Can HRCT be used as a marker of airway remodelling in children with difficult asthma?

BACKGROUND: Whole airway wall thickening on high resolution computed tomography (HRCT) is reported to parallel thickening of the bronchial epithelial reticular basement membrane (RBM) in adult asthmatics. A similar relationship in children with difficult asthma (DA), in whom RBM thickening is a known feature, may allow the use of HRCT as a non-invasive marker of airway remodelling. We evaluated this relationship in children with DA. METHODS: 27 children (median age 10.5 [range 4.1-16.7] years) with DA, underwent endobronchial biopsy from the right lower lobe and HRCT less than 4 months apart. HRCTs were assessed for bronchial wall thickening (BWT) of the right lower lobe using semi-quantitative and quantitative scoring techniques. The semi-quantitative score (grade 0-4) was an overall assessment of BWT of all clearly identifiable airways in HRCT scans. The quantitative score (BWT %; defined as [airway outer diameter - airway lumen diameter]/airway outer diameter x100) was the average score of all airways visible and calculated using electronic endpoint callipers. RBM thickness in endobronchial biopsies was measured using image analysis. 23/27 subjects performed spirometry and the relationships between RBM thickness and BWT with airflow obstruction evaluated. RESULTS: Median RBM thickness in endobronchial biopsies was 6.7(range 4.6-10.0) microm. Median qualitative score for BWT of the right lower lobe was 1(range 0-1.5) and quantitative score was 54.3 (range 48.2-65.6)%. There was no relationship between RBM thickness and BWT in the right lower lobe using either scoring technique. No relationship was found between FEV1 and BWT or RBM thickness. CONCLUSION: Although a relationship between RBM thickness and BWT on HRCT has been found in adults with asthma, this relationship does not appear to hold true in children with DA.

Immunologically cross-reactive 57 kDa and 53 kDa glycoprotein antigens of bovine milk fat globule membrane: isoforms with different N-linked sugar chains and differential glycosylation at early stages of lactation.

Two glycoprotein antigens with molecular masses of 57 kDa (MGP57) and 53 kDa (MGP53) were co-purified from bovine milk fat globule membrane (MFGM) by immunoaffinity chromatography using a monoclonal antibody raised against the MFGM. Their N-terminal sequences of 22 amino acids determined were identical, and the sequence was homologous (about 60% identical) to the deduced amino acid sequence of mouse milk fat globule epidermal growth factor (EGF) factor 8 (MFG-E8) (Ref. [12], Stubbs, J.D. et al., Proc. Natl. Acad. Sci. USA, 87, 8417-8421, 1990). This suggests that MGP57/53 are bovine MFGM components 15/16 (PAS-6 and PAS-7), which have recently been reported to be bovine homologs of MFG-E8. N-Glycanase treatment of these glycoproteins reduced their molecular masses, and consequently the enzymatically deglycosylated MGP57 and MGP53 converged on a single band of 50 kDa as measured by SDS-PAGE, indicating that the polypeptide portions of these two distinct glycoprotein antigens are very similar or identical and that their N-linked sugar chains contributed to minor difference in their molecular masses. Western blot analyses using lectins also revealed that they were differentially glycosylated; MGP57 was stained with concanavalin A (Con A) more strongly than MGP53, whereas MGP 53 was stained well with soybean agglutinin (SBA). Reactivity with SBA remarkably increased during early stages of lactation. Two-dimensional gel electrophoresis showed that MGP57 and MGP53 were electrically heterogeneous; from day 9 after parturition, both glycoproteins fell in almost the same range of isoelectric points between 6.4 and 7.6, also, such glycoproteins from day 1 after parturition were more acidic, probably due to terminal sialylation of their sugar chains.

Molecular cloning of the mouse osteoglycin-encoding gene.

Osteoglycin (OG) is a glycoprotein that was first isolated from bovine bone. The deduced amino acid (aa) sequence from the cDNA analysis showed that a precursor of OG has consensus leucine-rich repeats. In this study, we have isolated from a mouse limb-bud library cDNA clones encoding a 298-aa OG. This molecule shows 85 and 86% homology to human and bovine OG, respectively. Furthermore, the C-terminal two-thirds of the protein shows 48% homology to the corresponding portion of chick proteoglycan (PG)-Lb, a PG that has been shown to be preferentially expressed in the zone of flattened chondrocytes in the developing limb cartilage. Northern blot analysis of various mouse tissues revealed a 3.7-kb transcript in a limited number of these tissues.

