Advancing Opportunities for Clinical Inquiry and Professional Development During a Pandemic

A notable challenge faced by pediatric hospitals during the COVID-19 pandemic included the need to decrease inpatient census and socially distant non-clinical hospital employees to alternative work arrangements. In doing so, nurses and other clinical care services employees were reassigned to new roles, while others continue to work from home. This paper aims to describe how during the COVID-19 pandemic, a pediatric hospital-based center for nursing research and evidence-based practice used this opportunity to virtually engage staff across the department in topics of clinical inquiry through education sessions, office hours, and individualized/team consultation. Therefore, elevating and increasing the presence of nursing research and evidence-based practice while providing opportunities for the continued professional development of nurses, respiratory therapists, clinical dietitians, child life specialists and employees in neurodiagnostics.

Evidence in Hand: Optimizing the Unique Skill Set of a Hospital-Based Center for Nursing Research and Evidence-Based Practice

This paper describes how, as the COVID-19 pandemic emerged, one hospital-based center for nursing research and evidence-based practice capitalized on its unique skill mix to quickly pivot to provide hospital administrators and staff with timely, relevant evidence regarding the care of patients and families, as well as the protection of direct care providers and all support staff. The products produced by this center, both proactive and in direct response, contributed to clinical operations decision-making and thus, tangibly impacted practice. The positive outcomes described speak not only to the clinical environment, but also to the presence and specialized contributions of a multiprofessional center for nursing research and evidence-based practice in such a way that was not possible prior to COVID-19.

Predictors of specialty certification among paediatric hospital nurses

AIMS AND OBJECTIVES

To evaluate differences in hospitals' proportion of specialty certified nurses and to determine whether and to what extent individual nurse characteristics and organisational hospital characteristics are associated with a nurse's likelihood of having specialty certification.

BACKGROUND

Prior research has shown that patients in hospitals with high proportions of specialty certified nurses have better outcomes including lower mortality and fewer adverse events, yet less is known about what motivates nurses to obtain specialty certification.

METHODS AND DESIGN

Cross-sectional study of paediatric nurses in 119 acute care hospitals. Multivariate logistic regression models were used to determine the association between individual nurse characteristics, organisational hospital characteristics and an individual nurses' likelihood of holding a specialty certification. STROBE was followed.

RESULTS

The proportion of certified nurses varies substantially among hospitals, with Magnet^® hospitals being significantly more likely, on average, to have higher proportions of certified nurses. Nurses in children's hospitals were no more likely than paediatric nurses in general hospitals to be certified. A nurse's years of experience and bachelors-preparation were significantly associated with higher odds of having certification. The strongest predictors of certification were favourable nurse work environments and Magnet^® -designation of the hospital.

CONCLUSIONS

While individual attributes of the nurse were associated with a nurse's likelihood of having a specialty certification, the strongest predictors of certification were modifiable attributes of the hospital-a favourable nurse work environment and Magnet^® -designation.

RELEVANCE TO CLINICAL PRACTICE

Hospital administrators seeking to increase the proportion of specialty certified nurses in their organisation should look to improvements in the organisation's nurse work environment as a possible mechanism.

Safety and Quality of Pediatric Care in Freestanding Children's and General Hospitals

OBJECTIVES

The purpose of this study was to evaluate quality and safety of care in acute pediatric settings from the perspectives of nurses working at the bedside and to investigate hospital-level factors associated with more favorable quality and safety.

METHODS

Using data from a large survey of registered nurses in 330 acute care hospitals, we described nurses' assessments of safety and quality of care in inpatient pediatric settings, including freestanding children's hospitals (FCHs) (n = 21) and general hospitals with pediatric units (n = 309). Multivariate logistic regression models were used to estimate the effects of being a FCH on favorable reports on safety and quality before and after adjusting for hospital-level and nurse characteristics and Magnet status.

RESULTS

Nurses in FCHs were more likely to report favorably on quality and safety after we accounted for hospital-level and individual nurse characteristics; however, adjusting for a hospital's Magnet status rendered associations between FCHs and quality and safety insignificant. Nurses in Magnet hospitals were more likely to report favorably on quality and safety.

