Cytochemical staining and flow cytometry methods applied to the diagnosis of acute leukemia in the pediatric population: an assessment of relative usefulness

BACKGROUND

Cytochemical staining has been used in the diagnosis of acute leukemia for more than 20 years. The general availability of flow cytometers and an extensive panel of antibody reagents useful for characterizing blood cell lineage question the usefulness of continuing routine use of the cytochemical staining for the diagnosis of acute leukemia.

PATIENTS AND METHODS

Test results were evaluated in 122 (n = 122; 112 with acute lymphocytic leukemia and 10 with acute myeloid leukemia) patients selected from among 320 patients with acute leukemia at Texas Children's Hospital in 1997 and 1998. Results were selected for review if the clinical encounter represented the initial diagnostic work-up and if data were available from cytochemical staining and flow cytometry studies.

RESULTS

Cell lineage classification derived from flow cytometry and cytochemical stains were in agreement in all cases. Definitive diagnoses were feasible using flow cytometry results alone in 120 of 122 patients (98.4%) as compared with only 99 of 122 patients (81.2%) when only cytochemical staining results were considered. In two patients with inconclusive flow cytometry results, cytochemical staining alone provided information sufficient for diagnosis.

CONCLUSIONS

Results from this study indicate that with few exceptions, flow cytometry studies alone provide sufficient information for diagnosis and management of acute leukemia in children. Nevertheless, cytochemical staining should be available for those cases in which flow cytometry results fail to allow a definitive diagnosis. A modified testing protocol is recommended.

The metrics process: Baylor's development of a "report card" for faculty and departments

In 1996, Baylor College of Medicine began the first year of its "metrics process," collecting, analyzing, and reporting data on the performance of each individual faculty member and each department in achieving the school's missions of education, patient care, research, service, and finance. This article is a report of the first two years of the process, with updates about the 1999 process, future plans, and lessons learned. The primary goal of the metrics process is to provide meaningful data to assess and improve the performance of faculty and departments across all missions. The authors (1) indicate the categories chosen, within each mission of the school, for measuring faculty time and effort (e.g., patient care, with or without learners) and state the measures chosen (e.g., percentage of time); (2) describe the development of questionnaires in 1996 and 1997 to acquire data from faculty, in the chosen categories and measures, about the time and effort they spent; and (3) report highlights of the resulting departmental data that were gathered in 1997. Among the key categories and units of measure chosen for measuring faculty (and departmental) time and effort are research grant dollars (total and per research full-time equivalent, or FTE); basic research grant dollars per square foot of laboratory space; percentage of faculty who spend at least 50% of their time in research who are National Institutes of Health principal investigators; numbers of inpatient and outpatient visits per evaluation and management FTE; total relative value units (RVUs) per patient-care FTE; patient-care income/RVU and expense/RVU for total faculty and support staff; percentage of faculty with at least one leadership position in a state or national organization; and income in excess of expense, by mission (e.g., patient care). Results of comparing data from the first two years of the metrics process demonstrate marked improvements in performance for most research measures (i.e., items of measurement agreed upon for the metrics process). The process is continually being redeveloped; the ultimate challenge is to place the objective measurements in a context where less objective qualities (e.g., innovation) also figure importantly in the evaluation and fostering of excellence. The metrics process is providing important management data, encouraging significant discussions among faculty and chairs about performance and accountability, and aiding greatly in departmental goal-setting and ultimately in determining the overall performance of the school.

A conceptual framework for managing clinical processes

Reengineering of the health care delivery system is underway, as is the transformation of the processes and methods used for recording information describing patient care (i.e., the development of a computer-based record). This report describes the use of object-oriented analysis and design to develop and implement clinical process reengineering as well as the organization of clinical data. In addition, the facility of the proposed framework for implementing workflow computing is discussed.

Blood lead levels in a continuity clinic population

INTRODUCTION

Lead toxicity is well recognized as a significant cause of morbidity in children, especially those under the age of six years. While lead toxicity has not been recognized as a public health problem in Houston, it is possible that children in the area suffer from low-level lead effects on the central nervous system.

OBJECTIVES

To detect asymptomatic cases of lead toxicity in one population of Houston children and to assess the effectiveness of the lead risk questionnaire.

DESIGN

Venous blood samples for quantitative lead were analyzed utilizing the Anodic Stripping Voltameter. The Centers for Disease Control's lead risk assessment questionnaire was administered to each patient.

SETTING

Baylor College of Medicine Continuity Clinic at Texas Children's Hospital.

SUBJECTS

All patients, ages 9-72 months, seen for routine care between December 1992 and June 1994 were screened once.

