Office laboratory procedures, office economics, patient and parent education, and urinary tract infection

This review updates our readers on four important areas of office practice: office laboratory procedures, office economics, patient and parent education, and urinary tract infection. Michael Aldous reviews the recent literature on office laboratory procedures, which includes a report on the ongoing heated discussion of the Clinical Laboratory Improvement Amendments, an update of recent studies on new and better rapid streptococcal tests, and improved methods for urinalysis. Rickey Williams provides a report on office economics that includes a discussion of the effects of capitation, how preventive care can be cost effective, and the future prospects for greatly expanded office computerization. Burris Duncan discusses patient and parent education with an in-depth review of the potential economic value of a full implementation of the American Academy of Pediatrics' The Injury Prevention Program, and in addition he chronicles the rapid growth and development of school-based health centers. John Ey reviews the recent literature on urinary tract infections in children, including how we can make the diagnosis, methods for preventing recurrent urinary tract infections, the most effective studies for evaluating the urinary system, and what follow-up is necessary. We hope this review will provide the pediatrician with important information to help in the care of their patients.     

Procainamide-induced agranulocytosis differs serologically and clinically from procainamide-induced lupus

Agranulocytosis is a well recognized but uncommon complication of procainamide (PA) therapy, whereas a lupus-like syndrome occurs in approximately 20% of patients treated chronically with PA. In order to gain insight into the immunopathogenic relationships among these conditions, we compared the humoral immune abnormalities in these patient groups as well as in asymptomatic PA-treated patients. A relatively uniform profile of IgM but not IgG autoantibody reactivity with a set of chromatin-related antigens was observed in eight elderly men who developed agranulocytosis after treatment with PA. In contrast PA-induced lupus patients had predominant reactivity with [(H2A-H2B)-DNA] in both IgM and IgG classes. Five of eight patients with agranulocytosis had elevated levels of neutrophil-reactive IgG which appeared to be due to immune complexes based on Fc gamma receptor blocking studies. However, 12 of 15 patients with PA-induced lupus, none of whom had neutropenia, had similar levels of neutrophil-reactive IgG, suggesting that this reactivity was not causally related to agranulocytosis. Agranulocytosis developed after less than 3 months treatment with PA in six of eight patients. This time course was similar to that seen in 77 PA-induced agranulocytosis patients reported in the literature plus 127 patients reported to the U.S. Food and Drug Administration in whom 90% developed agranulocytosis within 3 months of starting PA. In contrast, the mode duration of treatment with PA before lupus-like symptoms develop is 10-12 months. These findings, together with the different profiles of autoantibodies and clinical presentations, suggest that agranulocytosis arises from a different mechanism than that underlying PA-induced lupus.     

Acute dilutional anemia and critical left anterior descending coronary artery stenosis impairs end organ oxygen delivery

OBJECTIVE: Limited cardiac reserve, secondary to coronary disease, may be associated with end organ morbidity. In this study, we investigate the significance of anemia in the pathogenesis of this phenomenon. DESIGN: Nonrandomized controlled animal trial. SETTINGS: Animal laboratory in a university hospital. SUBJECT: Anesthetized dogs. INTERVENTIONS/MEASUREMENTS: Fourteen anesthetized dogs underwent isovolemic hemodilution with 6% hetastarch from a baseline hematocrit of 40 to 20%. Radioactive microspheres were used to evaluate regional blood flow and cardiac index. Systemic oxygen delivery, consumption, serum lactate, and systemic vascular resistance were recorded during each experiment. Arterial venous oxygen difference was determined from arterial and mixed venous blood. Seven dogs had an iatrogenic critical stenosis of their left anterior descending coronary artery (experimental group); seven dogs did not (control). MAIN RESULTS: Only in the control animals, the cardiac index increased by 35% with hemodilution to 20%. Systemic oxygen delivery decreased in both the control and the experimental animals. Systemic oxygen consumption and lactate levels were unchanged in both groups. In the renal cortex, spleen, distal colon, ileum, gallbladder, and stomach body, regional O2 delivery was significantly decreased with hemodilution to 20% in both groups. This finding was also observed in the left ventricle and cervical spinal cord in the experimental group. In addition, regional O2 delivery was reduced in the spleen, distal colon, and gallbladder with hemodilution to only 30%. Regional blood flow in the stomach body, gallbladder, ileum, renal cortex, and distal colon, in both groups, and the spleen in the control group was unchanged from baseline with hemodilution to 20%. However, regional blood flow under all other circumstances (control or experimental) was significantly increased with hemodilution to 20% with the exception of the spleen, which showed significant regional blood flow decrease in the experimental group only. CONCLUSIONS: These data suggest that with limited cardiac reserve, anemia may compromise aerobic splanchnic circulation. These observations may further our understanding of the pathogenesis of cholecystitis, gastric stress ulcers, ileal endotoxin translocation, and ischemic colitis in critically ill patients with coronary artery disease.     

