Computer-assisted detection for CT colonography: external validation

AIM

To externally validate a computer-assisted detection (CAD) system for computed tomography (CT) colonography, using data from a single centre uninvolved with the software development.

MATERIALS AND METHODS

Twenty-five multi-detector CT colonography examinations of patients with validated polyps accumulated at a single centre were examined by two readers who used endoscopic and histopathological data to identify polyp coordinates. A CAD system that had been developed using data from elsewhere, and had not previously encountered the present data, was then applied to the data at sphericity filter settings of 0.75 and 0.50 and identified potential polyps. True-positive, false-negative, and false-positive counts were determined by comparison with the known polyp coordinates.

RESULTS

Twenty-five patients had 57 polyps, median size 6mm (range 1-15mm). Per-patient sensitivity for the CAD system was 96% (24 of 25). The CAD system detected 44 (77%) polyps at sphericity setting 0.75 and 49 (86%) polyps at sphericity 0.50: the additional five polyps detected all measured 5mm or less. Sphericity of 0.75 resulted in a median of 10 (one to 34) easily dismissed false-positive prompts per patient and a median of 4 (zero to 15) that needed three-dimensional rendering before dismissal. This rose to 32 (16 to 99) and 11 (three to 35), respectively, at sphericity 0.5.

CONCLUSIONS

A per-patient sensitivity of 96% was found for the CAD system (in patients with a median polyp diameter of 6mm) using external validation, a more stringent test than either internal cross-validation or temporal validation. Decreasing sphericity increases sensitivity for small polyps at the expense of decreased specificity.

Prescription compliance and persistency in chronic myelogenous leukemia (CML) and gastrointestinal stromal tumor (GIST) patients (pts) on imatinib (IM)

6119

Background: IM (Glivec, Gleevec) is an oral targeted therapy with unprecedented efficacy in CML and GIST. Prescription compliance and persistency of pts receiving IM were measured by analysis of pt-level pharmacy claims data. Methods: Compliance and persistency were determined by analyzing the prescription-filling activity of pts (N=4043) compared with the prescribing activity of their physicians (N=3316) using pt pharmacy records accrued over 24 months (1/03–12/04). Observed average daily consumption (DACON) and average prescribed days of therapy were calculated and compared. Also, compliance and persistency were examined by pt demographics and initial IM dose prescribed. Results: Overall compliance (defined as medication possession ratio = apparent mg taken/mg prescribed) was 75%, with CML pts showing slightly greater compliance (78%) than GIST pts (73%). Fifty percent of pts were 100% compliant, the greatest compliance being found in pts initially treated with IM 300 or 400 mg/day (77%). Persistency (time on therapy without significant gaps in refills) averaged 255 days over 24 months. The most persistent pts were those initially given 300 or 400 mg/day (13.0 and 12.9 months, respectively). DACON was 400 mg/day for 65% of patients, but fluctuated above and below 400 mg/day in 18% and 17% of pts, respectively. Conclusions: This is the first assessment of pt compliance and persistency with prescribed IM therapy. Although less pronounced than with most other non-oncology products, suboptimal compliance and persistency with IM are a concern as doses <300–400 mg may result in plasma levels lower than needed to eliminate cancer cells. Patient support programs and improved communication on the importance of adhering to recommended dosing could potentially optimize outcome and further reduce risk of relapse and progression.

[Table: see text]

Influence of palliative surgical resection on overall survival in patients with Advanced Colorectal Cancer: A retrospective single institutional study

13532

Background: The role of palliative surgical resection in patients presenting with locally advanced or metastatic colorectal cancer (CRC) is unclear. Resection is often limited to symptomatic management of bleeding, obstruction, perforation or for relief of pain, in patients with an adequate performance status and an expected life span of over several weeks. An exploratory analysis to evaluate the influence of a palliative surgical resection on survival outcome in patients with advanced CRC is reported. Methods: A retrospective review of medical records of all patients diagnosed with advanced CRC at our institution between the years 1998–2003 was undertaken. Tumor registry data were reviewed to identify age, gender, modalities of therapy (i.e. surgery (S), chemotherapy (C), radiation), and overall survival. IRB approval was obtained for this study. Results: 185 patients were identified. Mean age was 67 years (range 30–99). M: F ratio was 1:1. 62% of patients (115/185) underwent a palliative surgical intervention. Mean survival of patients who underwent S and those that did not undergo S was 27.7 months (mo) and 8.7 mo respectively (p<0.0001). 48% of patients (79/185) underwent systemic C. Mean survival of patients who received C + S, and patients who received C alone was 39 mo and 17.3 mo respectively (p<0.0004). 51% of patients who underwent S, received C; 30% of patients who did not undergo S, received C. Chemotherapy data were available on 46 of 79 patients. Patients treated with S + C, and C without S, received a median of 9 mo and 6 mo of therapy respectively. The median number of regimens used were similar in both. Conclusions: These exploratory data suggest a positive influence of a palliative resection performed during the disease course of patients with advanced CRC. The increased frequency of utilization and the more prolonged duration of C in the surgically treated patients may in part contribute to this improved survival . This may also be reflective of performance status at the time of diagnosis. Future trials enrolling patients with advanced CRC should prospectively stratify for surgical intervention to further clarify the influence of this modality on the outcome of systemic therapy in this disease.

