The course of life of survivors of childhood cancer

The developmental consequences in adulthood of growing up with childhood cancer are not well understood. The Course of life questionnaire was developed to assess the attainment of developmental milestones retrospectively and socio-demographic outcomes in young adulthood. The aim of this study was to assess the course of life and socio-demographic outcomes in young adult survivors of childhood cancer. Knowledge about possible gaps in the course of life could enable health care providers to aim for the most favourable course of life. A total of 353 Dutch survivors and a comparison group of 508 peers without a history of cancer, all aged between 18 and 30, filled in the Course of life questionnaire. The course of life of the survivors was found to be hampered. The young adult survivors of childhood cancer in the Netherlands turned out to have achieved fewer milestones than their peers with respect to autonomy development, social development, and psycho-sexual development, or to have achieved the milestones when they were older than their peers. In addition, survivors displayed less risk behaviour than the comparison group. The survivors and the comparison group also differed on some socio-demographic issues. A considerably lower percentage of survivors than peers in the comparison group were married or living together, and/or employed. Their educational level, on the other hand, was as high as that of their peers.

Quality of life in young adult survivors of childhood cancer

In recent years the necessity of measuring quality of life in childhood cancer survivors has been stressed. This paper gives an overview of the results of studies into the quality of life (QL) of young adult survivors of childhood cancer and suggest areas for future research. The review located 30 empirical studies published up to 2001. The results are described in terms of the following QL dimensions: physical functioning (QL, general health), psychological functioning (overall emotional functioning, depression and anxiety, self-esteem), social functioning (education, employment, insurance, living situation, marital status and family), and sexual functioning. Factors related to survivors' QL are reported: demographics and illness- and treatment related variables. Although the literature yields some inconsistent findings, a number of clear trends can be identified: (a) most survivors reported being in good health, with the exception of some bone tumour survivors; (b) most survivors function well psychologically; (c) survivors of CNS tumours and survivors of acute lymphoblastic leukaemia (ALL) are at risk for educational deficits; (d) job discrimination, difficulties in obtaining work and problems in obtaining health and life insurance were reported; (e) survivors have lower rates of marriage and parenthood; (f) survivors worry about their reproductive capacity and/or about future health problems their children might experience as a result of their cancer history. There is a need for methodological studies that measure QL among survivors of childhood cancer more precisely by taking into account the effects of the severity of the cancer and the long-term impact of different treatments. Additional data are needed to help us understand the needs of survivors and to identify those subgroups of survivors who are at greatest risk for the adverse sequelae of the disease and its treatment.

Social and emotional adjustment in young survivors of childhood cancer

An overview is given of the social and emotional adjustment in young survivors of childhood cancer. The results are described in terms of self-esteem, anxiety, depression and posttraumatic stress (emotional adjustment), and in terms of behavioral functioning, social competence and school performance (socio-behavioral adjustment). Furthermore, factors related to survivors' adjustment are reported: demographics, illness- and treatment-related factors, coping and social support, and family and parental functioning. Limitations of the studies and consequences for future research are discussed. On the whole, the adjustment of young cancer survivors as a group was reasonably good, but the findings with respect to the emotional and social adjustment were inconsistent. This might be attributed to limitations of the study designs and the fact that the studies were not all directly comparable. In order to gain more insight into the predictors of adjustment, longitudinal studies are recommended, which should include control groups or standardized instruments with norm data, and use cancer-specific measures in addition to generic measures.

Level of activities associated with mobility during everyday life in patients with chronic congestive heart failure as measured with an "activity monitor"

BACKGROUND AND PURPOSE

Because of dyspnea and fatigue, patients with congestive heart failure (CHF) may be restricted in the performance of normal everyday activities. The aim of this study was to obtain a preliminary indication of the level of activities associated with mobility during everyday life and between-day variance in activities in patients with mild to moderate CHF as measured with an "Activity Monitor."

SUBJECTS AND METHODS

The "Activity Monitor" is based on long-term (>24 hours) ambulatory monitoring of signals from accelerometers fixed to the subject's body during everyday activities with the aim of assessing the level of activities associated with mobility. Measurements were obtained over 3 days from 5 male subjects with CHF (mean age=64 years, SD=5, range=59-72) and over 2 days from 5 matched comparison subjects (mean age=65 years, SD=4, range=61-71).