CONCLUSIONS

Quality and safety of pediatric care remain uneven; however, the organizational attributes of Magnet hospitals explain, in large part, more favorable quality and safety in FCHs compared with pediatric units in general acute care hospitals. Modifiable features of the nurse work environment common to Magnet hospitals hold promise for improving quality and safety of care. Transforming nurse work environments to keep patients safe, as recommended by the National Academy of Medicine 20 years ago, remains an unfinished agenda in pediatric inpatient settings.

Parental Uncertainty: Parents' Perceptions of Health-Related Quality of Life in Newly Diagnosed Children With Cancer

BACKGROUND

Parents of children with cancer are predisposed to psychological distress symptoms, such as anxiety, depression, and uncertainty. This vulnerability may exacerbate underlying mood disturbances, including trait anxiety and depression, and influence parents' perception of health-related quality of life (HRQOL) in their children.

OBJECTIVES

This study examined the relationship between parental uncertainty and parent proxy reports of HRQOL in newly diagnosed children with cancer.

METHODS

A longitudinal descriptive approach was used to examine the relationship between parental uncertainty and parent proxy reports of HRQOL in 55 parent-child dyads. Parental trait anxiety, depression, and perceived social support were evaluated as potential predictor variables.

FINDINGS

Parents of newly diagnosed children with cancer reported lower parent proxy HRQOL scores. Parental uncertainty was prevalent and affected parents' perceptions of HRQOL three months following diagnosis; however, higher social support scores buffered these negative effects.

Predicting Pressure Injury Risk in Pediatric Patients: The Braden QD Scale

OBJECTIVE

To describe the development and initial testing of the Braden QD Scale to predict both immobility-related and medical device-related pressure injury risk in pediatric patients.

STUDY DESIGN

This was a multicenter, prospective cohort study enrolling hospitalized patients, preterm to 21 years of age, on bedrest for at least 24 hours with a medical device in place. Receiver operating characteristic curves using scores from the first observation day were used to characterize Braden QD Scale performance, including areas under the curve (AUC) with 95% CIs.

RESULTS

Eight centers enrolled 625 patients. A total of 86 hospital-acquired pressure injures were observed in 49 (8%) patients: 22 immobility-related pressure injuries in 14 (2%) patients and 64 medical device-related pressure injuries in 42 (7%) patients. The Braden QD Scale performed well in predicting immobility-related and medical device-related pressure injuries in the overall sample, with an AUC of 0.78 (95% CI 0.73-0.84). At a cutoff score of 13, the AUC was 0.72 (95% CI 0.67-0.78), providing a sensitivity of 0.86 (95% CI 0.76-0.92), specificity of 0.59 (95% CI 0.55-0.63), positive predictive value of 0.15 (95% CI 0.11-0.19), negative predictive value of 0.98 (95% CI 0.97-0.99), and a positive likelihood ratio of 2.09 (95% CI 0.95-4.58).

CONCLUSIONS

The Braden QD Scale reliably predicts both immobility-related and device-related pressure injuries in the pediatric acute care environment and will be helpful in monitoring care and in guiding resource use in the prevention of hospital-acquired pressure injuries.

Clinical research nursing: a critical resource in the national research enterprise

Translational clinical research has emerged as an important priority for the national research enterprise, with a clearly stated mandate to more quickly deliver prevention strategies, treatments and cures based on scientific innovations to the public. Within this national effort, a lack of consensus persists concerning the need for clinical nurses with expertise and specialized training in study implementation and the delivery of care to research participants. This paper reviews efforts to define and document the role of practicing nurses in implementing studies and coordinating clinical research in a variety of clinical settings, and differentiates this clinical role from the role of nurses as scientists and principal investigators. We propose an agenda for building evidence that having nurses provide and coordinate study treatments and procedures can potentially improve research efficiency, participant safety, and the quality of research data. We also provide recommendations for the development of the emerging specialty of clinical research nursing.

