(17)O multiple-quantum MAS NMR study of high-pressure hydrous magnesium silicates

Two (17)O-enriched hydrous magnesium silicates, the minerals hydroxyl-chondrodite (2Mg(2)SiO(4).Mg(OH)(2)) and hydroxyl-clinohumite (4Mg(2)SiO(4).Mg(OH)(2)), were synthesized. High-resolution "isotropic" (17)O (I = (5)/(2)) NMR spectra of the powdered solids were obtained using three- and five-quantum MAS NMR at magnetic field strengths of 9.4 and 16.4 T. These multiple-quantum (MQ) MAS spectra were analyzed to yield the (17)O isotropic chemical shifts (delta(CS)) and quadrupolar parameters (C(Q), eta and their "product" P(Q)) of the distinct oxygen sites resolved in each sample. The values obtained were compared with those found previously for forsterite (Mg(2)SiO(4)). The (17)O resonances of the protonated (hydroxyl) sites were recorded and assigned with the aid of (17)O [(1)H] cross-polarization and comparison with the spectrum of (17)O-enriched brucite (Mg(OH)(2)). Using all of these data, complete assignments of the five crystallographically inequivalent oxygen sites in hydroxyl-chondrodite and of the nine such sites in hydroxyl-clinohumite are suggested. The validity of these assignments are supported by the observation of a correlation between (17)O isotropic chemical shift and Si-O bond length. The (29)Si MAS NMR spectra of the two minerals were also obtained.

Age versus comorbidities as risk factors for complications after elective abdominal aortic reconstructive surgery

PURPOSE

This study estimated the association between age and in-hospital postoperative complications, controlling for known or suspected risk factors, in a series of patients undergoing elective abdominal aortic reconstructive surgery (AAR).

METHODS

This retrospective cohort study of outcome data with multivariate logistic regression analysis was conducted at Emory University Hospital, a tertiary care, university-affiliated hospital. All patients undergoing elective AAR between Jan 1, 1986, and Aug 1, 1996, were included (n = 856). An estimate of the odds ratio (OR) and 95% CI for the association between patient age and in-hospital major morbidity or mortality after elective AAR was made, controlling for significant risk factors.

RESULTS

Among the 856 patients, 170 had a nonfatal complication (136 with major and 34 with minor complications), and 11 patients (1.3%) died. The final logistic regression model demonstrated a mild association between increasing age and rate of major postoperative complications, including death (for each increase in age of 10 years: OR, 1.23; 95% CI, 1.00-1.52; P =.052). Other significant covariates in the final model included cardiac disease (OR, 2.84; 95% CI, 1.18-6.86; P =.020), pulmonary disease (OR, 1.96; 95% CI, 1.35-2.84; P =.0004), and renal disease (OR, 2.57; 95% CI, 1.66-3.99; P =.0001). Increasing age was associated with a moderate increase in the rate of death (for each increase in age of 10 years: OR, 2.74; 95% CI, 1.22-6.16; P =.015) in a model with cardiac disease as the only significant covariate (OR, 14.67; 95% CI, 3.46-62.16; P =.0003).

CONCLUSION

For patients undergoing elective AAR, increasing patient age is associated with a small increase in risk for in-hospital morbidity or mortality. However, significant cardiac, pulmonary, or renal disease is associated with a much greater risk of postoperative complications, and, therefore, advanced age should not be the sole basis of exclusion for otherwise suitable candidates for elective AAR.

The population genetics of the origin and divergence of the Drosophila simulans complex species

The origins and divergence of Drosophila simulans and close relatives D. mauritiana and D. sechellia were examined using the patterns of DNA sequence variation found within and between species at 14 different genes. D. sechellia consistently revealed low levels of polymorphism, and genes from D. sechellia have accumulated mutations at a rate that is approximately 50% higher than the same genes from D. simulans. At synonymous sites, D. sechellia has experienced a significant excess of unpreferred codon substitutions. Together these observations suggest that D. sechellia has had a reduced effective population size for some time, and that it is accumulating slightly deleterious mutations as a result. D. simulans and D. mauritiana are both highly polymorphic and the two species share many polymorphisms, probably since the time of common ancestry. A simple isolation speciation model, with zero gene flow following incipient species separation, was fitted to both the simulans/mauritiana divergence and the simulans/sechellia divergence. In both cases the model fit the data quite well, and the analyses revealed little evidence of gene flow between the species. The exception is one gene copy at one locus in D. sechellia, which closely resembled other D. simulans sequences. The overall picture is of two allopatric speciation events that occurred quite near one another in time.