A change in soybean agglutinin binding patterns of bovine milk fat globule membrane glycoproteins during early lactation.

Milk fat globule membrane (MFGM) glycoproteins were prepared from bovine milk at different stages of early lactation. Western blot analyses using several lectins revealed that reactivity of MFGM glycoproteins, especially 47K and 80K bands, to soybean agglutinin (SBA) remarkably increased during the lactation, while no change was observed for Ricinus communis agglutinin-I (RCA-I) binding. Sialidase treatment of MFGM glycoproteins revealed that the number of SBA-positive bands and the amount of SBA-positive oligosaccharides in these bands are increased during the lactation. Since SBA binds N-acetylgalactosamine terminated oligosaccharides, the results indicated that N-acetylgalactosaminylation of bovine MFGM glycoproteins is stimulated during the lactation.

Purification and properties of extracellular chitinases from the parasitic fungus Isaria japonica.

Two chitinases (P-1 and P-2) induced with colloidal chitin were purified from the culture supernatant of Isaria japonica by chromatography on DEAE Bio-Gel, chromatofocusing and gel filtration with Superdex 75 pg. The enzymes were electrophoretically homogeneous and estimated to have a molecular mass of 43,273 (+/-5) for P-1 and 31,134 (+/-6) for P-2 by MALDI-MS. The optimum pH and temperature was 3.5-4.0 and 50 degrees C for P-1 and 4.0-4.5 and 40 degrees C for P-2. P-1 acted against chitosan 7B (degree of deacetylation, 65-74%) = glycol chitin > colloidal chitin = chitosan 10B (degree of deacetylation, above 99%) and P-2 against chitosan 7B > glycol chitin = chitosan 10B > colloidal chitin in order of activity. The products of hydrolysis of chitin and chitosan hexamer were analyzed by MALDI-MS. The products from the chitin hexamer obtained with P-1 were almost all dimers with only a small amount of trimer whereas those obtained with P-2 were mainly trimers with some dimer and tetramer. No hydrolysis of chitosan hexamer was observed. High homology in the amino-terminal sequence for chitinase P-1 was exhibited by chitinases from Trichoderma harzianum, Candida albicans and Saccharomyces cerevisiae in the range of 48-39%. The highest homology for Chitinase P-2 was shown by an endochitinase from Metarhizium anisopliae of 66%, while 44% homology was exhibited by chitinases of Leguminosae plants.

[Treatment of an iliac artery pseudoaneurysm managed with a stent graft].

Recent developments have extended the indications for endovascular intervention to include endovascular lesions, such as aneurysms and sclerotic arterioocclusive disease. Although conventional treatment of pseudoaneurysms is mainly surgical intervention, the development of stent grafts has made this treatment less invasive than previously. We placed a stent graft in a pseudoaneurysm of the iliac artery with good results, as described in this report. Treatment of a pseudoaneurysm with a stent graft avoids the risk associated with general anesthesia and reduces surgical invasiveness, similar to laparotomy. We expect that this therapeutic mode will be developed further in the future.

Synthesis and enzymatic evaluation of mucin type core 4 O-glycan.

Lactosylaminylated core-4 tetrasaccharide found in mucin type O-glycans has been synthesized . The non-reducing galactose residue of the deblocked tetrasaccharide was removed by beta-galactosidase from E. coli to produce the corresponding GlcNAc terminated compound. The core-2 and core-4 tetrasaccharides were evaluated as acceptors for the beta-1,3-N-acetylglucosaminyltransferase (iGnT), beta-1,4-Galactosyltransferase IV(beta4GalTIV) and beta-1,4-Galactosyltransferase I(beta4GalTI).

Potentially distinctive features of sinonasal inverted papilloma on MR imaging.

OBJECTIVE: The objective of this study is to describe potentially distinctive MR features of sinonasal inverted papilloma and those of coexisting squamous cell carcinoma. CONCLUSION: A sinonasal mass with a convoluted cerebriform pattern on T2- or enhanced T1-weighted images suggests inverted papilloma as a histologic diagnosis. Necrosis in a mass with such an appearance strongly suggests coexistent carcinoma.

Appearance of the inferior phrenic artery and vein on CT scans of the chest: a CT and cadaveric study.