No significant financial relationships to disclose.

Impact of a right ventricular impedance sensor on the cardiovascular responses to exercise in pacemaker dependent patients

BACKGROUND

The evaluation of the heart rate (HR) response to exercise is important for the assessment of the rate response algorithm of sensor-controlled pacemakers. This study examined the effects of a right ventricular impedance sensor driven pacemaker on the cardiovascular responses to incremental exercise in pacemaker dependent patients.

METHODS

Twelve patients (70.5 +/- 9.5 years; 5 Females: 7 Males) implanted with an Inos(2+) closed loop stimulation (CLS) pacemaker were compared to 12 healthy age and sex matched controls (70.6 +/- 4.8 years). All subjects performed the chronotropic assessment exercise protocol (CAEP). Variables of interest included HR, cardiac output (Q), oxygen uptake (VO2) and blood pressure (BP). Data were analyzed at rest, throughout exercise and during recovery. Furthermore, patient chronotropic responses were compared to a reference chronotropic response slope for aerobic exercise.

RESULTS

There were no differences between groups for HR or Q response throughout exercise. At peak exercise, VO2 (mL x kg(-1) x min(-1)) was higher for the controls (p < 0.05). The patient chronotropic response slope was comparable to the CAEP reference slope from rest to both the anaerobic threshold (AT) and peak exercise. During recovery, no differences were observed between the groups for any parameters or for the HR decay slopes.

CONCLUSION

Up to the anaerobic threshold, the right ventricular impedance sensor driven pacemaker delivered a pacing rate that contributed to an overall cardiovascular response similar to that observed in healthy age matched subjects.

Role of the Endothelin System in Secondary Pulmonary Hypertension Related to Air Embolism: Lessons Learned from Testing Four Classes of Endothelin Blockers in a Rat Model

A rat model of acute pulmonary air embolism (APAE) was developed. These animals had a higher right ventricular systolic pressure (RVSP) (+ 69% at 15-minute peak, and 21-34% at 30-180 minutes), as well as a reduced mean arterial blood pressure (10-20% at 60-180 minutes), heart rate (20-26% at 60-180 minutes) and PaO2 (9-11% at 30-180 minutes) compared with control rats. The role of the endothelin (ET) system, known to be involved in pulmonary hypertension of various etiologies, was investigated by evaluating the effect of the four classes of ET blockers: ET-converting enzyme inhibitor (ECEi) (CGS 35066), selective endothelin-A receptor antagonist (ETA-Ra) (Atrasentan, ABT-627), endothelin-B receptor antagonist (ETB-Ra) (A-192621) or mixed endothelin-A/endothelin-B receptor antagonist (ETA/B-Ra) (A-182086) in this animal model. All four were effective, to various degrees, at reducing the APAE-induced rise in RVSP. The relative efficacy of those compounds in reducing the acute elevation (15 minutes) of RVSP was ECEi >or= ETA/B-Ra >> ETA-Ra = ETB-Ra. The sustained elevation (30-180 minutes) of RVSP was totally abolished by ECEi and attenuated by other ET blockers with a relative efficacy of ETA-Ra > ETA/B-Ra >or= ETB-Ra. ET receptor antagonists did not affect right ventricular basal tone (control rats) whereas ECEi reduced it by up to 12% after 2 hours. The APAE reduction in mean arterial blood pressure was unaffected by ETARa, was completely normalized by ETB-Ra, but was further reduced by either ETA/B-Ra or ECEi. The basal mean arterial blood pressure in control rats was unaffected by ETA-Ra, was elevated by ETB-Ra, but was depressed by ETA/B-Ra and ECEi. All ET blockers maintained normal oxygen saturation in APAE. These results support a role for ETs in rat APAE, since ET blockers can attenuate the cardiopulmonary deterioration and blood gas exchange. However, modulation of the central hemodynamic profile is more complex and may limit the usefulness of some ET blockers.

