RESUMEN
OBJECTIVE: It is widely believed that there are multiple sources of pain at a tissue level in osteoarthritis (OA). Magnetic Resonance Images (MRIs) provide a wealth of anatomic information and may allow identification of specific features associated with pain. We hypothesized that in knees with OA, bone marrow lesions (BMLs), synovitis, and effusion would be associated with weight-bearing and (less so with) non-weight-bearing pain independently. METHODS: In a cross-sectional study of persons with symptomatic knee OA using univariate and multivariate logistic regressions with maximal BML, effusion, and synovitis defined by Boston Leeds Osteoarthritis Knee Score as predictors, and knee pain using weight-bearing and non-weight-bearing Western Ontario and McMaster University OA Index pain questions as the outcome, we tested the association between MRI findings and knee symptoms. RESULTS: 160 participants, mean age 61 (+/-9.9), mean body mass index (BMI) 30.3 (+/-4.7) and 50% female, stronger associations were seen with weight-bearing compared with non-weight-bearing knee pain with adjusted risk ratios (RRs) of weight-bearing knee pain, for increasing maximal BML scores of 1.0 (referent) (maximal BML=0), 1.2, 1.9, and 2.0 (P for trend=0.006). For effusion scores, adjusted RRs of knee pain were 1.0, 1.7, 2.0, and 2.6 (P for trend=0.0004); and for synovitis scores, adjusted ORs were 1.0, 1.4, 1.5, and 1.9 (P for trend=0.22). CONCLUSION: Cross-sectionally, maximal BML and effusion scores are independently associated with weight-bearing and less so with non-weight-bearing knee pain, supporting the idea that pain in OA is multifactorial. These MRI features should be considered as possible new treatment targets in knee OA.
Asunto(s)
Artralgia/etiología , Enfermedades de la Médula Ósea/complicaciones , Cartílago Articular/patología , Articulación de la Rodilla/patología , Osteoartritis de la Rodilla/patología , Soporte de Peso/fisiología , Anciano , Artralgia/diagnóstico , Índice de Masa Corporal , Enfermedades de la Médula Ósea/diagnóstico , Estudios Transversales , Femenino , Humanos , Modelos Logísticos , Imagen por Resonancia Magnética/métodos , Masculino , Persona de Mediana Edad , Dimensión del Dolor , Índice de Severidad de la EnfermedadRESUMEN
OBJECTIVE: The performance characteristics of hyaline articular cartilage measurement on magnetic resonance imaging (MRI) need to be accurately delineated before widespread application of this technology. Our objective was to assess the rate of natural disease progression of cartilage morphometry measures from baseline to 1 year in knees with osteoarthritis (OA) from a subset of participants from the Osteoarthritis Initiative (OAI). METHODS: Subjects included for this exploratory analysis are a subset of the approximately 4700 participants in the OAI Study. Bilateral radiographs and 3T MRI (Siemans Trio) of the knees and clinical data were obtained at baseline and annually in all participants. 160 subjects from the OAI Progression subcohort all of whom had both frequent symptoms and, in the same knee, radiographic OA based on a screening reading done at the OAI clinics were eligible for this exploratory analysis. One knee from each subject was selected for analysis. 150 participants were included. Using sagittal 3D DESSwe (double echo, steady-state sequence with water excitation) MR images from the baseline and 12 follow-up month visit, a segmentation algorithm was applied to the cartilage plates of the index knee to compute the cartilage volume, normalised cartilage volume (volume normalised to bone surface interface area), and percentage denuded area (total cartilage bone interface area denuded of cartilage). RESULTS: Summary statistics of the changes (absolute and percentage) from baseline at 1 year and the standardised response mean (SRM), ie, mean change divided by the SD change were calculated. On average the subjects were 60.9 years of age and obese, with a mean body mass index of 30.3 kg/m2. The SRMs for cartilage volume of various locations are: central medial tibia -0.096; central medial femur -0.394; and patella -0.198. The SRMs for normalised cartilage volume of the various locations are central medial tibia -0.044, central medial femur -0.338 and patella -0.193. The majority of participants had a denuded area at baseline in the central medial femur (62%) and central medial tibia (60%). In general, the SRMs were small. CONCLUSIONS: These descriptive results of cartilage morphometry and its change at the 1-year time point from the first substantive MRI data release from the OAI Progression subcohort indicate that the annualised rates of change are small with the central medial femur showing the greatest consistent change.