Azithromycin as treatment for disseminated Mycobacterium avium complex in AIDS patients

This multicenter, randomized, dose-ranging study was performed to determine the safety and efficacy of two different doses of azithromycin for treating disseminated Mycobacterium avium complex (MAC) in patients with AIDS. Eighty-eight AIDS patients with symptoms and blood cultures consistent with disseminated MAC were treated with 600 or 1,200 mg of azithromycin daily for 6 weeks; 62 patients completed the entire 6 weeks of study. Of note, this study was done prior to the time when combination antiretroviral or anti-MAC regimens were the standard of care. Over the 6-week study period, symptomatic improvement was noted in both dose groups. Microbiological responses were comparable, with mean decreases of 1. 5 and 2.0 log CFU/ml in the high- and low-dose groups, respectively. Sterilization of blood cultures occurred in 54% of samples; patients with lower baseline colony counts were more likely to achieve culture negativity. Resistance developed in one patient. Gastrointestinal symptoms were the most common side effects and were more frequent in patients receiving 1,200 mg. Azithromycin is a useful alternative treatment for disseminated MAC infection in AIDS patients. Symptomatic improvement correlates with measurable decreases in mycobacterial load.

HIV infection: problems with patientsʼ anaesthetic management and healthcare workersʼ exposure

Although infection with HIV has become a global epidemic, current research has provided a better understanding of the virus and its effect on the immune system. Combinations of new antiretroviral agents have been shown to be effective in prolonging the life of infected individuals, and chemoprophylactic regimens have been useful in preventing opportunistic infections. Risk factors associated with the occupational transmission of HIV have been identified and prevention strategies proposed.

Individual differences in reactivity to daily events: examining the roles of stability and level of self-esteem

Unstable self-esteem is thought to reflect fragile and vulnerable feelings of self-worth that are affected by specific positive and negative events. Direct evidence for this contention is lacking, however. To redress this situation, we examined the extent to which level and stability of self-esteem predicted the impact that everyday positive and negative events had on individuals' feelings about themselves. Participants recorded the most positive and most negative event that occurred each day Monday through Thursday for a period of 2 weeks. They then indicated the extent to which each event made them feel better or worse about themselves. As anticipated, negative and positive events had a greater impact on the self-feelings of individuals with unstable as opposed to stable self-esteem (although the effect for positive events was marginal). Additional findings indicated that event qualities (i.e., self-esteem relevance and concerns about social acceptance/rejection) could account for the unstable self-esteem/greater reactivity link for negative events, but not for positive events. Negative, but not positive, events had a greater impact on the self-feelings of individuals with low as compared to high levels of self-esteem. Theoretical implications are discussed.

Multicenter study of contaminated percutaneous injuries in anesthesia personnel

BACKGROUND

Anesthesia personnel are at risk for occupational infection with bloodborne pathogens from contaminated percutaneous injuries (CPIs). Additional information is needed to formulate methods to reduce risk.

METHODS

The authors analyzed CPIs collected during a 2-yr period at 11 hospitals, assessed CPI underreporting, and estimated risks of infection with human immunodeficiency virus and hepatitis C virus.

RESULTS

Data regarding 138 CPIs were collected: 74% were associated with blood-contaminated hollow-bore needles, 74% were potentially preventable, 30% were considered high-risk injuries from devices used for intravascular catheter insertion or obtaining blood, and 45% were reported to hospital health services. Corrected for injury underreporting, the CPI rate was 0.27 CPIs per yr per person; per full-time equivalent worker, there were 0.42 CPIs/yr. The estimated average 30-yr risks of human immunodeficiency virus or hepatitis C virus infection per full-time equivalent are 0.049% and 0.45%, respectively. Projecting these findings to all anesthesia personnel in the United States, the authors estimate that there will be 17 human immunodeficiency virus infections and 155 hepatitis C virus infections in 30 yr.

