Polyalanine (poly-A) tracts exist in 494 annotated proteins; to date, expansions in these tracts have been associated with nine human diseases. The pathogenetic mechanism by which a poly-A tract results in these various human disorders remains uncertain. To understand the role of this mutation type, we investigated the change in functional properties of the transcription factor Arx when it has an expanded poly-A tract (ArxE), a mutation associated with infantile spasms and intellectual disabilities in humans. We found that although ArxE functions normally in the dorsal brain, its function in subpallial-derived populations of neurons is compromised. These contrasting functions are associated with the misregulation of Arx targets through the loss of the ability of ArxE to interact with the Arx cofactor Tle1. Our data demonstrate a novel mechanism for poly-A expansion diseases: the misregulation of a subset of target genes normally regulated by a transcription factor.
Mutations in the Aristaless-related homeobox gene (ARX) are associated with a wide variety of neurologic disorders including lissencephaly, hydrocephaly, West syndrome, Partington syndrome, and X-linked intellectual disability with or without epilepsy. A genotype-phenotype correlation exists for ARX mutations, however the molecular basis for this association has not been investigated. To begin understanding the molecular basis for ARX mutations, we tested the DNA binding sequence preference and transcriptional repression activity for Arx, deletion mutants and mutants associated with various neurologic disorders. We found DNA binding preferences of Arx are influenced by the amino acid sequences adjacent to the homeodomain. Mutations in the homeodomain show a loss DNA binding activity, while the T333N and P353R homeodomain mutants still possess DNA binding activities, although less than wild type. Transcription repression activity, the primary function of ARX, is reduced in all mutants except the L343Q, which has no DNA binding activity and does not functionally repress Arx targets. These data indicate that mutations in the homeodomain result in not only a loss of DNA binding activity but also loss of transcriptional repression activity. Our results provide novel insights into the pathogenesis of ARX related disorders and possible directions to pursue potential therapeutic interventions.
ARX; lissencephaly; X-linked intellectual disability and Homeodomain
Malformations of cortical development are frequently identified in surgical resections for intractable epilepsy. Among the more frequently identified are cortical dysplasia, pachygyria and polymicrogyria. The pathogenesis of these common developmental anomalies remains uncertain. Polymicrogyria is particularly vexing because there are multiple described forms (2, 4 and 6 layer) that have been attributed to multiple etiologies (e.g. ischemic, genetic, infectious, and toxic). We reviewed the pathology in 19 cases and performed cortical laminar analysis in 10 of these cases. Our data indicate that a defining feature of polymicrogyria is fusion of the molecular layer and that most often there is a well-defined grey matter-white matter junction. Unexpectedly, the cortical lamina were normally positioned but there were reduced neuronal populations within these lamina, particularly in the subgranular layers. Based on these data, we propose that the categorization of polymicrogyria according to the number of lamina is artificial and should be abandoned and polymicrogyria should be defined according to the presence or absence of coexisting neuropathological features. Furthermore, our data indicate that polymicrogyria is not a cell migration disorder and rather that it should be considered a post-migration malformation of cortical development.
Cell migration; Cerebral cortex; Cortical lamina; Malformation of cortical development; Polymicrogyria; Seizures
Sizn1 (Zcchc12) is a transcriptional co-activator that positively modulates BMP (Bone Morphogenic Protein) signaling through its interaction with Smad family members and CBP. We have demonstrated a role for Sizn1 in basal forebrain cholinergic neuron specific gene expression. Furthermore, mutations in SIZN1 have been associated with X-linked mental retardation. Given the defined role of SIZN1 in mental retardation, knowing its complete forebrain expression pattern is essential to further elucidating its role in cognition. To better define the dynamic expression pattern of Sizn1 during forebrain development, we investigated its expression in mouse brain development from embryonic day 8.0 (E8.0) to adult. We found that Sizn1 is primarily restricted to the ventral forebrain including the medial ganglionic eminence, the septum, amygdala, and striatum. In addition, Sizn1 expression is detected in the cortical hem and Pallial-subpallial boundary (PSB; anti-hem); both sources of Cajal-Retzius cells. Sizn1 expression in the dorsal forebrain is restricted to a subset of cells in the marginal zone that also express Reln, indicative of Cajal-Retzius cells. These data provide novel information on brain regions and cell types that express Sizn1, facilitating further investigations into the function of Sizn1 in both development and the pathogenesis of mental retardation.