Asunto(s)
Cartílago Articular/patología , Imagen por Resonancia Magnética , Osteoartritis de la Rodilla/patología , Anciano , Índice de Masa Corporal , Cartílago Articular/diagnóstico por imagen , Estudios de Cohortes , Progresión de la Enfermedad , Femenino , Fémur/patología , Humanos , Articulación de la Rodilla/diagnóstico por imagen , Estudios Longitudinales , Imagen por Resonancia Magnética/métodos , Masculino , Persona de Mediana Edad , Osteoartritis de la Rodilla/diagnóstico por imagen , Radiografía , Índice de Severidad de la Enfermedad , Tibia/patologíaRESUMEN
OBJECTIVE: To investigate, over 1-year, the relationship between X-ray and magnetic resonance imaging (MRI) findings in patients with knee osteoarthritis (OA). METHODS: Sixty-two osteoarthritic patients (46 women) were followed for 1 year. At baseline and after 1 year, volume and thickness of cartilage of the medial tibia, the lateral tibia and the femur were assessed by MRI. A global score from the multi-feature whole-organ MRI scoring system (WORMS) was calculated for each patient at baseline and after 1 year. This score combined individual scores for articular cartilage, osteophytes, bone marrow abnormality, subchondral cysts and bone attrition in 14 locations. It also incorporated scores for the medial and lateral menisci, anterior and posterior cruciate ligaments, medial and lateral collateral ligaments and synovial distension. Lateral and medial femoro-tibial joint space width (JSW) measurements, performed by digital image analysis, were assessed from fixed-flexion, postero-anterior knee radiographs. RESULTS: One-year changes in medial femoro-tibial JSW reach 6.7 (20.5) % and changes in medial cartilage volume and thickness reach 0.4 (16.7) % and 2.1 (11.3) %, respectively. Medial femoro-tibial joint space narrowing (JSN) after 1 year, assessed by radiography, was significantly correlated with a loss of medial tibial cartilage volume (r=0.25, P=0.046) and medial tibial cartilage thickness (r=0.28, P=0.025), over the same period. We found also a significant correlation between the progression of the WORMS and radiographic medial JSN over 1 year (r=-0.35, P=0.006). All these results remained statistically significant after adjusting for age, sex and body mass index. CONCLUSION: This study shows a moderate but significant association between changes in JSW and changes in cartilage volume or thickness in knee joint of osteoarthritic patients.
Asunto(s)
Cartílago Articular/patología , Osteoartritis/patología , Anciano , Cartílago Articular/diagnóstico por imagen , Estudios de Cohortes , Progresión de la Enfermedad , Femenino , Fémur , Humanos , Estudios Longitudinales , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Análisis Multivariante , Osteoartritis/diagnóstico por imagen , Radiografía , TibiaRESUMEN
OBJECTIVE: To investigate the relation between biochemical markers of bone, cartilage, and synovial remodelling and the structural progression of knee osteoarthritis. METHODS: 62 patients of both sexes with knee osteoarthritis were followed prospectively for one year. From magnetic resonance imaging (MRI), done at baseline and after one year, the volume and thickness of cartilage of the femur, the medial tibia, and the lateral tibia were assessed. A whole organ magnetic resonance imaging score (WORMS) of the knee was calculated for each patient at baseline and at the one year visits. This score consists in a validated, semiquantitative scoring system for whole organ assessment of the knee in osteoarthritis using MRI. Biochemical markers (serum hyaluronic acid, osteocalcin, cartilage glycoprotein 39 (YKL-40), cartilage oligomeric matrix protein (COMP), and C-telopeptide of type I collagen (CTX-I), and urine C-telopeptide of type II collagen (CTX-II)) were measured at baseline and after three months. RESULTS: Baseline markers were not correlated with one year changes observed in cartilage volume and thickness. However, an increase in CTX-II after three months was significantly correlated with a one year decrease in mean thickness of medial tibial and lateral tibial cartilage. Patients in the highest quartile of three month changes in CTX-II experienced a mean loss of 0.07 (0.08) mm of their medial thickness, compared with a mean increase of 0.05 (0.19) mm for patients in the lowest quartile (p = 0.04) Multiple regression analysis showed that high baseline levels of hyaluronic acid are predictive of a worsening in WORMS (p = 0.004). CONCLUSIONS: These results suggest that a single measurement of serum hyaluronic acid or short term changes in urine CTX-II could identify patients at greatest risk of progression of osteoarthritis.
