Novel functionalities of hybrid paper-polymer centrifugal devices for assay performance enhancement

The presented work demonstrates novel functionalities of hybrid paper-polymer centrifugal devices for assay performance enhancement that leverage the advantages of both paper-based and centrifugal microfluidic platforms. The fluid flow is manipulated by balancing the capillary force of paper inserts with the centrifugal force generated by disc rotation to enhance the signal of a colorimetric lateral flow immunoassay for pathogenic E. coli. Low-cost centrifugation for pre-concentration of bacteria was demonstrated by sample sedimentation at high rotational speeds before supernatant removal by a paper insert via capillary force after deceleration. The live bacteria capture efficiency of the device was similar to a commercial centrifuge. This pre-concentrated sample when combined with gold nanoparticle immunoconjugate probes resulted in a detection limit that is 10× lower than a non-concentrated sample for a lateral flow immunoassay. Signal enhancement was also demonstrated through rotational speed variation to prevent the flow for on-device incubation and to reduce the flow rate, thus increasing the sample residence time for the improved capture of gold nanoparticle-bacteria complexes in an integrated paper microfluidic assay. Finally, multiple sequential steps including sample pre-concentration, filtration, incubation, target capture by an integrated paper microfluidic assay, silver enhancement and quenching, and index matching were completed within a single device. The detection limit was 105 colony forming units per ml, a 100× improvement over a similar paper-based lateral flow assay. The techniques utilize the advantages of paper-based microfluidic devices, while facilitating additional functionalities with a centrifugal microfluidic platform for detection performance enhancement in a low-cost, automated platform amenable to point-of-care environments.

The Cost of the Gluten-Free Diet: Household Food Expenditures in Families With a Child or Adolescent With Celiac Disease

BACKGROUND: Celiac disease (CD) is a digestive disease that is caused by an immune reaction to the protein gluten. The gluten free diet (GFD) is the only treatment for CD. In 2012, the sale of GF processed foods reached up to $460million in Canada; an increase in 25% since 2008. Despite being the fastest growing food intolerance category in Canada, GFD consumers face challenges from various voluntary GF-labelling schemes and limited retail and food-service product options.

OBJECTIVES: To estimate GF-food expenditure patterns for affected families with children or adolescents with CD to identify the cost burden of following a GFD and compared against non-GFD Canadian families.

DESIGN/METHODS: A pilot study was conducted in families with a child with biopsy proven CD following the GFD (n=15; 10±3 years) and attending a GI/CD clinic. Family Socio-demographics (age of parents, number of children/number of members following GFD in households) and the receipts of food purchases over a one-month period were obtained from parents/caregivers. The cost of GFD was analyzed as “actual food costs on related receipts” and determined as total GFD cost (per household/per child with CD) basis. The result of this study was compared against average incomes and food expenditures of Canadian households as reported by Statistic Canada in 2013.

RESULTS: The mean age of the parents of child with CD was (44±5 years) and the mean number of children in households was 2.0±0.6. The average duration of following GFD was 4±2 years (age at diagnosis 6±2 years). The median income for Canadian family and for family with children with CD was C$ 84,000/year and C$ 100,000/year, respectively. The average food expenditure was C$ 842/month for the average Canadian household with children vs C$ 1105±393/month for comparable Canadian households affected by CD. The amount of money spent on GF packaged foods was C$ 145±100/month. The average food expenditure of GF food and gluten containing food was C$112±72/child/month (+GF) and C$ 29±14/house-hold member/month (-GF), respectively.

CONCLUSION: Total food expenditures in families with a child/adolescent with CD are higher than the Canadian averages. This has implications on economic access and adherence to GFD in children/adolescents with CD. CD and proper dietary adherence to GFD guidelines poses significant economic burdens on affected families. These results and unanswered questions of economic access, affordability and quality of life hold several Canadian policy implications.