RESULTS

Blood lead levels were obtained on 801 children; all but 47 completed lead risk questionnaires. The mean age of the study group was 2.37 years (SD 1.84) and they were 54% male. They were 39% Hispanic, 39% Black, and 18% White. Eighty-eight percent reported an annual income of < $20,000. They lived in 127 separate zip codes. Twenty-five (3.1%) patients had elevated blood lead, 21 between 10-14 micrograms/dL and 4 between 15-19 micrograms/dL. No patients had blood lead levels of > or = 20 micrograms/dL. No statistically significant differences were found between patients with blood lead < 10 micrograms/dL and those with > or = 10 micrograms/dL when comparing for age, sex, ethnicity, income, and zip code. Only those children living in or regularly visiting a pre-1960 home with peeling or chipping paint were significantly more likely to have elevated blood lead (p = .045).

CONCLUSION

Although the majority of children in our setting were poor and urban, the prevalence of blood lead > or = 10 micrograms/dL was 3.1%, well below the estimated 17% quoted by the Centers for Disease Control in recommending stringent screening guidelines. The lead risk assessment questionnaire failed to identify 32% of children with elevated blood lead levels. Since this questionnaire is critical to screening populations at low risk for lead toxicity, it is important to determine whether a revised questionnaire or a more careful elicitation of parental responses will improve identification of those children at risk.

Workflow computing. Improving management and efficiency of pathology diagnostic services

Traditionally, information technology in health care has helped practitioners to collect, store, and present information and also to add a degree of automation to simple tasks (instrument interfaces supporting result entry, for example). Thus commercially available information systems do little to support the need to model, execute, monitor, coordinate, and revise the various complex clinical processes required to support health-care delivery. Workflow computing, which is already implemented and improving the efficiency of operations in several nonmedical industries, can address the need to manage complex clinical processes. Workflow computing not only provides a means to define and manage the events, roles, and information integral to health-care delivery but also supports the explicit implementation of policy or rules appropriate to the process. This article explains how workflow computing may be applied to health-care and the inherent advantages of the technology, and it defines workflow system requirements for use in health-care delivery with special reference to diagnostic pathology.

Laboratory computing--process and information management supporting high-quality, cost-effective healthcare

One currently observes many healthcare institutions rushing to reengineer and install information systems with the expectation of achieving enhanced efficiency, competitiveness, and, it is hoped, higher patient satisfaction resulting from timely, high-quality care. Unfortunately, information system concepts, design, and implementation have not yet addressed the complexity of representing and managing clinical processes. As a result, much of the synergy one might expect to derive from understanding and designing clinical processes to gain efficiency and quality while maintaining humanness is not readily achievable by implementing traditional information systems. In this presentation, with laboratory services as an example, we describe a conceptually different information systems model, which we believe would aid care-givers in their efforts to deliver compassionate, quality care while addressing the highly competitive nature of market-driven healthcare.

Laboratory computing--process and information management supporting high-quality, cost-effective healthcare

One currently observes many healthcare institutions rushing to reengineer and install information systems with the expectation of achieving enhanced efficiency, competitiveness, and, it is hoped, higher patient satisfaction resulting from timely, high-quality care. Unfortunately, information system concepts, design, and implementation have not yet addressed the complexity of representing and managing clinical processes. As a result, much of the synergy one might expect to derive from understanding and designing clinical processes to gain efficiency and quality while maintaining humanness is not readily achievable by implementing traditional information systems. In this presentation, with laboratory services as an example, we describe a conceptually different information systems model, which we believe would aid care-givers in their efforts to deliver compassionate, quality care while addressing the highly competitive nature of market-driven healthcare.

A proposed architecture for ambulatory systems development

We have developed an architecture and application framework known as the Ambulatory Services Architecture (ASA) for computerized management of patient records for ambulatory care. Our primary design goals included the development of an architecture that will be readily adaptable to advances in technology needed to enhance computerized patient record systems (e.g., multimedia, human-computer interfaces such as voice-to-text, and a fully distributed objects, etc.) and a data model and database implementation capable of providing the flexibility and extensibility needed to support a broad spectrum of specialty medical practices. This report describes the data model, access control, and the client/server components of the Ambulatory Services Architecture.

Cost-effectiveness analysis for evaluation of screening programs: hereditary hemochromatosis

A significant body of research over the last 10-20 years supports the hypothesis that screening for hereditary hemochromatosis (HH) may be cost-effective, given the low-cost, low-risk therapeutic options available for most homozygous individuals. The factors that confound a straightforward test of this hypothesis include the fact that the disease is not fully penetrant and that, to achieve the anticipated life-year gains, therapy must be instituted before disease complications become irreversible. Recent articles and editorials, as well as practice guidelines prepared by the College of American Pathologists, recommend screening for HH with transferrin saturation and ferritin testing, and with percutaneous liver biopsy for those with positive laboratory test results. Patients at risk would be treated with phlebotomy for life and monitored with ferritin testing. We present a cost-effectiveness analysis that evaluates the efficacy of using a screening strategy to accomplish the desired healthcare goals.

