Citations

ABSTRACT Inefficient adenoviral vector (AdV)-mediated gene transfer to the ciliated respiratory epithelium has hindered gene transfer strategies for the treatment of cystic fibrosis lung disease. In part, the inefficiency is due to an absence of the coxsackie B and adenovirus type 2 and 5 receptor (CAR) from the apical membranes of polarized epithelia. In this study, using an in vitro model of human ciliated airway epithelium, we show that providing a glycosylphosphatidylinositol (GPI)-linked AdV receptor (GPI-CAR) at the apical surface did not significantly improve AdV gene transfer efficiency because the lumenal surface glycocalyx limited the access of AdV to apical GPI-CAR. The highly glycosylated tethered mucins were considered to be significant glycocalyx components that restricted AdV access because proteolytic digestion and inhibitors of O-linked glycosylation enhanced AdV gene transfer. To determine whether these in vitro observations are relevant to the in vivo situation, we generated transgenic mice expressing GPI-CAR at the surface of the airway epithelium, crossbred these mice with mice that were genetically devoid of tethered mucin type 1 (Muc1), and tested the efficiency of gene transfer to murine airways expressing apical GPI-human CAR (GPI-hCAR) in the presence and absence of Muc1. We determined that AdV gene transfer to the murine airway epithelium was inefficient even in GPI-hCAR transgenic mice but that the gene transfer efficiency improved in the absence of Muc1. However, the inability to achieve a high gene transfer efficiency, even in mice with a deletion of Muc1, suggested that other glycocalyx components, possibly other tethered mucin types, also provide a significant barrier to AdV interacting with the airway lumenal surface.

▪ Abstract The assembly of the cystic fibrosis transmembrane regulator (CFTR) chloride channel is of interest from the broad perspective of understanding how ion channels and ABC transporters are formed as well as dealing with the mis-assembly of CFTR in cystic fibrosis. CFTR is functionally distinct from other ABC transporters because it permits bidirectional permeation of anions rather than vectorial transport of solutes. This adaptation of the ABC transporter structure can be rationalized by considering CFTR as a hydrolyzable-ligand-gated channel with cytoplasmic ATP as ligand. Channel gating is initiated by ligand binding when the protein is also phosphorylated by protein kinase A and made reversible by ligand hydrolysis. The two nucleotide-binding sites play different roles in channel activation. CFTR self-associates, possibly as a function of its activation, but most evidence, including the low-resolution three-dimensional structure, indicates that the channel is monomeric. Domain assembly and interaction within the monomer is critical in maturation, stability, and function of the protein. Disease-associated mutations, including the most common, ΔF508, interfere with domain folding and association, which occur both co- and post-translationally. Intermolecular interactions of mature CFTR have been detected primarily with the N- and C-terminal tails, and these interactions have some impact not only on channel function but also on localization and processing within the cell. The biosynthetic processing of the nascent polypeptide leading to channel assembly involves transient interactions with numerous chaperones and enzymes on both sides of the endoplasmic reticulum membrane.

The breakpoint cluster region protein (Bcr) is a large soluble oligomeric multidomain protein best known because of its involvement in chronic myelogenous leukemia (CML). A chromosomal translocation between its gene and that of the c-abl kinase (`Philadelphia chromosome') plays a major causative role in that malignancy. Thus most attention has been paid to the role of the protein in hemopoietic cells. However, Bcr is also expressed in other cell types including epithelia. Bcr is generally considered to be a cytoplasmic protein but in addition to its kinase and GTPase exchange and activating domains it contains potentially membrane-interacting pleckstrin homology and C2 domains as well as a PDZ-binding C terminus mediating an interaction with a PDZ-domain protein at intercellular junctions of epithelial cells. We have examined the ability of Bcr to interact with other epithelial PDZ proteins and found specific binding to both the apical PDZK1 protein and the Golgi-localized Mint3. The former is important in the organization of several apical functions and the latter in vesicular trafficking in the secretory pathway. Hence these findings extend the interactions and likely signaling impact of Bcr in epithelia from the cytosol to at least these two membrane compartments.

Cystic fibrosis (CF) is a childhood hereditary disease in which the most common mutant form of the CF transmembrane conductance regulator (CFTR) ΔF508 fails to exit the endoplasmic reticulum (ER). Export of wild-type CFTR from the ER requires the coat complex II (COPII) machinery, as it is sensitive to Sar1 mutants that disrupt normal coat assembly and disassembly. In contrast, COPII is not used to deliver CFTR to ER-associated degradation. We find that exit of wild-type CFTR from the ER is blocked by mutation of a consensus di-acidic ER exit motif present in the first nucleotide binding domain. Mutation of the code disrupts interaction with the COPII coat selection complex Sec23/Sec24. We propose that the di-acidic exit code plays a key role in linking CFTR to the COPII coat machinery and is the primary defect responsible for CF in ΔF508-expressing patients.

