beef cattle to improve the cleanliness of animals presented for slaughter in an effort to control the entry of microbial contamination into abattoirs. Implications for the use of the tag scoring system in research are discussed.

Alterations of the retinoic acid receptor alpha (RAR alpha) gene in myeloid and lymphoid malignancies

The retinoic acid receptor alpha (RAR alpha) protein plays a central role in myeloid differentiation, and chromosomal translocations disrupting the RAR alpha gene are implicated in the development of acute myeloid leukaemia (AML). To identify haemopoietic malignant disorders which may also be linked to RAR alpha abnormalities, Southern blot analysis was performed in DNA from 153 patients with haematological malignancies other than AML FAB type M3 using RAR alpha cDNA probes. Alterations of RAR alpha were detected in 1/42 myelodysplastic syndromes (MDS), 2/24 AML, 3/47 B-chronic lymphocytic leukaemias (B-CLL), 0/40 lymphomas and 0/60 normal individuals. These data strongly suggest that alterations of RAR alpha might predispose for myeloid and lymphoid disorders.

Modulation of the vagal bradycardia evoked by stimulation of upper airway receptors by central 5-HT1 receptors in anaesthetized rabbits

1. The effects of central application of 5-HT1A and 5-HT1B/1D receptor ligands on the reflex bradycardia, apnoea, renal sympathoexcitation and pressor response evoked by stimulating upper airway receptors with smoke in atenolol-pretreated anaesthetized rabbits were studied. 2. Intracisternal administration of the 5-HT1A receptor antagonists WAY-100635 (100 microg kg(-1)) and (-)pindolol (100 microg kg(-1)) significantly reduced the smoke-induced bradycardia, attenuated the pressor response and in the case of (-)pindolol, sympathetic nerve activity. The same dose of WAY-100635 i.v. was without effect. 3. Buspirone (200 microg kg(-1), i.c.) potentiated the reflex bradycardia. This action was prevented if the animals were pretreated with WAY-100635 (100 Hg kg(-1), i.v.) 4. (+)8-OH-DPAT (25 microg kg(-1), i.c.) attenuated the evoked bradycardia, pressor response, apnoea and renal sympathoexcitation. The attenuation of the apnoea and renal sympathoexcitation, but not the bradycardia or pressor response was prevented in animals pretreated with WAY-100635 (100 microg kg(-1), i.v.). The attenuation of the reflex bradycardia and the reduction in the renal sympathoexcitation were reduced by pretreatment with the 5-HT1B/1D receptor antagonist GR127935 (100 microg kg(-1), i.v.). 5. In WAY-100635 (100 microg kg(-1), i.v.) pretreated animals, sumatriptan (a 5-HT1B/1D receptor agonist) reduced the reflex bradycardia and the pressor response. The 5-HT1B/1D receptor antagonist GR127935 (20 microg kg(-1), i.c. or 100 microg kg(-1), i.v.) had no effect on the reflex responses. 6. In conclusion, the present data are consistent with the hypothesis that activation of central 5-HT1A receptors potentiate whilst activation of 5-HT1B/1D receptors attenuate the reflex activation of cardiac preganglionic vagal motoneurones evoked by stimulation of upper airway receptors with smoke in rabbits.

Herd-level test performance based on uncertain estimates of individual test performance, individual true prevalence and herd true prevalence