Perceptions of school nurses and teachers of fatigue in children

The aim of this study was to elicit school nurses' and teachers' perceptions of fatigue in school settings. Fatigue was defined as tiredness, not relieved by usual sleep or rest; a symptom that persists beyond an isolated experience of feeling tired. Four focus groups were conducted to elicit data for this qualitative descriptive study. Purposive sampling was used to identify school nurse and teacher participants who were asked to discuss their perceptions of fatigue. Content analysis of verbatim transcripts yielded several major themes. Forty-six codes emerged from the data and were routinely applied during the analysis. Nineteen of these codes were used 20 times or more and applied to all four transcripts. Participants could clearly identify and readily discuss behaviors related to fatigue. Data describe how children attending school express fatigue in their everyday life. Findings validate the need for nurses in ambulatory pediatric settings to be aware of fatigue as a symptom that children and adolescents may experience.

Quantification of cytomegalovirus (CMV) viral load by the hybrid capture assay allows for early detection of CMV disease in lung transplant recipients

BACKGROUND

We prospectively compared the hybrid capture system (HCS) assay with conventional cell culture and shell vial assay for the detection of cytomegalovirus (CMV) infection and disease in the lung transplant population.

METHODS

Between January 1999 and February 2000, 34 lung transplant patients at Loyola University Medical Center, who were considered to be at risk for CMV disease, underwent surveillance testing for CMV cell culture, shell vial assay and HCS assay according to a pre-determined schedule. In addition, bronchoscopy with bronchoalveolar lavage (BAL) and transbronchial biopsy were performed at regular intervals and for clinical indications. All BAL samples were sent for CMV cultures and biopsy specimens were analyzed for histopathologic evidence of CMV by immunoperoxidase staining using antibody to early immediate nuclear antigen.

RESULTS

Ten patients developed CMV disease/syndrome during the course of the study. The sensitivity, specificity, positive predictive value and negative predictive value were >90% for the HCS assay. The sensitivity of the HCS assay (90%) was statistically significantly higher than the sensitivity of either the SV assay (40%) or the cell culture (50%). In addition, the HCS assay was able to detect CMV 50 +/- 67 days prior to clinical evidence of CMV disease and an average of 36 days prior to the other detection techniques.

CONCLUSION

The HCS assay is a sensitive diagnostic technique able to reliably detect CMV disease earlier than other diagnostic methods in the lung transplant population. Future studies may be able to evaluate whether pre-emptive anti-viral therapy targeted to specific viral loads using the HCS assay will be beneficial in preventing morbidity associated with CMV disease.

Care before and after lung transplant and quality of life research

Lung transplantation is a growing surgical option for patients with end-stage lung and pulmonary vascular diseases. After completing an extensive evaluation and meeting the selection criteria, patients are listed for either single or bilateral-sequential lung transplantation. Immediate postoperative management requires detailed attention to fluid management, monitoring for infection, reperfusion injury, pulmonary hygiene, and pain management. Length of stay depends on the patient's condition before transplant and postoperative complications. Discharge from the hospital can be as early as 7 days after transplantation. Newer immunosuppressive medications offer more options for treating and preventing rejection. Advanced practice nurses, such as coordinators, case managers, nurse practitioners, and clinical nurse specialists, are uniquely positioned to play key roles in coordinating the care of transplant patients across settings and both before and after the transplant procedure. The perioperative needs of lung transplant patients and the impact of this complex procedure on the recipients' and family's quality of life merit further investigation by clinicians and researchers.

Liberalization of donor criteria may expand the donor pool without adverse consequence in lung transplantation

BACKGROUND

Currently the most important limitation in lung transplantation is donor availability. Although liberalization of donor criteria may aid in expanding the donor pool, the long-term effects of the use of "marginal" or "extended" donors remains unexplored.

METHODS

In this study, we included all patients who underwent lung transplantation from January 1996 to December 1999 at Loyola University Medical Center. We categorized patients as either receiving lungs from an "ideal" donor or an "extended" donor. Extended donors were defined as having any 1 of the following criteria: donor age > 55 years, tobacco history > 20 pack years, presence of infiltrate on chest x-ray, donor ventilator time > 5 days, or donor use of inhaled drugs (cocaine or marijuana). We then compared the 2 groups with regard to short-term (operating room [OR] complications, intensive care unit [ICU] complications) and long-term outcomes (1-year pulmonary function and survival).