RESULTS

Mean duration of movement-related activities (walking, cycling, or general movement) (expressed as a percentage of the duration of the measurement day) was lower in the subjects with CHF (X=3.9, SD=1.5, range=2.2-6.7) than in the comparison subjects (X=11.3, SD=3.0, range=6.6-14.1). In the patients, between-day variance was smaller for different weekdays (eg, Monday versus Tuesday) than for similar weekdays (eg, 2 Mondays) (1.11% and 7.28%, respectively).

DISCUSSION AND CONCLUSION

The results show how activities associated with mobility during everyday life may be restricted in people with CHF.

Microorganisms with a taste for vanilla: microbial ecology of traditional Indonesian vanilla curing

The microbial ecology of traditional postharvesting processing of vanilla beans (curing) was examined using a polyphasic approach consisting of conventional cultivation, substrate utilization-based and molecular identification of isolates, and cultivation-independent community profiling by 16S ribosomal DNA based PCR-denaturing gradient gel electrophoresis. At two different locations, a batch of curing beans was monitored. In both batches a major shift in microbial communities occurred after short-term scalding of the beans in hot water. Fungi and yeast disappeared, although regrowth of fungi occurred in one batch during a period in which process conditions were temporarily not optimal. Conventional plating showed that microbial communities consisting of thermophilic and thermotolerant bacilli (mainly closely related to Bacillus subtilis, B. licheniformis, and B. smithii) developed under the high temperatures (up to 65 degrees C) that were maintained for over a week after scalding. Only small changes in the communities of culturable bacteria occurred after this period. Molecular analysis revealed that a proportion of the microbial communities could not be cultured on conventional agar medium, especially during the high-temperature period. Large differences between both batches were observed in the numbers of microorganisms, in species composition, and in the enzymatic abilities of isolated bacteria. These large differences indicate that the effects of microbial activities on the development of vanilla flavor could be different for each batch of cured vanilla beans.

Effects of family interventions on burden of relatives of psychiatric patients in The Netherlands: a pilot study

In this study, the effects of psychoeducational family support groups in the Netherlands on relatives' burden were investigated, using a quasi-experimental design. The experimental group consisted of 119 participants of 19 family support groups, the control group of 45 relatives of once-only informational meetings. Subjects from both groups filled in a questionnaire before the group started and one year later. While controlling for confounding variables in multiple regression analyses, significant effects of family support groups were found on elements of burnout and burden.

Burnout among relatives of psychiatric patients attending psychoeducational support groups

OBJECTIVE

The effectiveness of family interventions may be improved by concentrating on elements of objective burden that best predict subjective burden. The relationship between subjective burden and objective burden was investigated among caregivers of patients with serious mental illness in the Netherlands who were attending psychoeducational support groups.

METHODS

The study used pretest data from an intervention study in which psychoeducational family support groups in the Netherlands were evaluated. A total of 164 participants from 19 psychoeducational groups organized by nine community mental health centers completed the Dutch translation of the Maslach Burnout Inventory and the Involvement Evaluation Questionnaire. Regression analyses were conducted, with elements of subjective burden as dependent variables and elements of objective burden, demographic characteristics, and characteristics of the patient's disorder as predictors.

RESULTS

Burden in general and emotional exhaustion were the aspects of subjective burden best predicted by objective burden. In two regression models, objective burden together with the other predictors explained 57 percent and 54 percent of the variance in subjective burden. Two aspects of objective burden-strain on the relationship with the patient and ability to cope with the patient's behavior-were related to almost all the investigated aspects of subjective burden.

CONCLUSIONS

Strong evidence was found for the relationship between objective and subjective burden and for the hypothesis that particular elements of objective burden contribute more to subjective burden than others. The findings suggest that psychoeducation should concentrate on helping relatives cope with the strain on the relationship with the patient and on improving their ability to cope with the patient's behavior.

Evaluation of diffusing capacity in patients with a restrictive lung disease

BACKGROUND

In healthy volunteers, the single-breath diffusing capacity of the lung for carbon monoxide (DLCO) decreases and DLCO normalized per liter alveolar volume (VA; DLCO/VA) increases if VA is decreased. We hypothesized that comparison of DLCO/VA with its predicted value at predicted total lung capacity (TLC) will result in an underestimation of the diffusion disorder in patients with a restrictive lung disease, if a similar relationship exists between DLCO/VA and lung volume as found in healthy volunteers.