CONCLUSIONS

Performance of anesthesia tasks is associated with CPIs from blood-contaminated hollow-bore needles. Thirty percent of all CPIs would have been high-risk for bloodborne pathogen transmission if the source patients were infected. Most CPIs were potentially preventable, and fewer than half were reported to hospital health services. The results identify devices and mechanisms responsible for CPIs, provide estimates of risk levels, and permit formulation of strategies to reduce risks.

Percutaneous injuries in anesthesia personnel

Anesthesia personnel are at risk for occupationally acquired blood-borne infections from human immunodeficiency virus, hepatitis viruses, and others after percutaneous exposures to infected blood or body fluids. The risk is greater after an infected, blood-contaminated, percutaneous injury, especially from a hollow-bore blood-filled needle, than from other types of exposures. Few data are available on the specific occupational hazards to anesthesia personnel from needles and other sharp devices. Fifty-eight percutaneous injuries (PIs) from anesthesia personnel in nine hospitals were analyzed. Thirty-nine of 58 PIs were from contaminated devices (all needles), and 19 were from uncontaminated devices or of unknown contamination status. Forty-three percent of contaminated percutaneous injuries (CPI) were classified as moderate (some bleeding) or severe (deep injury with profuse bleeding), and most were to health-care workers' hands. Fifty-nine percent of CPI were potentially preventable. Eighty-seven percent of CPI were from hollow-bore needles, and 68% of these were potentially preventable. The largest categories of devices causing CPI were needle on syringe, intravenous (i.v.) or arterial catheter needle-stylet, suture needle, and standard hollow-bore needle for secondary i.v. infusion. Most CPI occurred between steps of a multistep procedure (8%), were recapping related (13%), or occurred at other times after use (41%). No CPI were reported from use of needlestick-prevention safety devices. The devices and mechanisms of injury identified in this study provide specific data that may lead to prevention strategies to reduce the risk of PI.

Tuberculosis makes a comeback

Tuberculosis (TB) has plagued mankind for many centuries. In the past, the number of people affected with this potentially deadly disease declined, but there has been a recent dramatic increase in TB incidence. This increase is attributed largely to people who are coinfected with TB and HIV and to the development of resistant strains of Mycobacterium tuberculosis during the last decade. The US social infrastructure also has contributed to a rapid rise in TB cases due to adverse socioeconomic factors and an increase in the number of immigrants and people infected with HIV. This article gives a historical overview of TB; discusses its diagnosis, transmission and prevention modalities; and provides a case study about a TB-infected patient who required emergent surgical intervention.

Injury prevention in anesthesiology

Anesthesia personnel routinely perform procedures that put them at risk for contact with blood and body fluids. Some of these exposures are to skin and mucous membranes; many are percutaneous injuries associated with the frequent use of needled devices. The high risk in anesthesia procedures for contact with infected body fluids is associated with a high incidence rate of actual infection with bloodborne pathogens.

The use of needles in the practice of anesthesiology and the effect of a needleless intravenous administration system

Anesthesia personnel are at risk for occupationally acquired blood-borne infections transmitted through needlestick injuries. To formulate strategies for the prevention of needlestick injuries, it is necessary to identify the types of needles used by anesthesia personnel and the devices associated with injuries. The introduction of a needleless intravenous (i.v.) administration system provided an opportunity to assess its effect on needle usage in the practice of anesthesiology. The contents of needle disposal containers placed in the preoperative holding area and five operating rooms before (control) and after the introduction of a needleless administration system (study) were categorized by needle type. The information on needles used by anesthesia personnel was compared with that on needles purchased for the entire hospital. During the control period, most of the needles used were 18-23-gauge hollow needles (51.6%), i.c. catheter stylets (23%), and 25-26-gauge small-bore hollow needles (17.1%). There was no difference in the total number of needles collected after the introduction of the needleless administration system, but there was an increase in capped 18-23-gauge hollow needles. Anesthesia personnel used a relatively greater number of small-bore hollow needles (25-26 gauge), i.v. catheters, and spinal and epidural needles, but fewer hollow needles (18-23 gauge) than were purchased for hospital-wide use. Small-bore hollow needles (25-26 gauge) were responsible for 31.6% of the 19 needlestick injuries reported by anesthesia personnel to the Employee Health Service.(ABSTRACT TRUNCATED AT 250 WORDS)