RESULTS

Sixty-one (54%) patients received lungs from ideal donors and 52 (46%) patients received lungs from extended donors as defined above. We observed no significant differences between the 2 groups in OR complications (cardiopulmonary bypass, bleeding complications, life-threatening arrhythmias) or ICU complications (pneumonia, airway dehiscence, reoperation within 30 days related to transplantation). In addition, the 2 groups had similar median intubation times (21 hours in the ideal donor group and 20 hours in the extended donor group; p = n.s.), hospital length of stay (14+/-12 days in the ideal donor group and 12+/-8 days in the extended donor group; p = n.s.), and hospital survival (80% and 88% in the ideal and extended donor groups, respectively). One-year follow-up revealed similar pulmonary function (forced expiratory volume in 1 sec [FEV(1)] = 2.4 liters and 2.4 liters in the recipients of bilateral ideal and extended donors, respectively, and FEV(1) = 1.9 liters and 1.5 liters in the recipients of single ideal and extended donors) and survival (72% and 79% in the ideal and extended donor groups, respectively; p = n.s.) between the 2 groups.

CONCLUSIONS

Liberalization of donor criteria does not affect outcome in the first year after lung transplantation. By liberalizing donor criteria, we can expand the donor pool while assessing other possible mechanisms to increase donor availability.

Family functioning, neurocognitive functioning, and behavior problems in children with sickle cell disease

OBJECTIVE

To investigate the independent and combined contributions of neurocognitive and family functioning to mother-reported behavior problems in children with sickle cell disease (SCD) and evaluate the factor structure of the Family Environment Scale (FES) with African American families.

METHOD

The study sample included 289 children enrolled in the multisite Cooperative Study of Sickle Cell Disease. The study protocol included neuropsychological evaluation and brain magnetic resonance imaging (MRI) of the children, and mothers completed the Child Behavior Checklist and Family Environment Scale.

RESULTS

With child and maternal demographic parameters controlled, conflicted family functioning, but not neurocognitive functioning, accounted for a significant portion of the variance in mother-reported behavior problems. The factor structure of the FES for families of children with SCD was found to be similar to that for other families.

CONCLUSIONS

Family functioning may be a salient target for fostering adaptation to chronic childhood illness.

Risk of abuse of diphenhydramine in children and adolescents with chronic illnesses

Diphenhydramine is generally considered an innocuous drug with a minimal risk for abuse and untoward side effects. We describe children and adolescents with chronic hematologic and oncologic diseases who exhibited drug-seeking behavior or anticholinergic symptoms with the use of diphenhydramine. These cases illustrate that the assumption that this drugs is without significant adverse effects may be unwarranted, especially for children and adolescents with chronic diseases.

Rapid deconvolution of NMR powder spectra by weighted fast Fourier transformation

The resolution enhancement conferred by numerical deconvolution of powder pattern spectra to spectra characteristic of a single alignment greatly simplifies solid state NMR spectral analysis. This is especially beneficial when the spectrum is a superposition of signals from multiple environments or sites of labelling. We have developed an innovative method to deconvolute (depake) spectra governed by axially symmetric second rank tensor interactions which possess a P2(cos theta) dependence upon orientation, where theta is the angle between the symmetry axis and the external magnetic field. Our approach differs substantially from previously published procedures which are iterative or require matrix inversion and, hence, are slow. The new method, instead, utilizes weighting functions in time and frequency domains to facilitate a rapidly executed solution based upon fast Fourier transformation (FFT). Its efficacy is demonstrated with 2H and 31P NMR data for model membranes.

Neurodevelopmental side effects of bone marrow transplantation: two case illustrations of identical twins

PURPOSE

Bone marrow transplantation (BMT), particularly preparative regimens, may have a significant impact on the developing nervous system. However, the effects of various BMT regimens on children's growth and development have been poorly documented to date. Twins serve as ideal subjects to study the impact of medical treatment, since they control for nonmedical (genetic and environmental) influences upon neurodevelopmental outcome.

PATIENTS AND METHODS

Two cases of monozygotic twins are presented to illustrate the impact of BMT regimens. Growth data and neurocognitive testing are presented for each patient (affected twin) in relation to his/her syngeneic BMT donor and case control (control twin).