OBJECTIVE

To test this hypothesis, we studied total gas transfer DLCO and DLCO/VA as functions of VA in patients who developed a restrictive lung disease and a diffusion disorder in a short period of time.

DESIGN

An observational survey.

SETTING

Pulmonary function department.

PATIENTS

Thirteen patients without any initial pulmonary pathology who developed the mentioned pulmonary pathology due to bleomycin treatment.

INTERVENTIONS

Bleomycin treatment.

MEASUREMENTS AND RESULTS

We performed the single-breath test at various VA levels before, during, and after bleomycin treatment. In the majority of the patients, the DLCO vs VA relationship remained parabolic, but shifted downwards during therapy. Therefore, the linear DLCO/VA vs VA relationship shifted downwards, while the negative slope was not changed, indicating the development of a decreased gas transfer. Six patients also developed a volume restriction.

CONCLUSIONS

The agreement of the data with the hypothesis increased its probability. Consequently, to evaluate a diffusion disorder, DLCO/VA at a lower actual TLC of patients with a lung restriction should be compared to a reference DLCO/VA at a lung volume equal to the actual TLC.

ORCA: the versatile CPR

The introduction of computer-based patient records (CPRs) that fully replace paper records proves especially difficult in specialized care, despite the potential advantages of CPRs for patient care and research. Improved data legibility, availability, sharing of records, and decision support may directly benefit patient care. Barriers to the introduction of CPR applications at institutions may be caused by lack of infrastructure, or by financial or organizational issues. To have clinicians interactively enter data at the point of care is still a big challenge. This paper presents an overview of ORCA (Open Record of CAre): a generic CPR, designed for integration with existing systems, presentation of multi-media patient data, and the collection of structured data, directly by clinicians. ORCA can easily be tailored to the needs of a variety of medical specialists without the need for changes to its data model, functionality, or interface. The paper describes the essence of the architecture of ORCA and the user benefits with emphasis on the support of structured data entry.

Integration and communication for the continuity of cardiac care (I4C)

The project I4C (Integration and Communication for the Continuity of Cardiac Care) is carried out for the advancement of cardiac care, from prevention to follow-up. The goals of I4C are: (1) integrated access to patient data, wherever they are stored; (2) support of evidence-based care; (3) consistent recording of patient data (eg, patient history, electrocardiograms IECGs] or cine-angios) in a multimedia patient record; and (4) a documented reference data set for research. In several clinics, workstations are being installed to serve the four goals. Integration with other information systems in clinical care is realized by encapsulation. A computer-based patient record (ORCA) has been developed to support the collection, consultation, and sharing of patient data. In I4C, ORCA is intended for use in a research setting as well as routine patient care. The functionality of ORCA covers the collection of patient history data in a highly structured manner, the recording of drug prescriptions, an overview of laboratory test results, and viewers for ECGs and angiographic images. At present, structured data entry and consultation is supported in six European languages.

A rebreathing method to determine carbon monoxide diffusing capacity in children: reference values for 6- to 18-year-olds [corrected] and validation in adult volunteers

The diffusing capacity of carbon monoxide (D(L,CO)) and its value normalized to alveolar volume (D(L,CO)/V(A)) are usually estimated with the single breath method at total lung capacity (TLC). Severely ill patients and small children are not able to deliver a satisfactory vital capacity (VC) or hold their breath for 10 s at TLC. The aim of this study was to develop a rebreathing procedure in which diffusing capacity can be determined during spontaneous tidal breathing. The conventional rebreathing method during hyperventilation was modified so that rebreathing volume and gas concentrations were kept constant by CO2 absorption and O2 supplementation. In adult healthy volunteers and in patients who were able to perform both tests, the diffusion indices obtained with this rebreathing method during resting ventilation were compared with those obtained by the single breath method. Predicted (reference) values for rebreathing D(L,CO) and D(L,CO)/V(A) for children were determined. D(L,CO)/V(A) decreased with alveolar volume (V(A)) and increased with alveolar ventilation (V'(A)). In adults at V'(A) above 35 L x min(-1) rebreathing D(L,CO)/V(A) was similar to single breath D(L,CO)/V(A) at similar alveolar volumes. The D(L,CO)/V(A) relative to their corresponding reference values were the same for both methods in adult patients, irrespective of ventilation distribution disturbances. In children the newly described diffusing capacity obtained by the rebreathing method during resting ventilation can serve as a valuable index to assess and follow a diffusion disorder.