A generalized model was derived for understanding the performance of herd-testing protocols when there is uncertainty and variability in individual-level sensitivity, specificity, prevalence of infection within infected herds, and prevalence of infected herds in the population. The model uses Monte-Carlo techniques to provide estimates of test performance for a dichotomous classification of herd-disease status. Uncertainty and variability in input assumptions are described using empirical and parametric probability distributions. The model permits both cluster-correlated behavior of inputs and sampling of animals without replacement. Disease due to obligate parasites is modeled differently from that due to organisms that persist for long periods in the environment. Dependence among model outcomes is assessed using Spearman's rank correlation. Model output is suitable for inclusion in risk-assessment models requiring probabilistic estimates of herd-level test performance, such as those developed for food-safety decision making and import-export risk assessment. The model was demonstrated using an example scenario based on Shiga-like toxin (SLT) producing Escherichia coli O157 in Ontario beef-cattle herds. Inputs were derived from the literature and Statistics Canada agricultural census data. Where appropriate, these data were subjected to distribution-fitting techniques. Otherwise, subjective interpretation was used to select input distributions and their parameters. Simulation revealed that the distribution of herd-level sensitivity for detecting herds infected with SLT producing E. coli O157 has a large range (0.003-0.99) and a median of 0.19. Herd-level specificity also had a large range (0.58-1) and a median of 0.94. Distributions of herd-level positive and negative predictive values exhibited similar degrees of uncertainty. In combination with poor likelihood ratios for positive and negative herd tests, results indicate that the testing protocol investigated has limited ability to discriminate between herds infected and not infected with SLT producing E. coli O157.

Paediatric cardiac anaesthesia in a developing country. Guatemala Heart Team

During the week of October 15-24, 1995 a team of 65 medical, anaesthesiology, surgical, nursing and paramedical personnel travelled to Guatemala City, Guatemala to perform cardiac surgery on children with complex congenital and acquired valvular heart disease. During this mission 42 patients had their lesions surgically repaired. Cardiopulmonary bypass was required in 36 cases. There were no anaesthetic or surgical deaths. All six patients who did not require cardiopulmonary bypass were extubated in the operating room. Of the patients who required cardiopulmonary bypass, 23 were extubated in the operating room (64%). There was no intraoperative anaesthetic morbidity nor postoperative respiratory complications. No patients was reintubated after planned extubation. Cardiac surgery in paediatric age patients can safely be performed in developing countries if close attention is paid to proper patient selection and one maintains the standards of care practised in developed countries.

Presynaptic 5-HT3 receptors evoke an excitatory response in dorsal vagal preganglionic neurones in anaesthetized rats

1. Recordings were made from a total of sixty-four vagal preganglionic neurones in the dorsal vagal motor nucleus (DVMN) of pentobarbitone sodium anaesthetized rats. The effects of ionophoretic administration of Mg2+ and Cd2+, inhibitors of neurotransmitter release, and the selective NMDA and non-NMDA receptor antagonists (+/-)-2-amino-5-phosphono-pentanoic acid (AP5) and 6,7-dinitroquinoxaline-2,3-dione (DNQX) on the excitatory actions of the 5-HT3 receptor agonist 1-phenylbiguanide (PBG) were studied. 2. In extracellular recording experiments, PBG (0-40 nA) increased the firing rate of thirty-five of the thirty-nine neurones tested. The PBG-evoked excitation was attenuated by application of Mg2+ (1-10 nA) in sixteen of seventeen neurones or Cd2+ (2-10 nA) in seven of eight neurones tested. At these low ejection currents neither Mg2+ nor Cd2+ altered baseline firing rates and Mg2+ had no effect on the excitations evoked by DL-homocysteic acid (n = 4), NMDA (n = 4) or (AMPA; n = 2). 3. Ionophoresis of AP5 (2-10 nA), at currents which selectively inhibited NMDA-evoked excitations, attenuated PBG-evoked excitations in all eight neurones tested. DNQX (5-20 nA), at currents which selectively inhibited AMPA-evoked excitations, also attenuated PBG-evoked excitations (n = 3). 4. Intracellular activity was recorded in nine DVMN neurones. In six neurones ionophoretic application of PBG (10-200 nA) depolarized the membrane and increased firing rate whilst in the other three neurones, PBG had no effect on membrane potential though it increased synaptic noise (n = 3) and firing rate (n = 2). In all six neurones tested, ionophoresis of Mg2+ (10-120 nA) attenuated the PBG-evoked increases in synaptic noise and firing rate. 5. In conclusion, the data are consistent with the hypothesis that 5-HT3 receptor agonists activate DVMN neurones partly by acting on receptors located at sites presynaptic to the neurones. Activation of these receptors appears to facilitate release of glutamate, which, in turn, acts on postsynaptic NMDA and non-NMDA receptors to activate the neurones.