Work hours of residents in seven anesthesiology training programs

Medical educators and credentialing organizations recently have called attention to the long hours that some house staff are required to spend in the hospital during training. To determine the average duration of in-hospital work hours of anesthesiology residents, 148 residents at seven, university-affiliated training programs kept daily logs of their activities for one week. Residents in clinical anesthesia years 1, 2, and 3 spent an average of 66, 65, and 64 hours per week, respectively, in the hospital with a range of 43 to 104 hours per week. Although there was not a difference in in-hospital work time among years of training, there was a statistical difference between two of the seven programs studied. The largest portion of the in-hospital time was devoted to patient care activities in the operating room. Residents had time for educational activities, conferences, and reading while in the hospital. The overall work hours of the residents in the anesthesiology training programs included in this survey appeared to be within current guidelines.

The risk of needlestick injuries and needlestick-transmitted diseases in the practice of anesthesiology

Anesthesiologists are at risk for acquiring blood-borne infections through contact with blood or body fluids. From prospective studies, the greatest risk of transmission is through a percutaneous exposure such as needlestick injury. Personal protective equipment such as gloves and gowns do not completely prevent these exposures. Although educational efforts can reduce the frequency of recapping of needles, they generally have not decreased the incidence of needlesticks. Therefore, in addition to practicing universal precautions, anesthesiologists can attempt to reduce their risk of needlestick injuries by eliminating nonessential unprotected needle use, through the use of needleless or protected needle devices (engineering controls) and by modifying anesthetic procedures requiring needles (work practice controls). Needleless or protected needle products are commercially available for use in many procedures performed by anesthesiologists. For tasks that require the use of needled devices, the practitioner should use safe techniques for handling (i.e., one-handed recapping if recapping is needed) and disposal (i.e., puncture-resistant containers) of these devices. Evaluation of the efficacy, cost, and safety of needleless or protected needle products should be continued as they are introduced into wider use. Additionally, anesthesiologists should be encouraged to report needlestick injuries so that appropriate postexposure treatment can be given and so that the incident can be studied to permit design of a work protocol or device to prevent similar accidents in the future.

Initiating a crystallographic study of a class II fructose-1,6-bisphosphate aldolase

We have reproducibly crystallized the metal-dependent Class II fructose-1,6-bisphosphate aldolase from Escherichia coli. Crystals in the shape of truncated hexagonal bipyramids have unit cell dimensions of a = b = 78.4 A, c = 290.6 A and are suitable for a detailed structural analysis. The space group has been identified as P6(1)22 or enantiomorph. Data sets to approximately 2.9 A resolution have been recorded using both the Rigaku R-AXIS IIc image plate area detector coupled to a copper target rotating anode X-ray source and using the MAR image plate systems with synchrotron radiation at the EMBL outstation DESY in Hamburg, and at S.R.S. Daresbury. Diffraction beyond 2.5 A has been observed when large freshly grown crystals are used with the synchrotron beam. A data set to this resolution has been collected. Several putative heavy-atom derivative data sets have also been measured using synchrotron radiation facilities and analysis of these data sets is in progress.

Use of high-dose fluconazole as salvage therapy for cryptococcal meningitis in patients with AIDS

Eight patients with AIDS were treated orally with 800 mg of fluconazole daily for cryptococcal meningitis for a mean duration of 4.5 months. Previous antifungal treatment had failed for all of the patients. No major toxicity was observed. Three patients died from cryptococcal infection. High-dose fluconazole may be effective salvage therapy for cryptococcal meningitis.

Lack of polymorphism on the Drosophila fourth chromosome resulting from selection

Evolutionary processes can be inferred from comparisons of intraspecific polymorphism and interspecific divergence. We sequenced a 1.1-kb fragment of the cubitus interruptus Dominant (ciD) locus located on the nonrecombining fourth chromosome for ten natural lines of Drosophila melanogaster and nine of Drosophila simulans. We found no polymorphism within D. melanogaster and a single polymorphism within D. simulans; divergence between the species was about 5%. Comparison with the alcohol dehydrogenase gene and its two flanking regions in D. melanogaster, for which comparable data are available, revealed a statistically significant departure from neutrality in all three tests. This lack of polymorphism in the ciD locus may reflect recent positive selective sweeps on the fourth chromosome with extreme hitchhiking generated by the lack of recombination. By simulation, we estimate there to be a 50% chance that the selective sweeps occurred within the past 30,000 years in D. melanogaster and 75,000 in D. simulans.

