Biophysical and mutagenic analysis of Thermoanaerobacter ethanolicus secondary-alcohol dehydrogenase activity and specificity

The Thermoanaerobacter ethanolicus 39E adhB gene encoding the secondary-alcohol dehydrogenase (secondary ADH) was overexpressed in Escherichia coli at more than 10% of total protein. The recombinant enzyme was purified in high yield (67%) by heat-treatment at 85 degrees C and (NH4)2SO4 precipitation. Site-directed mutants (C37S, H59N, D150N, D150Eand D150C were analysed to test the peptide sequence comparison-based predictions of amino acids responsible for putative catalytic Zn binding. X-ray absorption spectroscopy confirmed the presence of a protein-bound Zn atom with ZnS1(imid)1(N,O)3 co-ordination sphere. Inductively coupled plasma atomic emission spectrometry measured 0.48 Zn atoms per wild-type secondary ADH subunit. The C37S, H59N and D150N mutant enzymes bound only 0.11, 0.13 and 0.33 Zn per subunit respectively,suggesting that these residues are involved in Zn liganding. The D150E and D150C mutants retained 0.47 and 1.2 Zn atoms per subunit, indicating that an anionic side-chain moiety at this position preserves the bound Zn. All five mutant enzymes had </= 3% of wild-type catalytic activity, suggesting that the T. ethanolicus secondary ADH requires a properly co-ordinated catalytic Zn atom. The His-59 and Asp-150 mutations also altered secondary ADH affinity for propan-2-ol over a 140-fold range, whereas the overall change in affinity for ethanol spanned a range of only 7-fold, supporting the importance of the metal in secondary ADH substrate binding. The lack of significant changes in cofactor affinity as a result of these catalytic Zn ligand mutations suggested that secondary ADH substrate-and cofactor-binding sites are structurally distinct. Altering Gly198 to Asp reduced the enzyme specific activity 2.7-fold, increased the Km(app) for NADP+ 225-fold, and decreased the Km(app) for NAD+ 3-fold, supporting the prediction that the enzyme binds nicotinamide cofactor in a Rossmann fold. Our data indicate therefore that, unlike the liver primary ADH,the Rossmann-fold-containing T. ethanolicus secondary ADH binds its catalytic Zn atom using a sorbitol dehydrogenase-like Cys-His-Asp motif and does not bind a structural Zn atom.

Antigenic variation during malaria infection--the contribution from the murine parasite Plasmodium chabaudi

P. chabaudi AS strain in laboratory mice provides an accessible and useful model for investigating antigenic variation in malaria parasites. Evidence that P. chabaudi AS undergoes antigenic variation is summarized. A live indirect fluorescent test (IFAT) detects a variable antigen on the surface of schizont-infected erythrocytes. Five different variable antigen types (VATS) (detected using the live IFAT) are described from a cloned mosquito transmitted parent population. Even during the rising primary parasitaemia VATS switch at high and variable rates (1.2-1.6%). Work towards cloning genes coding for the variable antigen is briefly summarized. Acquired immunity to blood-stage P. chabaudi AS is initially mediated through Th1 CD4+ T cells and after the primary parasitaemia there is a switch to Th2 CD4+ T cells. Acquired immune effector mechanisms are discussed in the context of antigenic variation by the parasite.

Cloning, sequence, and expression of kynureninase from Pseudomonas fluorescens

We have cloned the gene encoding kynureninase from Pseudomonas fluorescens using a restriction site polymerase chain reaction technique (RS-PCR) (G. Sarkar, R. T. Turner, and M. E. Bolander PCR Methods Appl. 2, 318-322, 1993) and expressed the enzyme in Escherichia coli DH5a F'. The kynureninase gene has an open reading frame (ORF) of 1251 base pairs that codes for a protein of 416 amino acids with a calculated molecular weight of 45,906. The protein purified from P. fluorescens has N-terminal threonine and an observed molecular weight of 45,787 by electrospray mass spectrometry, suggesting that the N-terminal methionine is removed by posttranslational processing. The complete gene was obtained by PCR and inserted into pTZ18U. The resultant plasmid was used to transform E. coli DH5alpha F', and these cells overexpressed kynureninase to about 37% of total soluble protein. The isolated recombinant protein has molecular weight and Km values identical to those of the native protein from P. fluorescens. The amino acid sequence exhibits 29% identity with those of rat and human kynureninases and 32% identity with the amino acid sequence translated from a Saccharomyces cerevisiae ORF. Alignment of the four sequences shows a highly conserved region which corresponds to the pyridoxal-5'-phosphate (PLP) binding site of rat kynureninase. Based on this alignment, we predict that Lys227 and Asp212 in P. fluorescens kynureninase are involved in pyridoxal-5'-phosphate binding. P. fluorescens kynureninase also exhibits significant homology to the nifS gene product, cysteine desulfurase, and to eucaryotic serine/pyruvate aminotransferases, suggesting that it is a member of subgroup IV of the aminotransferase family of PLP-dependent enzymes.

Outcomes and cost-effectiveness of initiating dialysis and continuing aggressive care in seriously ill hospitalized adults. SUPPORT Investigators. Study to Understand Prognoses and Preferences for Outcomes and Risks of Treatments

BACKGROUND

Renal failure requiring dialysis in the setting of hospitalization for serious illness is a poor prognostic sign, and dialysis and aggressive care are sometimes withheld.

OBJECTIVE

To evaluate the clinical outcomes and cost-effectiveness of initiating dialysis and continuing aggressive care for seriously ill hospitalized patients.

DESIGN

Prospective cohort study and cost-effectiveness analysis.

SETTING

Five geographically diverse teaching hospitals.

PATIENTS

490 patients (median age, 61 years; 58% women) enrolled in the Study to Understand Prognoses and Preferences for Outcomes and Risks of Treatments (SUPPORT) in whom dialysis was initiated.

MEASUREMENTS

Survival, functional status, quality of life, and health care costs. Life expectancy was estimated by extrapolating survival data (up to 4.4 years of follow-up) using a declining exponential function. Utilities (quality-of-life weights) were estimated by using time-tradeoff questions. Costs were based on data from SUPPORT and published Medicare data.