Effect of duration of fasting and a short-term high-roughage ration on the concentration of Escherichia coli biotype 1 in cattle feces

A field trial using cattle from a commercial feedlot was conducted to quantify the effect of duration of fasting and a temporary change in ration on the concentration of Escherichia coli biotype 1 in feces. A nested hierarchical design with repeated measures through time was used. Two groups of 20 British x European breed beef steers having reached slaughter weight (mean live weight 685 kg; SD 50 kg) were fed entirely on a high-energy ration typical of that used in the Ontario beef finishing industry or were switched for 4 days onto a high-roughage ration. This was followed by a period of fasting and water deprivation to mimic that which occurs prior to slaughter. Fecal samples were collected at 0, 24, and 48 h of fasting, and for each sample the total presumptive E. coli (biotype 1) CFU/g of feces was enumerated by spiral plating. Estimates of effect for the design factors were obtained by restricted maximum likelihood, and these were compared to robust counterparts obtained from generalized estimating equations. Results indicated that the ration, the duration of fasting, and their interaction had significant effects on total log E. coli concentration in feces. Cattle on the high-roughage ration for four days had a significantly lower initial log E. coli CFU/g of feces compared to cattle on the normal ration, but after 48 h of fasting they had a significantly higher concentration. It is concluded that while a temporary change in ration and duration of fasting does affect E. coli concentration in feces, these changes do not seem large enough to deliver a drastic improvement in beef carcass hygiene should they be incorporated in hazard analysis and critical control point (HACCP) plans for the preslaughter period of beef production.

Clinical trials of antibacterial agents: a practical guide to design and analysis. Statisticians in the Pharmaceutical Industry Working Party

Guidelines on the conduct of clinical trials of antibacterial agents produced by the US Food and Drug Administration, the British Society for Antimicrobial Chemotherapy, the Infectious Diseases Society of America and a European Working Party have been reviewed. Although very informative, these guidelines provide limited practical guidance on the design and statistical aspects of phase III studies of antimicrobial agents. This paper describes the differences between antibacterial trials and clinical studies in other therapeutic areas with regard to subjective endpoints, dual clinical and bacteriological endpoints, frequent protocol violations and difficulty of using placebo controls. The importance of a detailed protocol and planned analysis strategy is emphasized. The choice of comparator agents, practical issues with the blinding of trial materials and the documentation of patients excluded from study entry are discussed. The use of different patient groups and different endpoints in analyses are described. The principles of equivalence and their application to trials of antibacterial agents are discussed, together with an approach to calculating sample size. A variety of statistical analyses of results are compared for different situations indicating some of the problems that can arise. Different methods of presentation of study data are included with emphasis on regulatory submissions rather than scientific publications. Some graphical presentations are recommended and issues regarding data across different studies are discussed.

Autoradiographic distribution of brainstem substance P binding sites in humans: ontogenic study and relation to sudden infant death syndrome (SIDS)

The precise distribution of substance P (SP) binding sites in the human brainstem was investigated in normal cases (3 fetuses and 24 new-borns) and in 9 cases of Sudden Infant Death Syndrome (SIDS) by in vitro quantitative autoradiography. We discussed the widely but uneven distribution of SP binding sites as regards to the role of SP in brainstem cardio-respiratory ontogenic control and its possible involvement in SIDS.