OBJECTIVE: Central linear densities are often seen at the level of the diaphragm on CT scans of the chest. To determine the cause of these densities, we evaluated helical CT scans and correlated the results with the findings from a study of cadavers. SUBJECTS AND METHODS: Forty patients who had normal findings on conventional CT scans had helical CT of the entire chest. For the cadaveric study, we examined the lung bases and extrapleural spaces on the diaphragmatic surface in 22 formalinized cadavers. RESULTS: On helical CT scans, linear densities extending laterally from the mid-part of the right side of the inferior vena cava and from the posterior margin of the left ventricle were seen on the right side of the chest in 12 subjects (30%) and on the left side in 17 subjects (42%). In the cadavers, the inferior phrenic artery and the accompanying vein ran over the diaphragmatic dome in the extrapleural space from the region of the inferior vena cava on the right and from the posterior margin of the left ventricle on the left. These supradiaphragmatic vessels were seen on the right side in 10 cadavers (45%) and on the left side in four cadavers (18%). CONCLUSION: We conclude that these linear densities at the level of the diaphragm on CT scans of the chest represent the inferior phrenic artery and vein.

Synthesis of selectively radiolabeled hexasaccharides for the determination of enzymatic regioselectivity.

Poly-N-acetyllactosamines provide backbone structures for functional modifications such as sialyl Lewis X. To understand how the biosynthesis of poly-N-acetyllactosamines is regulated, two branched oligosaccharides of the structure Galbeta1,4GlcNAcbeta1, 6(Galbeta1,4GlcNAcbeta1,2)-Manalpha1,6Manbeta-octyl 1 and 2 were synthesized in which one of the terminal galactose units was selectively radiolabeled. Hexasaccharides 1 and 2 were assembled from the chemically synthesized pentasaccharide precursors GlcNAcbeta1,6(Galbeta1,4GlcNAcbeta1,2)-Manalpha1,6Manbeta-octyl3 and Galbeta1,4GlcNAcbeta1,6(GlcNAcbeta1,2) - Manalpha1,6 Manbeta-octyl 4 respectively, through treatment with UDP-1-[3H]-Gal and beta1,4 galactosyltransferase. Compounds 1 and 2 were subsequently incubated with UDP-GlcNAc and the UDP-GlcNAc: Galbeta1-4Glc(NAc) beta1,3-N-acetylglucosaminyltransferase (i-GlcNAc transferase) resulting in a partial conversion to a mixture of heptasaccharides which were purified by HPLC. The branch selectivity of the addition of N-acetylglucosamine to compounds 1 and 2 was then characterized by endo-beta-galactosidase digestion of the heptasaccharides, followed by isolation of the resultant pentasaccharides on C18 reverse-phase silica cartridges. Comparison of the amount of radiolabel to a control reaction lacking endo-beta-galactosidase indicated the favored site of GlcNAc addition to be the lower beta1,2-branch over the beta1,6 branch by a 3 :1 ratio.

Expression and binding activity of the carboxyl-terminal portion of the core protein of PG-M, a large chondroitin sulfate proteoglycan.

PG-M is a large chondroitin sulfate proteoglycan that has been shown to be expressed in the prechondrogenic condensation area of the developing chick limb buds. We previously isolated cDNA clones encoding the core protein of PG-M (Shinomura, T., Nishida, Y., Ito, K., and Kimata, K. (1993) J. Biol. Chem. 268, 14461-14469). The amino acid sequence deduced from the cDNA analysis revealed the presence of two epidermal growth factor-like domains, a C-type lectin-like domain, and a complement regulatory protein (CRP)-like domain at the COOH terminus. The COOH-terminal portion has been expressed as a fusion protein with glutathione S-transferase in Escherichia coli to test its carbohydrate binding activity using affinity chromatography. The purified fusion protein binds to immobilized D-mannose, D-galactose, L-fucose, and N-acetyl-D-glucosamine in a calcium-dependent manner. Furthermore, the fusion protein binds to heparin- or heparan sulfate-Sepharose. To investigate roles of each COOH-terminal domain, we have made a truncated construct which lacks the CRP-like domain and determined if the CRP-like domain is involved in the binding activity. The removal of this domain resulted in the complete loss of both C-type lectin-like and heparin binding activities. The results suggest that a whole set of epidermal growth factor-, lectin-, and CRP-like domains may serve a functional structure for these bindings.

Intraarterial low-dose cisplatin via an indwelling port and concurrent radiotherapy for invasive bladder cancer.