Cost-effectiveness analysis for evaluation of screening programs: hereditary hemochromatosis

A significant body of research over the last 10-20 years supports the hypothesis that screening for hereditary hemochromatosis (HH) may be cost-effective, given the low-cost, low-risk therapeutic options available for most homozygous individuals. The factors that confound a straightforward test of this hypothesis include the fact that the disease is not fully penetrant and that, to achieve the anticipated life-year gains, therapy must be instituted before disease complications become irreversible. Recent articles and editorials, as well as practice guidelines prepared by the College of American Pathologists, recommend screening for HH with transferrin saturation and ferritin testing, and with percutaneous liver biopsy for those with positive laboratory test results. Patients at risk would be treated with phlebotomy for life and monitored with ferritin testing. We present a cost-effectiveness analysis that evaluates the efficacy of using a screening strategy to accomplish the desired healthcare goals.

Polymerase chain reaction to detect cytomegalovirus DNA in the cerebrospinal fluid of neonates with congenital infection

To determine if cytomegalovirus (CMV) DNA could be detected in the cerebrospinal fluid (CSF) of infants with congenital infection with CMV, polymerase chain reaction (PCR) was done on CSF samples from 13 infants (10 with confirmed, 1 with possible, and 2 with asymptomatic congenital CMV infection) and on CSF samples from 100 control patients with alternative diagnoses. By use of two sets of primers that targeted different areas of the CMV genome, CMV DNA was amplified in the CSF of 6 of 10 symptomatic infants, 0 of 3 infants with asymptomatic CMV infection or possible congenital CMV disease, and 2 control patients (one primer set only). A positive CSF PCR result at birth correlated with a poor neurodevelopmental outcome (P = .048; two-tailed Fisher's exact test).

Facilitation of health care delivery through enhanced communications

To realize the advantages of advanced computing technology in medicine we will have to blend computing and communications facilities into a seamless entity that can support ubiquitous computing for medical use. Work-group computing applications, high speed networks linking a multiplicity of servers, and mobile computing platforms can provide the next generation of devices and services for the physician. Ultimately, the biggest challenge for communications and computing in medicine will be found in the requirement for standards in semantics and syntax in the highest levels of the OSI model. We present here our view of the functional requirements for physician communications and computing to meet standard medical practice in Western societies.

Analysis, requirements and development of a collaborative social and medical services data model

In any medical and social service setting, patient data must be readily shared among multiple providers for delivery of expeditious, quality care. This paper describes the development and implementation of a generalized social and medical services data model for an ambulatory population. The model, part of the Collaborative Social and Medical Services System Project, is based on the data needs of the Baylor College of Medicine Teen Health Clinics and follows the guidelines of the ANSI HISPP/MSDS JWG for a Common Data Model. Design details were determined by informal staff interviews, operational observations, and examination of clinic guidelines and forms. The social and medical services data model is implemented using object-oriented data modeling techniques and will be implemented in C++ using an Object-Oriented Database Management System.

The development of a client application for the collaborative social and medical services system

This paper describes the design and implementation of a client application for the Baylor College of Medicine Teen Health Clinics. The application is the front end to the Collaborative Social and Medical Services System (CSMSS) under development by Baylor's Medical Informatics and Computing Research Program [8]. The application provides distributed access to an underlying object oriented database system. A process driven and patient centered design will provide staff members with a complete set of services, including forms for data entry and viewing, query, and access management to facilitate efficient and effective delivery of services. Role-specific interfaces will be supplied for clerks, nurses, nurse practitioners, physicians, and social workers. The client application is being designed using object oriented methodologies and technologies with the C++ programming language, and will operate within a Microsoft Windows operating environment utilizing Object Linking and Embedding for application interoperability.

The development of a data security model for the Collaborative Social and Medical Services System

This paper presents the development of the Collaborative Social and Medical Services System's (CSMSS) data security mechanism. This mechanism was synthesized from an analysis of the CSMSS problem domain, and from a study of the methods used by modern operating systems and database management systems. The resulting mechanism is more flexible and expressive than traditional access control methods and is generally applicable to the management of privacy and multi-provider access.

Rapid diagnosis of herpes simplex virus encephalitis by using the polymerase chain reaction

To determine the diagnostic value of the polymerase chain reaction (PCR) in establishing the rapid diagnosis of herpes simplex virus encephalitis (HSE) in the pediatric age group, we performed PCR to detect herpes simplex virus (HSV) in the cerebrospinal fluid of 8 neonates with HSV infection (4 with central nervous system involvement), 11 infants and children with suspected HSE (4 proved, 1 presumed, 6 excluded), and 105 control patients who had cerebrospinal fluid obtained as part of the evaluation for other diagnoses. The HSV DNA was amplified and typed by using primers specific for the DNA polymerase gene of HSV types 1 and 2. Herpes simplex virus DNA was detected in the cerebrospinal fluid of 3 of 4 neonates with CNS involvement (all with HSV type 2) and 3 of the 4 patients with proved HSE (all with HSV type 1). No HSV DNA was detected in the 4 neonates without CNS disease, the 1 patient with presumed HSE, the 6 patients who had HSE excluded from the diagnosis, and the 105 control patients. Overall, HSV PCR had a sensitivity of 75%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 98%. These results indicate that PCR is a useful noninvasive test in establishing the diagnosis of acute HSE, but a negative result did not exclude the diagnosis.