Activity of C fibre cardiac vagal efferents in anaesthetized cats and rats

1. Bradycardia can be evoked by stimulation of both myelinated and non-myelinated vagal efferent fibres. The on-going activity and synaptic inputs to cardiac vagal preganglionic neurones with myelinated axons have been studied in detail, but there is little information regarding cardiac preganglionic neurones with non-myelinated axons. In the present study, the on-going discharge and afferent inputs to cardiac vagal efferents with non-myelinated axons were studied in anaesthetized rats and cats. 2. Extracellular recordings were made from vagal preganglionic neurones in the dorsal vagal motor nucleus (DVMN) of anaesthetized rats following electrical stimulation of the cervical vagus nerve. Based on calculated axonal conduction velocities, fifty-six neurones had non-myelinated axons. Sixteen of these C fibre neurones had on-going activity but this showed no relationship to central respiratory drive, lung inflation or the cardiac cycle. Activity of twenty-one of these fifty-six neurones was increased at short latency following right atrial injections of phenylbiguanide (PBG). 3. Eight presumed cardiac vagal preganglionic neurones were also recorded in the DVMN. Five of these were activated by PBG administration, and the one neurone with resting activity showed no indication of respiratory-related activity. 4. Finally, twenty-one single C fibres were recorded in peripheral branches of the cardiac vagus. They had a low rate of on-going activity, and in twelve fibres this on-going discharge was analysed in detail. On-going activity in seven of these fibres showed no relationship to central respiratory drive, lung inflation or the cardiac cycle, whereas the other five had prominent relationships with both central respiratory drive and lung inflation, and two of these also showed a relationship to heart period. PBG administration evoked an increased activity in fourteen of the fifteen fibres tested, and the latencies of nine of these responses (1.3 +/- 0.5 s) were within the pulmonary circulation time. 5. In anaesthetized cats, extracellular recordings were made in the DVMN from thirty-three cardiac vagal preganglionic neurones with C fibre axons. The on-going activity of these neurones, when present, never exhibited an on-going- or reflexly induced respiratory rhythm, nor any indication of an input from the arterial baroreceptors. Right atrial injection of PBG evoked a short-latency response in four of the five spontaneously active neurones but was without effect on the eight neurones tested which did not exhibit on-going activity. 6. In conclusion, the majority of cardiac vagal preganglionic neurones located in the DVMN have C fibre axons, show no obvious input from central or peripheral respiratory- or cardiac-related inputs, but are activated by stimulation of pulmonary C fibre afferent fibres.

Expression of genes from Rahnella aquatilis that are necessary for mineral phosphate solubilization in Escherichia coli

Rahnella aquatilis is a Gram-negative bacterium that can fix atmospheric nitrogen and also has the ability to solubilize mineral phosphate. We have cloned the genes that confer the mineral phosphate solubilizing (Mps) trait from this organism by mobilizing a cosmid library of R. aquatilis into Escherichia coli HB101. A 7.0-kb EcoRI fragment from a cosmid, when transferred into E. coli strains HB101 and DH5 alpha, conferred the ability to solubilize hydroxyapatite and the production of gluconic acid to E. coli. The relative amounts of soluble phosphate and gluconic acid produced by the cloned 7.0-kb EcoRI fragment in E. coli were significantly higher than those of R. aquatilis. Nucleotide sequence analysis revealed two complete open reading frames (ORF1 and ORF2) and a partial ORF, ORF1 and ORF2 encoded proteins of molecular mass 10 kDa and 44 kDa. The 44-kDa protein showed extensive sequence similarity to pqqE of Erwinia herbicola, Klebsiella pneumoniae and A. Acinetobacter calcoaceticus. The 10-kDa protein revealed strong similarity to the pqqD of K. pneumoniae and A. calcoaceticus.