Cell migration is required for normal embryonic development, yet how cells navigate complex paths while integrating multiple guidance cues remains poorly understood. During brain development, interneurons migrate from the ventral ganglionic eminence to the cerebral cortex within several migratory streams. They must exit these streams to invade the cortical plate. While SDF1-signaling is necessary for normal interneuron stream migration, how they switch from tangential stream migration to invade the cortical plate is unknown. Here we demonstrate that SDF1-signaling reduces interneuron branching frequency by reducing cAMP levels via a Gi-signaling pathway using an in vitro mouse explant system, resulting in the maintenance of stream migration. Blocking SDF1-signaling, or increasing branching frequency, results in stream exit and cortical plate invasion in mouse brain slices. These data support a novel model to understand how migrating interneurons switch from tangential migration to invade the cortical plate in which reducing SDF1-signaling increases leading process branching and slows the migration rate, permitting migrating interneurons to sense cortically directed guidance cues.
Interneuron; migration; branching; SDF1; guidance
Mammalian forebrain development requires extensive migration, yet the mechanisms through which migrating neurons sense and respond to guidance cues are not well understood. Similar to the axon growth cone, the leading process and branches of neurons may guide migration, but the cytoskeletal events that regulate branching are unknown. We have previously shown that loss of microtubule-associated protein Lis1 reduces branching during migration compared with wild-type neurons. Using time-lapse imaging of Lis1+/− and Lis1+/+ cells migrating from medial ganglionic eminence explant cultures, we show that the branching defect is not due to a failure to initiate branches but a defect in the stabilization of new branches. The leading processes of Lis1+/− neurons have reduced expression of stabilized, acetylated microtubules compared with Lis1+/+ neurons. To determine whether Lis1 modulates branch stability through its role as the noncatalytic β regulatory subunit of platelet-activating factor (PAF) acetylhydrolase 1b, exogenous PAF was applied to wild-type cells. Excess PAF added to wild-type neurons phenocopies the branch instability observed in Lis1+/− neurons, and a PAF antagonist rescues leading process branching in Lis1+/− neurons. These data highlight a role for Lis1, acting through the PAF pathway, in leading process branching and microtubule stabilization.
branching; leading process; microtubules; migration; PAFAH1b
Idiopathic pulmonary fibrosis is a diffuse fibrotic lung disease of unknown etiology with no effective treatment. Emerging data support a role for chronic microaspiration (i.e. subclinical aspiration of small droplets) in the pathogenesis and natural history of idiopathic pulmonary fibrosis. However, the precise relationship between chronic microaspiration and idiopathic pulmonary fibrosis remains unknown. Gastroesophageal reflux, a presumed risk factor for microaspiration, has been strongly associated with idiopathic pulmonary fibrosis with an estimated prevalence of 90%. This review aims to describe the relationship between chronic microaspiration and idiopathic pulmonary fibrosis by laying out the clinical and biologic rationale for this relationship and exploring the scientific evidence available. The gaps in our current understanding of the diagnosis of chronic microaspiration and idiopathic pulmonary fibrosis and the ongoing uncertainties in management and treatment will be highlighted. Defining the role of chronic microaspiration in idiopathic pulmonary fibrosis is essential as it has potential clinical, pathobiological and treatment implications for this deadly disease.
pulmonary fibrosis; respiratory aspiration; gastroesophageal reflux; etiology; diagnostic techniques and procedures
Proapoptotic Bcl-2 family members have been proposed to play a central role in regulating apoptosis. However, mice lacking bax display limited phenotypic abnormalities. As presented here, bak–/– mice were found to be developmentally normal and reproductively fit and failed to develop any age-related disorders. However, when Bak-deficient mice were mated to Bax-deficient mice to create mice lacking both genes, the majority of bax–/–bak–/– animals died perinatally with fewer than 10% surviving into adulthood. bax–/–bak–/– mice displayed multiple developmental defects, including persistence of interdigital webs, an imperforate vaginal canal, and accumulation of excess cells within both the central nervous and hematopoietic systems. Thus, Bax and Bak have overlapping roles in the regulation of apoptosis during mammalian development and tissue homeostasis.