Clinical data entry

Routine capture of patient data for a computer-based patient record system remains a subject of study. Time constraints that require fast data entry and maximal expression power are in favor of free text data entry. However, using patient data directly for decision support systems, for quality assessment, etc. requires structured data entry, which appears to be more tedious and time consuming. In this paper, a prototype clinical data entry application is described that combines free text and structured data entry in one single application and allows clinicians to smoothly switch between these two different input styles. A knowledge base involving a semantic network of clinical data entry terms and their properties and relationships is used by this application to support structured data entry. From structured data, sentences are generated and shown in a text processor together with the free text. This presentation metaphor allows for easy integrated presentation of structured data and free text.

Restructuring routinely collected patient data: ORCA applied to andrology

Hospital information systems do not always cover all required detail per specialty. This may lead to scattering of data over disparate systems and the paper record. The ORCA (Open Record for CAre) CPR offers a generic structure for record sharing, and record keeping tailored to specific needs. We studied whether a semantic integration of existing and new data was possible, using the ORCA structure. Existing andrology data, originating from separate sources, were utilized for this purpose. During normalization, validation and explication steps, latent problems in the source data were exposed and removed, followed by a merge with new data items. By conversion of source data to ORCA, a unique representation of medical concepts in the database was attained, facilitating retrieval of univocal data for multiple purposes. We conclude that the expansion to the andrology domain, including transparent integration of existing data, provides support for the generality of ORCA.

Cloning and characterization of two rhamnogalacturonan hydrolase genes from Aspergillus niger

A rhamnogalacturonan hydrolase gene of Aspergillus aculeatus was used as a probe for the cloning of two rhamnogalacturonan hydrolase genes of Aspergillus niger. The corresponding proteins, rhamnogalacturonan hydrolases A and B, are 78 and 72% identical, respectively, with the A. aculeatus enzyme. In A. niger cultures which were shifted from growth on sucrose to growth on apple pectin as a carbon source, the expression of the rhamnogalacturonan hydrolase A gene (rhgA) was transiently induced after 3 h of growth on apple pectin. The rhamnogalacturonan hydrolase B gene was not induced by apple pectin, but the rhgB gene was derepressed after 18 h of growth on either apple pectin or sucrose. Gene fusions of the A. niger rhgA and rhgB coding regions with the strong and inducible Aspergillus awamori exlA promoter were used to obtain high-producing A. awamori transformants which were then used for the purification of the two A. niger rhamnogalacturonan hydrolases. High-performance anion-exchange chromatography of oligomeric degradation products showed that optimal degradation of an isolated highly branched pectin fraction by A. niger rhamnogalacturonan hydrolases A and B occurred at pH 3.6 and 4.1, respectively. The specific activities of rhamnogalacturonan hydrolases A and B were then 0.9 and 0.4 U/mg, respectively, which is significantly lower than the specific activity of A. aculeatus rhamnogalacturonan hydrolase (2.5 U/mg at an optimal pH of 4.5). Compared to the A enzymes, the A. niger B enzyme appears to have a different substrate specificity, since additional oligomers are formed.

Can data representation and interface demands be reconciled? Approach in ORCA

Research in the domain of computer-based patient records had always faced the conflicting demands of efficiency for the practicing physician and suitability of the record contents for data analysis in view of decision support, research, and quality assessment. Interface and contents pose different demands on the data model underlying the record. The challenge is to combine the most suitable model for data representation with the interface that best fits the clinical setting. ORCA (Open Record for CAre) provides a solution by making the distinction between domain dependent and domain independent data and letting domain dependence be decisive for the choice of model. Interactive definition of custom-views provides interface flexibility for domain dependent data. Views on domain independent data need not cope with the limitations of multiple table views in relational DBMSs. A standard set of single table queries can support recording of domain independent data, irrespective of the clinical setting.