RESULTS

Median duration of survival was 32 days, and only 27% of patients were alive after 5 months. Survivors reported a median of one dependency in activities of daily living, and 62% rated their quality of life as "good" or better. Overall, the estimated cost per quality-adjusted life-year saved by initiating dialysis and continuing aggressive care rather than withholding dialysis and allowing death to occur was $128,200. For the 103 patients in the worst prognostic category, the estimated cost per quality-adjusted life-year was $274,100; for the 94 patients in the best prognostic category, the cost per quality-adjusted life-year was $61,900.

CONCLUSIONS

For the few patients who survived, clinical outcomes were fairly good. With the exception of patients with the best prognoses, however, the cost-effectiveness of initiating dialysis and continuing aggressive care far exceeded $50,000 per quality-adjusted life-year, a commonly cited threshold for cost-effective care.

Patient preferences for communication with physicians about end-of-life decisions. SUPPORT Investigators. Study to Understand Prognoses and Preference for Outcomes and Risks of Treatment

BACKGROUND

Physicians are frequently unaware of patient preferences for end-of-life care. Identifying and exploring barriers to patient-physician communication about end-of-life issues may help guide physicians and their patients toward more effective discussions.

OBJECTIVE

To examine correlates and associated outcomes of patient communication and patient preferences for communication with physicians about cardiopulmonary resuscitation and prolonged mechanical ventilation.

DESIGN

Prospective cohort study.

SETTING

Five tertiary care hospitals.

PATIENTS

1832 (85%) of 2162 eligible patients completed interviews.

MEASUREMENTS

Surveys of patient characteristics and preferences for end-of-life care; perceptions of prognosis, decision making, and quality of life; and patient preferences for communication with physicians about end-of-life decisions.

RESULTS

Fewer than one fourth (23%) of seriously ill patients had discussed preferences for cardiopulmonary resuscitation with their physicians. Of patients who had not discussed their preferences for resuscitation, 58% were not interested in doing so. Of patients who had not discussed and did not want to discuss their preferences, 25% did not want resuscitation. In multivariable analyses, patient factors independently associated with not wanting to discuss preferences for cardiopulmonary resuscitation included being of an ethnicity other than black (adjusted odds ratio [OR], 1.48 [95% CI, 1.10 to 1.99), not having an advance directive (OR, 1.35 [CI, 1.04 to 1.76]), estimating an excellent prognosis (OR, 1.72 [CI, 1.32 to 2.59]), reporting fair to excellent quality of life (OR, 1.36 [CI, 1.05 to 1.76]), and not desiring active involvement in medical decisions (OR, 1.33 [CI, 1.07 to 1.65]). Factors independently associated with wanting to discuss preferences for resuscitation but not doing so included being black (OR, 1.53 [CI, 1.11 to 2.11]) and being younger (OR, 1.14 per 10-year interval younger [CI, 1.04 to 1.25]).

CONCLUSIONS

Among seriously ill hospitalized adults, communication about preferences for cardiopulmonary resuscitation is uncommon. A majority of patients who have not discussed preferences for end-of-life care do not want to do so. For patients who do not want to discuss their preferences, as well as patients with an unmet need for such discussions, failure to discuss preferences for cardiopulmonary resuscitation and mechanical ventilation may result in unwanted interventions.

The crystal structure of Citrobacter freundii tyrosine phenol-lyase complexed with 3-(4'-hydroxyphenyl)propionic acid, together with site-directed mutagenesis and kinetic analysis, demonstrates that arginine 381 is required for substrate specificity

The X-ray structure of tyrosine phenol-lyase (TPL) complexed with a substrate analog, 3-(4'-hydroxyphenyl)propionic acid, shows that Arg 381 is located in the substrate binding site, with the side-chain NH1 4.1 A from the 4'-OH of the analog. The structure has been deduced at 2.5 A resolution using crystals that belong to the P2(1)2(1)2 space group with a = 135.07 A, b = 143.91 A, and c = 59.80 A. To evaluate the role of Arg 381 in TPL catalysis, we prepared mutant proteins replacing arginine with alanine (R381A), with isoleucine (R381I), and with valine (R381V). The beta-elimination activity of R381A TPL has been reduced by 10(-4)-fold compared to wild type, whereas R381I and R381V TPL exhibit no detectable beta-elimination activity with L-tyrosine as substrate. However, R381A, R381I, and R381V TPL react with S-(o-nitrophenyl)-L-cysteine, beta-chloro-L-alanine, O-benzoyl-L-serine, and S-methyl-L-cysteine and exhibit k(cat) and k(cat)/Km values comparable to those of wild-type TPL. Furthermore, the Ki values for competitive inhibition by L-tryptophan and L-phenylalanine are similar for wild-type, R381A, and R381I TPL. Rapid-scanning-stopped flow spectroscopic analyses also show that wild-type and mutant proteins can bind L-tyrosine and form quinonoid complexes with similar rate constants. The binding of 3-(4'-hydroxyphenyl)propionic acid to wild-type TPL decreases at high pH values with a pKa of 8.4 and is thus dependent on an acidic group, possibly Arg404, which forms an ion pair with the analog carboxylate, or the pyridoxal 5'-phosphate Schiff base. R381A TPL shows only a small decrease in k(cat)/Km for tyrosine at lower pH, in contrast to wild-type TPL, which shows two basic pKas with an average value of about 7.8. Thus, it is possible that Arg 381 is one of the catalytic bases previously observed in the pH dependence of k(cat)/Km of TPL with L-tyrosine [Kiick, D. M., & Phillips. R. S. (1988) Biochemistry 27, 7333-7338], and hence Arg 381 is at least partially responsible for the substrate specificity of TPL.

Patient-physician communication at hospital discharge and patients' understanding of the postdischarge treatment plan

BACKGROUND

The quality of discharge planning is an important determinant of patient outcomes following hospital discharge. Patients often report inadequate discussion prior to discharge regarding major elements of the postdischarge treatment plan, including medication and daily activities.