Psychological distress and negative appraisals in survivors of severe acute respiratory syndrome (SARS)

BACKGROUND

Severe acute respiratory syndrome (SARS) is a novel disease. The authors have limited knowledge of its impact on mental health. The present study aimed to examine the level and extent of psychological distress of SARS survivors following 1-month recovery, to explore patients' negative appraisals of the impact of SARS, and to evaluate the associations between psychological distress and negative appraisals.

METHOD

The Beck Anxiety Inventory, the Beck Depression Inventory, and a newly developed measure, the SARS Impact Scale (SIS), were mailed to 453 Hong Kong Chinese SARS survivors discharged from hospital for 4 weeks or more.

RESULTS

A total of 425 patients received the questionnaires and 180 (mean age 36.9 years; 120 women) gave valid replies. The response rate was 42.4 %. The participants also represented 13.6 % of all adult survivors in Hong Kong. About 35 % of respondents reported 'moderate to severe' or 'severe' ranges of anxiety and/or depressive symptoms. It was found that those working as healthcare workers or having family members killed by SARS were more prone to develop subsequent high levels of distress. Factor analyses extracted three meaningful factors of the SIS, namely 'survival threat', 'physical impact', and 'social impact'. Negative appraisals at the acute phase and 1-month recovery significantly accounted for substantial portions of variances for anxiety and depressive symptoms, after the effects of other psychosocial variables were controlled.

CONCLUSIONS

Psychological distress of SARS survivors at 1-month recovery is real and significant. Negative appraisals may play a pivotal role in the development of psychological distress for SARS survivors, at least in the short term.

Plasma levels of endothelin-1, big endothelin-1 and thromboxane following acute pulmonary air embolism

Acute pulmonary air embolism (APAE) was induced in nine piglets by repeated intravenous bolus injection of room air into a large bore central venous catheter at time=0 min so that the mean pulmonary artery pressure (MPAP) was maintained at two times the baseline value for 4 h. Another five animals served as controls. At time=0, 30, 60, 120, 240 min, circulating arterial plasma levels of endothelin-1 (ET-1), its precursor big ET-1, and thromboxane (Tx), were measured by RIA and EIA, respectively, along with hemodynamics and blood gases. The data showed that following APAE, there was a rapid increase in MPAP and a persistent decrease in Pa(O(2)), while the mean arterial blood pressure and cardiac output remained comparable. Plasma levels of ET-1, big ET-1 and Tx were also increased steadily in these first 4 h. These results showed that during APAE, the resulted changes in the pulmonary vascular and airway tones mediated by these potent mediators could explain the observed pulmonary hypertension and the deterioration of gas exchange.

Impact of adaptive rate pacing controlled by a right ventricular impedance sensor on cardiac output in response to exercise

This study examined the effects of adaptive rate pacing controlled by closed-loop right ventricular impedance sensing on exercise hemodynamics. Twelve patients in whom Biotronik INOS2+ pacemakers had been implanted 4-6 weeks earlier participated in the study. All patients completed two graded, symptom-limited exercise tests. The pacemaker was programmed to DDDR with an upper rate limit of 75-85% of the age-predicted maximum heart rate and a lower rate limit of 45-60 ppm. Heart rate was recorded continuously. An average of 5 beats during the last 10 seconds of each exercise stage was used in the analysis. Oxygen uptake (VO2) was measured using open circuit spirometry. The VO2 values from the final 15 seconds of each exercise stage were used for analysis. Stroke volume and cardiac output were measured during the last minute of each stage using impedance cardiography. The test-retest reliability of heart rate and cardiac output responses to graded exercise was assessed using repeated measures analysis of variance, for which the reliability coefficients were r = 0.993 and r = 0.954, respectively (P < 0.01). There were significant correlations (P < 0.01) between VO2 and heart rate and between VO2 and cardiac output, with correlation coefficients of r = 0.907 and r = 0.824, respectively. This method of adaptive rate pacing produced reliable, positive hemodynamic responses to graded exercise on a test-retest basis.