Thirteen patients with invasive bladder cancer who had residual tumor after transurethral resections, were treated with consecutive intraarterial (IA) cisplatin (15 mg/d; total, 150 mg) and concurrent radiation (1.8 Gy/d; total, 30.6 Gy). All patients received unilateral or bilateral placement of vascular access devices (VAD) to perform daily cisplatin infusion after alteration of intrapelvic blood flow by coil embolizations. Tumor response was evaluated by transurethral biopsy 2 weeks after treatment. Complete response, defined as no viable tumor cell in the biopsy specimen, was achieved in seven patients (54%). After a median follow-up of 30 months (range, 12-48 months), 10 patients (77%) were alive, five (38%) of whom had no recurrence. Two cancer-related deaths were observed. All complete response cases survived with a median follow-up of 35 months (range, 25-48 months). Cause-specific and disease-free survival rates at 4 years were 85% and 28%, respectively. The regimen was well-tolerated, with no dose-limiting toxic events. There were no VAD-related complications. Consecutive IA low-dose cisplatin and concurrent radiation may be an acceptable alternative treatment for patients with bladder cancer who are not suitable for systemic chemotherapy. The use of a VAD contributed to successful consecutive IA infusions.

Poly-N-acetyllactosamine extension in N-glycans and core 2- and core 4-branched O-glycans is differentially controlled by i-extension enzyme and different members of the beta 1,4-galactosyltransferase gene family.

Poly-N-acetyllactosamines are attached to N-glycans, O-glycans, and glycolipids and serve as underlying glycans that provide functional oligosaccharides such as sialyl Lewis(X). Poly-N-acetyllactosaminyl repeats are synthesized by the alternate addition of beta1,3-linked GlcNAc and beta1,4-linked Gal by i-extension enzyme (iGnT) and a member of the beta1,4-galactosyltransferase (beta4Gal-T) gene family. In the present study, we first found that poly-N-acetyllactosamines in N-glycans are most efficiently synthesized by beta4Gal-TI and iGnT. We also found that iGnT acts less efficiently on acceptors containing increasing numbers of N-acetyllactosamine repeats, in contrast to beta4Gal-TI, which exhibits no significant change. In O-glycan biosynthesis, N-acetyllactosamine extension of core 4 branches was found to be synthesized most efficiently by iGnT and beta4Gal-TI, in contrast to core 2 branch synthesis, which requires iGnT and beta4Gal-TIV. Poly-N-acetyllactosamine extension of core 4 branches is, however, less efficient than that of N-glycans or core 2 branches. Such inefficiency is apparently due to competition between a donor substrate and acceptor in both galactosylation and N-acetylglucosaminylation, since a core 4-branched acceptor contains both Gal and GlcNAc terminals. These results, taken together, indicate that poly-N-acetyllactosamine synthesis in N-glycans and core 2- and core 4-branched O-glycans is achieved by iGnT and distinct members of the beta4Gal-T gene family. The results also exemplify intricate interactions between acceptors and specific glycosyltransferases, which play important roles in how poly-N-acetyllactosamines are synthesized in different acceptor molecules.

Occurrence of PG-Lb, a leucine-rich small chondroitin/dermatan sulphate proteoglycan in mammalian epiphyseal cartilage: molecular cloning and sequence analysis of the mouse cDNA.

PG-Lb is a chondroitin/dermatan sulphate proteoglycan first isolated from chick embryo limb cartilage. It had been assumed that osteoglycin represents its mammalian homologue. However, partial amino acid sequences of a novel proteoglycan from bovine epiphyseal cartilage showed high identity with those of chick PG-Lb (P. Neame, L. Rosenberg and M. Höök, personal communication). Reverse transcriptase PCR using degenerate oligonucleotide primers gave a cDNA fragment that might correspond to mouse PG-Lb. We isolated a clone from a cDNA library of newborn mouse epiphyseal cartilage using the cDNA fragment as a probe. The cloned cDNA was 1430 bp long and contained a 966 bp open reading frame which encoded the core protein consisting of 322 amino acid residues. The deduced amino acid sequence showed a high overall identity with chick PG-Lb (about 62%, reaching about 80% over the carboxyl two-thirds). In addition, the amino acid sequence contained a signal peptide, six cysteine residues at the invariant relative position to chick PG-Lb, six leucine-rich repeats at the carboxyl two-thirds, three possible glycosaminoglycan-attachment sites (two sites at the N-terminal side and one site at the C-terminus) and two possible Asn-glycosylation sites near the C-terminus. Northernblot analysis demonstrated the specific expression of a 1.5 kb message in cartilage and testis. These structural features and the characteristic expression suggest that the cloned molecule is mouse PG-Lb.