Reliability of the Romanian version of the alcohol module of the WHO Alcohol Use Disorder and Associated Disabilities: Interview Schedule --Alcohol/Drug-Revised

Alcohol Use Disorder and Associated Disabilities Interview Schedule - Alcohol/Drug-Revised (AUDADIS-A/D-R) is a fully structured, standardized and precoded instrument designed to evaluate alcohol and drug use disorders according to DSM-III-R, DSM-IV, and ICD-10 criteria. The AUDADIS-A/D-R has shown good to excellent reliability in both large clinical and general population samples, but prior to the conduct of the present study no data on the reliability of the Romanian version of the AUDADIS-A/D-R existed. The purpose of the present study was to examine the test-retest reliability of the alcohol module of the AUDADIS-A/D-R in a general population and clinical sample in Romania. The overall reliability of ICD-10 and DSM-IV abuse, harmful and dependence diagnoses, was found to be good to excellent, but was somewhat lower for abuse and harmful use diagnoses. The results are discussed in terms of the cultural applicability of the symptom items and within the context of the analysis of discrepant responses between the test and retest interviews.

Test-retest reliability of the alcohol and drug use disorder sections of the schedules for clinical assessment in neuropsychiatry (SCAN)

This report presents the results of a test-retest reliability study of the alcohol and drug dependence, as well as harmful use/abuse were investigated in Ankara, Turkey and Farmington, Connecticut (US). Reliabilities for the past year, prior to past year, and lifetime diagnosis of alcohol and drug use disorders were evaluated using ICD-IO, DSM-III-R and DSM-IV criteria. The results indicate that SCAN alcohol and drug diagnosis have good to excellent levels of reliability for dependence across different substances, different diagnostic systems, and different cultural groups. Diagnostic classification of alcohol and drug abuse/harmful use was considerably less reliable. Implications of the findings are discussed.

Concordance of DSM-IV alcohol and drug use disorder criteria and diagnoses as measured by AUDADIS-ADR, CIDI and SCAN

This study was designed to examine the agreement of DSM-IV alcohol and drug use disorder diagnoses generated by three WHO/NIH diagnostic instruments, the AUDADIS-ADR, the CIDI, and the SCAN. This substudy, conducted in three countries, Greece, Luxembourg, and the United States, was part of the larger joint project on diagnosis and classification of mental disorders and alcohol and drug-related problems, which was initiated to evaluate the cross-cultural applicability of the instruments and the criteria. Overall, concordance among the three assessments was good for alcohol and opiate dependence, fair to good for cocaine and sedative dependence, and low for amphetamine dependence. Cannabis dependence concordance was significantly more discrepant than any other substance. Agreement on abuse was low for all substances examined. In addition, the concordance of DSM-IV criteria for each substance was examined. Finally, reasons for discrepancies in responses among assessments were examined, based on discrepancy interview protocol methodology. Further investigation will help to refine these instruments in order to provide a more thorough understanding of alcohol and drug abuse diagnoses.

Concordance between ICD-10 alcohol and drug use disorder criteria and diagnoses as measured by the AUDADIS-ADR, CIDI and SCAN: results of a cross-national study

Agreement between the AUDADIS-ADR, CIDI and SCAN in case identification for ICD-10 alcohol and drug use disorders and diagnostic criteria was investigated in three countries, Luxembourg, Greece and the US. Overall, agreement for ICD-10 dependence diagnoses between the three instruments was fair to good for alcohol, opioids and cocaine, but generally lower for dependence diagnoses for other substance. In contrast, concordance between instruments for harmful use diagnoses was extremely poor for all substances. Implications of these major findings are discussed in terms of the relationship between prevalence, reliability and concordance and indications and cautions regarding cross-instrument comparisons.

Reliability of the alcohol and drug modules of the Alcohol Use Disorder and Associated Disabilities Interview Schedule--Alcohol/Drug-Revised (AUDADIS-ADR): an international comparison

The purpose of the present study was to examine the test-retest reliability of the alcohol and drug modules of the AUDADIS-ADR in three sites: Bangalore, India, Jebel, Romania and Sydney, Australia. The overall reliability of ICD-10, DSM-IV and DSM-III-R dependence diagnoses was found to be good to excellent for each substance, including alcohol, for each time frame, regardless of whether the total sample or user subsample figured into the calculations. Reliability associated with corresponding harmful use and abuse diagnoses were mixed, but generally lower. Reliability statistics for Bangalore were generally lower than those of the Jebel and Sydney sites, particularly for alcohol diagnostic criteria. Implications of these results are discussed, in conjunction with results from the discrepancy interview protocol analyses within sites, in terms of future revisions to the AUDADIS-ADR and its training procedures tailored to developing countries.