Effects of a selective endothelin A receptor antagonist, ABT-627, in healthy normotensive anaesthetized rats developing acute pulmonary air embolism

Acute pulmonary air embolism (APAE) injures the vascular endothelium in the lung and results in pulmonary hypertension (PH). Endothelins (ETs), a family of potent vasoactive peptides, are known to be associated with PH of various aetiologies. We evaluated the effects of ABT-627, a selective ET(A) receptor (ET(A)-R) antagonist in a rat model of APAE over 3 h. APAE rats developed a higher right ventricular systolic pressure (RVSP), lower mean arterial blood pressure (MABP), and had lower PaO(2). At 3 h, arterial plasma levels of ET-1 were increased. ABT-627-treated controls showed no effects. However, ABT-627 significantly lowered RVSP during APAE, abolished the short recovery phase (within 10-25 min) of MABP without affecting the subsequent lowering of MABP, and improved oxygen saturation in APAE rats. These results show that ET(A)-R subtype is involved in the pathogenesis of APAE since a blockade of this receptor subtype attenuated the cardiopulmonary deterioration and improved blood gas exchanges in rats with this disease.

Proinflammatory cytokines are not released in the circulation following acute pulmonary thromboembolism in pigs

Histological examination of acute lung injury associated with sepsis often revealed thromboembolic lesions in the pulmonary microcirculation. Several inflammatory mediators such as platelet activating factor, thromboxane, and endothelins have also been implicated in the pathogenesis of acute pulmonary thromboembolism (APTE). In the present study we examined the roles of three proinflammatory cytokines, tumor necrosis factor-alpha (TNF-alpha), interleukin 1beta (IL-1beta), and IL-8, in the early phase of APTE. APTE was induced in 13 anesthetized piglets (22+/-4 kg) by injecting thrombin-induced blood clots directly into the left lower lobar pulmonary artery. Five animals that received only warm sterile saline served as controls. Arterial plasma samples were collected regularly over 8 h so that cytokine levels could be measured later by enzyme-linked immunosorbent assay (ELISA). Administration of clots doubled the mean pulmonary arterial pressure (from 13+/-5 to 26+/-7 mm Hg) and caused significant decrease in arterial oxygen tension (PaO2 from 390+/-85 to 256+/-89 mm Hg while the FiO2 was maintained at 1.0). Mean arterial blood pressure and cardiac output remained comparable throughout the experiments after initial fluid resuscitation. Plasma levels of TNF-alpha, IL-1beta, and IL-8 were not significantly increased in the APTE group when compared with their baseline values or the control group. Our results thus show that APTE is associated with pulmonary hypertension and deterioration of gas exchange but not with the systemic release of TNF-alpha, IL-1beta, or IL-8. We conclude that these cytokines have minimal impact on the systemic circulation during APTE.

Coronary stenting in diabetic patients: Results from the ROSETTA registry

OBJECTIVE

Diabetes mellitus is associated with high rates of restenosis and adverse outcomes after percutaneous transluminal coronary angioplasty (PTCA). It is unclear whether coronary stenting reduces adverse events in diabetic patients after PTCA. Our purpose was to determine whether coronary stenting improves clinical event rates in diabetic patients after PTCA.

METHODS

The Routine Versus Selective Exercise Treadmill Testing After Angioplasty (ROSETTA) registry was a prospective multicenter observational study examining functional testing and adverse outcomes after successful PTCA.

RESULTS

Among the 791 patients enrolled, 180 were diabetic. A total of 90 diabetics received stents while the remaining 90 patients did not. Baseline clinical characteristics were similar between the 2 groups of patients. However, patients with stents were more likely to have complex lesions, whereas those without stents were more likely to undergo atherectomy and have greater residual coronary stenosis. At 6-month follow-up, the composite end point defined as cardiac death, unstable angina, myocardial infarction, need for repeat PTCA, or coronary artery bypass graft surgery (CABG) occurred in 25.0% of stented and 22.2% of nonstented diabetic patients (P not significant [NS]). A multivariate logistic regression analysis showed that coronary stenting was not associated with a reduced incidence of the composite end point among diabetic patients (odds ratio 0.97, 95% CI 0.46-2.05, P NS).

CONCLUSION

Coronary stenting does not improve clinical event rates in diabetic patients after PTCA.