RESULTS

These two cases illustrate the growth retardation that has been reported after BMT. However, changes in growth trends across twins appear to have begun after diagnosis, rather than after BMT per se. Comparisons of cognitive test results within these twin pairs illustrate learning problems in the affected twins. However, there was also evidence of learning anomalies in the unaffected twins.

CONCLUSIONS

Results underscore the importance of longitudinal assessment in order to identify the side effects of BMT regimens for children. Differences across the two cases highlight important research questions regarding variables associated with patients, disease, and treatment (e.g., age at the time of BMT, previous neurotoxic treatments, underlying disease) and emphasize the importance of controls in this line of research.

Involving children and adolescents in medical decision making: developmental and clinical considerations

Outlined the issues in informed consent, as well as goals for involving children and adolescents in decisions regarding their own medical treatment. This paper reviews the developmental and clinical considerations, and provides recommendations, for determining particular children's level of involvement. Finally, there are distinct roles for pediatric psychologists in this process, which are described. As medical treatment becomes increasingly sophisticated, there is an obligation for pediatric psychologists to appreciate the ethical and clinical issues in medical decision making for families.

Aspergillus and lung transplantation

BACKGROUND

Aspergillus infection is a known complication of transplantation.

METHODS

We describe our experience with 37 patients who received lung transplants over 2 years at Loyola University Medical Center. All patients who had evidence of aspergillus on culture of clinical specimens or had biopsies with hyphal forms consistent with aspergillus were categorized according to the clinical manifestations. Important risk factors were analyzed in comparison with other lung transplant recipients during the same period.

RESULTS

The incidence of invasive aspergillosis was high (16%). No patient with disseminated disease survived. Locally invasive disease responded well to treatment with amphotericin B and itraconazole.

CONCLUSIONS

Lung transplantation patients may have a higher incidence of aspergillosis as compared with other transplantation groups. Prophylactic measures need to be explored.

Survivors of medulloblastoma: implications for program planning

A growing literature documents the deleterious effects of radiation therapy in children treated for malignant brain tumors. However, the clinical relevance of previous research has been limited by reliance on global IQ and achievement test scores. The present study of a sample of long-term survivors of medulloblastoma examined their cognitive and socioemotional functioning in depth with standardized psychologic measures. Participants' levels of intellectual functioning ranged from moderately mentally retarded to low average, with marked scatter across individual skills. Thirty-nine percent of participants had formal learning disabilities, with achievement substantially below their learning potential. In terms of specific areas of deficit, almost one half the patients tested (47%) showed considerable impairment in perceptual-motor coordination, fine-motor dexterity, attention and concentration, sequencing, and memory, particularly visual memory. More than one half of the sample (54%) was also described as displaying severe impairment in terms of maladaptive behaviors. Results are discussed in terms of the implications for special education, everyday skills, and psychosocial program development.

Primary and secondary control among children undergoing medical procedures: adjustment as a function of coping style

The literature suggests that optimal adjustment to relatively uncontrollable stressors may require adjusting oneself to the stressors rather than trying to alter them. This possibility was explored, for low-controllability stressors (e.g., painful medical procedures) associated with leukemia. Children's reports of coping strategies and goals were classified as primary control coping (attempts to alter objective conditions), secondary control coping (attempts to adjust oneself to objective conditions), or relinquished control (no attempt to cope). Secondary control coping was positively associated with (a) general behavioral adjustment assessed by the Child Behavior Checklist and (b) illness-specific adjustment assessed by children's own distress ratings and by behavioral observations during painful procedures. All significant group differences showed better adjustment among secondary control children than among the primary or relinquished groups.