WHO Study on the reliability and validity of the alcohol and drug use disorder instruments: overview of methods and results

The WHO Study on the reliability and validity of the alcohol and drug use disorder instruments in an international study which has taken place in centres in ten countries, aiming to test the reliability and validity of three diagnostic instruments for alcohol and drug use disorders: the Composite International Diagnostic Interview (CIDI), the Schedules for Clinical Assessment in Neuropsychiatry (SCAN) and a special version of the Alcohol Use Disorder and Associated Disabilities Interview schedule-alcohol/drug-revised (AUDADIS-ADR). The purpose of the reliability and validity (R&V) study is to further develop the alcohol and drug sections of these instruments so that a range of substance-related diagnoses can be made in a systematic, consistent, and reliable way. The study focuses on new criteria proposed in the tenth revision of the International Classification of Diseases (ICD-10) and the fourth revision of the diagnostic and statistical manual of mental disorders (DSM-IV) for dependence, harmful use and abuse categories for alcohol and psychoactive substance use disorders. A systematic study including a scientifically rigorous measure of reliability (i.e. 1 week test-retest reliability) and validity (i.e. comparison between clinical and non-clinical measures) has been undertaken. Results have yielded useful information on reliability and validity of these instruments at diagnosis, criteria and question level. Overall the diagnostic concordance coefficients (kappa, kappa) were very good for dependence disorders (0.7-0.9), but were somewhat lower for the abuse and harmful use categories. The comparisons among instruments and independent clinical evaluations and debriefing interviews gave important information about possible sources of unreliability, and provided useful clues on the applicability and consistency of nosological concepts across cultures.

Expression of different members of the Ly-49 gene family defines distinct natural killer cell subsets and cell adhesion properties

The murine Ly-49 antigen belongs to a family of type II transmembrane molecules containing lectin-like domains. The original member of this family, Ly-49A, has been demonstrated to be expressed by a subpopulation of natural killer (NK) cells, bind certain class I major histocompatibility complexes (MHC), and act as a negative regulator of lytic activity. The expression patterns and functional activities of the other Ly-49s, however, is unknown. We extended the study of this family by isolating cDNAs encoding two new Ly-49 molecules. The reactivity of these and previously identified Ly-49 molecules with NK antibodies was tested in a COS cell expression system. YE1/32 and YE1/48 bound Ly-49A specifically, and 5E6 reacted only with Ly-49C. Three-color flow cytometric analysis demonstrated Ly-49A and Ly-49C expression defines complex, but distinct subsets within NK1.1+ cells. Some NK1.1-CD3+ as well as NK1.1-CD3- cells expressing Ly-49A or C were also detected. Analysis of MHC congenic strains of mice demonstrated that YE1/32+ and YE1/48+ NK cells are not deleted, as has been shown with the Ly-49A mAb A1. Furthermore, COS cells transfected with Ly-49A bound H-2d and H-2k cell lines, whereas Ly-49C transfectants bound H-2d, H-2k, H-2b, and H-2s. The antibodies 5E6 and 34-1-2S (anti-class I MHC) inhibited the binding of Ly-49C to an H-2s cell line. These results imply that the NK cell antigens Ly-49A and C bind to different repertoires of class I MHC molecules.

Subjective reports of withdrawal among cocaine users: recommendations for DSM-IV

The proposed DSM-IV criteria for substance use disorders have included, as an option, a subtyping for physiologic dependence, characterized by either tolerance or withdrawal. Even if this option is not chosen at this stage of system revision, this weighting scheme justifies wider surveillance of these symptoms, especially for the more newly described cocaine dependence disorder. Wider surveillance of withdrawal is possible with the CIDI Substance Abuse Module (SAM), a WHO/ADAMHA diagnostic interview which covers criteria of substance use disorders according to the DSM-III, III-R, ICD-10 and proposed DSM-IV systems. To aid in this effort, we used the SAM, which includes a master list of all symptoms (n = 16) in the DSM manuals related to withdrawal from any substance to assess withdrawal symptoms from all substances. In this study, we hypothesized that the persons who used opiates with cocaine might misattribute their symptoms to cocaine; thus, we compared the responses of persons who used cocaine and opiates (opiate users) with the responses of persons who used cocaine without opiates (non-opiate users). Data from two St. Louis studies were combined for these analyses, users not in treatment or newly enrolled to drug-free or methadone treatment from a NIDA demonstration project and users selected for the St. Louis DSM-IV Field Trial. Of the 196 persons included from the field trial, 80% reported lifetime cocaine use compared with 91% of the 412 persons from the demonstration project. The symptoms mentioned in the diagnostic manuals were among the most frequently endorsed by both cocaine use groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Posttraumatic stress disorder among substance users from the general population

OBJECTIVE

The purpose of the study was to evaluate the prevalence of posttraumatic stress disorder (PTSD) among substance users in the general population.