Asunto(s)
Articulación de la Rodilla/patología , Imagen por Resonancia Magnética , Osteoartritis de la Rodilla/patología , Adipoquinas , Anciano , Biomarcadores/sangre , Remodelación Ósea , Proteína de la Matriz Oligomérica del Cartílago , Cartílago Articular/patología , Proteína 1 Similar a Quitinasa-3 , Colágeno Tipo II/sangre , Colágeno Tipo II/orina , Progresión de la Enfermedad , Ensayo de Inmunoadsorción Enzimática/métodos , Proteínas de la Matriz Extracelular/sangre , Femenino , Glicoproteínas/sangre , Humanos , Ácido Hialurónico/sangre , Lectinas , Masculino , Proteínas Matrilinas , Persona de Mediana Edad , Osteoartritis de la Rodilla/sangre , Osteoartritis de la Rodilla/orina , Osteocalcina/sangre , Fragmentos de Péptidos/sangre , Fragmentos de Péptidos/orina , Estudios Prospectivos , Análisis de Regresión , Membrana Sinovial/patologíaRESUMEN
Herpes simplex virus type 1 (HSV-1) and varicella-zoster virus (VZV) establish latent infections in the peripheral nervous system following primary infection. During latency both virus genomes exhibit limited transcription, with the HSV-1 LATs and at least four VZV transcripts consistently detected in latently infected human ganglia. In this study we used real-time PCR quantitation to determine the viral DNA copy number in individual trigeminal ganglia (TG) from 17 subjects. The number of HSV-1 genomes was not significantly different between the left and right TG from the same individual and varied per subject from 42.9 to 677.9 copies per 100 ng of DNA. The number of VZV genomes was also not significantly different between left and right TG from the same individual and varied per subject from 37.0 to 3,560.5 copies per 100 ng of DNA. HSV-1 LAT transcripts were consistently detected in ganglia containing latent HSV-1 and varied in relative expression by >500-fold. Of the three VZV transcripts analyzed, only transcripts mapping to gene 63 were consistently detected in latently infected ganglia and varied in relative expression by >2,000-fold. Thus, it appears that, similar to LAT transcription in HSV-1 latently infected ganglia, VZV gene 63 transcription is a hallmark of VZV latency.
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Herpes Simple/virología , Herpes Zóster/virología , Herpesvirus Humano 1/fisiología , Herpesvirus Humano 3/fisiología , Ganglio del Trigémino/virología , Latencia del Virus , Anciano , Anciano de 80 o más Años , ADN Viral/análisis , Femenino , Genoma Viral , Humanos , Masculino , Persona de Mediana Edad , Reacción en Cadena de la PolimerasaRESUMEN
Cinnamyl derivatives of thieno[2,3-d]oxazinones are mechanism-based inhibitors of the HSV-2, VZV and CMV herpes proteases which demonstrate nanomolar potency. Compounds 5 and 28 inhibit protease processing in HSV-2 infected cells with a selectivity index of at least 30.
Asunto(s)
Antivirales/farmacología , Herpesviridae/enzimología , Oxazinas/farmacología , Inhibidores de Proteasas/farmacología , Antivirales/química , Línea Celular , Oxazinas/química , Inhibidores de Proteasas/químicaRESUMEN
Enedione derivatives of thieno[2,3-d]oxazinones are nanomolar inhibitors of CMV protease which act through a novel dual acylation of the catalytic serine and alkylation of the protease cysteine 161 via a Michael addition to the enedione moiety of the inhibitor.
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Oxazinas/farmacología , Serina Endopeptidasas/efectos de los fármacos , Inhibidores de Serina Proteinasa/farmacología , Acilación , Alquilación , Supervivencia Celular/efectos de los fármacos , Modelos Moleculares , Oxazinas/química , Inhibidores de Serina Proteinasa/química , Espectrometría de Masa Bombardeada por Átomos Veloces , Espectrometría de Masa por Láser de Matriz Asistida de Ionización DesorciónRESUMEN
We have recently identified a novel 53-kDa herpes simplex virus type 1 (HSV-1) protein encoded by, and in frame with, the 3' half of the UL9 open reading frame, designated OBPC (K. Baradaran, C. Dabrowski and P. A. Schaffer, J. Virol. 68:4251-4261, 1994). Here we show that OBPC is a nuclear protein synthesized at both early and late times postinfection. In gel-shift assays in vitro-synthesized OBPC bound to oriS site I DNA to form a complex identical in mobility to complex A, generated with infected cell extracts and site I DNA. OBPC inhibited both plaque formation and viral DNA replication in transient assays, consistent with its ability to bind to site I DNA and its limited ability to interact with other essential DNA replication proteins. These properties suggest that OBPC may play a role in the initiation, elongation, or packaging of viral DNA.