A simplified approach to the diagnosis of alopecia

Specific types of alopecia can be readily identified by history and physical examination with a high degree of accuracy in 97% of cases. Although some confirmatory laboratory studies may be required, two elements of the medical history and four elements of the physical examination can lead a dermatologist knowledgeable in the common scalp diseases to a rapid diagnosis. The key elements of history are age and duration of alopecia. The key elements of the examination are scalp status, pattern of loss, pull test results, and the integrity of the follicular units.     

Activation of intrinsic and synaptic currents in leech heart interneurons by realistic waveforms

Leech heart interneurons were voltage-clamped with realistic waveforms to investigate the currents underlying the oscillation in the cells. By estimating the leak current parameters in regions in which there was little contamination by voltage-gated currents, it was possible to measure the Ca2+ current, the persistent Na+ current, Ip, and the hyperpolarization-activated inward current, Ih. The experiments verified a prediction of a computer model of HN cells that the shape of the typical waveform was such that the low-threshold Ca2+ currents were partially inactivated during a slow up-ramp to a plateau potential. A step within the same range of the membrane potential as the realistic waveform produced > 4 times as much Ca2+ current. In two-cell voltage-clamp experiments, the step produced 20 times more graded inhibition than the normal presynaptic waveform. When the presynaptic heart interneuron oscillated with spikes, the graded inhibition was larger. The difference may arise from integration of a slowly decaying component of the spike-mediated inhibition. The persistent Na+ current had a very low threshold. During the most hyperpolarized phase of the waveform, Ip deactivated to 50% of its maximum conductance. A substantial part of Ip, therefore, was effectively contributing to the leak current in the HN cells. The h-current increased for waveforms that had longer periods, whereas increasing the h-current in the model reduced the period. The h-current thus provides negative feedback to perturbations that alter the period of the oscillation.     

CD8+ T cells in intracellular bacterial infections of mice

In the normal course of an immune response, both CD4+ and CD8+ T cells respond to each of the bacterial pathogens we have discussed and both responses may be required for the most potent immunity to infection. In this discussion, we have focused on the ability of these organisms to prime CD8+ T-cell responses in vivo and the ability of CD8+ T cells as sole mediators of acquired immunity, to protect against infection. It is clear that the vacuolar location of bacterial pathogens such as Salmonella or Mycobacteria does not prevent in vivo priming of CD8+ T-cell responses to these pathogens. However, vacuolar localization may affect the potency of CD8+ T-cell responses under experimental conditions that assess the capacity of CD8+ T cells as the sole mediators of acquired immunity. In the case of cytoplasmic L. monocytogenes, clear evidence exists that antigen-specific CD8+ T cells, in the absence of immune CD4+ T cells, can provide substantial acquired immunity to naive mice. Similar clear experimental results with Salmonella and Mycobacteria are lacking. Such results would provide stronger support for vaccines that elicit CD8+ T-cell responses to these vacuolar pathogens. Although our discussion has focused on only three specific organisms, we suggest that detection of an in vivo CD8+ T-cell response to a bacterial antigen does not ensure that the response will be protective against infection in a vaccine setting. In the case of Salmonella and Mycobacteria, this issue remains unresolved.