METHOD

The St. Louis Epidemiologic Catchment Area study, a survey of psychiatric illness in the general population, collected data on PTSD and substance use with the Diagnostic Interview Schedule. Among the 2,663 respondents, 430 reported a traumatic event that could qualify for PTSD; however, the rate of PTSD was low, 1.35% overall. To evaluate the relationship between PTSD and substance use, respondents were hierarchically classified into one of four substance use categories ranging from polydrug use to alcohol use only. Substance users from each category as well as substance users in general were compared with persons who did not meet the substance use threshold (comparison subjects).

RESULTS

Findings indicate that cocaine/opiate users are over three times as likely as comparison subjects to report a traumatic event, report more symptoms and events, and are more likely to meet diagnostic criteria for PTSD. Physical attack, but not combat-related events, was the most prevalent event reported among cocaine/opiate users. Onset of substance use preceded onset of posttraumatic symptoms, suggesting that substance use predisposes the individual to exposure to traumatic events. When other variables--including antisocial behavior--were controlled, female gender and use of cocaine/opiates predicted PTSD.

CONCLUSIONS

These analyses of the co-occurrence of substance abuse and PTSD warrant further study and suggest that PTSD is much more common among substance abusers than was previously known.

Legal needle buying in St. Louis

This study sought to determine if and why barriers to the over-the-counter purchase of syringes in the St. Louis metropolitan area might exist, given that no ordinance prohibits such a sale there. Two male research assistants (one African American, one White) approached 33 of the area's pharmacies to buy syringes. In 14 of those pharmacies, either the purchase was refused or the minimum number of syringes that could be bought was so large (at least 100) that the sale was not practical. Racial bias in rates of refusal and implications for prohibiting or restricting legal availability of syringes are discussed.

Agreement between DSM-III and III-R substance use disorders

With proposed criteria for DSM-IV substance dependence imminent, an evaluation of the impact of changes from DSM-III to DSM-III-R would be informative. Recent admissions to St. Louis drug treatment centers were interviewed with the DIS-III-R, which covers criteria from both systems. Kappa values for system agreement, diagnostic overlap and percent positive agreement are reported by substance. The DSM-III-R system cast a wider net for dependence than DSM-III for alcohol, tobacco and amphetamines. Neither system predominated for cannabis, opioids and barbiturates/sedatives/hypnotics. Reasons for differences and implications of findings are discussed.

Ly-49 multigene family. New members of a superfamily of type II membrane proteins with lectin-like domains

Ly-49 (YE1/48, A1) is a dimer protein expressed on subpopulations of murine NK cells. It is a member of a superfamily of type II transmembrane proteins containing carbohydrate recognition domains (CRD). In the mouse genome, the detection of multiple restriction fragments that cross-hybridize with Ly-49 cDNA probes suggests the presence of related genes. In this study, we have isolated several genomic clones encoding portions of CRD sequences highly homologous to the CRD of Ly-49. By using primers based on the consensus sequences of the genomic clones, expression of Ly-49-related genes was detected by the polymerase chain reaction in various organs, including lung, kidney, liver, spleen, and thymus. Two full-length cDNA clones that are highly homologous to the Ly-49 gene were subsequently isolated from a lung cDNA library. At the nucleotide level, the two clones are 72% and 80% identical to Ly-49 in their translated regions, but their sequences are different from those of the genomic clones characterized to date. The two cDNA clones potentially encode type II transmembrane proteins containing CRD that are very similar to Ly-49. These amino acid sequences are also homologous to other members of the superfamily of CRD-containing type II transmembrane proteins, including hepatic lectins and the low affinity IgER (CD23). The homology is most evident in the CRD but is also significant in other domains. These results demonstrate the existence of several functional genes that are highly related to Ly-49. These genes comprise a subfamily within the superfamily of type II transmembrane proteins containing CRD.