Asunto(s)
Proteínas de Unión al ADN/aislamiento & purificación , Simplexvirus/metabolismo , Proteínas Virales/aislamiento & purificación , Proteínas de Unión al ADN/metabolismo , Proteínas Virales/metabolismoRESUMEN
The region of the UL component of the herpes simplex virus type 1 genome between nucleotides 17,793 and 25,150 includes three open reading frames that code for the protein products of the UL8, UL9, and UL10 genes (D.J. McGeogh, M.A. Dalrymple, A.J. Davison, A. Dolan, M.C. Frame, D. McNab, L.J. Perry, J.E. Scott, and P. Taylor, J. Gen. Virol. 69:1531-1574, 1988). We have mapped and characterized the overlapping transcripts in this region and have found that, in addition to the low-abundance UL8 and UL9 transcripts and the abundant UL10 transcript, at least two additional transcription units, designated UL8.5 and UL9.5, are specified by this region of the genome. The 5' ends of the UL8, UL8.5, and UL9 transcripts were mapped to nucleotides 20,682, 22,351, and 23,381, respectively. The 5' terminus of the UL9.5 transcript has not yet been mapped. The 3' ends of the UL8, UL8.5, UL9, and UL9.5 transcripts are coterminal at nucleotide 18,197. The 5' end of the UL10 mRNA, which is transcribed from the strand opposite that specifying the UL8, UL8.5, UL9, and UL9.5 transcripts, lies within the UL9 open reading frame at nucleotide 22,944, while the 3' terminus was mapped to nucleotide 24,666. Time course studies demonstrated that the UL8 and UL9 transcripts are members of the early kinetic class, the UL8.5 mRNA is a delayed-early transcript, and the UL9.5 and UL10 transcripts belong to the true-late kinetic class. Examination of the nucleotide sequence of the UL8.5 transcript revealed a potential open reading frame that overlaps and is in frame with the C-terminal half of the open reading frame encoding the origin-binding protein (OBP), the product of the UL9 gene. In vitro translation of the UL8.5 transcript demonstrated that it encodes a protein with an apparent molecular mass of 53 kDa. This protein was recognized by antibody directed against the C-terminal region of OBP and has thus been designated OBPC. A protein with an identical apparent molecular mass was also recognized by this antibody in infected-cell lysates, indicating that OBPC is synthesized during viral infection.
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Genoma Viral , Herpesvirus Humano 1/genética , Proteínas Inmediatas-Precoces/genética , Glicoproteínas de Membrana , Transcripción Genética , Animales , Secuencia de Bases , Chlorocebus aethiops , ADN Helicasas/genética , ADN Primasa , ADN Viral , Proteínas de Unión al ADN/genética , Proteínas Inmediatas-Precoces/metabolismo , Cinética , Proteínas de la Membrana/genética , Datos de Secuencia Molecular , ARN Mensajero/metabolismo , ARN Viral/metabolismo , Células Vero , Proteínas Virales/genéticaRESUMEN
The herpes simplex virus type 1 (HSV-1) origin of DNA replication, oriS, contains an AT-rich region and three highly homologous sequences, sites I, II, and III, identified as binding sites for the HSV-1 origin-binding protein (OBP). In the present study, interactions between specific oriS DNA sequences and proteins in uninfected cell extracts were characterized. The formation of one predominant protein-DNA complex, M, was demonstrated in gel shift assays following incubation of uninfected cell extracts with site I DNA. The cellular protein(s) that comprises complex M has been designated origin factor I (OF-I). The OF-I binding site was shown to partially overlap the OBP binding site within site I. Complexes with mobilities indistinguishable from that of complex M also formed with site II and III DNAs in gel shift assays. oriS-containing plasmid DNA mutated in the OF-I binding site exhibited reduced replication efficiency in transient assays, demonstrating a role for this site in oriS function. The OF-I binding site is highly homologous to binding sites for the cellular CCAAT DNA-binding proteins. The binding site for the CCAAT protein CP2 was found to compete for OF-I binding to site I DNA. These studies support a model involving the participation of cellular proteins in the initiation of HSV-1 DNA synthesis at oriS.