This prospective study evaluated the plasma and intrapulmonary pharmacokinetics and pharmacodynamics (PKPD) of posaconazole (POS) in lung transplant recipients. Twenty adult lung transplant patients were instructed to take a 400-mg POS oral suspension twice daily (BID) with a high-fat meal for a total of 14 doses. Pulmonary epithelial lining fluid (ELF) and alveolar cell (AC) samples were obtained via bronchoalveolar lavage, and blood samples were collected at the approximate time of bronchoscopy. POS concentrations were assayed using liquid chromatography with tandem mass spectrometry. The maximum concentrations (Cmax) (mean ± standard deviation [SD]) in plasma, ELF, and AC were 1.3 ± 0.4, 1.3 ± 1.7, and 55.4 ± 44.0 μg/ml. POS concentrations in plasma, ELF, and AC did not decrease significantly, indicating slow elimination after multiple dosing. Mean concentrations of POS in plasma, ELF, and AC were above the MIC90 (0.5 μg/ml) for Aspergillus species over the 12-h dosing interval and for 24 h following the last dose. Area under the concentration-time curve from 0 to 12 h (AUC0-12)/MIC90 ratios in plasma, ELF, and AC were 21.98, 22.42, and 1,060. We concluded that a dose of 400 mg BID resulted in sustained plasma, ELF, and AC concentrations above the MIC90 for Aspergillus spp. during the dosing interval. Confirmation of the therapeutic value of these observations requires further investigation. The intrapulmonary PKPD of POS may be favorable for treatment or prevention of aspergillosis, although further research on the relevant PKPD parameters and the effect of POS protein binding is required.
Invasive pulmonary aspergillosis is a life-threatening infection in lung transplant recipients; however, no studies of the pharmacokinetics and pharmacodynamics (PKPD) of echinocandins in transplanted lungs have been reported. We conducted a single-dose prospective study of the intrapulmonary and plasma PKPD of 150 mg of micafungin administered intravenously in 20 adult lung transplant recipients. Epithelial lining fluid (ELF) and alveolar cell (AC) samples were obtained via bronchoalveolar lavage performed 3, 5, 8, 18, or 24 h after initiation of infusion. Micafungin concentrations in plasma, ELF, and ACs were determined using high-pressure liquid chromatography. Noncompartmental methods, population analysis, and multiple-dose simulations were used to calculate PKPD parameters. Cmax in plasma, ELF, and ACs was 4.93, 1.38, and 17.41 μg/ml, respectively. The elimination half-life in plasma was 12.1 h. Elevated concentrations in ELF and ACs were sustained during the 24-h sampling period, indicating prolonged compartmental half-lives. The mean micafungin concentration exceeded the MIC90 of Aspergillus fumigatus (0.0156 μg/ml) in plasma (total and free), ELF, and ACs throughout the dosing interval. The area under the time-concentration curve from 0 to 24 h (AUC0-24)/MIC90 ratios in plasma, ELF, and ACs were 5,077, 923.1, and 13,340, respectively. Multiple-dose simulations demonstrated that ELF and AC concentrations of micafungin would continue to increase during 14 days of administration. We conclude that a single 150-mg intravenous dose of micafungin resulted in plasma, ELF, and AC concentrations that exceeded the MIC90 of A. fumigatus for 24 h and that these concentrations would continue to increase during 14 days of administration, supporting its potential activity for prevention and early treatment of pulmonary aspergillosis.
Rationale: In 2005, lung allocation for transplantation in the United States changed from a system based on waiting time to a system based on the Lung Allocation Score (LAS).
Objectives: To study the effect of the LAS on lung transplantation for idiopathic pulmonary arterial hypertension (IPAH) compared with other major diagnoses.
Methods: We studied 7,952 adults listed for lung transplantation between 2002 and 2008. Analyses were restricted to patients with IPAH, idiopathic pulmonary fibrosis (IPF), chronic obstructive pulmonary disease (COPD), and cystic fibrosis (CF). Transplantation, waiting list mortality, and post-transplant mortality were compared between diagnoses for patients listed before and after implementation of the LAS.