An alternative strategy for infection control of anesthesia breathing circuits: a laboratory assessment of the Pall HME Filter

Contaminated breathing systems have been responsible for nosocomial upper respiratory tract and pulmonary infections in patients undergoing general anesthesia. The current infection control guidelines for anesthesia breathing circuits require single-patient use or high-level disinfection of breathing tubes, y-connector, and reservoir bag. An alternative infection control strategy has been suggested that incorporates placement of a microbial filter downstream from the y-connector between the circuit and the patient. This laboratory study assessed the capacity of the Pall HME Filter as a bidirectional barrier to transmission of bacteria between the y-connector of an anesthesia circle breathing system and a test lung. The investigators modified a sterile circle system to allow aerosolization of a suspension of 10(9) Micrococcus luteus over 5 h into the inspiratory limb proximal to the y-connector or downstream from the filter into the test lung. Cultures indicated that the Pall HME Filter placed between the y-connector and the test lung completely prevented transmission of bacteria in both directions. The results of this study suggest that the Pall HME Filter could be used as an effective microbial barrier between the anesthesia circle breathing system and the patient as part of an alternative strategy for infection control.

The value of pulmonary artery and central venous monitoring in patients undergoing abdominal aortic reconstructive surgery: a comparative study of two selected, randomized groups

One hundred two patients undergoing abdominal aortic reconstructive surgery were prospectively, randomly allocated to two groups, one of which was monitored with a central venous catheter and the other with a pulmonary artery catheter. Patients with uncompensated cardiopulmonary or renal disease were excluded from the study. General anesthesia was administered for the surgical procedure, and the patients were followed through hospital discharge. No statistically significant differences occurred between the two groups with regard to morbidity (perioperative cardiac, pulmonary or renal sequelae), mortality rate, duration of intensive care, postoperative hospital stay, or cost of hospitalization. The one statistically significant difference between groups was the professional fee charged for anesthetic care, which was higher for patients with pulmonary artery catheters than for those with central venous catheters. In conclusion, we prospectively gathered data from most patients presented for abdominal aortic reconstructive surgery. Our data seem to indicate that the choice of central venous catheter or pulmonary artery catheter monitoring makes little difference in outcome after abdominal aortic reconstructive surgery, and that for many patients pulmonary artery catheters are not necessary to give appropriate, adequate care. Because of the size of the sample, however, declarations of epidemiologic significance would be unfounded. Therefore large-scale, multicenter studies addressing such outcomes remain necessary.

The prevention of infection with Staphylococcus aureus in continuous ambulatory peritoneal dialysis

We describe the control of wound infection with Staphylococcus aureus in patients undergoing continuous ambulatory peritoneal dialysis at St. Thomas' Hospital. Forty-nine percent of 61 catheters inserted in 1985 and 1986 became infected, and the majority of these infections were acquired in hospital. Infection was impossible to eradicate and was frequently associated with the subsequent development of S. aureus peritonitis, which was the most important cause of catheter loss. Strict adherence to aseptic techniques for catheter insertion and care, combined with eradication of S. aureus carriage, reduced the infection rate to 12% for the 50 catheters inserted in 1987, abolished hospital-acquired infection and reduced the S. aureus peritonitis rate tenfold, without the use of prophylactic antibiotics. S. aureus infection is a serious but avoidable complication of continuous ambulatory peritoneal dialysis.

Eflornithine for the treatment of Pneumocystis carinii pneumonia in patients with the acquired immunodeficiency syndrome: a preliminary review

Pneumocystis carinii pneumonia (PCP) is the most common opportunistic infection in patients with acquired immunodeficiency syndrome (AIDS). Eflornithine is an antiprotozoal agent active against P. carinii. It acts by inhibiting ornithine decarboxylase, an enzyme that is essential for cellular function. The drug is initially administered intravenously, followed by oral therapy. Eflornithine has been used on a compassionate basis in AIDS patients with PCP who were intolerant of or unresponsive to traditional agents. Overall, the response rate has been about 35%; however, conclusions are difficult to make since patients had different stages of disease and received treatment for varying periods of time. Side effects include depression of bone marrow function, diarrhea, hearing loss, seizures, alterations in liver function tests, and rash. While the need for safer and more efficacious antipneumocystis drugs grows, widespread use of seemingly promising agents should be based on well-conducted clinical trials.