Kinetics of mRNA and protein synthesis of genes controlled by the 1,4-beta-endoxylanase A promoter in controlled fermentations of Aspergillus awamori

In this study, induction and repression kinetics of the expression of the Aspergillus awamori 1,4-beta-endoxylanase A (exlA) gene under defined physiological conditions was analyzed at the mRNA and the protein levels. Induction was analyzed by pulsing D-xylose to a sucrose-limited continuous culture of an A. awamori 1,4-beta-endoxylanase A (EXLA)-overproducing strain. Directly after the D-xylose pulse, exIA mRNA was synthesized, and it reached a constant maximal level after 45 to 60 min. This level was maintained as long as D-xylose was present. The kinetics of mRNA synthesis of the genes encoding Thermomyces lanuginosa lipase (lplA) and Escherichia coli beta-glucuronidase (uidA), which were also under the control of the exlA promoter, were similar to those observed for exlA mRNA. The repression of exlA expression was analyzed by pulsing D-glucose to a D-xylose-limited continuous culture. Immediately after the glucose pulse, the exlA mRNA level declined rapidly, with a half-life of approximately 20 to 30 min, and it reached a minimal level after 60 to 90 min. The time span between mRNA synthesis and the secretion of proteins was determined for EXLA and lipase. In both cases, mRNA became visible after approximately 7.5 min. After 1 h, both proteins became detectable in the medium but the rate of secretion of EXLA was faster than that of lipase.

An expression system based on the promoter region of the Aspergillus awamori 1,4-beta-endoxylanase A gene

A new, highly inducible fungal promoter derived from the Aspergillus awamori 1,4-beta-endoxylanase A (exlA) gene is described. Induction analysis, carried out with the wild-type strain in shake flasks, showed that exlA expression in regulated at the transcriptional level. Using a beta-glucuronidase (uidA) reporter strategy, D-xylose was shown to be an efficient inducer of the exlA promoter, whereas sucrose or maltodextrin were not. Upon D-xylose induction, the exlA promoter was threefold more efficient than the frequently used A. niger glucoamylase (glaA) promoter under maltodextrin induction. Detailed induction analyses demonstrated that induction was dependent on the presence of D-xylose in the medium. Carbon-source-limited chemostat cultures with the uidA reporter strain showed that D-xylose was also a very good inducer in a fermenter, even in the presence of sucrose.

A multi-strategy approach for medical records of specialists

Despite a number of well recognized shortcomings of paper medical records, the use of a Computer Patient Record (CPR) is not widespread among specialists. The complexity of specialized care combined with the diversity of their domains of expertise, make it a challenge to design a CPR that satisfies the needs of a specialist. Ideally, CPRs are tailored to the specific tasks of each user, and yet general enough to permit exchange and sharing of information. The basic philosophy behind our CPR is a 'mother' record, which is extended with specialized sub-records. Two different types of subrecords are discussed: one to accommodate standardized data entry in the context of a specialty or research protocol, and another for structured recording of accidental findings outside one's own domain of expertise. The CPR supports the entry of free text and does not impose structured data entry on the physician, but stimulates him to do so by confronting him with the benefits of a structured CPR.

Pulmonary diffusing capacity at reduced alveolar volumes in children

The diffusing capacity, when normalized per liter of alveolar volume (DL,CO/VA) decreases in normal adults, whereas their total diffusing capacity (DL,CO) increases as alveolar volume (VA) increases. We studied these relationships in a group of normal children below 20 years of age. Diffusion variables were determined using the single breath technique. The effects of sex, age, and height on these relationships were estimated. DL,CO increased and DL,CO/VA decreased as alveolar volume increased. DL,CO and DL,CO/VA reference values at total lung capacity (TLC) appeared to be comparable to reference values at TLC in the literature. Reference values of DL,CO and DL,CO/VA derived from measurements at various alveolar volumes also predict similar values at TLC. The advantage of our reference equations is their applicability to patients with restrictive lung disease. Actual DL,CO/VA can be compared with reference DL,CO/VA at actual (restrictive) TLC instead of reference DL,CO/VA at reference TLC. This comparison extends the evaluation of a diffusion disorder.

Cloning, sequence and expression of the gene coding for rhamnogalacturonase of Aspergillus aculeatus; a novel pectinolytic enzyme

Rhamnogalacturonase was purified from culture filtrate of Aspergillus aculeatus after growth in medium with sugar-beet pulp as carbon source. Purified protein was used to raise antibodies in mice and with the antiserum obtained a gene coding for rhamnogalacturonase (rhgA) was isolated from a lambda cDNA expression library. The cloned rhgA gene has an open-reading frame of 1320 base pairs encoding a protein of 440 amino acids with a predicted molecular mass of 45 962 Da. The protein contains a potential signal peptidase cleavage site behind Gly-18 and three potential sites for N-glycosylation. Limited homology with A. niger polygalacturonase amino acid sequences is found. A genomic clone of rhgA was isolated from a recombinant phage lambda genomic library. Comparison of the genomic and cDNA sequences revealed that the coding region of the gene is interrupted by three introns. Furthermore, amino acid sequences of four different peptides, derived from purified A. aculeatus rhamnogalacturonase, were also found in the deduced amino acid sequence of rhgA. A. aculeatus strains overexpressing rhamnogalacturonase were obtained by cotransformation using either the A. niger pyrA gene or the A. aculeatus pyrA gene as selection marker. For expression of rhamnogalacturonase in A. awamori the A. awamori pyrA gene was used as selection marker. Degradation patterns of modified hairy regions, determined by HPLC, show the recombinant rhamnogalacturonase to be active, and the enzyme was found to have a positive effect in the apple hot-mash liquefaction process.