Measurements and Main Results: The likelihood of transplantation from the waiting list increased for all diagnoses after implementation of the LAS. Waiting list mortality decreased for every diagnosis, except for IPAH, which remained unchanged. Implementation of the LAS was not associated with changes in post-transplant mortality for any diagnosis. Under the LAS system, patients with IPAH were less likely to be transplanted than patients with IPF (hazard ratio [HR], 0.53; P < 0.001) or CF (HR, 0.49; P < 0.001) and at greater risk of death on the waiting list than patients with COPD (HR, 3.09; P < 0.001) or CF (HR, 1.83; P = 0.025) after adjustment for demographics and transplant type. Post-transplant mortality for IPAH was not statistically different from that of other diagnoses.
Conclusions: Implementation of the LAS has improved the likelihood of lung transplantation for listed patients with IPAH, but mortality on the waiting list remains high compared with other major diagnoses.
lung transplantation; pulmonary arterial hypertension; lung allocation score
Mutations in the X-linked aristaless-related homeobox gene (ARX) have been linked to structural brain anomalies as well as multiple neurocognitive deficits. The generation of Arx-deficient mice revealed several morphological anomalies, resembling those observed in patients and an interneuron migration defect but perinatal lethality precluded analyses of later phenotypes. Interestingly, many of the neurological phenotypes observed in patients with various ARX mutations can be attributed, in part, to interneuron dysfunction. To directly test this possibility, mice carrying a floxed Arx allele were generated and crossed to Dlx5/6CRE-IRES-GFP(Dlx5/6CIG) mice, conditionally deleting Arx from ganglionic eminence derived neurons including cortical interneurons. We now report that Arx−/y;Dlx5/6CIG (male) mice exhibit a variety of seizure types beginning in early-life, including seizures that behaviourally and electroencephalographically resembles infantile spasms, and show evolution through development. Thus, this represents a new genetic model of a malignant form of paediatric epilepsy, with some characteristics resembling infantile spasms, caused by mutations in a known infantile spasms gene. Unexpectedly, approximately half of the female mice carrying a single mutant Arx allele (Arx−/+;Dlx5/6CIG) also developed seizures. We also found that a subset of human female carriers have seizures and neurocognitive deficits. In summary, we have identified a previously unrecognized patient population with neurological deficits attributed to ARX mutations that are recapitulated in our mouse model. Furthermore, we show that perturbation of interneuron subpopulations is an important mechanism underling the pathogenesis of developmental epilepsy in both hemizygous males and carrier females. Given the frequency of ARX mutations in patients with infantile spasms and related disorders, our data unveil a new model for further understanding the pathogenesis of these disorders.
Epilepsy; development; conditional knockout; genetic model; interneurons
Undifferentiated connective tissue disease (UCTD) is a distinct clinical entity that may be accompanied by interstitial lung disease (ILD). The natural history of UCTD-ILD is unknown. We hypothesized that patients with UCTD-ILD would be more likely to have improvement in lung function than those with idiopathic pulmonary fibrosis (IPF) during longitudinal follow-up. We identified subjects enrolled in the UCSF ILD cohort study with a diagnosis of IPF or UCTD. The primary outcome compared the presence or absence of a ≥5% increase in percent predicted forced vital capacity (FVC) in IPF and UCTD. Regression models were used to account for potential confounding variables. Ninety subjects were identified; 59 subjects (30 IPF, 29 UCTD) had longitudinal pulmonary function data for inclusion in the analysis. After accounting for baseline pulmonary function tests, treatment, and duration between studies, UCTD was associated with substantial improvement in FVC (odds ratio = 8.23, 95% confidence interval, 1.27–53.2; p = 0.03) during follow-up (median, 8 months) compared with IPF. Patients with UCTD-ILD are more likely to have improved pulmonary function during follow-up than those with IPF. These findings demonstrate the clinical importance of identifying UCTD in patients presenting with an “idiopathic” interstitial pneumonia.