The diagnosis of CMV pneumonitis in lung and heart/lung transplant patients by PCR compared with traditional laboratory criteria

Polymerase chain reaction (PCR) amplification of CMV DNA recovered from bronchial alveolar lavage (BAL) and peripheral blood samples was compared with tissue culture, cytology, and/or histology for the earlier detection of CMV pneumonitis in 12 recipients of single-lung or heart/lung transplants. In patients with confirmed CMV pneumonitis, cytological evidence of CMV disease in BAL samples was detected 38 +/- 14 days posttransplantation, while tissue culture and PCR-positive results were noted as early as 30 +/- 4.0 days and 18 +/- 4.6 days, respectively. While PCR was positive earlier than culture in a number of cases, culture-positive results were subsequently obtained in each case, consistent with earlier detection of viral replication by PCR as opposed to detection of latent virus. CMV was detected by PCR in 6 of 24 blood samples from patients with confirmed or suspected CMV pneumonitis, while results of all 24 blood samples were negative when assayed by tissue culture. PCR-based testing was more sensitive than traditional tests, allowing detection of viral replication earlier than tissue culture in the posttransplant period. PCR could provide a powerful means of monitoring the immunocompromised patients in whom preemptive therapeutic intervention for CMV disease is desirable.

Informatics. A subspecialty in pathology

The emerging discipline of pathology informatics is reviewed, and its placement as a subspecialty within the broader field of pathology and laboratory medicine is proposed. Informatics concepts should guide the development of the next generation of laboratory information systems. Advanced laboratory systems will incorporate decision support leading to improvements in quality and in interpretive reporting providing support for clinical diagnosis and decision making. Training programs in pathology should take into account the need for expertise in informatics and develop fellowships in this area to adequately prepare junior faculty members for their future professional role.

Prenatal diagnosis of cytomegalovirus (CMV) infection: a preliminary report

Eight patients were referred for prenatal diagnosis for suspected fetal cytomegalovirus infection (CMV): six for documented first-trimester infection and two for abnormal ultrasound evaluation suggestive of fetal infection. Three methods of diagnosis were employed: (1) amniotic fluid viral cultures and CMV-specific IgM in fetal serum; (2) amniotic fluid cultures and detection by polymerase chain reaction amplification of CMV-specific DNA in chorionic villi; and (3) detection of CMV-specific DNA in villus samples only. Amniotic fluid cultures detected all cases of infection, but CMV-specific IgM was not a reliable indicator of infection in any case. DNA analysis correlated well with both culture results and clinical outcome.

Rapid epidemiologic analysis of cytomegalovirus by using polymerase chain reaction amplification of the L-S junction region

A technique based on polymerase chain reaction (PCR) amplification was developed to facilitate the study of the epidemiology of cytomegalovirus (CMV). Consensus oligonucleotide primers from repetitive DNA sequences were designed to amplify interspersed repetitive sequences in an area of heterogeneity within the L-S junction region of the CMV genome, and PCR products were detected by gel electrophoresis. Purified CMV DNAs from 25 CMV isolates, 13 from members of five families in which person-to-person transmission was documented, 9 random clinical isolates of CMV, and 3 laboratory reference strains of CMV (Towne, Davis, and AD169), were analyzed. The gel electrophoretic patterns of DNA bands, or PCR profiles, produced by amplification with the L-S primers were unique for epidemiologically unrelated strains and laboratory reference strains, yet similar patterns were observed for epidemiologically related strains isolated from members of the same family. This method of rapid fingerprinting of CMV DNA within the hypervariable L-S junction region by PCR to produce strain-specific, variably sized PCR products should simplify the molecular epidemiologic analysis of CMV.

Heart allograft involvement with Epstein-Barr virus-associated posttransplant lymphoproliferative disorder

We describe a 60-year-old man who underwent heart transplant and died 5 months later. At autopsy, the patient was found to have posttransplant lymphoproliferative disorder (PTLD), which was not suspected ante mortem. The PTLD involved the lung, lymph nodes, spleen, and kidney and the intima of right coronary artery of the transplanted heart. Epstein-Barr virus infection was demonstrated on direct gel and dot blot after polymerase chain reaction amplification. In situ hybridization for Epstein-Barr virus DNA confirmed the presence of Epstein-Barr virus-infected lymphocytes in the intima of the right coronary artery of the cardiac allograft. To our knowledge, this case represents the first report of involvement of a heart allograft by PTLD in which Epstein-Barr virus infection of the atypical cells is documented. Although primary allograft involvement by PTLD has rarely been reported in heart transplant recipients, recognition that this may occur is important, since the lymphoid infiltrate of PTLD must be distinguished from the lymphoid infiltrate of acute rejection to avoid inappropriate therapy.