Purpose To determine whether weekly epoetin alfa could improve hemoglobin (HgB) levels, reduce RBC transfusions, and improve quality of life (QOL) in patients with advanced cancer and with anemia after receiving myelosuppressive chemotherapy. Patients and Methods This double-blind, placebo-controlled study randomly assigned patients to placebo or epoetin alfa (Ortho Biotech, Bridgewater, NJ) 40,000 U subcutaneous weekly for 16 weeks. QOL, HgB, and RBC transfusions were measured pretreatment and monthly. Results The study accrued 344 patients; 330 were assessable for efficacy and 305 were assessable for QOL. Placebo-treated patients had a mean increase in HgB of 0.9 g/dL (range, −3.8 to +5.3) compared with 2.8 g/dL (range, −2.2 to +7.5) for epoetin-treated patients (P < .0001). During the study, 31.7% of placebo-treated patients achieved a ≥ 2 g/dL HgB increase compared with 72.7% of epoetin-treated patients (P < .0001). The incidence of RBC transfusion for placebo and epoetin treatment arms was 39.6% and 25.3% (P = .005), respectively. The placebo group received 256 units of RBCs compared with 127 units in the epoetin group (P < .0001). The incidence of toxicity in the groups was similar. Changes in the average QOL scores from baseline to the end of the study were similar in the two groups (P = not significant). The HgB responders (irrespective of treatment arm) had a mean change in Functional Assessment of Cancer Therapy (FACT) fatigue score from a baseline of +5.1 compared with −2.1 for the nonresponders (P = .006). Conclusion Epoetin alfa significantly improved HgB and reduced transfusions in this patient population. These results support the use of weekly epoetin alfa as an ameliorative agent for cancer-related anemia.

Objective. Surgery for craniosynostosis has evolved rapidly over the past two decades, with increased emphasis on early, extensive operations. Older published series may not accurately reflect more recent experience. Our study was designed to analyze outcome in a large series of consecutive patients treated recently at a single center.Methods. We reviewed 250 consecutive patients who underwent surgical treatment of craniosynostosis between January 1, 1987 and December 31, 1992. They were divided into nine groups by suture involvement: sagittal, unilateral coronal, bilateral coronal, unilateral lambdoid, bilateral lambdoid, metopic, multiple suture, the Klee-blattschädel deformity (cloverleaf skull), and acquired craniosynostosis. Outcome was analyzed in terms of residual deformities and irregularities, complications, mortality, as well as the need for additional surgery.Results. There were 157 males (62.8%) and 93 females (37.2%), with most of the male preponderance accounted for by the large sagittal synostosis group, which consisted of 82 males and 25 females. Median age at first operation was 147 days. A named syndrome was present in 23 patients (9.2%) and was more common than expected with bilateral and unilateral coronal synostosis, the Kleeblattschädel deformity, and multiple suture synostosis. There were two deaths (0.8%), both with Klee-blattschädel patients, and 17 other complications (6.8%). Morbidity and mortality were significantly associated with secondary vs primary operations and syndromic vs nonsyndromic patients. Outcome analysis revealed the best surgical results with metopic synostosis and significantly less good results with the Kleeblattschädel deformity, multiple suture synostosis, and bilateral coronal synostosis.Conclusions. Using modern surgical techniques, craniosynostosis can be corrected with good outcomes and relatively low morbidity and mortality, particularly for otherwise healthy, nonsyndromic infants.

Purpose Some patients with colon cancer have a high risk of local recurrence postoperatively. This trial was undertaken to determine whether radiation therapy added to an adjuvant chemotherapy regimen improves outcome in high-risk patients. Patients and Methods Patients with resected colon cancer with tumor adherence or invasion of surrounding structures, or with T3N1 or T3N2 tumors of the ascending or descending colon were randomly assigned to receive fluorouracil and levamisole therapy with or without radiation therapy. Patients who received chemotherapy and radiation therapy (chemoRT) received 45 to 50.4 Gy in 25 to 28 fractions beginning 28 days after starting chemotherapy. Patient enrollment was terminated because of slow accrual after 222 patients enrolled (original goal was 700 patients); 187 patients were assessable. Results Overall 5-year survival was 62% for chemotherapy patients and 58% for chemoRT patients (P > .50); 5-year disease-free survival was 51% for both groups (P > .50). Toxicity (≥ grade 3) occurred in 42% of chemotherapy patients and 54% of chemoRT patients (P = .04). Leukopenia (≥ grade 3) occurred in 10% of chemotherapy patients and 22% of chemoRT patients (P = .02). No significant difference in nonhematologic toxicity (≥ grade 3) was observed between chemoRT and chemotherapy patients (35% v 44%; P = .26). Conclusion Patients who received chemotherapy or chemoRT had similar overall survival and disease-free survival. Toxicity was higher among chemoRT patients. These results must be interpreted with caution because of the high number of ineligible patients and the limited power of the study to detect potentially meaningful differences.

Abstract Background: Transthyretin-associated hereditary amyloidosis (ATTR) is an inherited disease in which variants in the primary structure of transthyretin (TTR; prealbumin) lead to the extracellular polymerization of insoluble protein fibrils, causing organ failure and ultimately death when major organs are involved. We have developed an integrated approach to molecular diagnosis with initial analysis of intact plasma TTR by electrospray ionization mass spectrometry (MS) and referral of positive samples for DNA sequence analysis and real-time PCR to confirm the common Gly6Ser polymorphism. Methods: Samples from 6 patients previously diagnosed with ATTR and from 25 controls with (n = 15) or without (n = 10) polyneuropathy were analyzed in a blinded fashion for the presence of variant TTR. TTR protein was extracted with an immunoaffinity resin from 20 μL of archived plasma samples. The purified TTR was reduced with tris(2-carboxyethyl)phosphine and analyzed by MS. The appearance of two peaks (or a single peak shifted in mass indicative of a homozygous variant), including the wild-type mass of 13 761 Da, was indicative of the presence of a variant, and the individual was referred for DNA sequence analysis. Results: MS analysis of intact reduced TTR correctly identified each of six samples known to contain variant TTR. These results were corroborated by subsequent DNA sequence analysis. Additionally, all Gly6Ser polymorphisms were correctly called based on the +30 mass shift and an equal relative abundance of the +30 polymorphism relative to wild-type TTR. No false-positive results were seen. Conclusions: This referral method eliminates the necessity of sequencing most samples and allows screening for the familial forms of amyloidosis in a broad patient population in a timely fashion. This method correctly identified all previously known variants and also identified a novel variant, Val94Ala.