Development of an HIV educational needs assessment tool

The learning needs of persons with HIV/AIDS continue to grow more complex as new treatments are developed and HIV disease shifts from being a terminal to a chronic illness. Clinicians could use a simple tool to help them to focus on what clients think is important to know about living with HIV/AIDS. This article describes the development of the HIV Educational Needs Assessment Tool (HENAT). HIV+ persons (N = 363) who were receiving health care in a variety of ambulatory and institutional settings participated in this research during 1990 and 1993-1994. Factor analysis was used to shorten the instrument into a form that could be used in any nurse/client interaction. Principal axis factor extraction and varimax rotation deleted 16 items. The remaining 34 items were grouped into six factors: Treatments, Entitlements, Relationships, Preventing Infections, Social Support, and Working. Cronbach's alphas were computed and results ranged from .70 to .88. Two month test-retest correlations for a subset of participants (n = 195) ranged from .54 to .67. HENAT can be used (a) to examine differences in perception of learning needs between clients with HIV disease and their health care providers, (b) to measure shifts in learning needs over time, (c) to relate HIV-specific learning needs to length of time living with HIV disease, (d) to give clients an opportunity to assess their learning needs, and (e) as part of a larger intervention study that evaluates the effectiveness of patient education.

Evaluation of an intercostal myoneurovascular transposition as a lower esophageal neosphincter

Previous work has shown promising results for an intercostal myoneurovascular transposition in the prevention of gastroesophageal reflux following esophagectomy. A first study evaluated the intercostal transposition procedure and compared it with the Nissen fundoplication using a rabbit model of gastroesophageal reflux. Group A underwent partial cardiomyectomy to produce gastroesophageal reflux. Group B underwent cardiomyectomy, and intercostal transposition around the gastric cardia. Group C underwent Nissen fundoplication and cardiomyectomy. All animals had preoperative and 1-week and 4-week postoperative intraesophageal manometry and pH studies. At the 4-week interval, macroscopic and microscopic esophageal histopathology was assessed. The mean change in values from preoperative to 4 weeks postoperative were compared. Group B showed significantly lower reflux time (P < 0.001) and grade of esophagitis (P < 0.005), and significantly greater average lower esophageal sphincter basal pressure (P < 0.001) and abdominal length of sphincter (P < 0.01) when compared with Group A. There was no statistical significance between the results of Group B and Group C. A second study assessed whether reflux was prevented by an anatomical structure, or a muscle flap acting in a physiological manner. At autopsy, the ten rabbits from Group B underwent removal of the intercostal wrap, and the right 11th intercostal muscle as a control. There was a significant difference in the quantity of viable muscle tissue between muscle flaps and controls (P < 0.001), the muscle flaps having generally little viable muscle left 4 weeks after surgery. A further experiment to evaluate this result found that loss of muscle tissue was due to excessive stretch and not due to damage of the intercostal neurovascular bundle during mobilization. Two groups of animals underwent electromyographic studies. The first group underwent recordings of all intercostal muscles. The second group underwent intercostal transposition around the gastric cardia, and insertion of recording electrodes into the muscle flap. The electromyographic activity of the muscle flap was recorded at 0, 2, and 4 weeks after surgery. The second group demonstrated activity in the muscle flaps simultaneous with diaphragmatic contractions. This activity, although much reduced, was still present 4 weeks after surgery. These studies showed that the intercostal transposition and Nissen fundoplication procedures are equally effective in preventing experimental gastroesophageal reflux. The antireflux properties of the intercostal transposition were possibly the result of anatomical buttressing of the gastroesophageal junction, and not due to a fully viable contracting muscle flap.

Insights into the increased oxygen demand during chest physiotherapy

OBJECTIVES

To determine the mechanism responsible for the increase in oxygen consumption (VO2) during chest physical therapy. Specifically, to examine the hypothesis that muscular activity is the major contributor to the increase in oxygen demand.

DESIGN

Prospective, observational study.

SETTING

University hospital surgical intensive care unit.

PATIENTS

Phase one included 13 patients who were mechanically ventilated after coronary artery bypass surgery. Phase two involved seven mechanically ventilated patients who had undergone major vascular or abdominal surgery.