OBJECTIVE

To determine whether this apparent lack of communication might be the result of differing perceptions on the part of patients and physicians regarding the patients' understanding of the treatment plan.

METHODS

We surveyed 99 patients and their attending physicians. All patients had been discharged recently from an academic medical center with the diagnosis of acute myocardial infarction or pneumonia. We asked both patients and physicians about time spent prior to discharge discussing the postdischarge treatment plan and the patients' understanding of this plan. McNemar test was used to determine whether responses of patients and physicians differed.

RESULTS

Physicians reported spending more time discussing postdischarge care than did patients (P = .10). Physicians believed that 89% of patients understood the potential side effects of their medications, but only 57% of patients reported that they understood (P < .001). Similarly, physicians believed that 95% of patients understood when to resume normal activities, while only 58% of patients reported that they understood (P < .001).

CONCLUSIONS

Physicians overestimate patients' understanding of the postdischarge treatment plan. Steps should be taken to improve communication about postdischarge treatment.

The illusion of end-of-life resource savings with advance directives. SUPPORT Investigators. Study to Understand Prognoses and Preferences for Outcomes and Risks of Treatment

OBJECTIVE

Would increasing the documentation of advance directives (ADs) lead to a reduction in resource utilization? We examined this question by conducting three secondary analyses: (1) we tested for a change in resource use among those who died in the hospital at a time before and after an intervention that increased the documentation of ADs in the medical record; (2) we replicated analyses of published studies that reported an association of chart documentation of ADs and hospital resource use; and (3) we examined whether a potential explanation of the observed association is biased documentation of ADs among patients who have completed an AD.

DESIGN

Replication of analysis of previous published studies using data from a prospective cohort study and block-randomized controlled trial.

SETTING

Five teaching hospitals in the United States.

PATIENTS

A total of 9105 seriously ill patients were enrolled in the Study to Understand Prognoses and Preferences for Outcomes and Risks of Treatments (SUPPORT), including 4301 patients in the 2 years (1989-91) before the Patient Self-Determination Act (PSDA) and 4804 in the 2 years (1992-94) after the PSDA implementation, with 2652 patients receiving the intervention and 2152 serving as controls.

INTERVENTIONS

The SUPPORT intervention provided a nurse to facilitate communication among patients, surrogates, and physicians about preferences for and outcomes of treatments. Documenting existing advance directives was also one of this nurse's tasks. The Patient Self-Determination Act required that health care institutions inquire about and document existing advance directives at the time of hospital admission.

MEASUREMENT

Hospital resource use was derived from the Therapeutic Intensity Scoring System and hospital length of stay, converted into 1994 dollars.

RESULTS

Chart documentation of existing advance directives at the time of study admission increased with both the PSDA and the SUPPORT intervention. We found that intervention patients were more likely to have pre-existing ADs documented. Despite this increase, there was no corresponding change in hospital resource use for those who died during the enrollment hospitalization. Replication of analyses from published studies using data from the block randomized controlled trial found that ADs documented by the third day of serious illness were associated with a 23% reduction in hospital resource use among control patients ($21,284 with ADs documented compared with $26,127 without, 95% CI 1-48% reduction). However, this association was not observed among intervention patients, who had more pre-existing ADs documented in the medical record. Intervention patients with early documentation of ADs showed a trend toward greater cost ($28,017 compared with $24,178 among those without AD documentation, 95% CI 0-25% increase). The rate of documentation and characteristics of those with documentation differed between control and intervention patients. Intervention patients were more likely (as reported by patient or surrogate interview) to have ADs documented in the medical record by the third day (55% vs 32%, P < .001). In contrast to intervention patients, control patients who were older, less wealthy, less educated, more likely to prefer to forgo CPR, and more likely to want life-sustaining treatment limited had their ADs documented. These associations were not found among intervention patients when comparison was made between those with and those without an AD documented in the medical record.

CONCLUSION

Increasing the documentation of pre-existing ADs was not associated with a reduction in hospital resource use. ADs documented without further intervention by the third day of a serious illness were associated with decreased hospital resource use. However, we did not find this association with an intervention that increased AD documentation. One potential explanation of these findings is that classification of those with an AD was based on cha

Advance directives for seriously ill hospitalized patients: effectiveness with the patient self-determination act and the SUPPORT intervention. SUPPORT Investigators. Study to Understand Prognoses and Preferences for Outcomes and Risks of Treatment

OBJECTIVE

To assess the effectiveness of written advance directives (ADs) in the care of seriously ill, hospitalized patients. In particular, to conduct an assessment after ADs were promoted by the Patient Self-Determination Act (PSDA) and enhanced by the effort to improve decision-making in the Study to Understand Prognoses and Preferences for Outcomes and Risks of Treatments (SUPPORT), focusing upon the impact of ADs on decision-making about resuscitation.

DESIGN

Observational cohort study conducted for 2 years before (PRE) and for 2 years after (POST) the PSDA, with a randomized, controlled trial of an additional intervention to improve decision-making after PSDA (POST+SUPPORT).

SETTING

Five teaching hospitals in the United States.

PATIENTS

A total of 9105 seriously ill patients treated in five teaching hospitals.

INTERVENTIONS

The PSDA mandated patient education about ADs at hospital entry and documentation of ADs in the medical record. The SUPPORT intervention, in addition, provided a nurse to facilitate communication among patients, surrogates, and physicians about preferences for and outcomes of treatment alternatives and, when clinically appropriate, to encourage completion and utilization of ADs.

MEASUREMENTS

Interviews were conducted with patients, surrogates, and attending physicians about awareness, completion, and impact of ADs. Medical records were reviewed for discussion about preferences concerning resuscitation, timing and writing of "Do Not Resuscitate" (DNR) orders, evidence of ADs, and the use or forgoing of resuscitation at the time of death.