Survey of hospital doctors' attitudes and knowledge of oral conditions in older patients

The study was designed to assess the views and knowledge of hospital doctors in general and geriatric medicine on oral health in older people. Eighty two doctors in general and geriatric medicine at two hospitals were shown 12 colour slides of oral mucosal conditions and asked to give a diagnosis for each slide and complete a questionnaire. Completed questionnaires with the answers to the coloured slides were returned completed by 70 doctors. The majority of doctors (84%) felt it was important to examine older patients' mouths, however only 19% (chi(2) p=0.0001) routinely do so. If asked to prescribe nystatin by the nursing staff, 30% said they would do so without examining the mouth itself. Only 9% of doctors knew that wearing dentures was a specific risk factor for oral candidiasis (chi(2) p=0.001). Altogether 56% of doctors did not feel confident in examining the oral cavity and most (77%) did not think they had had sufficient training in this examination. Only two doctors correctly diagnosed all of the slides. An early squamous carcinoma was misdiagnosed by 80% of the doctors (chi(2) p=0.0001). Hospital doctors do not routinely inspect older patients' mouths. Even if shown slides of typical oral mucosal lesions many hospital doctors are unable to diagnose them. Issues on training need to be addressed. From the patients' point of view a public health campaign is required to educate older people on the need for a regular dental review and be aware that doctors may not be able to diagnose serious oral conditions.

Biphasic release of immunoreactive endothelins following acute pulmonary thromboembolism in pigs

The purpose of this investigation was to study the role of endothelins (ETs) in the pathogenesis of acute pulmonary thromboembolism (PTE). Eighteen piglets (20 +/- 3 kg) were anesthetized and ventilated with 100% oxygen, five of them then served as controls. Acute thromboembolic injury in the lung was induced by injecting 15-25 ml of preformed clots into the left lower lobar pulmonary artery during thoracotomy. Pulmonary arterial pressure (Ppa) increased by at least 2.5-fold from baseline. During the subsequent 8 h, seven blood samples were collected from the left atrium and assayed for immunoreactive ETs. The results showed that following PTE: (1) Ppa remained elevated but cardiac output remained constant throughout the experiments; (2) plasma level of immunoreactive ETs increased in the embolized group compared to controls and the profile of immunoreactive ET release suggested a biphasic response. We conclude that the release of these vasocontractile and bronchoconstrictive mediators after PTE may contribute to ventilation perfusion mismatching and account for the pulmonary hypertension and deterioration of gas exchange that are often seen clinically.

Primary right atrial synovial sarcoma manifesting as transient ischemic attacks

Primary tumors of the heart are rare and most of them benign. The majority of benign cardiac tumors are myxomas while almost all malignant cardiac tumors are sarcomas. We present a case of primary right atrial synovial sarcoma, a form of sarcoma particularly rare in the heart. The tumor manifested clinically as transient ischemic attacks probably related to a patent foramen ovale allowing paradoxical tumor embolization.

Aneurysm after subclavian flap angioplasty repair of coarctation of the aorta

We report a case of aortic aneurysm at the site of subclavian flap angioplasty repair for coarctation of the aorta. The dilatation involved the lateral wall of the proximal descending aorta that had been constructed by the flap. Five other similar cases have been reported in the literature. Diligent long-term follow-up is needed after surgical repair of coarctation of the aorta to detect late complications such as restenosis or aneurysm formation.

Patient-controlled analgesia in postoperative cardiac surgery

The purpose of this study was to assess, in the early postoperative period of cardiac surgery, the efficacy of patient-controlled analgesia (PCA) versus nurse-administered intravenous morphine followed by oral acetaminophen with or without codeine. Patients undergoing coronary bypass and/or valvular surgery were recruited. All were under 75 years of age and were in stable angina with no ischaemic attacks within the last three months. Visual analog scores (VAS) were used for pain assessment. Pulmonary function tests were done preoperatively and measured every six hours after surgery until discharge from the intensive care unit. Patients allocated to the PCA group received morphine intravenously by a PCA Plus Micro Delivery Device for at least 48 hours. Patients entered into the nurse-administered intravenous morphine group received intravenous morphine followed by oral acetaminophen with or without codeine in 24 to 36 hours according to the clinical assessment of the critical care nurse. The data showed that the quality of pain control and pulmonary function were comparable in both groups. The equipotent morphine dosage requirements were also not statistically different. It was concluded that there was no significant advantage in using PCA routinely in the early postoperative period after cardiac surgery. Furthermore, repetition of PCA instructions was often required during the study period.

Delayed diaphragmatic herniation masquerading as a complicated parapneumonic effusion

Injury to the diaphragm following blunt or penetrating thoracoabdominal trauma is not uncommon. Recognition of this important complication of trauma continues to be a challenge because of the lack of specific clinical and plain radiographic features, the frequent presence of other serious injuries and the potential for delayed presentation. Delayed diaphragmatic herniation often presents with catastrophic bowel obstruction or strangulation. Early recognition of diaphragmatic injury is required to avoid this potentially lethal complication. The case of a 35-year-old man with a history of a knife wound to the left flank 15 years previously, who presented with unexplained acute hypoxemic respiratory failure and a unilateral exudative pleural effusion that was refractory to tube thoracostomy drainage, is reported. After admission to hospital, he developed gross dilation of his colon; emergency laparotomy revealed an incarcerated colonic herniation into the left hemithorax. Interesting clinical features of this patient's case included the patient's hobby of weightlifting, a persistently deviated mediastinum despite drainage of the pleural effusion and deceptive pleural fluid biochemical indices.