2H NMR studies of isomeric omega 3 and omega 6 polyunsaturated phospholipid membranes

The properties of aqueous multilamellar dispersions of [2H31]16:0-alpha 18:3 PC (1-[2H31]palmitoyl-2-cis,cis,cis-octa-9,12,15- trienoylphosphatidylcholine) and of [2H31]16:0-gamma 18:3 PC (1-[2H31]palmitoyl-2-cis,cis,cis-octa-6,9,12-trienoylphosphatid ylcholine) were compared by broadline 2H NMR spectroscopy. These isomeric phospholipids differ only in the location of the unsaturations in the sn-2 chain. The alpha 18:3 chain has double bonds at delta 9, 12, and 15 positions whereas in the gamma 18:3 chain they are at positions delta 6, 9, and 12. Moment analysis of spectra recorded as a function of temperature reveals dramatically distinct phase behavior for the two isomers. The gel to liquid crystalline transition for [2H31]16:0-alpha 18:3 PC membranes exhibits broad hysteresis which is characterized by a mid point temperature of -9 degrees C and -20 degrees C on heating and cooling, respectively. In contrast, the phase transition of [2H31]16:0-gamma 18:3 PC membranes does not exhibit hysteresis and occurs over a lower temperature range centred on -27 degrees C. Appreciably different molecular ordering also exists within the membranes in the liquid crystalline state. Average order parameters SCD are smaller in [2H31] 16:0-alpha 18:3 PC than in [2H31]16:0-gamma 18:3 PC by 10% at the same temperature and by 20% at equal reduced temperature. Smoothed order parameter profiles generated from depaked spectra clarify the nature of the difference.(ABSTRACT TRUNCATED AT 250 WORDS)

Quality of long-term survival in young children with medulloblastoma

The reported success of treatment for children with medulloblastoma must be balanced against the effect that treatment has on the quality of life of long-term survivors. The outcome of long-term survivors reported in previous studies has been conflicting. The authors evaluate the mental and behavioral skills of a group of medulloblastoma survivors from their institution, all of whom had survived for more than 5 years postdiagnosis. A review of the institutional records yielded 32 patients. Twenty-three families were interviewed by telephone and, of these, 13 subjects came to the hospital for detailed neuropsychological and neurological evaluations. Intelligence quotient (IQ) was less than 90 for all participants tested, and patients diagnosed before the age of 3 years had lower IQ scores on average than those diagnosed later. Mean IQ and achievement test scores in reading, spelling, and mathematics were all higher in survivors who had undergone shunting. Achievement test results were often not in accord with intellectual potential, and individual intellectual skills varied widely. Perceptual-motor task performance was below average in more than 50% of the participants, but motor dexterity was more severely affected than perception. Problems in learning and a delay in both physical growth and development were seen in a majority of participants. This study directs attention to the serious difficulties faced by long-term survivors of medulloblastoma and their families, and underscores the importance of routine neuropsychological testing. Moreover, the study provides further impetus to seek alternatives to irradiation in the treatment of malignant brain tumors.

Primary and secondary control among children undergoing medical procedures: adjustment as a function of coping style

The literature suggests that optimal adjustment to relatively uncontrollable stressors may require adjusting oneself to the stressors rather than trying to alter them. This possibility was explored, for low-controllability stressors (e.g., painful medical procedures) associated with leukemia. Children's reports of coping strategies and goals were classified as primary control coping (attempts to alter objective conditions), secondary control coping (attempts to adjust oneself to objective conditions), or relinquished control (no attempt to cope). Secondary control coping was positively associated with (a) general behavioral adjustment assessed by the Child Behavior Checklist and (b) illness-specific adjustment assessed by children's own distress ratings and by behavioral observations during painful procedures. All significant group differences showed better adjustment among secondary control children than among the primary or relinquished groups.

Measurement of nutrient intake by deuterium dilution in premature infants

To assess whether a simple nonrestrictive method of determining nutrient intake could be applied to premature infants, we compared actual measured formula intake during a 7-day period with intake calculated from deuterium dilution in 13 hospitalized, growing, premature newborn infants. An oral dose of deuterium oxide (D2O) was administered, and urine samples were analyzed by deuterium nuclear magnetic resonance spectrometry for D2O concentration. Using an exponential model, we calculated formula intake from the decline in D2O concentration during the 7-day study period. Intake as assessed by the deuterium model correlated well with actual intake (r = 0.93; p < 0.001). However, because the deuterium dilution model measures both dietary and nondietary water intake (metabolic and cutaneous water influx), deuterium dilution-derived intake exceeded actual intake by 25 +/- 18 ml/kg per day (16% +/- 11%). When corrections were applied to account for nondietary water intake, deuterium dilution-derived nutrient intake (160 +/- 30 ml/kg per day) closely approximated actual intake (155 +/- 17 ml/kg per day). If corrections are made for nondietary water intake, the deuterium dilution method may be a useful nonrestrictive method of measuring nutrient intake in a variety of neonatal populations.