RESULTS

In the three cohorts, PRE, POST, and POST+SUPPORT, average age was 63. One-quarter of patients died during the initial hospitalization, one-half were dead within 6 months, and one-half were unconscious for their last 3 days. Before the PSDA (PRE), 62% were familiar with a living will, and 21% had an AD. These rates were similar for the POST and POST+SUPPORT cohorts. Just 36 (6%) of these directives were mentioned in the medical records for PRE, but a stable 35% were documented for POST, and POST+SUPPORT had an increasing rate averaging 78% (P < .001). As previously reported for PRE patients, the POST patients with and without ADs had no significant differences in the rates of medical record documentation of discussions about resuscitation (33% vs 38%, POST without AD vs POST with AD), DNR orders among those who wanted to forgo resuscitation (54% vs 58%), and attempted resuscitations at death (17% vs 9%). The POST+SUPPORT patients had similar results, with no evidence that the intervention enhanced the effect of ADs on these three measures of resuscitation decision-making. Patients with ADs more often reported that preferences about resuscitation were discussed with a physician (e.g., for POST patients, 30% for those with no AD and 43% for those with an AD, P < .05). Only 12% of patients with ADs had talked with a physician when completing the AD. Only 42% reported ever having discussed the AD with their physician. By the second study week, only one in four physicians was aware of patients' ADs.

CONCLUSIONS

In these seriously ill patients, ADs did not substantially enhance physician-patient communication or decision-making about resuscitation. This lack of effect was not altered by the PSDA or by the enhanced efforts in SUPPORT, although these interventions each substantially increased documentation of existing ADs. Current practice patterns indicate that increasing the frequency of ADs is unlikely to be a substantial element in improving the care of seriously ill patients. Future work to improve decision-making should focus upon improving the current pattern of practice through better communication and more comprehensive advance care planning.

Do advance directives provide instructions that direct care? SUPPORT Investigators. Study to Understand Prognoses and Preferences for Outcomes and Risks of Treatment

OBJECTIVE

To evaluate whether the lack of effect of advance directives (ADs) on decision-making in SUPPORT might arise, in part, from the content of the actual documents.

DESIGN

Advance directives placed in the medical records were abstracted for date of completion and content of additional written instructions. We examined directives with instructions to forgo life-sustaining treatment in the current state of health to determine whether care given was consistent with preferences noted in those directives.

SETTINGS

Five teaching hospitals in the United States.

PATIENTS

A total of 4804 patients with at least one of nine serious illnesses were admitted to five teaching hospitals in the 2 years following implementation of the Patient Self-Determination Act. Patients were part of a randomized controlled trial to improve decision-making and outcomes.

RESULTS

From the medical records of 4804 patients, a total of 688 directives were collected from 569 patients. The majority of these directives (66%) were durable powers of attorney; in addition, 31% were standard living wills or other forms of written instructions (3%). Only 90 documents (13%) provided additional instructions for medical care beyond naming a proxy or stating the preferences of a standard living will. Only 36 contained specific instructions about the use of life-sustaining medical treatment, and only 22 of these directed forgoing life-sustaining treatment in the patient's current situation. For these, the treatment course was consistent with the instruction for nine patients. In two cases, patients may have changed an inconsistent directive after discussion with hospital staff.

CONCLUSION

Advance directives placed in the medical records of seriously ill patients often did not guide medical decision-making beyond naming a healthcare proxy or documenting general preferences in a standard living will format. Even when specific instructions were present, care was potentially inconsistent in half of the cases.

Is experience a good teacher? How interns and attending physicians understand patients' choices for end-of-life care. SUPPORT Investigators. Study to Understand Prognoses and Preferences for Outcomes and Risks of Treatments

BACKGROUND

Recent studies have shown that physicians do not accurately assess patients' health status or treatment preferences. Little is known, however, about how physicians' levels of training or experience relate to their abilities to assess these preferences. To better understand this phenomenon, the authors compared the abilities of medical interns and attending physicians to predict the choices of their adult patients for end-of-life care.

METHODS

230 seriously-ill adult inpatients were surveyed about their desires for cardiopulmonary resuscitation, their current quality of life, and their attitudes toward six other common adverse outcomes. The medical intern and attending physician who cared for these patients were asked to estimate the patient's responses for all of the same items. Agreement was assessed using the kappa statistic.

RESULTS

Compared with interns, attending physicians had known patients longer, had talked with patients more frequently about prognosis, and felt they knew more about their patients' preferences (all p < .0001). Despite this, the attending physicians were no more accurate than the interns in assessing patients' preferences. Both interns and attending physicians had only a fair understanding of patients' preferences for cardiopulmonary resuscitation or their quality of life (kappa statistics 0.32 to 0.47), and even less understanding of their willingness to tolerate adverse outcomes (kappa statistics -0.03 to 0.37).

CONCLUSIONS

For this cohort of seriously ill patients, neither medical interns nor their attending physicians were consistently accurate in assessing patients' preferences, and attending physicians were not more accurate than medical interns. Attending physicians should not assume that they can infer patients' preferences any better than the interns caring for these hospitalized patients.

Effects of tyrosine ring fluorination on rates and equilibria of formation of intermediates in the reactions of carbon-carbon lyases