Intraoperative urinary output and postoperative blood urea nitrogen and creatinine levels in patients undergoing aortic reconstructive surgery

Urinary output has been used as a measure of adequate renal perfusion during anesthesia and surgery. In this study, 40 consecutive patients undergoing elective aortic reconstruction were studied to determine whether intraoperative urinary output was predictive of postoperative renal function as measured by blood urea nitrogen (BUN) and creatinine concentrations on postoperative days 1, 3 and 6, or 7. Pulmonary capillary wedge pressures or central venous pressures were kept at or above preoperative values. All patients received 22.5 g of mannitol IV prior to aortic crossclamping. No significant correlation was noted between either mean intraoperative urine output or lowest hourly urine output and postoperative BUN and creatinine concentrations. Complete interruption of renal blood flow in nine of the 40 patients had no significant effect on the correlations. Consequently, intraoperative urine output does not appear predictive of postoperative renal insufficiency in patients undergoing elective aortic reconstruction.

Laboratory diagnosis of peritonitis in patients on continuous ambulatory peritoneal dialysis

The clinical course and laboratory diagnosis of peritonitis in patients undergoing continuous ambulatory peritoneal dialysis was studied in 32 consecutive episodes. Peritonitis was associated with a failure in aseptic technique in eight episodes and with an exit-site infection in four episodes. Intraperitoneal vancomycin and ceftazidime were safe, effective, and convenient. Most patients administered their antibiotics at home, and symptoms usually resolved by day 4. Culture of the deposit obtained by centrifugation of 50 ml of effluent after leukocyte lysis provided the best rate of recovery (84% culture positive) but was technically demanding. Filtration of the same volume without leukocyte lysis was simple to perform and almost as effective. Enrichment was less satisfactory (65% culture positive) owing to the presence of antibiotic or infection with fastidious microorganisms. Culture of 50 ml of effluent after concentration by a commonly used laboratory technique, centrifugation without leukocyte lysis, performed poorly (59% culture positive at 48 h), as this method caused sequestration and death of microorganisms within the leukocytes. Culture of nearly 1 liter of effluent from 33 asymptomatic patients by the same techniques yielded no microorganisms.

Tissue-specific regulatory differences for the alcohol dehydrogenase genes of Hawaiian Drosophila are conserved in Drosophila melanogaster transformants

Naturally occurring regulatory variation is a source of genetic variability that is well documented but poorly understood. Two members of the Hawaiian picture-winged Drosophila, D. affinidisjuncta and D. hawaiiensis, display markedly different levels of alcohol dehydrogenase (alcohol: NAD+ oxidoreductase, EC 1.1.1.1) in the larval midgut and Malpighian tubules. To analyze the regulation of the alcohol dehydrogenase genes from these two species, their homologous alcohol dehydrogenase genes were cloned and introduced, via P element-mediated transformation, into the germ line of Drosophila melanogaster. Histochemical and electrophoretic analyses of larval transformants demonstrate that major differences in the tissue-specific levels of alcohol dehydrogenase production are characteristic of the alcohol dehydrogenase genes themselves. While these results do not directly address possible species-specific differences in the tissue distribution of trans-acting regulatory components, they indicate that demonstrable differences in cis-dominant regulatory information are sufficient to account for the observed regulatory variation.

Medical care costs of patients with acquired immunodeficiency syndrome in Richmond, Va. A quantitative analysis

This study examines inpatient charges for 52 adult patients with the acquired immunodeficiency syndrome (AIDS) who had 102 admissions to the Medical College of Virginia Hospitals, Richmond, from October 1983 through December 1986. Complete charge data were available for 81 hospitalizations; the mean charge per hospitalization was +13,830 (SD, +13,610), the average length of stay was 14.8 days (SD, 13.1 days), and the mean per diem charge was +1058 (SD, +802). For patients who received all their AIDS-related medical care at the Medical College of Virginia Hospitals, total lifetime hospital charges averaged +27,264, the mean number of hospital stays was 2.29, and the average length of stay was 12 days. The average length of hospital stay, total charges per hospitalization, and average charge per day of hospitalization decreased over the study period. These findings suggest that inpatient costs of treating individual patients with AIDS are less than initially estimated and are decreasing due to the ability to more effectively manage these patients.