Idiopathic interstitial pneumonia; Systemic rheumatic disease; Undifferentiated connective tissue; Collagen vascular disease; Autoimmune disease
An estimated 1-3% of individuals within the United States are diagnosed with mental retardation (MR), yet the cause is unknown in nearly 50% of the patients. While several environmental, genetic and combined teratogenetic etiologies have been identified, many causative genes remain to be identified. Furthermore, the pathogenetic mechanisms underlying MR are known for very few of these genes. Males have a much higher incidence of MR implicating genes on the X-chromosome. We have recently identified a novel gene, SIZN1, on the X-chromosome and showed that it functions in modulating the BMP signaling pathway. Furthermore, we have shown this gene is necessary for basal forebrain cholinergic neuron (BFCN) specific gene expression. Given that cognitive function is impaired when BFCNs are lost or functionally disrupted, we undertook a screen of cognitively impaired males for SIZN1 mutations. We report on four different sequence variants in SIZN1 in 11 individuals with nonsyndromic X-linked mental retardation. Our data implicate SIZN1 as a candidate gene for X-linked mental retardation and/or as a neurocognitive functional modifier.
BMP; SIZN1(ZCCHC12); forebrain cholinergic neuron; X-linked mental retardation
We evaluated the pharmacokinetics (PK) and pharmacodynamics (PD) of posaconazole (POS) in a prospective, open-label study. Twenty-five healthy adults received 14 doses of POS oral suspension (400 mg twice daily) with a high-fat meal over 8 days. Pulmonary epithelial lining fluid (ELF) and alveolar cell (AC) samples were obtained via bronchoalveolar lavage, and blood samples were collected during the 24 h after the last dose. POS concentrations were determined using liquid chromatography with tandem mass spectrometry parameters. The maximum concentrations (Cmax) (mean ± standard deviation) in plasma, ELF, and ACs were 2.08 ± 0.93, 1.86 ± 1.30, and 87.7 ± 65.0 μg/ml. The POS concentrations in plasma, ELF, and ACs did not decrease significantly, indicating slow elimination after multiple dosing. The mean concentrations of POS in plasma, ELF, and ACs were above the MIC90 (0.5 μg/ml) for Aspergillus spp. over the 12-h dosing interval and for 24 h following the last dose. Area under the curve from 0 to 12 h (AUC0-12) ratios for ELF/plasma and AC/plasma were 0.84 and 33. AUC0-24/MIC90 ratios in plasma, ELF, and AC were 87.6, 73.2, and 2,860. Nine (36%) of 25 subjects had treatment-related adverse events during the course of the study, which were all mild or moderate. We conclude that a dose of 400 mg twice daily resulted in sustained plasma, ELF, and AC concentrations above the MIC90 for Aspergillus spp. during the dosing interval. The intrapulmonary PK/PD of POS are favorable for treatment or prevention of aspergillosis, and oral POS was well tolerated in healthy adults.
Rationale: The Scleroderma Lung Study enrolled 158 patients with scleroderma-related interstitial lung disease in a placebo-controlled trial of oral cyclophosphamide (CYC). Although treatment-related benefits in pulmonary function, skin scores, and patient-centered outcomes were demonstrated after 1 year of therapy, the duration of benefit beyond 1 year was unclear.
Objectives: A second year of follow-up was performed to determine if these effects persisted after stopping treatment.
Methods: A detailed analysis of data obtained over the two years of the study was performed.
Measurements and Main Results: Using a longitudinal joint model, we analyzed FVC, total lung capacity, transitional dyspnea index, Rodnan skin scores, and the Health Assessment Questionnaire–Disability Index during the second year, after adjusting for baseline values, baseline fibrosis score, and nonignorable missing data. Evaluable subjects (72 CYC; 73 placebo) included 93 who completed all visits plus 52 who completed at least 6 months of therapy and returned at 24 month or had their 24-month data imputed. The beneficial effects of CYC on pulmonary function and health status continued to increase through 18 months, after which they dissipated, whereas skin improvements dissipated after 12 months. In contrast, the positive effect on dyspnea persisted through 24 months. Adverse events were uncommon.
Conclusions: One year of CYC improved lung function, skin scores, dyspnea, and health status/disability, effects which either persisted or increased further for several months after stopping therapy. However, except for a sustained impact on dyspnea, all of these effects waned and were no longer apparent at 24 months. Treatment strategies aimed at extending the positive therapeutic effects observed with CYC should be considered.