The interactions of ring fluorinated analogs of tyrosine with tyrosine phenol-lyase and tryptophan indole-lyase (tryptophanase) were studied by rapid-scanning stopped-flow spectrophotometry. The reaction of L-tyrosine with tyrosine phenol-lyase resulted in rapid formation of a small absorbance peak at 500 nm, attributed to a quinonoid intermediate. The reaction of 3-fluoro-L-tyrosine with tyrosine phenol-lyase resulted in a peak at 500 nm with much higher absorbance, as did the reaction of 3,5-difluoro-L-tyrosine, due to increased accumulation of quinonoid intermediates. In constrast, complexes with 2-fluoro-L-tyrosine, 2,3-difluoro-L-tyrosine, 2,5-difluoro-L-tyrosine, and 2,6-difluoro-L-tyrosine exhibited much lower absorbance intensity at 500 nm. The rate constant for quinonoid intermediate formation from 3-fluoro-L-tyrosine was comparable to that for L-tyrosine. However, 3,5-difluoro-L-tyrosine reacted to form a quinonoid intermediate at about half the rate of L-tyrosine, while 2,3-difluoro-L-tyrosine reacted at twice the rate of L-tyrosine. In addition, the 2-substituted difluorotyrosines exhibited an intermediate, which was formed rapidly, absorbing strongly at about 340 nm, which is likely due to a gem-diamine intermediate. Tyrosine is not a substrate for tryptophan indole-lyase; the reaction of tryptophan indole-lyase with L-tyrosine resulted in formation of external aldimine, which absorbed at 420 nm, and a very small absorbance peak at 500 nm. 3-Fluoro-L-tyrosine reacted with tryptophan indole-lyase to produce a prominent quinonoid absorbance peak at 500 nm, whereas L-tyrosine, 2-fluoro-L-tyrosine, and all difluoro-L-tyrosines, had a much reduced intensity for this peak. Thus, the presence of ring fluorine substituents in L-tyrosine that are remote from the site of the chemical transformation has significant effects on the rates and equilibria of intermediate formation in the reactions with both tyrosine phenol-lyase and tryptophan indole-lyase. Although it is commonly thought that fluorine substitution will not result in any significant steric effects, our results suggest that the effects of fluorine substitution in the reactions of fluorinated tyrosines with tyrosine phenol-lyase and tryptophan indole-lyase are due to a combination of steric and electronic effects.

Pain during hospitalization is associated with continued pain six months later in survivors of serious illness. The SUPPORT Investigators. Study to Understand Prognoses and Preferences for Outcomes and Risks of Treatments

PURPOSE

To determine the level of pain reported by survivors of serious illness 2 and 6 months after study enrollment and to identify variables associated with later pain.

PATIENTS AND METHODS

Observational cohort study of patients with interviews during hospitalization (5,652) and 2 (3,782) and 6 (2,984) months later admitted between June 1989 and January 1994 with 1 or more of 9 high mortality diagnoses admitted to 5 tertiary care academic centers in the United States. Patients' level of pain during the hospitalization and 2 and 6 months later was determined from interviews with patients and surrogates (most often family members). Separate ordinal logistic regressions were constructed with level of pain at months 2 or 6 as the dependent variable and 22 demographic, psychological, chronic, and acute illness measures at the time of hospitalization as independent variables.

RESULTS

Of patients reporting level 4 (moderately severe pain occurring most of the time or extremely severe pain occurring half of the time) or 5 (moderately severe pain occurring most or all of the time or extremely severe pain occurring at least half of the time) pain to 5 during hospital interviews, 39.5% and 39.7% reported level 4 or 5 pain 2 and 6 months later, respectively. Level of hospital pain was the variable most strongly associated with later pain. Compared with patients with level 1 hospital pain, those with level 2 (not at all severe pain or moderate, occasional) had a 2.91 (95% confidence interval [CI] 2.50, 3.37) and 1.75 (CI 1.48, 2.07) times greater adjusted odds of increased levels of pain 2 and 6 months later, respectively. Compared with patients with level 1 hospital pain, those with level 5 pain had a 9.20 (CI 7.27, 11.65) and 4.40 (CI 3.39, 5.71) times greater adjusted odds of increased levels of pain 2 and 6 months later, respectively. Age, number of dependencies in activities of daily living, depression, and type of comorbid illnesses were also independently associated with level of pain both 2 and 6 months later.

CONCLUSION

Survivors of the serious and common illnesses that we studied have a high level of pain during hospitalization and up to 6 months after hospitalization. Level of hospital pain was most strongly associated with later pain. Better pain control both during hospitalization and after discharge should be given a high priority. Pain during hospitalization should trigger future inquiries about pain and its treatment.

The effect of erythromycin on resolution of symptoms among adults with pharyngitis not caused by group A streptococcus

OBJECTIVE

To determine the effect of treatment with erythromycin on the resolution of symptoms among adults with pharyngitis not caused by group A streptococcus (GAS).

DESIGN

Randomized, double-blind, placebo-controlled trial.

SETTING

Ambulatory setting (hospital-based general internal medicine practices, walk-in clinic, employee health service, and university health service).

PATIENTS

One hundred and eighty-six adults who met eligibility criteria and whose chief complaint included sore throat. Patients with positive cultures for GAS were excluded.

INTERVENTION

Ninety-three patients received erythromycin (333 mg three times daily for 10 days) and 93 control patients received placebo.

MEASUREMENTS AND MAIN RESULTS

Major outcome measurements included time to improvement in sore throat, time to improvement in cough, time to improvement in activity level, and subjective sense of well-being. The average age of the patients studied was 26.6 years; 35% were men. Patients given erythromycin had more rapid resolution of sore throat symptoms (hazard ratio 1.43: 95% confidence interval [CI] 1.00, 2.03: p = .049). Cough also resolved more rapidly in patients receiving erythromycin (hazard ratio 2.22: 95% CI 1.01, 4.88: p = .05). There were no differences between the two treatment groups in improvement of activity level or how sick patients felt in general. Most of the benefit in resolution of sore throat was conferred on patients who sought medical care within 2 days of onset.

CONCLUSIONS

Our results suggest that the benefit of erythromycin treatment for patients with non-GAS pharyngitis is small and of borderline statistical significance. Because of the small size of the effect and because widespread use of erythromycin could promote drug resistance, we do not recommend routine use of erythromycin in adult patients with this type of pharyngitis.

Perceptions by family members of the dying experience of older and seriously ill patients. SUPPORT Investigators. Study to Understand Prognoses and Preferences for Outcomes and Risks of Treatments

BACKGROUND

Alleviating the problems faced by dying persons and their families has drawn substantial public attention, but little is known about the experience of dying.

OBJECTIVE

To characterize the experience of dying from the perspective of surrogate decision makers, usually close family members (89%).

DESIGN

Prospective cohort study.

SETTING

Five teaching hospitals.

PATIENTS

Persons who had one of nine serious medical conditions or were 80 years of age or older who died and for whom a surrogate decision maker completed an interview about the death.