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Replicación del ADN , Proteínas de Unión al ADN/metabolismo , ADN/metabolismo , Herpesvirus Humano 1/genética , Herpesvirus Humano 1/metabolismo , Proteínas Virales/metabolismo , Animales , Secuencia de Bases , Sitios de Unión , Unión Competitiva , Secuencia de Consenso , Cinética , Datos de Secuencia Molecular , Mutagénesis , Sondas de Oligonucleótidos , Homología de Secuencia de Ácido Nucleico , Células VeroRESUMEN
We have examined the contribution of 5' leader sequences to expression directed by the simian virus 40 (SV40) late promoter. These studies showed that addition of sequences which contain the late leader 3' splice site to the late promoter led to an increase in the accumulation of mRNA expressed by the promoter. No other sequences within the leader region, between SV40 positions 334 and 560, exhibited a substantial influence on mRNA accumulation. The increase was due, at least in part, to the creation of a spliceable mRNA transcript, since mutation of either the 5' or 3' splice site could attenuate the effect. However, sequences at or near the 3' splice site appeared to play a more important role than did the 5' splice site in bringing about this increase. In many instances, mutation of the 3' splice site also led to the accumulation of extended transcripts, whereas mutation of the 5' splice site did not produce this result in any instance. Analysis of these extended transcripts showed that they retained sequences normally lost upon cleavage and polyadenylation. This finding suggested that mutation of the 3' splice site sequence led to decreases in the efficiency of polyadenylation. We propose that the SV40 late leader sequences positively contribute to expression of the viral late genes by increasing mRNA accumulation via multiple mechanisms, including the enhancement of pre-mRNA polyadenylation efficiency.
Asunto(s)
Poli A/genética , Regiones Promotoras Genéticas , Empalme del ARN , ARN Mensajero/genética , ARN Viral/genética , Virus 40 de los Simios/genética , Animales , Northern Blotting , Línea Celular , Regulación Viral de la Expresión Génica , Genes Virales , Plásmidos , ARN Mensajero/aislamiento & purificación , ARN Mensajero/metabolismo , ARN Viral/aislamiento & purificación , ARN Viral/metabolismo , Transcripción Genética , TransfecciónRESUMEN
The herpes simplex virus type 1 (HSV-1) origin of replication, oriS, contains three highly homologous sequences, sites I, II, and III. The HSV-1 origin-binding protein (OBP), the product of the UL9 gene, has been shown to bind specifically to sites I and II. In this study, gel shift analysis was used to characterize interactions between site I DNA and proteins in infected and uninfected cell extracts. The formation of two protein-DNA complexes, bands A and B, was demonstrated with infected cell extracts, and one predominant protein-DNA complex, band M, was identified with mock-infected extracts. Protein interactions with the highly homologous site II and III DNAs were also characterized. Incubation of infected cell extracts with the lower-affinity site II DNA as a probe resulted in the appearance of two protein-DNA complexes with mobilities identical to those of the A and B complexes, while incubation with site III DNA resulted in the formation of a single complex with the mobility of band B; no A-like band was observed. Incubation of high concentrations of partially purified OBP with site I DNA resulted in the formation of two novel complexes, bands 9-1 and 9-2. Addition of uninfected or HSV-1-infected cell extracts to the purified OBP-site I DNA mix significantly enhanced the formation of complex 9-1. The enhanced formation of complex 9-1 by uninfected cell extracts implicates a cellular factor or factors in the formation or stabilization of the OBP-site I DNA complex.