Bronchial dehiscence associated with a large broncholith in a lung transplant recipient

A 63-year-old man who underwent single lung transplantation for advanced emphysema had a postoperative course complicated by asymptomatic bronchial dehiscence associated with a large broncholith. The stone eventually caused airway obstruction requiring partial fragmentation and incomplete extrication. We suggest that calcified nodes of significant size be removed at the time of surgery in the lung transplant recipient.

The growth-promoting effect of bacterial iron for serum-exposed bacteria

Bacterial ability to obtain iron in bovine serum or in media containing transferrin (Tr) or conalbumin (Ca) was investigated by using serum-resistant (virulent) and serum-sensitive (avirulent) strains of Escherichia coli and Salmonella typhimurium. Bacteria growing in bovine serum enriched with radioactive iron-saturated Tr or with radioactive iron-saturated enterobactin (E) did not acquire radioactive iron. It has been found that the passage of siderophore (Si)-iron complexes into bacteria is blocked in serum by Tr and in Ca-containing medium by Ca. The investigation of bacterial ability to take iron in synthetic media showed that bacteria take in Si-bound but no Tr-bound radioactive iron. In the absence of free iron, the growth of serum-exposed virulent bacteria was supported by their stored iron. Virulent bacteria passaged in medium void of usable iron became depleted in stored iron and did not grow in animal sera unless sera were enriched by the addition of exogenous iron. Experiments with serum-exposed avirulent bacteria showed that their growth in Si-enriched serum should not be attributed to the iron-providing activity of Si but to the stimulating effect of Si which facilitates the use of stored iron. As distinct from avirulent bacteria, virulent bacteria used stored iron without the stimulating activity of extracellular Si.

Effects of injected iron and siderophores on infections in normal and immune mice

The fate of virulent and avirulent strains of Salmonella typhimurium in untreated and iron-injected mice and in transferrin-containing media demonstrated a direct relationship between bacterial virulence and the ability of bacteria to acquire transferrin-bound iron. Effects of injected iron on the development of infections with virulent and avirulent bacterial strains were determined in normal and immune mice by determinations of bacterial numbers in tissue homogenates and the mortality of infected animals. Results showed that infected and iron-injected mice died much more rapidly and frequently from overwhelming infections than infected and saline-injected mice. The infection-promoting effect of iron varied with the degree of bacterial virulence; the more virulent the bacteria, the more helpful was iron for the development of lethal infections. Siderophores promoted lethal infections in mice infected with virulent but not with avirulent bacteria. Experiments with vaccinated animals showed that iron exerted a deleterious effect on acquired immunity. Immune mice infected with virulent bacteria and injected with iron developed lethal infections as rapidly and nearly as frequently as similarly treated normal mice. Siderophores did not promote the development of lethal infections in immune mice. The effectiveness of iron, but not of siderophores, to promote bacterial infections in vaccinated mice revealed that acquired immunity is dependent upon the activity of an iron-neutralizable antibacterial system.

Determinants of lengths of outpatient visits in a prepaid group practice setting

In this paper we have examined the amount of time that physicians (MDs) and physician's assistants (PAs) expended on office visits. The purpose was to determine the extent to which a series of patient-related and system-related characteristics explain variations in that time. Using regression analyses, we found most of the explained variation generally to be due to system-related characteristics. Whether the provider was an MD or PA made little difference in the length of time spent with patients. The principal determinant of provider time for unscheduled and scheduled 15-minute visits was the patient-load (number of patients per minute); for scheduled 30-minute visits, the number of associated morbidities was relatively more important than patient-load. Discriminant analysis was used to identify factors that could distinguish PA visits that require an MD input from those that do not. The data were collected from three months of observation in the department of medicine of a prepaid group practice.