MEASUREMENTS

Medical records were reviewed and surrogate decision makers were interviewed.

RESULTS

4124 of 9105 seriously ill patients died (46%); 408 of 1176 elderly patients died (35%). The patients' family members were interviewed after 3357 persons (73%) had died. Of 1541 patients who survived the enrollment hospitalization, 46% died during a later hospitalization. In the last 3 days of life, 55% of patients were conscious. Among these patients, pain, dyspnea, and fatigue were prevalent. Four in 10 patients had severe pain most of the time. Severe fatigue affected almost 8 in 10 patients. More than 1 in 4 patients had moderate dysphoria. Sixty-three percent of patients had difficulty tolerating physical or emotional symptoms. Overall, 11% of patients had a final resuscitation attempt. A ventilator was used in one fourth of patients, and a feeding tube was used in four tenths of patients. Most patients (59%) were reported to prefer a treatment plan that focused on comfort, but care was reported to be contrary to the preferred approach in 10% of cases.

CONCLUSIONS

Most elderly and seriously ill patients died in acute care hospitals. Pain and other symptoms were commonplace and troubling to patients. Family members believed that patients preferred comfort, but life-sustaining treatments were often used. These findings indicate important opportunities to improve the care of dying patients.

Functional status among survivors of in-hospital cardiopulmonary resuscitation. SUPPORT Investigators Study to Understand Progress and Preferences for Outcomes and Risks of Treatment

OBJECTIVES

To describe functional outcomes of seriously III patients who survived 2 months after in-hospital cardiopulmonary resuscitation (CPR) and to identify patient and clinical characteristics associated with worse functional status after CPR.

METHODS

Multicenter prospective observational analysis of 162 seriously ill hospitalized patients who survived 2 months after CPR. Analysis of clinical characteristics associated with worse functional outcome.

RESULTS

Among 162 survivors of in-hospital CPR, 56% had the same or improved function and 44% had worse function at 2 months compared with functional status before CPR. Patients with worse function deteriorated by a mean of 3.9 activities of daily living and were less likely to survive to hospital discharge (P < .001) or to 6 months after study entry (P < .001). Worse functional outcome was associated with greater age and longer hospital stay before CPR.

CONCLUSIONS

More than half of CPR survivors had preserved functional status 2 months after CPR. However, patients with worse function are profoundly disabled. In anticipation of possible severe disability after CPR, preferences for care in such health states should be discussed with patients before the need for CPR, particularly among older patients and those with long hospital stays.

Effects of alpha-deuteration and of aza and thia analogs of L-tryptophan on formation of intermediates in the reaction of Escherichia coli tryptophan indole-lyase

Tryptophan indole-lyase catalyzes the hydrolytic cleavage of L-tryptophan to indole and ammonium pyruvate. After the enzyme is mixed with L-tryptophan in the rapid-scanning stopped-flow spectrophotometer, there is an absorbance increase at 505 nm in the pre-steady state attributed to formation of a quinonoid intermediate, which occurs in at least three consecutive first-order phases. Reaction with [alpha-2H]-L-tryptophan results in significant primary kinetic isotope effects on the first two phases, and there is a significant isotope effect on the amplitude of the absorbance increase in the second phase. This result suggests that proton transfer to carbon to form the indolenine intermediate is relatively slow and is probably at least partially rate-determining. Reaction of L-tryptophan in the presence of benzimidazole results in a rapid increase in absorbance in the first phase, followed by a decrease in absorbance in the second phase, with rate constants very similar to those observed without benzimidazole. We have also examined aza and thia analogs of L-tryptophan, with the benzene ring of the indole replaced by pyridine or thiophene. Both 4,5-thiatryptophan and 6,7-thiatryptophan form quinonoid intermediates in the reaction with tryptophan indole-lyase; however, 6,7-thiatryptophan is a better substrate (kcat/K(m) = 32% of L-trp) for tryptophan indole-lyase than is 4,5-thiatryptophan (kcat/K(m) = 4% of L-trp). Benzimidazole affects the pre-steady-state reaction of 6,7-thiatryptophan in a way similar to L-tryptophan, while benzimidazole does not affect the pre-steady-state reaction of 4,5-thiatryptophan. 4-Aza-, 5-aza-, 6-aza-, and 7-aza-L-tryptophan are all very slow substrates (kcat < 1% of L-trp) for Escherichia coli tryptophan indole-lyase. beta-Indazolyl-L-alanine is a relatively good substrate and exhibits a quinonoid intermediate in its reaction with tryptophan indole-lyase. 6-Aza- and 7-azatryptophan accumulate quinonoid intermediates in the reaction with tryptophan indole-lyase, whereas 4-aza- and 5-azatryptophans do not significantly accumulate quinonoid intermediates, and these latter compounds exhibit very high K(m) values. Addition of benzimidazole does not change the rapid-scanning stopped-flow spectra of 6-aza- and 7-azatryptophan. This suggests that the rate-determining step in the reaction changes depending on the position and type of heteroatom substitution. For 6-aza- and 7-azatryptophan, the very slow rates of elimination may be due to slow C-protonation of the azaindole, while for 4,5-thiatryptophan, the elimination of thienopyrrole is probably slow. Of all analogs examined, 6,7-thiatryptophan is most similar to tryptophan in its reaction with E. coli tryptophan indole-lyase.

Pain and satisfaction with pain control in seriously ill hospitalized adults: findings from the SUPPORT research investigations. For the SUPPORT investigators. Study to Understand Prognoses and Preferences for Outcomes and Risks of Treatmentm

OBJECTIVES

To evaluate the pain experience of seriously ill hospitalized patients and their satisfaction with control of pain during hospitalization. To understand the relationship of level of pain and dissatisfaction with pain control to demographic, psychological, and illness-related variables.

DESIGN

Prospective, cohort study.

SETTING

Five teaching hospitals.