Clinical trial registered with www.clinicaltrials.gov (NCT 000004563).
cyclophosphamide; interstitial lung disease; scleroderma; systemic sclerosis
Mutations in the aristaless-related homeobox (ARX) gene are associated with multiple neurologic disorders in humans. Studies in mice indicate Arx plays a role in neuronal progenitor proliferation and development of the cerebral cortex, thalamus, hippocampus, striatum, and olfactory bulbs. Specific defects associated with Arx loss of function include abnormal interneuron migration and subtype differentiation. How disruptions in ARX result in human disease and how loss of Arx in mice results in these phenotypes remains poorly understood. To gain insight into the biological functions of Arx, we performed a genome-wide expression screen to identify transcriptional changes within the subpallium in the absence of Arx. We have identified 84 genes whose expression was dysregulated in the absence of Arx. This population was enriched in genes involved in cell migration, axonal guidance, neurogenesis, and regulation of transcription and includes genes implicated in autism, epilepsy, and mental retardation; all features recognized in patients with ARX mutations. Additionally, we found Arx directly repressed three of the identified transcription factors: Lmo1, Ebf3 and Shox2. To further understand how the identified genes are involved in neural development, we used gene set enrichment algorithms to compare the Arx gene regulatory network (GRN) to the Dlx1/2 GRN and interneuron transcriptome. These analyses identified a subset of genes in the Arx GRN that are shared with that of the Dlx1/2 GRN and that are enriched in the interneuron transcriptome. These data indicate Arx plays multiple roles in forebrain development, both dependent and independent of Dlx1/2, and thus provides further insights into the understanding of the mechanisms underlying the pathology of mental retardation and epilepsy phenotypes resulting from ARX mutations.
Integrins are required for normal muscle differentiation and disruptions in integrin signaling result in human muscle disease. The intracellular components that regulate integrin function during myogenesis are poorly understood. Unc-112 is an integrin-associated protein required for muscle development in C. elegans. To better understand the intracellular effectors of integrin signaling in muscle, we examined the mammalian homolog of Unc-112, kindlin-2.
Kindlin-2 expression is upregulated during differentiation and highly enriched at sites of integrin localization. RNAi knockdown of kindlin-2 in C2C12 cells results in significant abnormalities during the early stages of myogenesis. Specifically, differentiating myocytes lacking kindlin-2 are unable to elongate and fail to fuse into multinucleated myotubes. These changes are correlated with decreased cell substratum adhesion and increased cell motility. They are also associated with redistribution of a known kindlin-2 binding partner, integrin linked kinase (ILK), to the membrane insoluble subcellular fraction.
In all, our study reveals kindlin-2 as a novel integrin adaptor protein important for muscle differentiation, and identifies it particularly as a critical regulator of myocyte elongation.
Bone morphogenic proteins (BMPs) play pleotrophic roles in nervous system development, and their signaling is highly regulated at virtually every step in the pathway. We have cloned a novel gene, Sizn1 (Smad-interacting zinc finger protein), which functions as a transcriptional coactivator of BMP signaling. It positively modulates BMP signaling by interacting with Smad family members and associating with CBP in the transcription complex. Sizn1 is expressed in the ventral embryonic forebrain, where, as we will show, it contributes to BMP-dependent, cholinergic-neuron-specific gene expression. These data indicate that Sizn1 is a positive modulator of BMP signaling and provide further insight into how BMP signaling can be modulated in neuronal progenitor subsets to influence cell-type-specific gene expression and development.
Rejection and obliterative bronchiolitis are barriers to sustained graft function in recipients of transplanted lungs. Early detection is hindered by inadequate tests and an incomplete understanding of the molecular events preceding or accompanying graft deterioration.
Hypothesizing that genes involved in immune responses and tissue remodeling produce biomarkers of rejection, we measured the expression of 192 selected genes in 72 sets of biopsy specimens from human lung allografts. Gene transcripts were quantified using a 2-step, multiplex, real-time polymerase chain reaction approach in endobronchial and transbronchial biopsy specimens from transplant recipients without acute infections undergoing routine surveillance bronchoscopy.