INTERVENTIONS

Phase one involved turning patients to the lateral decubitus position. During the second phase, patients were given midazolam (0.15 microg/kg) 2 mins before an initial chest physiotherapy session and midazolam plus vecuronium (0.7 mg/kg) before a subsequent session. Physiologic measurements were made during the resting periods before and following each session, as well as at the completion of the intervention.

MEASUREMENTS AND MAIN RESULTS

Turning patients to the lateral position resulted in significant increases in oxygen uptake and CO2 elimination (VCO2). VO2 increased from 219 +/- 21 (SD) mL/min at rest to 324 +/- 58 mL/min (p <.05) with turning. These increases in oxygen demand were met by increases in both oxygen delivery (852 +/- 238 mL/min at rest to 1116 +/- 430 mL/min, p < .05) and extraction (0.27 +/- 0.7 at rest to 0.32 +/- 0.09, p < .05). There were associated increases in hemodynamic and respiratory variables including heart rate and systolic blood pressure. The administration of vecuronium completely suppressed the 50% increases in VO2 and VCO2 seen without the use of a muscle relaxant. The increases in systolic blood pressure were unaffected by vecuronium. The magnitude of the increase in PaCO2 (32 +/- 5 torr [4.3 +/- 0.7 kPa] at rest to 36 +/- 5 torr [4.8 +/- 0.7 kPa] during therapy, p < .05), was not accentuated by vecuronium (30 +/- 4 torr [4.0 +/- 0.5 kPa] to 35 +/- 6 torr [4.7 +/- 0.8 kPa], p < .05) despite a lack of any increase in minute ventilation or respiratory rate. This change was due to the parallel suppression of VCO2.

CONCLUSIONS

The increase in metabolic demand during chest physiotherapy is the result of increased muscular activity as evidenced by the suppression of VO2 following the administration of the muscle relaxant and the observation that turning a patient into the lateral decubitus position produces similar increases in VO2. The increases in blood pressure and cardiac output are due to another mechanism, most likely enhanced sympathetic output. The increase in physiologic activity produced by chest physiotherapy is thus secondary to both exercise-like and stress-like responses.

The melanin-concentrating hormone gene in human: flanking region analysis, fine chromosome mapping, and tissue-specific expression

Genomic sequences encoding the human melanin-concentrating hormone (MCH) were isolated from a YAC library and subcloned in pUC vector using a novel E. coli transformation method. A 4.1-kb fragment encompassing approximately 1.0 kb of the 5'-end-flanking region, the three exons-two introns of the coding region and approximately 1.7 kb of the 3'-end-flanking region, was sequenced. Comparison with the rat MCH gene indicated strong conservation in the 5'-flanking region, in particular over the putative TATA box, CAAT box, GRE and AP-1 elements that could potentially regulate MCH gene expression. FISH with a fluorescent MCH genomic probe on human chromosomes and PCR analysis of a YAC panel mapped MCH to chromosome 12q23.1 in a region flanked by D12S1074 and D12S1030 markers. Expression of the MCH RNA species and pro-MCH-derived peptides (MCH and NEI) was investigated in human tissues by combining Northern blotting, RT-PCR, in situ hybridization, immunohistochemistry and RIA. In the human brain, MCH mRNA and MCH/NEI peptides were predominantely expressed in the lateral hypothalamus in agreement with the known distribution of MCH expression in rat. In addition, MCH gene products were detected in extra-hypothalamic sites, such as the pallidum, neocortex and cerebellum. In peripheral tissues, MCH mRNA was identified in several organs, including the thymus, brown adipose tissue, duodenum and testis. An additional shorter MCH gene transcript, likely the result of alternate splicing, was revealed in several brain areas and peripheral tissues. While only fully processed MCH and NEI were found in hypothalamus, a different peptide form, bearing MCH and NEI epitopes, was detected in peripheral organs. This represents the first evidence for differential processing of pro-MCH in mammals.

Continuity of do-not resuscitate orders between hospital and nursing home settings

OBJECTIVE

To determine the relationship between interinstitutional communication and continuity of advance directives from hospital to nursing home (NH) settings.