PATIENTS

Patients for whom interviews were available about pain (n = 5,176) from a total of 9,105 patients in the Study to Understand Prognoses and Preferences for Outcomes and Risks of Treatments (SUPPORT).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients were interviewed after study enrollment about their experiences with pain. When patients could not be interviewed due to illness, we used surrogate (usually a family member) responses calibrated to patient responses (from the subset of interviews with both patient and surrogate responses). Ordinal logistic regression was used to study the association of variables with level of pain and satisfaction with its control. Nearly 50% of patients reported pain. Nearly 15% reported extremely severe pain or moderately severe pain occurring at least half of the time, and nearly 15% of those patients with pain were dissatisfied with its control. After adjustment for confounding variables, older and sicker patients reported less pain, while patients with more dependencies in activities of daily living, more comorbid conditions, more depression, more anxiety, and poor quality of life reported more pain. Patients with colon cancer reported more pain than patients in other disease categories. Levels of reported pain varied among the five hospitals and also by physician specialty. After adjustment for confounding variables, dissatisfaction with pain control was more likely among patients with more severe pain, greater anxiety, depression, and alteration of mental status, and lower reported income; dissatisfaction with pain control also varied among study hospitals and by physician specialty.

CONCLUSIONS

Pain is common among severely ill hospitalized patients. The most important variables associated with pain and satisfaction with pain control were patient demographics and those variables that reflected the acute illness. Pain and satisfaction with pain control varied significantly among study sites, even after adjustment for many potential confounders. Better pain management strategies are needed for patients with the serious and common illnesses studied in SUPPORT.

Portal hypertensive gastropathy

PHG is a common condition that is now recognized as a complication of advanced liver disease. This vascular disorder has been shown to be a significant cause of upper gastrointestinal bleeding in patients with portal hypertension. Although its pathogenesis is directly related to portal hypertension, the exact mechanisms remain to be determined. Decreased mucosal blood flow and passive congestion of the gastric submucosal layer appear to play a role in the development of PHG. Its endoscopic appearance is characterized by a "snake skin" mucosal pattern with gastric biopsies revealing vascular congestion. PHG may present as either acute or chronic gastrointestinal bleeding and has been noted to worsen after endoscopic sclerotherapy and band ligation therapy for esophageal varices. Unlike variceal bleeding, this condition cannot be treated with either sclerotherapy or band ligation. Effective treatment requires a reduction in portal pressure. This can be accomplished through the use of beta-blockers, radiographic or surgical shunting, or liver transplantation.

Seriously ill hospitalized adults: do we spend less on older patients? Support Investigators. Study to Understand Prognoses and Preference for Outcomes and Risks of Treatments

OBJECTIVE

To determine the effect of age on hospital resource use for seriously ill adults, and to explore whether age-related differences in resource use are explained by patients' severity of illness and preferences for life-extending care.

STUDY DESIGN

Prospective cohort study.

SETTING

Five geographically diverse academic acute care medical centers participating in the SUPPORT Project.

PATIENTS

A total of 4301 hospitalized adults with at least one of nine serious illnesses associated with an average 6-month mortality of 50%.

MEASUREMENTS

Resource utilization was measured using a modified version of the Therapeutic Intervention Scoring System (TISS); the performance of three invasive procedures (major surgery, dialysis, and right heart catheter placement); and estimated hospital costs.

RESULTS

The median patient age was 65; 43% were female, and 48% died within 6 months. After adjustment for severity of illness, prior functional status, and study site, when compared with patients younger than 50, patients 80 years or older were less likely to undergo major surgery (adjusted odds ratio .46), dialysis (.19), and right heart catheter placement (.59) and had median TISS scores and estimated hospital costs that were 3.4 points and $ 71.61 lower, respectively. These differences persisted after further adjustment for patients' preferences for life-extending care.

CONCLUSIONS

Compared with similar younger patients, seriously ill older patients receive fewer invasive procedures and hospital care that is less resource-intensive and less costly. This preferential allocation of hospital services to younger patients is not based on differences in patients' severity of illness or general preferences for life-extending care.

Factors associated with do-not-resuscitate orders: patients' preferences, prognoses, and physicians' judgments. SUPPORT Investigators. Study to Understand Prognoses and Preferences for Outcomes and Risks of Treatment

BACKGROUND

Medical treatment decisions should be based on the preferences of informed patients or their proxies and on the expected outcomes of treatment. Because seriously ill patients are at risk for cardiac arrest, examination of do-not-resuscitate (DNR) practices affecting them provides useful insights into the associations between various factors and medical decision making.

OBJECTIVE

To examine the association between patients' preferences for resuscitation (along with other patient and physician characteristics) and the frequency and timing of DNR orders.

DESIGN

Prospective cohort study.

SETTING

5 teaching hospitals.

PATIENTS

6802 seriously ill hospitalized patients enrolled in the Study to Understand Prognoses and Preferences for Outcomes and Risks of Treatment (SUPPORT) between 1989 and 1994.

MEASUREMENTS

Patients and their surrogates were interviewed about patients' cardiopulmonary resuscitation preferences, medical records were reviewed to determine disease severity, and a multivariable regression model was constructed to predict the time to the first DNR order.

RESULTS

The patients' preference for cardiopulmonary resuscitation was the most important predictor of the timing of DNR orders, but only 52% of patients who preferred not to be resuscitated actually had DNR orders written. The probability of surviving for 2 months was the next most important predictor of the timing of DNR orders. Although DNR orders were not linearly related to the probability of surviving for 2 months, they were written earlier and more frequently for patients with a 50% or lower probability of surviving for 2 months. Orders were written more quickly for patients older than 75 years of age, regardless of prognosis. After adjustment for these and other influential patient characteristics, the use and timing of DNR orders varied significantly among physician specialties and among hospitals.

CONCLUSIONS

Patients' preferences and short-term prognoses are associated with the timing of DNR orders. However, the substantial variation seen among hospital sites and among physician specialties suggests that there is room for improvement. In this study, DNR orders were written earlier for patients older than 75 years of age, regardless of prognosis. This finding suggests that physicians may be using age in a way that is inconsistent with the reported association between age and survival. The process for making decisions about DNR orders needs to be improved if such orders are to routinely and accurately reflect patients' preferences and probable outcomes.