Electrostatics and the membrane association of Src: theory and experiment

The binding of Src to phospholipid membranes requires both hydrophobic insertion of its myristate into the hydrocarbon interior of the membrane and nonspecific electrostatic interaction of its N-terminal cluster of basic residues with acidic phospholipids. We provide a theoretical description of the electrostatic partitioning of Src onto phospholipid membranes. Specifically, we use molecular models to represent a nonmyristoylated peptide corresponding to residues 2-19 of Src [nonmyr-Src(2-19); GSSKSKPKDPSQRRRSLE-NH2] and a phospholipid bilayer, calculate the electrostatic interaction by solving the nonlinear Poisson-Boltzmann equation, and predict the molar partition coefficient using statistical thermodynamics. The theoretical predictions agree with experimental data obtained by measuring the partitioning of nonmyr-Src(2-19) onto phospholipid vesicles: membrane binding increases as the mole percent of acidic lipid in the vesicles is increased, the ionic strength of the solution is decreased, or the net positive charge of the peptide is increased. The theoretical model also correctly predicts the measured partitioning of the myristoylated peptide, myr-Src(2-19); for example, adding 33% acidic lipid to electrically neutral vesicles increases the partitioning of myr-Src(2-19) 100-fold. Phosphorylating either serine 12 (by protein kinase C) or serine 17 (by cAMP-dependent protein kinase) decreases the partitioning of myr-Src(2-19) onto vesicles containing acidic lipid 10-fold. We investigated the effect of phosphorylation on the localization of Src to biological membranes by expressing fusion constructs of Src's N terminus with a soluble carrier protein in COS-1 cells; phosphorylation produces a small shift in the distribution of the Src chimeras from the plasma membrane to the cytosol.

Attitudes toward life-sustaining treatment of older persons in Hong Kong

OBJECTIVES

There have been few studies of the attitudes of older Asians toward life-sustaining therapy. This paper presents the knowledge of and attitudes toward cardiopulmonary resuscitation (CPR) and life support in a group of subjects in Hong Kong.

DESIGN

Cross-sectional, descriptive study.

PARTICIPANTS

Of the 543 subjects, 382 were old-age home residents and 161 were in-patients of geriatric wards.

MEASUREMENTS

Sociodemographic data, functional ability (using the Barthel Index), self-perceived health scale, knowledge of life-sustaining procedures, and subjects' preferences for such treatments were studied. They were also asked to give the most important reason for wanting or declining CPR, and to indicate who they believe should be the decision-maker(s) regarding whether they should receive life-sustaining treatment.

RESULTS

Approximately 80% of old-age home residents and 60% of hospitalized patients had no knowledge of life-sustaining therapy. The success rate of CPR was overestimated by older subjects, and most wished to be resuscitated. However, up to 20% changed their minds and declined CPR after they knew the true outcome of the procedure. Half of the subjects wanted life support. Univariate analysis found that advanced age and not having a spouse were associated significantly with CPR preference, whereas subjects' knowledge was associated with preference for life support. Multivariate analysis revealed that advanced age, not having a spouse, and female sex were independently associated with a tendency to decline CPR. A considerable proportion of older people wished to be involved in decision-making regarding life-sustaining treatment.

CONCLUSION

Knowledge of life-sustaining procedures was poor among older people in Hong Kong compared with their counterparts in western countries. Although most older subjects wanted CPR, a number of them changed their minds after they knew the poor outcome. Therefore, older patients should be given more information about life-sustaining therapy and encouraged to take part in their treatment plans.