Ly-49 multigene family. New members of a superfamily of type II membrane proteins with lectin-like domains

Ly-49 (YE1/48, A1) is a dimer protein expressed on subpopulations of murine NK cells. It is a member of a superfamily of type II transmembrane proteins containing carbohydrate recognition domains (CRD). In the mouse genome, the detection of multiple restriction fragments that cross-hybridize with Ly-49 cDNA probes suggests the presence of related genes. In this study, we have isolated several genomic clones encoding portions of CRD sequences highly homologous to the CRD of Ly-49. By using primers based on the consensus sequences of the genomic clones, expression of Ly-49-related genes was detected by the polymerase chain reaction in various organs, including lung, kidney, liver, spleen, and thymus. Two full-length cDNA clones that are highly homologous to the Ly-49 gene were subsequently isolated from a lung cDNA library. At the nucleotide level, the two clones are 72% and 80% identical to Ly-49 in their translated regions, but their sequences are different from those of the genomic clones characterized to date. The two cDNA clones potentially encode type II transmembrane proteins containing CRD that are very similar to Ly-49. These amino acid sequences are also homologous to other members of the superfamily of CRD-containing type II transmembrane proteins, including hepatic lectins and the low affinity IgER (CD23). The homology is most evident in the CRD but is also significant in other domains. These results demonstrate the existence of several functional genes that are highly related to Ly-49. These genes comprise a subfamily within the superfamily of type II transmembrane proteins containing CRD.

Translocation of an erythroid-specific hypersensitive site in deletion-type hereditary persistence of fetal hemoglobin

Hereditary persistence of fetal hemoglobin (HPFH) can involve large deletions which eliminate the 3' end of the beta-like globin gene cluster and more than 70 kilobases (kb) of flanking DNA. Blot hybridization revealed a DNase I-hypersensitive site extending from 1.1 to 1.4 kb downstream of the HPFH-1 3' deletion endpoint. The site was found in normal fetal and adult nucleated erythroid cells and in two erythroleukemia cell lines but not in nonerythroid cells and tissues. Simian virus 40 core enhancer-like sequences were found nonrandomly distributed within the boundaries of the site, which is contained in a fragment of known enhancer activity (E. A. Feingold and B. G. Forget, Blood, in press). A second hypersensitive site was found 0.5 kb upstream of the HPFH-1 3' deletion endpoint but was not erythroid specific. A third site, most prominent in fetal liver-derived erythroid cells, was found 1 kb upstream of the HPFH-2 deletion endpoint. As predicted by the locations of the deletion endpoints, the first two sites were translocated to within 12 kb of the A gamma gene in erythroid colonies derived from an HPFH-2 heterozygote and in hybrid mouse-human erythroid cells carrying the HPFH-2 deletion chromosome. Further analysis of this region showed that it was DNase I sensitive in erythroid and myeloid cells, indicating that it resides in an open chromatin domain. These observations suggest that alterations of chromatin structure flanking the fetal globin genes may contribute to abnormal gene regulation in deletion-type HPFH.

Functional heterogeneity of a large family of human LTR-like promoters and enhancers

The human genome contains a variety of elements similar in structure to retroviruses and retrotransposons. We have shown that the long terminal repeat (LTR) sequences of a large family of human retrovirus-like elements, RTVL-H, are heterogeneous in their ability to regulate the expression of linked genes. Although all of five LTRs tested could promote expression of the chloramphenicol acetyltransferase (CAT) gene, their relative promoter activities as well as range of activities varied widely. Several of the LTRs tested also exhibited bidirectional promoter activity either alone or when activated by an SV40 early enhancer. One LTR, H6, displayed strong promoter activity in human (NTera2D1, 293, Hep2), monkey (COS-1), and mouse (3T3) cells. In fact, the activity of this LTR was similar to that of the SV40 early promoter/enhancer in 293, COS-1, and 3T3 cells. RNA mapping studies have localized the transcription start site to the expected location in the H6 LTR. RTVL-H LTRs were also shown to contain sequences which could increase transcription from the human beta-globin promoter and be influenced by SV40 enhancer sequences. As the human genome contains several hundred related RTVL-H sequences and a similar number of solitary LTRs, these findings raise the possibility that RTVL-H LTRs could have diverse effects on the expression of adjacent cellular genes.