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ADN Viral/metabolismo , Proteínas de Unión al ADN/genética , Simplexvirus/genética , Proteínas Virales/genética , Animales , Secuencia de Bases , Sitios de Unión , Células Cultivadas , Genes Virales , Herpes Simple/genética , Datos de Secuencia Molecular , Mutación , Proteínas Recombinantes/genéticaRESUMEN
The simian virus 40 (SV40) 19S late mRNA is polycistronic, encoding multiple late proteins: agnoprotein, VP2, and VP3. We constructed a chloramphenicol acetyltransferase (CAT) transient expression vector in which the SV40 sequences between nucleotides 5171 and 1046 (via the SV40 origin of replication and including the late promoter) were inserted 5' to the cat gene; therefore, the AUG for CAT expression occurs after the AUGs for agnoprotein, VP2, and VP3. CAT enzyme activity assayed after transfection of these constructions indicates the level of CAT AUG utilization and, therefore, can be used as a measure of the ability of prior AUGs to intercept scanning ribosomes. Specifically, deletions and point mutations of the viral AUGs resulted in increased CAT enzyme activity owing to increased utilization of the downstream CAT AUG. To compare a variety of mutants, we used the levels of increase to calculate the translational efficiency of the viral AUGs. Some of our data agree with predictions of the modified scanning model (MSM). Little variation in downstream CAT AUG utilization was noted regardless of whether the VP2 AUG (in a weak MSM sequence context) was intact or removed. Hence, a scanning ribosome may easily bypass it. Similar analysis of the VP3 AUG (in a favorable MSM sequence context) demonstrated that it could efficiently intercept ribosomes prior to the downstream AUG. Overall, these data indicate that the structure of the 19S late mRNA and the relative efficiency of translational start codon utilization can account for the VP3/VP2 ratio found in infected cells. The agnoprotein reading frame, depending on how the mRNA precursor is spliced, is either not contained in the mRNA or is terminated near the VP2 AUG. Under these conditions, the ability of the agnoprotein AUG to block downstream CAT AUG utilization was found to be minimal in our assay. However, we directly tested the blocking ability of the agnoprotein AUG under conditions in which the reading frame terminated well after the CAT AUG. Although the agnoprotein AUG lies in a very good sequence context, this direct analysis showed that it interfered minimally with utilization of the CAT AUG when under the control of the SV40 late promoter. However, expected high levels of interference were regained when the late promoter was replaced with the Rous sarcoma virus long terminal repeat.(ABSTRACT TRUNCATED AT 400 WORDS)
Asunto(s)
Biosíntesis de Proteínas , ARN Mensajero/genética , Virus 40 de los Simios/genética , Proteínas Virales/biosíntesis , Acetiltransferasas/genética , Animales , Línea Celular Transformada , Cloranfenicol O-Acetiltransferasa , Codón/genética , Enzimas de Restricción del ADN , Endonucleasas , Regulación de la Expresión Génica , Vectores Genéticos , Mutación , Hibridación de Ácido Nucleico , Plásmidos , Regiones Promotoras Genéticas , Virus 40 de los Simios/metabolismo , Endonucleasas Específicas del ADN y ARN con un Solo Filamento , Transfección , Proteínas Virales/genética , Proteínas Reguladoras y Accesorias ViralesRESUMEN
Using cultured skin fibroblasts, we studied the heterogeneity of inborn errors of leucine metabolism such as isovaleric acidemia (IVA), glutaric aciduria type II (GA II), and multiple carboxylase deficiency (MC). We first developed a simple macromolecular-labeling test to measure the ability of cells to oxidize [1-14C]isovaleric acid in situ in culture. Cells from two different lines were fused using polyethylene glycol, and the ability of the heterokaryons to oxidize [1-14C]isovaleric acid was tested by the macromolecular-labeling test. The MC line complemented with all 10 IVA lines tested; heterokaryons showed 99 +/- 68% more activity than the unfused mixture of component cells. GA II/IVA heterokaryons exhibited poor growth, but when the culture remained confluent, the GA II cells complemented with all six IVA lines tested, showing a 71 +/- 41% increase in activity. The relatively large standard deviations are due to a few experiments in which significant enhancement of macromolecular-labeling test activity was not observed upon fusion, but significant complementation was clearly observed in repeats of the same combinations. These results are consistent with our previous findings, which indicated that the decreased ability of GA II cells to oxidize isovaleryl-CoA involves a defective electron-transporting system rather than a defective isovaleryl-CoA dehydrogenase. IVA/IVA heterokaryons showed no complementation in any combination tested, indicating no detectable heterogeneity in isovaleric acidemia. This finding indicates that the same gene is mutated in all IVA lines. Previous results indicated that this gene codes for isovaleryl-CoA dehydrogenase.