Improved amplification of cytomegalovirus DNA from urine after purification of DNA with glass beads

Cytomegalovirus can be detected in a variety of specimens including leukocytes, urine, saliva, feces, and various tissues by polymerase chain reaction (PCR) amplification of viral DNA. Although methods for amplification are fairly standard, sample preparation is not well characterized, especially for tissue. Typically, preparation of samples for PCR amplification ranges from simple boiling to phenol/chloroform extraction and quantification before testing. Several reports have described inhibition of the PCR in some samples types. Here we show that reliable detection of cytomegalovirus DNA in urine is obtained only after some degree of DNA purification, presumably because of PCR inhibition by a yet unidentified component present in a few of the urine samples tested. Glass, in the form of fine beads, was used to adsorb DNA such that protein and other substances could be selectively eluted before the recovery of DNA for PCR amplification. Urine samples prepared by this method did not show inhibition, and results correlated well with those by tissue culture for detection of cytomegalovirus.

Improved amplification of cytomegalovirus DNA from urine after purification of DNA with glass beads

Cytomegalovirus can be detected in a variety of specimens including leukocytes, urine, saliva, feces, and various tissues by polymerase chain reaction (PCR) amplification of viral DNA. Although methods for amplification are fairly standard, sample preparation is not well characterized, especially for tissue. Typically, preparation of samples for PCR amplification ranges from simple boiling to phenol/chloroform extraction and quantification before testing. Several reports have described inhibition of the PCR in some samples types. Here we show that reliable detection of cytomegalovirus DNA in urine is obtained only after some degree of DNA purification, presumably because of PCR inhibition by a yet unidentified component present in a few of the urine samples tested. Glass, in the form of fine beads, was used to adsorb DNA such that protein and other substances could be selectively eluted before the recovery of DNA for PCR amplification. Urine samples prepared by this method did not show inhibition, and results correlated well with those by tissue culture for detection of cytomegalovirus.

Demonstration of Epstein-Barr virus in primary central nervous system lymphomas by the polymerase chain reaction and in situ hybridization

Primary lymphomas of the central nervous system (CNS) account for 0.3% to 1.5% of all intracranial neoplasms. Several reports have noted a coincidence between this neoplasm and serologic evidence of Epstein-Barr virus (EBV) infection, but in only a few instances has the EBV genome been demonstrated in these tumors. To further evaluate the frequency of this occurrence, we analyzed primary CNS lymphomas using nucleic acid hybridization methods and the polymerase chain reaction (PCR). In situ hybridization was used in selected cases. Sequences of EBV were found in two of nine cases by PCR and in situ hybridization. Southern blot hybridization of genomic DNA from these samples was negative for EBV. Both tumors arose in patients with conditions shown to produce secondary immunodeficiency, namely, chronic alcohol abuse and diabetes mellitus. We conclude that the association of EBV and CNS lymphoma is not restricted to patients with severe primary immune deficiency, and that PCR can be applied successfully to paraffin-embedded tissue for the detection of low-abundance viral sequences.

Detection of mRNA from the immediate early gene of human cytomegalovirus in infected cells by in vitro amplification

It would be desirable to have a facile means of detecting the presence of viral DNA or mRNA in any given biological sample, especially in view of the growing immunocompromised population in which the diagnosis of viral disease is a common problem. In vitro amplification of DNA using methods such as the polymerase chain reaction, offers a sensitive means of detecting both DNA and mRNA. We have used the polymerase chain reaction to detect DNA and mRNA from human cytomegalovirus infected human fibroblasts. Viral mRNA was differentiated from DNA using primers which flank a splice junction, resulting in a smaller product for the mRNA template. A cDNA was prepared from total RNA using a primer specific for the gene of interest, in this case the major immediate early transcript of human cytomegalovirus. The cDNA was then amplified using a modified polymerase chain reaction protocol. mRNA from the major immediate early gene was detected in cultured fibroblasts as early as 6 h after infection, and continued to be expressed for at least 96 h post infection. Sensitive and facile detection of viral mRNA should facilitate diagnostic and basic studies of viral pathogenesis.

Analysis of DNA in fresh and fixed tissue by the polymerase chain reaction

The polymerase chain reaction (PCR) was used to amplify viral or oncogene sequences from frozen or formalin-fixed, paraffin-embedded tissue sections. Methods for preparing fixed, embedded colonic tissue for PCR amplification of c-K-ras sequences from genomic DNA and for amplification of viral DNA from other tissues, including brain, lung, and liver, were evaluated. The effect of formalin fixation on the efficiency of amplification was also determined. While there seemed to be only a modest variation in the efficiency of the PCR for amplification of single-copy human genes, regardless of the methods used for tissue preparation, amplification of viral DNA sequences against a human genomic DNA background was more efficient when the DNA was purified to some degree before amplification of the tissue. We used the PCR to examine frozen and fixed embedded tissue sections for the presence of Epstein-Barr virus (EBV) and cytomegalovirus (CMV) DNA. One patient with a heart-lung transplant succumbed to a lymphoproliferative disorder, and EBV genome was present in tissues with abnormal lymphoid infiltrates. CMV was also present in bronchial lavages from the same patient, where cytologic diagnosis was not apparent. Another patient with a liver transplant showed CMV genome in multiple liver biopsies, with negative histologic results for CMV. In vitro DNA amplification with the PCR demonstrated sensitivity superior to that of histology in detecting CMV and EBV in the cases examined.