Outcome studies for burn patients in Hong Kong: patients' satisfaction

With the recent advances in burns treatment, many more survive the burn to experience pain, scarring, physical deformity, loss of function and psychological trauma. Pressure therapy prescribed by occupational therapists for more than 20 years in Hong Kong has proved its effectiveness in treating the visible scars. However, the inconvenience and impaired appearance that is brought about by these garments during the long phase of therapy bears some weight in worsening patients' social acceptance and happiness in life, also their families especially in children. The objects of the studies were to measure the subjective rating of the effectiveness of pressure therapy through patients' satisfaction towards treatment effectiveness and its effect on daily life. Seventy cases with burn injuries over 1 year previously were selected randomly among the centres for the survey. The scale used was ordinal from 1 to 6. Eleven items concerning treatment effectiveness, life at home, work and leisure aspects were questioned. Results were analysed into two streams-satisfaction towards pressure therapy and change of life satisfaction pre- and post-injury. Non-parametric tests were used for data analysis. Through the Wilcoxon Sign Rank Test and Cluster analysis, major determinants were identified. These factors also showed significant correlation with this demographic data. The conclusions helped to evaluate and improve the existing service in both the garment properties and our scope of therapy for these patients, especially in work rehabilitation and finally (sexual) counselling which should be addressed by a team with interdepartmental support.

Specialization of the DNA-cleaving activity of a group I ribozyme through in vitro evolution

In an earlier study, an in vitro evolution procedure was applied to a large population of variants of the Tetrahymena group I ribozyme to obtain individuals with a 10(5)-fold improved ability to cleave a target single-stranded DNA substrate under simulated physiological conditions. The evolved ribozymes also showed a twofold improvement, compared to the wild-type, in their ability to cleave a single-stranded RNA substrate. Here, we report continuation of the in vitro evolution process using a new selection strategy to achieve both enhanced DNA and diminished RNA-cleavage activity. Our strategy combines a positive selection for DNA cleavage with a negative selection against RNA binding. After 36 "generations" of in vitro evolution, the evolved population showed an approximately 100-fold increase in the ratio of DNA to RNA-cleavage activity. Site-directed mutagenesis experiments confirmed the selective advantage of two covarying mutations within the catalytic core of the ribozyme that are largely responsible for this modified behavior. The population of ribozymes has now undergone a total of 63 successive generations of evolution, resulting in an average of 28 mutations relative to the wild-type that are responsible for the altered phenotype.

Lung water is increased in regions of higher neutrophil retention after acute bead embolization

Previous reports have shown that neutrophils are retained in the lung after acute embolization and that these neutrophils play an important role in the subsequent formation of permeability pulmonary edema. The present study was designed to test the hypothesis that acute embolic injury results in microvascular damage in lung regions with the greater retention of neutrophils. Seventeen pigs (20 +/- 2 kg) were embolized by injecting polystyrene beads (250 microns; labeled with 131I) into the right atrium over 5 min. Five pigs, which received no embolic beads, served as controls. Neutrophils (89 +/- 5% pure), isolated on Ficoll-Histopaque gradient, were radiolabeled with 111In-oxine. Twenty minutes after embolization, the radiolabeled neutrophils were injected into the right atrium along with 85Sr-labeled microspheres to mark the initial neutrophil distribution within the lung as well as the regional pulmonary blood flow at the time of their delivery. The animals were killed 50 min after embolization, and the lungs were removed, frozen over liquid nitrogen, and cut into 60 samples. The data show that after embolization regional neutrophil retention was inversely related to the regional blood flow but was not affected by the embolic load in the same region. Regional extravascular lung water was increased in regions of higher neutrophil retention, but the regions with increased edema did not receive a greater embolic load. These results show that microvascular injury occurs in the lung regions with the greatest neutrophil retention and that this increased retention of neutrophils is unrelated to the extent of embolization.

Unusual trigonal-planar copper configuration revealed in the atomic structure of yeast copper-zinc superoxide dismutase

The three-dimensional structure of yeast copper-zinc superoxide dismutase (CuZnSOD) has been determined in a new crystal form in space group R32 and refined against X-ray diffraction data using difference Fourier and restrained crystallographic refinement techniques. The unexpected result is that the copper ion has moved approximately 1 angstrom from its position in previously reported CuZnSOD models, the copper-imidazolate bridge is broken, and a roughly trigonal planar ligand geometry characteristic of Cu(I) rather than Cu(II) is revealed. Final R values for the two nearly identical room temperature structures are 18.6% for all 19 149 reflections in the 10.0-1.7 angstrom resolution range and 18. 2% for 17 682 reflections (F > 2 sigma) in the 10.0-1.73 angstrom resolution range. A third structure has been determined using X-ray data collected at -180 degrees C. The final R value for this structure is 19.0% (R(free) = 22.9%) for all 24 356 reflections in the 10.0-1.55 angstrom resolution range. Virtually no change in the positions of the ligands to the zinc center is observed in these models. The origin of the broken bridge and altered Cu-ligand geometry is discussed.