DESIGN

Retrospective chart review of discharges to hospital affiliated or community NHs.

SETTING

Teaching Veterans Affairs Hospital and affiliated and community nursing homes.

MEASUREMENTS

Demographic characteristics, medical diagnoses, presence of advance directives, and documentation that relates to the topic.

RESULTS

A total of 83 patients were discharged to either setting. Before discharge to a NH, the prevalence of chronic obstructive pulmonary disease and cancer was higher among those who had a DNR order. Overall, subsequent discussions about advance directives were equally common in NHs. Having a hospital discussion about advance directives or having a hospital DNR order were associated with a higher rate of advance directive discussions in NHs. Hospital DNR orders were continued for 93% and 41% of patients admitted to the hospital-affiliated NH compared with community NHs, respectively (P < .001). Specific communication of hospital DNR status to the receiving NH was associated with better continuity of DNR orders (49% vs 9%, P = .001). Factors that predicted continuity of DNR orders in logistic regression analysis correctly included hospital DNR status, communication of advance directives to the receiving NH, and NH advance directive discussions.

CONCLUSIONS

There is higher continuation rate of DNR orders between the hospital under study and its affiliated NH than to community NHs despite a similar frequency of confirmation discussions. Completing advance directives before patients are discharged to NHs, communication of advance directives to the receiving NH, and follow-up discussions at the NH may improve the continuity of advance directives between hospitals and nursing homes.

In vivo effects of 5-hydroxytryptamine receptor activation on rat nucleus tractus solitarius neurones excited by vagal C-fibre afferents

The effects of ionophoretically applied 5-hydroxytryptamine (5-HT) and 5-HT receptor agonists were studied on rat nucleus tractus solitarius (NTS) neurones receiving unmyelinated vagal afferent input. 5-HT excited 15 of 34 neurones (44%), inhibited 10 (29%) and had no effect on nine. 8-Hydroxy-2-(di-N-propylamino)tetralin HBr (8-OH-DPAT) excited 23 of 53 neurones (43%), inhibited 24 (45%) and had no effect on six neurones and (+/-)-2,5-dimethoxy-4-iodoamphetamine HCl activated 18 of 37 neurones (49%), inhibited nine (24%) and had no effect on 10. These results demonstrate that activation of 5-HT1A and 5-HT2 receptors can excite or inhibit populations of NTS neurones. Phenylbiguanide, however, excited 20 of 23 neurones (87%), inhibited only one (4%) and had no effect on two indicating that 5-HT3 receptor activation has an excitatory action. NTS neurones receiving cardiac vagal afferent input were more likely to be excited by 5-HT (five of five, 100%) or 8-OH-DPAT (four of five. 80%) than the population as a whole. In conclusion, the data demonstrate that 5-HT1A, 5-HT2, and 5-HT3 receptor subtypes are functionally present on NTS neurones receiving excitatory vagal afferent input. Further, the subpopulation of NTS neurones receiving input from cardiac afferents are excited by 5-HT, possibly by an action on 5-HT1A or 5-HT3 receptors.

A flexible lid controls access to the active site in 1,3,8-trihydroxynaphthalene reductase

The crystal structures of apo-1,3,8-trihydroxynaphthalene reductase from Magnaporthe grisea and a binary complex of the enzyme with NADPH have been determined to 2.8 A resolution. In both cases, the overall structure is preserved compared to the structure of the ternary complex of the enzyme with NADPH and an active site inhibitor. No electron density for the helix-loop-helix region comprising residues 214-244 is observed indicating structural disorder in this part of the apoenzyme and the binary complex. In the ternary complex, this region is in contact with NADPH and the inhibitor and closes off the active site. The observed increase in flexibility in the absence of the inhibitor indicates that this region acts as a lid which closes the active site upon binding of the inhibitor and, possibly the substrate, 1,3,8-trihydroxynaphthalene.