A novel strategy for the isolation of defined pyrG mutants and the development of a site-specific integration system for Aspergillus awamori

A homologous gene transfer system for Aspergillus awamori for site-specific integration is described, based on two components. First, a defined A. awamori pyrG mutant strain constructed by a selection strategy for gene-replacement in fungi. Second, a vector with a homologous pyrG selection marker containing a defined mutation at a site different from that of the mutations in the pyrG gene of the defined mutant strain. Defined mutation in the A. awamori pyrG gene, isolated from a genomic library by heterologous hybridisation with the A. niger pyrG gene as a probe, were introduced by specifically altering sequences at restriction sites in the coding region of the gene. After transformation of the A. awamori wild-type strain with vectors containing these mutated pyrG genes, and selection for 5-fluoro-orotic acid resistance (5-FOAR), on the average 60% of the 5-FOAR colonies originated from replacement of the wild-type pyrG gene by the mutated pyrG allele. After transformation of a mutant strain, carrying a mutation near the 5' end of the pyrG gene with vectors containing a mutation near the 3' end of the pyrG gene, 35% of the resulting transformants contained one copy of the vector at the pyrG locus.

ARIS: integrating multi-source data for research in andrology

Although the concept of distributed systems for the storage of patient data is more and more commonly accepted, for some considerable time yet most patient data will be stored in centralized rather than departmental systems. An important advantage of storage in a central system is hospital-wide access to much of the patient data. Disadvantages are however that these data cannot be reviewed through one user interface, and that the structure of the data does not lend itself to exploitation for other purposes. We describe the implementation of an Andrology Research Information System in which these data are integrated in a well-structured database facilitating multiple views on the patient data through a graphical user interface, and clinical research, quality control and summary reports. The data can be analyzed directly using the Hermes workstation. In this way the strengths of the centralized system are combined with those of the dedicated ARIS system.

Can one patient record accommodate the diversity of specialized care?

Despite a quarter century of developments, few specialists directly use a computerized patient record, that fully replaces the paper chart. Because of the diversity of domains in specialized care, medical decision-making and the continuity of care may suffer from scattering of patient data over various records. The challenge was to develop a computerized patient record, that would be versatile enough to tailor it to specific needs, while keeping it uniform enough to permit physicians to share data on the same patient. In our CPR, the key that reconciles versatility with uniformity lies in the design of the data model. The CPR consists of a mother record with specialized sub-records, that all share the same data model. A physician can enlarge his scope for decision-making by consulting other specialized records on the same patient or by viewing the combined information of all sub-records without the need to convert data or to familiarize himself with different interfaces.

Diffusing capacity dependent on lung volume and age in normal subjects

In this study we determined reference values of total diffusing capacity of carbon monoxide (DLCO) and DLCO per liter alveolar volume (DLCO/VA) at total lung capacity (TLC) and at lung volumes below TLC in sitting position. In 55 healthy nonsmoking volunteers (20-85 yr old), we determined reference values at TLC level in which age was the only parameter. In a subgroup (n = 16) these references did not change by correction for normal variability in hemoglobin concentration. In all volunteers DLCO decreased and DLCO/VA increased with decreasing VA. The increase in DLCO/VA was linear and less in older subjects. We derived equations to calculate reference values of DLCO/VA for lung volumes at and below TLC with two methods: 1) "random coefficients linear" model, which calculates the reference values directly, and 2) a conversion method, which calculates DLCO/VA for lower VA levels from reference values at TLC. An advantage of the conversion method is the suitability of DLCO/VA reference values at TLC of other populations. A disadvantage is the greater standard deviation of these reference values compared with those obtained by the random coefficients linear method. DLCO can be found by multiplying DLCO/VA with VA.