Factors contributing to mortality in lung transplant recipients: an autopsy study

Despite improved surgical techniques and advances in immunosuppressive therapy, posttransplant mortality rates remain significantly high in lung transplant patients. Since 1985, 3 of 6 single lung recipients, 3 of 3 double lung recipients, and 4 of 7 heart-lung recipients have died and undergone autopsy. We reviewed the autopsy findings in these patients to determine the type and frequency of pathologic processes associated with mortality. One or more infectious processes was found in every patient at autopsy. Gram-negative bacterial pneumonia and sepsis, found in 7 and 8 of 10 autopsy cases, respectively, were by far the most frequent contributing factors to mortality. Epstein-Barr virus infection was demonstrated in one patient using polymerase chain reaction amplification. Acute transplant rejection was found in only 2 patients and therefore is a much less common factor in the death of lung transplant recipients. Diffuse alveolar damage occurred in 6 patients and bronchiolitis obliterans occurred in 3 patients. These latter two processes may have different etiologies in different patients.

Linkage disequilibrium, cystic fibrosis, and genetic counseling

Strong linkage disequilibrium occurs between the cystic fibrosis (CF) locus and polymorphisms detected with the DNA probes XV-2c and KM-19. In a North American population, 86% of CF chromosomes occur with a haplotype which occurs on only 14% of normal chromosomes. An individual homozygous for the highest-risk haplotype has an 81-fold greater probability of carrying a CF allele than does an individual homozygous for the lowest-risk haplotype. The linkage-disequilibrium data can be used for prenatal diagnosis and genetic counseling in CF families. The data are useful in 1-in-4-risk pregnancies when DNA is not available from the propositus and in counseling close relatives of CF families. Serious problems arise with some pregnancies which remain at intermediate risks after analysis, and families are left with difficult decisions. It is not clear that genetic testing for couples at less than 1-in-4 risk is cost-effective or standard care, but use of linkage-disequilibrium data will provide more accurate risk probabilities in a substantial proportion of cases if such testing is carried out. Our results emphasize the need for a specific biological or molecular carrier test. This experience in using linkage-disequilibrium and linkage data in combination for genetic counseling provides a model system for the diagnosis of other disorders.

New methodologies. Their role in pediatric pathology

Recombinant DNA technology is providing the means for early and specific etiologic diagnoses of infectious and immunologic diseases, replacing or complementing older methodologies. The new tools that have been so useful in detecting gene rearrangements in leukemias and lymphomas are being applied to the unresolved questions of embryogenesis and disorderly cell differentiation and are being used to completely re-map the nervous system. Flow cytometry and cell sorting are becoming standard features of clinical laboratories and are instrumental not only in defining alterations in lymphoid cell populations but in examining cellular functions as well as surface markers. Bone marrow and organ transplantation for genetic, metabolic, and neoplastic diseases will be performed much more effectively as these newer technologies are applied to the selection of compatible donors and to the follow-up of rejection and infectious complications.

Detection of cytomegalovirus in urine from newborns by using polymerase chain reaction DNA amplification

Polymerase chain reaction (PCR) amplification was used to detect cytomegalovirus (CMV) in tissue culture and in urine specimens from newborns. Synthetic oligonucleotide primer pairs were used to amplify DNA from the major immediate-early and the late antigen genes of CMV. Amplified products were detected by gel electrophoresis and by dot-blot hybridization with oligonucleotide probes. Using one or both of the primer pairs and associated probes, we found 46 different tissue culture isolates of CMV that were positive; no reaction products were detected when the same primers and probes were used to amplify other herpes family viruses or human genomic DNA. Urine samples from 44 congenitally infected infants were positive when tested with one or both primer pairs and probes. When compared with tissue culture, detection by gel electrophoresis provided a sensitivity of 93%, a specificity of 100%, and a predictive value of a positive result of 100%. Dot-blot analysis raised the sensitivity to 100%. We conclude that PCR amplification may be a valuable tool for diagnosing congenital CMV infection.

DNA hybridization assay for congenital cytomegalovirus infection

An in vitro DNA hybridization assay was used to test 281 newborns for congenital infection with cytomegalovirus. The assay utilized an abbreviated method for DNA preparation and a dot blot assay that provided good sensitivity (100%) and specificity (98.9%) when compared with standard tissue culture, yet substantially reduced the total time of analysis. This assay would be a useful adjunct to tissue culture to diagnose newborns with congenital infection with cytomegalovirus.