Is economic hardship on the families of the seriously ill associated with patient and surrogate care preferences? SUPPORT Investigators

BACKGROUND

Serious illness often causes economic hardship for patients' families. However, it is not known whether this hardship is associated with a preference for the goal of care to focus on maximizing comfort instead of maximizing life expectancy or whether economic hardship might give rise to disagreement between patients and surrogates over the goal of care.

METHODS

We performed a cross-sectional study of 3158 seriously ill patients (median age, 63 years; 44% women) at 5 tertiary medical centers with 1 of 9 diagnoses associated with a high risk of mortality. Two months after their index hospitalization, patients and surrogates were surveyed about patients' preferences for the primary goal of care: either care focused on extending life or care focused on maximizing comfort. Patients and surrogates were also surveyed about the financial impact of the illness on the patient's family.

RESULTS

A report of economic hardship on the family as a result of the illness was associated with a preference for comfort care over life-extending care (odds ratio, 1.26; 95% confidence interval, 1.07-1.48) in an age-stratified bivariate analysis. Similarly, in a multivariable analysis controlling for patient demographics, illness severity, functional dependency, depression, anxiety, and pain, economic hardship on the family remained associated with a preference for comfort care over life-extending care (odds ratio, 1.31; 95% confidence interval, 1.10-1.57). Economic hardship on the family did not affect either the frequency or direction of patient-surrogate disagreements about the goal of care.

CONCLUSIONS

In patients with serious illness, economic hardship on the family is associated with preferences for comfort care over life-extending care. However, economic hardship on the family does not appear to be a factor in patient-surrogate disagreements about the goal of care.

Kinetics of nitric oxide production during infection and reinfection of mice with Plasmodium chabaudi

We have shown previously that at the time of peak primary parasitaemia of P. chabaudi infection in NIH mice, significant levels of nitric oxide are produced, detectable as nitrate in the serum, and that these contribute to the protective immune response to infection. Here, we demonstrate that following reinfection, mice show a markedly diminished ability to produce nitrate. However, if mice are treated with L-NG-monomethyl arginine specifically to block nitric oxide metabolism during the primary infection, and are then reinfected, production of nitrate is restored to levels approaching those attained at peak primary parasitaemia. These experiments, together with others we have reported, indicate that whereas nitric oxide appears to play a significant role in control of the primary parasitaemia of P. chabaudi infection, it performs no such function during subsequent patent parasitaemias. Furthermore, they suggest that factors as yet unknown may regulate nitric oxide activity during malaria infection, such that under normal circumstances its production comes under strict control. This is exemplified by the observation that after the burst of nitric oxide activity that coincides with peak primary parasitaemia, there follows a prolonged period of immunological tolerance during which nitrate levels remain low even at secondary challenge infection. This tolerized state is lifted only several months after initial infection, when the nitric oxide activity at reinfection appears to correlate with the size of the parasite challenge and the presence of a patent parasitaemia. The implications of these findings for protective immunity to malaria, malarial immunosuppression, and immunoregulation in general, are discussed.

DP-2, a heterodimeric partner of E2F: identification and characterization of DP-2 proteins expressed in vivo

E2F is a heterodimeric transcription factor that regulates the expression of genes at the G1/S boundary and is composed of two related but distinct families of proteins, E2F and DP. E2F/DP heterodimers form complexes with the retinoblastoma (Rb) protein, the Rb-related proteins p107 and p130, and cyclins/cdks in a cell cycle-dependent fashion in vivo. E2F is encoded by at least five closely related genes, E2F-1 through -5. Here we report studies of DP-2, the second member of the DP family of genes. Our results indicate that (i) DP-2 encodes at least five distinct mRNAs, (ii) a site of alternative splicing occurs within the 5' untranslated region of DP-2 mRNA, (iii) at least three DP-2-related proteins (of 55, 48, and 43 kDa) are expressed in vivo, (iv) each of these proteins is phosphorylated, and (v) one DP-2 protein (43 kDa) carries a truncated amino terminus. Our data also strongly suggest that the 55-kDa DP-2-related protein is a novel DP-2 isoform that results from alternative splicing. Thus, we conclude that DP-2 encodes a set of structurally, and perhaps functionally, distinct proteins in vivo.

Factors associated with change in resuscitation preference of seriously ill patients. The SUPPORT Investigators. Study to Understand Prognoses and Preferences for Outcomes and Risks of Treatments

BACKGROUND

During serious illness, patient preferences regarding life-sustaining treatments play an important role in medical decisions. However, little is known about life-sustaining preference stability in this population or about factors associated with preference change.

METHODS

We evaluated 2-month cardiopulmonary resuscitation (CPR) preference stability in a cohort of 1590 seriously ill hospitalized patients at 5 acute care teaching hospitals. Using multiple logistic regression, we measured the association of patient demographic and health-related factors (quality of life, function, depression, prognosis, and diagnostic group) with change in CPR preference between interviews.

RESULTS

Of 1590 patients analyzed, 73% of patients preferred CPR at baseline interview and 70% chose CPR at follow-up. Preference stability was 80% overall-85% in patients initially preferring CPR and 69% in those initially choosing do not resuscitate (DNR). For patients initially preferring CPR, older age, non-African American race, and greater depression at baseline were independently associated with a change to preferring DNR at follow-up. For patients initially preferring DNR, younger age, male gender, less depression at baseline, improvement in depression between interviews, and an initial admission diagnosis of acute respiratory failure or multiorgan system failure were associated with a change to preferring CPR at follow-up. For patients initially preferring DNR, patients with substantial improvements in depression score between interviews were more than 5 times as likely to change preference to CPR than were patients with substantial worsening in depression score.

CONCLUSIONS

More than two thirds of seriously ill patients prefer CPR for cardiac arrest and 80% had stable preferences over 2 months. Factors associated with preference change suggest that depression may lead patients to refuse life-sustaining care. Providers should evaluate mood state when eliciting patients' preferences for life-sustaining treatments.