Evolutionary optimization of the catalytic properties of a DNA-cleaving ribozyme

In a previous study [Beaudry, A. A., & Joyce, G. F. (1992) Science 257, 635-641], an in vitro evolution procedure was used to obtain variants of the Tetrahymena ribozyme with 100-fold improved ability to cleave a target single-stranded DNA under physiologic conditions. Here we report continuation of the in vitro evolution process to achieve 10(5)-fold overall improvement in DNA-cleavage activity. In addition, we demonstrate that, by appropriate manipulation of the selection constraints, one can optimize specific catalytic properties of the evolved ribozymes. We first reduced the concentration of the DNA substrate 50-fold to favor ribozymes with improved substrate binding affinity. We then reduced the reaction time 12-fold to favor ribozymes with improved catalytic rate. In both cases, the evolving population responded as expected, first improving substrate binding 25-fold, and then improving catalytic rate about 50-fold. The population of ribozymes has undergone 27 successive generations of in vitro evolution, resulting in, on average, 17 mutations relative to the wild type that are responsible for the improved DNA-cleavage activity.

Proteinuria and renal function in diabetic patients fed a diet moderately restricted in protein

Protein restriction has been used in the treatment of renal disease and may also be beneficial in the management of diabetic nephropathy. We evaluated the effects of moderate protein restriction (0.6 g/kg ideal body weight per day) for a 3-mo period on renal function in seven diabetic patients. Moderate protein restriction led to a decrease of approximately 50% in the albumin excretion rate in patients with overt proteinuria or microalbuminuria. This decrease occurred in some patients without a decrease in glomerular filtration rate, renal plasma flow, or plasma albumin concentration and may reflect subtle changes in filtration properties or permeability of glomeruli. In this pilot study moderate protein restriction has marked effects on albumin excretion irrespective of the initial degree of renal impairment. It is therefore suitable for longer-term study of its effects on the progression of renal disease in both patients with overt and incipient diabetic nephropathy.

Alveolar epithelial damage. A critical difference between high pressure and oleic acid-induced low pressure pulmonary edema

The present study was designed to compare high pressure pulmonary edema (HPPE) and oleic acid-induced low pressure pulmonary edema (OAPE) in dogs when similar amounts of extra vascular water were present in the lung. The high pressure edema was produced by intravenous fluid overload and by inflating an aortic balloon catheter (n = 6). The low pressure edema was produced by the injecting 0.08 mg/kg oleic acid suspended in 5 ml saline (n = 6). Comparison of the difference between initial control measurements and final measurements in the edematous states showed that the animals with OAPE had a greater fall in percent oxygen saturation and a greater increase in shunt fractions. The light microscopic studies showed that OAPE was associated with greater amounts of alveolar flooding than HPPE where the edema fluid was located to a greater extent in the peribronchial interstitial space. The electron microscopy studies showed that the alveolar flooding in OAPE was associated with epithelial disruption, and tracer studies carried out in rabbits showed that dextran (150,000 mol wt) could pass from blood to airspace and that dextran (40,000 mol wt) could pass from air-space to blood in OAPE. We conclude that epithelial disruption is responsible for the excessive alveolar flooding in OAPE and that this results in a greater impairment in gas exchange.

Growth-dependent alterations in oligomannosyl cores of glycopeptides

Mannose-labeled glycopeptides from the surface of growing and nongrowing human diploid cells (KL-2) were separated into neutral glycopeptides and acidic glycopeptides by paper electrophoresis. Growth-dependent alterations occurred in oligomannosyl cores in the neutral glycopeptides; namely, the neutral glycopeptides from the surface of growing cells were more resistant to endo-beta-N-acetylglucosaminidase D but were more susceptible to alpha-mannosidase (EC 3.2.1.24; alpha-D-mannose mannohydrolase) than those derived from the surface of nongrowing cells. Another growth-dependent change was found when the endoglycosidase-resistant material from acidic glycopeptides was compared by paper electrophoresis at pH 1.9. The material from the surface of nongrowing cells contained a component that was absent or greatly reduced in growing cells.

Starch peritonitis--a hazard of surgical glove powder

Starch peritonitis, a granulomatous reacton to surgical glove powder, is reported in four patients. The condition presents as a well defined clinical syndrome, and should perferably be diagnosed clinically to avoid reoperation and the risk of introduction of more starch. Studies show that a mean of 107 mg of starch per pair is present on the outside of Austrailn-made surgical gloves. It is suggested that gloves be rinsed and dried before operation and it is recommended that a warning to this effect be printed on glove packets.