Prenatal diagnosis of cystic fibrosis: microvillar enzymes and DNA analysis compared

We have established reference ranges for three microvillar intestinal enzymes--alkaline phosphatase (EC 3.1.3.1), gamma-glutamyltransferase (EC 2.3.2.1), and leucine aminopeptidase (EC 3.4.1.1)--measured in amniotic fluid in a reference population of 1875 women presenting for routine amniocentesis. These data were derived for use in prenatal diagnostic studies in a population at risk (1:4) for cystic fibrosis. False-positive or indeterminate results were noted for fewer than 3.5% of all low-risk cases for each enzyme evaluated. Total alkaline phosphatase and its isoenzymes and leucine amino-peptidase and gamma-glutamyltransferase were measured in amniotic fluid sampled between the 15th and 19th weeks of gestation. Restriction fragment length polymorphism analysis of DNA was also performed when possible. In 52 cases examined for cystic fibrosis thus far, 46 were diagnosed on the basis of DNA analysis and (or) by sweat testing; for the other six cases, only abnormal enzyme results were obtained before termination of pregnancy. Predictions based on microvillar enzyme results were falsely negative in three cases. In only one case was there a discrepancy between enzyme results and DNA analysis. Diagnostic accuracy was highest during the 17th and 18th week of gestation. Preliminary results suggest the false-negative rate of this diagnostic strategy may be greater than or equal to 10%.

Prenatal diagnosis of cystic fibrosis: microvillar enzymes and DNA analysis compared

We have established reference ranges for three microvillar intestinal enzymes--alkaline phosphatase (EC 3.1.3.1), gamma-glutamyltransferase (EC 2.3.2.1), and leucine aminopeptidase (EC 3.4.1.1)--measured in amniotic fluid in a reference population of 1875 women presenting for routine amniocentesis. These data were derived for use in prenatal diagnostic studies in a population at risk (1:4) for cystic fibrosis. False-positive or indeterminate results were noted for fewer than 3.5% of all low-risk cases for each enzyme evaluated. Total alkaline phosphatase and its isoenzymes and leucine amino-peptidase and gamma-glutamyltransferase were measured in amniotic fluid sampled between the 15th and 19th weeks of gestation. Restriction fragment length polymorphism analysis of DNA was also performed when possible. In 52 cases examined for cystic fibrosis thus far, 46 were diagnosed on the basis of DNA analysis and (or) by sweat testing; for the other six cases, only abnormal enzyme results were obtained before termination of pregnancy. Predictions based on microvillar enzyme results were falsely negative in three cases. In only one case was there a discrepancy between enzyme results and DNA analysis. Diagnostic accuracy was highest during the 17th and 18th week of gestation. Preliminary results suggest the false-negative rate of this diagnostic strategy may be greater than or equal to 10%.

Transferrin analysis by immunofixation as an aid in the diagnosis of cerebrospinal fluid otorrhea

Laboratory diagnosis of cerebrospinal fluid leakage has been unreliable and has required expensive, labor-intensive radiographic procedures. Recently, using protein electrophoresis and immunofixation, the presence of an isoform of transferrin present only in cerebrospinal fluid has been identified. We describe the value of this simple test in a patient with recurrent meningitis in whom repeated radiographic studies failed to demonstrate a leak.

Growth and hepatospecific gene expression of human hepatoma cells in a defined medium

The production of albumin, alpha-fetoprotein (AFP), and alpha-1 antitrypsin has been compared among human hepatoma cells cultured in medium containing serum, medium containing hormones and growth factors, and a basal medium containing selenium as the only supplement. Growth is sustained in all three media, and the expression of all three proteins was maintained for over 4 mo. in the various media. However, the quantitative production of albumin and AFP were dramatically different in the three media. Two hormones, insulin and triiodothyronine, influenced the level of secreted proteins. Triiodothyronine increases the amount of secreted albumin whereas insulin at 10 micrograms/ml reduced the level of total secreted protein.

Prenatal diagnosis of cystic fibrosis using linked DNA markers and microvillar intestinal enzyme analysis

Prenatal diagnosis was performed for 47 pregnancies with 1 in 4 risk of cystic fibrosis, including 7 cases analyzed with linked DNA markers, 16 cases analyzed by microvillar intestinal enzyme testing, and 24 cases where both methods of testing were attempted. DNA was obtained by chorionic villus sampling in 10 cases and by amniocentesis in 21 cases, and diagnosis was based on analysis with the tightly linked DNA markers D7S8 and met. DNA analysis using these probes was fully informative in 74.4% of 90 couples with 1 in 4 risk. In 18 cases where both DNA results and microvillar intestinal enzyme data were diagnostic, there was agreement regarding the predicted status of the fetus. No adequate diagnosis was achieved in two cases where both diagnostic tests were attempted. Outcome is known for 24 pregnancies including 10 where DNA analysis was diagnostic, and no errors in diagnosis were detected. Prenatal diagnosis of cystic fibrosis using DNA markers is highly informative and accurate, but microvillar intestinal enzyme analysis remains a valuable part of a complete diagnostic program.

Liquid chromatography used in diagnosis of a rare hemoglobin combination: hemoglobin S/LeporeBoston

"High-performance" liquid chromatography (HPLC), applied to hemoglobin analysis, is decidely more sensitive and gives better resolution than do routine electrophoretic methods. Here we present a case with a rare double heterozygote hemoglobin S/LeporeBoston, originally diagnosed as homozygous hemoglobin S by routine electrophoretic methods. Using a gradient elution weak cation-exchange HPLC technique, we could separate hemoglobin S and hemoglobin LeporeBoston and make the correct diagnosis. This case demonstrates how HPLC can be a useful adjunct to routine electrophoresis.