Comparisons of histopathology in parallel biopsy specimens identified 6 genes correlating with rejection as manifested by lymphocytic bronchitis, a suspected harbinger of obliterative bronchiolitis. For example, β2-defensin and collagenase transcripts in inflamed bronchi increased 37-fold and 163-fold, respectively. By contrast, these transcripts did not correlate with acute rejection in transbronchial specimens. Further, no correspondence was noted between histopathologic bronchitis and parenchymal rejection when endobronchial and transbronchial samples were obtained from the same patient.
Our highly sensitive method permits quantitation of many gene transcripts simultaneously in small, bronchoscopically acquired biopsy specimens of allografts. Transcript signatures obtained by this approach suggest that airway and alveolar responses to rejection differ and that endobronchial biopsy specimens assess lymphocytic bronchitis and chronic rejection but are not proxies for transbronchial biopsy specimens. Further, they reveal changes in airway expression of the specific genes involved in host defense and remodeling and suggest that the measurement of transcripts correlating with lymphocytic bronchitis may be diagnostic adjuncts to histopathology.
Reducing body myopathy (RBM) is a rare disorder causing progressive muscular weakness characterized by aggresome-like inclusions in the myofibrils. Identification of genes responsible for RBM by traditional genetic approaches has been impossible due to the frequently sporadic occurrence in affected patients and small family sizes. As an alternative approach to gene identification, we used laser microdissection of intracytoplasmic inclusions identified in patient muscle biopsies, followed by nanoflow liquid chromatography–tandem mass spectrometry and proteomic analysis. The most prominent component of the inclusions was the Xq26.3-encoded four and a half LIM domain 1 (FHL1) protein, expressed predominantly in skeletal but also in cardiac muscle. Mutational analysis identified 4 FHL1 mutations in 2 sporadic unrelated females and in 2 families with severely affected boys and less-affected mothers. Transfection of kidney COS-7 and skeletal muscle C2C12 cells with mutant FHL1 induced the formation of aggresome-like inclusions that incorporated both mutant and wild-type FHL1 and trapped other proteins in a dominant-negative manner. Thus, a novel laser microdissection/proteomics approach has helped identify both inherited and de novo mutations in FHL1, thereby defining a new X-linked protein aggregation disorder of muscle.
Using a tissue-specific microarray screen in combination with chromosome anomalies in the mouse, we identified a novel imprinted gene, Inpp5f_v2 on mouse chromosome 7. Characterization of this gene reveals a 3.2-kb transcript that is paternally expressed in the brain. Inpp5f_v2 is a variant of the related 4.7-kb transcript, Inpp5f, an inositol phosphatase gene that is biallelically expressed in the mouse. Inpp5f_v2 uses an alternative transcriptional start site within an intron of Inpp5f and thus has a unique alternative first exon. Whereas other imprinted transcripts have a unique first exon located within intron 1 of a longer transcript variant (such as at the Gnas and WT1 loci), Inpp5f_v2 is the first example of which we are aware in which the alternative first exon of an imprinted gene is embedded in a downstream intron (intron 15) of a transcript variant. The CpG island associated with the nonimprinted Inpp5f gene is hypomethylated on both alleles, a finding consistent with biallelic expression, whereas the CpG island present 5′ of Inpp5f_v2 is differentially methylated on the maternal versus paternal alleles consistent with its imprinting status.
A growing number of human disorders have been associated with expansions of a tract of a single amino acid. Recently, polyalanine (polyA) tract expansions in the Aristaless-related homeobox (ARX) protein have been identified in a subset of patients with infantile spasms and mental retardation. How alanine expansions in ARX, or any other transcription factor, cause disease have not been determined. We generated a series of polyA expansions in Arx and expressed these in cell culture and brain slices. Transfection of these constructs results in nuclear protein aggregation, filamentous nuclear inclusions, and an increase in cell death. These inclusions are ubiquitinated and recruit Hsp70. Coexpressing Hsp70 decreases the percentage of cells with nuclear inclusions. Finally, we show that expressing mutant Arx in mouse brains results in neuronal nuclear inclusion formation. Our data suggest expansions in one of the ARX polyA tracts results in nuclear protein aggregation and an increase in cell death; likely underlying the pathogenesis of the associated infantile spasms and mental retardation.