The coordinate replication of the human beta-globin gene domain reflects its transcriptional activity and nuclease hypersensitivity

The temporal order of replication of DNA sequences in the chromosomal domain containing the human beta-globin gene cluster and its flanking sequences (140 kilobases) was measured and compared in two different human cell lines. In human erythroleukemia (K562) cells, in which embryonic and fetal globin genes are transcribed, all of the sequences we examined from the beta-globin domain replicated early during S phase, while in HeLa cells, in which globin genes are transcriptionally silent, these sequences replicated late during S. Potential sites of initiation of DNA replication within this domain were identified. The beta-globin gene domain was also found to differ with respect to the nuclease sensitivity of the chromatin in these two cell lines. In K562 cells, hypersensitive sites for endogenous nucleases and DNase I were present in the chromatin near the earliest-replicating segments in the beta-globin domain.

Normal dosage of the insulin and insulin-like growth factor II genes in patients with the Beckwith-Wiedemann syndrome

Several patients in whom the Beckwith-Wiedemann syndrome (BWS) is associated with duplication of chromosomal region 11p15 have recently been observed. The genes encoding insulin and insulin-like growth factor II (IGF-II), proteins that affect cellular growth and pancreatic function, have been mapped to 11p15, and their increased expression might, thus, account for the physical features of BWS. To determine whether BWS is frequently associated with small duplications of 11p15, we performed dosage analyses of the insulin and IGF-II genes in somatic DNAs of seven patients with BWS. In each case, we observed apparent diploid representation of these genes. These data suggest that BWS is not frequently associated with small duplications of 11p15 material that embed the insulin and IGF-II genes.

Prolactin binding protein in human milk

Milk samples at day 16 of lactation were from six mothers delivering infants at 28-30 weeks of gestation and six mothers delivering normal full term infants. These early morning samples were used in a prolactin binding assay to determine whether 125I-labelled human prolactin was selectively bound to a soluble protein fraction. After Sephadex G-100 column chromatography, 7 samples contained a protein fraction which bound human prolactin. Binding was not apparent in the remaining 5 samples. Prior binding of maternal prolactin, total binding capacity and differing free prolactin levels may be significant factors responsible for these observations.

Clonal analysis of early and late stages of erythroleukemia induced by molecular clones of integrated spleen focus-forming virus

The integrated proviral DNA of the polycythemia-inducing isolate of Friend spleen focus-forming virus (SFFVp) has been identified in rat cell clones nonproductively infected with this replication-defective erythroleukemia virus and cloned in phage lambda vectors. These lambda SFFVp recombinants, lambda SFFVp502 and lambda SFFVp542, contain endonuclease EcoRI inserts of size 7.4 and 8.2 kilobases, respectively, and include full copies of the SFFVp genome, along with host flanking sequences. Infectivity of the cloned SFFVp genomes was tested by a two-step DNA transfer procedure involving transfection of the cloned DNA into 3T3 mouse fibroblasts or cotransfer of the cloned DNA into thymidine kinase-deficient 3T3 cells together with the cloned thymidine kinase gene of herpes simplex virus, followed by rescue of the transferred DNA by superinfection with a helper virus. Inoculation of the rescued virus into adult mice resulted in the appearance of spleen foci, rapid splenomegaly, and polycythemia. Early after infection, spleen cell populations contained large numbers of cells capable of forming small erythroid colonies in vitro (CFU-E) in the absence of erythropoietin. Late after infection, these mice contained cells capable of forming macroscopic colonies (CFU-FV) in vitro. These data indicate that molecular clones of SFFVp, in conjunction with a helper virus, induce the appearance of hemopoietic colony-forming cells characteristic of both the early and late stages of Friend leukemia.