Conjugated bilirubin versus direct bilirubin in neonates

Conjugated and direct bilirubin were measured in 288 samples from 107 neonates less than 15 days old. Retrospective analysis of the medical records showed that 53 neonates were hepatobiliary-normal, 42 patients had no obvious evidence of hepatobiliary disease but had received total parenteral nutrition, and 12 were clearly hepatobiliary-abnormal. Neither the mean values nor the distributions of either the conjugated bilirubin, as measured by a multilayered slide, or the direct bilirubin, measured by a solution diazo procedure, differed when comparing the hepatobiliary-normal population to that receiving total parenteral nutrition. However, as would be predicted, the hepatobiliary-abnormal population differed significantly from both of these groups using either direct bilirubin or conjugated bilirubin results. Samples obtained from hepatobiliary-abnormal neonates were reviewed in chronologic sequence if direct bilirubin results differed from conjugated bilirubin with respect to classification of normality/abnormality. In two of three neonates with developing cholestasis, conjugated bilirubin exceeded its upper limit of normal earlier than did direct bilirubin. Conjugated bilirubin returned to normal earlier than direct bilirubin for two neonates with an improving clinical status. Conjugated bilirubin measurement was judged to be more responsive to developing or resolving cholestasis then direct bilirubin. In addition, conjugated bilirubin measurement from the slide is known to agree well with that determined by high performance liquid chromatography fractionation of bilirubin and is less susceptible to interference than is direct bilirubin measurement, characteristics that recommend its use over direct bilirubin analysis in a clinical setting.

Unconjugated hyperbilirubinemia is overestimated in neonates with cholestasis. A more reliable method is proposed

Unconjugated bilirubin was determined in 458 serum samples from 160 neonatal and pediatric patients by using two approaches. The first approach was to calculate indirect bilirubin by subtracting direct bilirubin, as measured by a diazo solution assay, from total bilirubin quantified by a Jendrassik-Grof procedure. The second approach was actually to measure the unconjugated bilirubin fraction using a multilayered slide. For samples containing little or no conjugated bilirubin, correlation between the calculated indirect bilirubin value and the unconjugated bilirubin measured by the slide was judged acceptable. Samples containing increased levels of conjugated bilirubin, however, yielded discrepancies between the approaches including differences of up to 5-10 mg/dL and more. Moreover, the magnitudes of the differences correlated with the amounts of conjugated bilirubin present in the samples. The unconjugated bilirubin values given by the slide were found to correlate more closely than the calculated indirect values with results obtained by an HPLC procedure that may be regarded as the most reliable method available. Therefore, we find that the slide provides a more accurate measure of unconjugated bilirubin than does the indirect bilirubin value in specimens from pediatric patients having evidence of cholestasis. The authors also believe that the magnitude of the difference in the values could make a difference in therapeutic strategies.

High-performance liquid chromatography in the diagnosis of hemoglobinopathies and thalassemias. Report of three cases

High-performance liquid chromatography is a technic that has recently been applied to the diagnosis of hemoglobinopathies and thalassemias. Its advantages over other methods include increased sensitivity, resolution and simplicity, as well as speed. In this report, the authors present an HPLC procedure that uses a weak cation exchange column and a gradient elution system for the diagnosis of hemoglobinopathies and thalassemias. The authors illustrate the utility of this procedure by reporting three cases in which the technic enabled them to make the correct diagnosis, which by traditional methods would have been missed or equivocal.

Characterization and evaluation of immunochemical methods for the measurement of fecal alpha 1-antitrypsin

Measurement of alpha 1-antitrypsin in feces has been proposed as a method of diagnosing a protein-losing enteropathy. This approach makes use of an endogenous marker rather than radioisotopically labeled materials such as 51CrCl3 or 131albumin to measure protein clearance. The validity of using fecal alpha 1-antitrypsin measurement as a reflection of protein loss through the gastrointestinal tract has been demonstrated by several investigators. The authors report here the characterization of excreted alpha 1-antitrypsin and an evaluation of the immunochemical methods used to measure this protein. They find alpha 1-antitrypsin to be excreted both as a protease-antiprotease complex and in a form that is relatively unaltered compared with serum alpha 1-antitrypsin. The proportion of alpha 1-antitrypsin excreted as a complex was found to vary from patient to patient. Formation of the protease-antiprotease complex was found to decrease the apparent alpha 1-antitrypsin concentration when radial immunodiffusion or immunonephelometry were used. The observed bias was greater for radial immunodiffusion. When these methods were applied to a newborn population at risk for necrotizing enterocolitis, radial immunodiffusion was found to have better sensitivity and a higher predictive value for a positive result than the nephelometric method. The use of fecal alpha 1-antitrypsin for diagnosis of protein-losing enteropathy appears to be best accomplished by radial immunodiffusion.