We determined the steady-state intrapulmonary pharmacokinetic and pharmacodynamic parameters of orally administered itraconazole (ITRA), 200 mg every 12 h (twice a day [b.i.d.]), on an empty stomach, for a total of 10 doses, in 26 healthy volunteers. Five subgroups each underwent standardized bronchoscopy and bronchoalveolar lavage (BAL) at 4, 8, 12, 16, and 24 h after administration of the last dose. ITRA and its main metabolite, 14-hydroxyitraconazole (OH-IT), were measured in plasma, BAL fluid, and alveolar cells (AC) using high-pressure liquid chromatography. Half-life and area under the concentration-time curves (AUC) in plasma, epithelial lining fluid (ELF), and AC were derived using noncompartmental analysis. ITRA and OH-IT maximum concentrations of drug (Cmax) (mean ± standard deviation) in plasma, ELF, and AC were 2.1 ± 0.8 and 3.3 ± 1.0, 0.5 ± 0.7 and 1.0 ± 0.9, and 5.5 ± 2.9 and 6.6 ± 3.1 μg/ml, respectively. The ITRA and OH-IT AUC for plasma, ELF, and AC were 34.4 and 60.2, 7.4 and 18.9, and 101 and 134 μg · hr/ml. The ratio of the Cmax and the MIC at which 90% of the isolates were inhibited (MIC90), the AUC/MIC90 ratio, and the percent dosing interval above MIC90 for ITRA and OH-IT concentrations in AC were 1.1 and 3.2, 51 and 67, and 100 and 100%, respectively. Plasma, ELF, and AC concentrations of ITRA and OH-IT declined monoexponentially with half-lives of 23.1 and 37.2, 33.2 and 48.3, and 15.7 and 45.6 h, respectively. An oral dosing regimen of ITRA at 200 mg b.i.d. results in concentrations of ITRA and OH-ITRA in AC that are significantly greater than those in plasma or ELF and intrapulmonary pharmacodynamics that are favorable for the treatment of fungal respiratory infection.
The objective of this study was to determine the steady-state plasma and intrapulmonary pharmacokinetic parameters of orally administered cethromycin in healthy volunteers. The study design included administering 150 or 300 mg of cethromycin once daily to 25 or 35 healthy adult subjects, respectively, for a total of five doses. Standardized and timed bronchoalveolar lavage (BAL) was performed after the last dose. Blood was obtained for drug assay prior to the first and last dose, at multiple time points following the last dose, and at the time of BAL. Cethromycin was measured in plasma, BAL, and alveolar cell (AC) by using a combined high-performance liquid chromatography-mass spectrometric technique. Plasma, epithelial lining fluid (ELF), and AC pharmacokinetics were derived by noncompartmental methods. Cmax/90% minimum inhibitory concentration (MIC90) ratios, area under the concentration-time curve (AUC)/MIC90 ratios, intrapulmonary drug exposure ratios, and percent time above MIC90 during the dosing interval (%T > MIC90) were calculated for recently reported respiratory pathogens. The kinetics were nonlinear, i.e., not proportional to dose. In the 150-mg-dose group, the Cmax (mean ± standard deviations), AUC0-24, and half-life for plasma were 0.181 ± 0.084 μg/ml, 0.902 ± 0.469 μg · h/ml, and 4.85 ± 1.10 h, respectively; for ELF the values were 0.9 ± 0.2 μg/ml, 11.4 μg · h/ml, and 6.43 h, respectively; for AC the values were 12.7 ± 6.4 μg/ml, 160.8 μg · h/ml, and 10.0 h, respectively. In the 300-mg-dose group, the Cmax (mean ± standard deviations), AUC0-24, and half-life for plasma were 0.500 ± 0.168 μg/ml, 3.067 ± 1.205 μg · h/ml, and 4.94 ± 0.66 h, respectively; for ELF the values were 2.7 ± 2.0 μg/ml, 24.15 μg · h/ml, and 5.26 h, respectively; for AC the values were 55.4 ± 38.7 μg/ml, 636.2 μg · h/ml, and 11.6 h, respectively. We concluded that the Cmax/MIC90 ratios, AUC/MIC90 ratios, %T > MIC90 values, and extended plasma and intrapulmonary half-lives provide a pharmacokinetic rationale for once-daily administration and are favorable for the treatment of cethromycin-susceptible pulmonary infections.