Clonal analysis of the late stages of erythroleukemia induced by two distinct strains of Friend leukemia virus

We observed striking differences between the tumorigenic colony-forming cells present in the spleens of mice late after infection with the anemia-inducing strain of Friend leukemia virus (strain FV-A) and those present after infection with the polycythemia-inducing strain (strain FV-P). Cells within primary colonies derived from FV-A- and FV-P-transformed cells (CFU-FV-A and CFU-FV-P, respectively) contained hemoglobin and spectrin, indicating that the CFU-FV-A and CFU-FV-P were transformed erythroid progenitor cells. The proportion of cells containing hemoglobin was relatively high (> 25%) in newly isolated cell lines derived from CFU-FV-P colonies, whereas cell lines derived from CFU-FV-A colonies had only low levels (0 to 2%) of hemoglobin-containing cells. A high proportion of the cell lines derived from CFU-FV-A colonies responded to pure erythropoietin and accumulated spectrin and hemoglobin, whereas the cell lines derived from CFU-FV-P colonies did not. A cytogenetic analysis indicated that primary CFU-FV-P colony cells were diploid, whereas chromosomal aberrations were observed in the immediate progeny of CFU-FV-A. The presence of unique chromosomal markers in the majority of the cells within individual colonies derived from CFU-FV-A suggested that these colonies originated from single cells. Finally, leukemic progenitor cells transformed by strain FV-A appeared to have an extensive capacity to self-renew (i.e., form secondary colonies in methylcellulose), whereas a significant proportion of the corresponding cells transformed by strain FV-P did not. In addition, the self-renewal capacity of both CFU-FV-A and CFU-FV-P increased as the disease progressed. From these observations, we propose a model for the multistage nature of Friend disease; this model involves clonal evolution and expansion from a differentiating population with limited proliferative capacity to a population with a high capacity for self-renewal and proliferation.

Friend leukaemia virus-transformed cells, unlike normal stem cells, form spleen colonies in Sl/sld mice

Neoplastic cells are characterized by partial or total autonomy from the interactions that regulate the behaviour of normal cells in the intact animal. Despite the role of the host cellular environment in governing the proliferation and differentiation of both normal and malignant cells, little is known about these host factors. The characterization of host genes that influence both normal cellular processes, as well as susceptibility to tumour induction, is one approach to identifying such factors. Mice carrying two recessive mutations at the steel (Sl) locus have an environmental defect that affects both normal haematopoietic stem cell function as well as susceptibility to Friend leukaemia virus. In this study, we have used Sl/sld mice to examine whether malignant transformation by this RNA tumour virus results in a population of cells capable of proliferating even in the defective cellular microenvironment of Sl/sld mice. We report here that late after infection, the leukaemic spleens of Friend virus-infected mice contain cells which, unlike normal haematopoietic stem cells, are able to form macroscopic spleen colonies in irradiated mice of genotype Sl/Sld. This observation forms the basis for the first in vivo colony assay for leukaemic cells transformed by Friend virus.

Phorbol ester tumor promoters block the transition from the early to the heme-dependent late program of Friend cell differentiation

In this study, the mechanism of inhibition of differentiation of Friend erythroleukemia cells by the phorbol ester tumor promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA), has been examined. These studies indicate that some early events associated with Friend cell differentiation, including an early change in 86Rb+ transport and a decrease in cell volume, still occur in the presence of TPA. However, several late events in the program of Friend cell differentiation, including the induction of heme synthesis and the loss of proliferative capacity, are inhibited by TPA. These effects of TPA can be reversed by hemin, which alone does not induce Friend cells to differentiate. The addition of hemin to cultures grown in the presence of inducer plus TPA for several days results in the rapid restoration of hemoglobin synthesis, and also causes a parallel decrease in colony-forming ability. These results suggest that tumor promoters may inhibit only heme-dependent events, rather than the entire program of Friend cell differentiation.

The role of heme in the regulation of the late program of Friend cell erythroid differentiation

The addition of a chemical inducer, such as dimethylsulfoxide (DMSO), to cultures of mouse Friend erythroleukemic cells results in the induction of a number of late erythroid events, including the accumulation of globin mRNA, the inducation of hemoglobin synthesis, the appearance of erythrocyte membrane antigens (EMA), and the cessation of cell division. The experiments presented in this study demonstrate that heme is necessary but not sufficient for the loss of proliferative capacity associated with DMSO-induced Friend cell differentiation, whereas the accumulation of globin mRNA and EMA can occur in the absence of heme synthesis or heme itself. These conclusions were reached by selectively inhibiting heme synthesis in DMSO-treated cells in two independent ways: (i) Inducible cells were treated with 3-amino-1,2,4-triazole (AT), a drug which inhibits the induction of heme synthesis in Friend cells in a dose-dependent manner. Treatment of inducible Friend cells with 1.5% DMSO for five days caused the plating efficiency in methyl cellulose to decrease to 1% of that in untreated cultures. However, treatment of the cells with DMSO plus AT almost totally prevented this decrease in plating efficiency. The addition of exogenous hemin, which alone had no significant effect on plating efficiency, largely reversed the effect of AT in DMSO-treated cells, reducing the plating efficiency to below 5%. In contrast to the marked effects of AT on the proliferative capacity of differentiating Friend cells, the levels of globin mRNA and EMA were only partially decreased in cells treated with DMSO plus AT, compared to cells treated with DMSO alone. (ii) The relationship between heme synthesis, terminal cell division, and the induction of globin mRNA was investigated further through the use of non-inducible Friend cell variant clones. One such non-inducible clone, M18, appears to be a phenotypic analog of inducible cells treated with DMSO plus AT. Clone M18 did not accumulate heme or hemoglobin, as detected by benzidine staining, nor lose its proliferative capacity in response to DMSO. However, globin mRNA was induced by DMSO in this clone. Treatment of clone M18 with DMSO plus hemin overcame the block in hemoglobin accumulation suggesting that M18 has a defect in the induction of heme biosynthesis. In addition, exposure of M18 cells to DMSO plus hemin caused a gradual decrease in plating efficiency which was not due to non-specific toxicity. Prior incubation of M18 cells in DMSO for three to five days was necessary before hemin caused a rapid loss of proliferative capacity. Thus, these results, in agreement with the AT studies on inducible Friend cells and previous studies on the induction of EMA in clone M18, indicate that there may be both heme-dependent and heme-independent events in the program of Friend cell differentiation.

Early transport changes during erythroid differentiation of Friend leukemic cells

Early transport changes occurring during Friend erythroleukemic cell differentiation are reported. A decrease in the rate of 86Rb transport was observed beginning approximately five hours after stimulation with 1.5% dimethylsulfoxide (DMSO), a potent inducer of Friend cell differentiation. By 12 to 14 hours after DMSO addition, the transport rate had stabilized at close to 60% of control level. This decrease in the rate of 86Rb transport preceded a previously reported decrease in cell volume. Other chemical inducers of Friend cells, such as hypoxanthine and ouabain, also caused early decreases in 86Rb influx. In contrast, xanthine, which does not induce Friend cell differentiation, also did not affect 86Rb influx. The transport of two amino acid analogues, alpha-aminoisobutyric acid and 2-aminobicyclo [2,2,1]-heptane-2-carboxylic acid, which differ in their mode of uptake, was also measured following induction by DMSO. The transport rates of both compounds decreased after a 12-hour exposure to DMSO. In contrast, the uptake of 3H-colchicine, a drug which diffuses passively across the cell membrane, was not significantly affected. Studies with several variant cell lines which do not synthesize hemoglobin in response to DMSO indicate that these non-inducible cells can be divided into two classes--those that demonstrate early changes in transport very similar to the changes observed in inducible cell lines and those which exhibit only small changes in transport. Results obtained using a revertant clone have helped to distinguish between those transport changes which are associated with the induction of hemoglobin synthesis and those which are not. In addition, these early transport changes may be useful in defining the stage in the differentiation process at which a particular variant line is blocked.

The program of Friend cell erythroid differentiation: early changes in Na+/K+ ATPase function

Treatment of Friend erythroleukemia cells with several different chemical agents causes an early decrease in the 86Rb+ influx mediated by Na+/K+ adenosine triphosphatase (ATPase). These agents, which induce Friend cells to differentiate, include dimethylsulfoxide (DMSO), ouabain, hypoxanthine, and actinomycin D. The magnitude of the early decrease in 86Rb+ influx correlates with the proportion of cells in cultures of inducible Friend cell clones which later go on to synthesize hemoglobin. Compounds which do not incude differentiation in these cells, such as xanthine, exogenous hematin, and erythropoietin, do not cause a change in 86Rb+ influx. A change in the intracellular K+ ion concentration does not occur during induction by DMSO because, although there is a decrease in K+ content per cell soon after induction, there is a parallel decrease in cell volume. These results and previous observations from this laboratory are discussed in terms of the posible involvement of the Na+/K+ ATPase in Friend cell differentiation.