The gene structure and organization of mouse PG-M, a large chondroitin sulfate proteoglycan. Genomic background for the generation of multiple PG-M transcripts.

We previously showed not only the presence of multiple RNA transcripts of different sizes encoding the core protein of mouse PG-M, but also their tissue-dependent expression. Major causes for the multiple forms were found to be due to alternative usage of the two different chondroitin sulfate attachment domains (alpha and beta). In this study, genomic DNA analysis has revealed that these domains are encoded by two large exons, exon VII (2880 base pairs) and exon VIII (5229 base pairs). The splice sites of these two exons were consistent with the occurrence of alternative splicing without frameshift. Furthermore, the mouse PG-M gene was shown to have four distinct polyadenylation signals and three candidates for the transcription initiation site as well. These genomic structural variations may contribute to the multiplicity of PG-M transcripts. Northern hybridization analysis showed that at least three different transcripts were generated by different usage of the distinct polyadenylation signals.

Multiple forms of mouse PG-M, a large chondroitin sulfate proteoglycan generated by alternative splicing.

We have isolated and sequenced cDNA clones that encode the core protein of PG-M-like proteoglycan produced by cultured mouse aortic endothelial cells (Morita, H., Takeuchi, T., Suzuki, S., Maeda, K., Yamada, K., Eguchi, G., and Kimata, K. (1990) Biochem. J. 265, 61-68). A homology search of the cDNA sequence has suggested that the core protein is a mouse equivalent of chick PG-M(V1), one of the alternatively spliced forms of the PG-M core protein, which may correspond to human versican. Northern blot analysis revealed three mRNA species of 10, 9, and 8 kilobases (kb) in size. The analysis of PG-M mRNA species in embryonic limb buds and adult brain revealed the presence of other mRNA species with different sizes; the one with the largest size (12 kb) was found in embryonic limb buds, and the ones with smaller sizes of 7.5 and 6.5 kb were in adult brain. Sequencing of cDNA clones for the smaller forms in the adult brain showed that they were different from PG-M(V1) in encoding the second chondroitin sulfate attachment domain (CS alpha) alone. Occurrence of the PCR products striding over the junction of the first and second chondroitin sulfate attachment domains suggested that a mRNA of 12 kb in size corresponded to a transcript without the alternative splicing (PG-M(V0)). It is likely, therefore, that multiforms of the PG-M core protein may be generated by alternative usage of either or both of the two different chondroitin sulfate attachment domains (alpha and beta) and that molecular forms of PG-M may vary from tissue to tissue by such an alternative splicing.

Expression of PG-M(V3), an alternatively spliced form of PG-M without a chondroitin sulfate attachment in region in mouse and human tissues.

We showed previously that the alternative splicing of chondroitin sulfate attachment domains (CS alpha and CS beta) yielded multiforms of the PG-M core protein in mouse. A transcript encoding a new short form of the core protein PG-M(V3) was found in various mouse tissues using polymerase chain reaction. DNA sequences of the polymerase chain reaction products suggested that PG-M(V3) had no chondroitin sulfate attachment domain. PG-M(V3) was also detected in various human tissues. The presence of a transcript for PG-M(V3) was further supported by Northern blot analysis. Southern blot analysis confirmed that multiforms of the PG-M core protein, including PG-M(V3), were derived from a single genomic locus by an alternative splicing mechanism. Because PG-M(V3) has no chondroitin sulfate attachment region, which is the most distinctive portion of a proteoglycan molecule, this form may have a unique function.

[Usefulness of CO2 US angiography in treating hepatocellular carcinoma].

We evaluated the usefulness of CO2 US angiography in the detectability of and the effectiveness of TAE and/or PEIT for hepatocellular carcinoma (HCC). Twenty-three patients with HCC underwent CO2 angiography during the interventional procedure to treat HCC after examination of CT and conventional US. CO2 US angiography was observed on the US monitor by injecting CO2 microbubbles through a catheter placed in the hepatic artery. Contrast materials for CO2 US angiography were 3 ml of CO2 microbubbles prepared by vigorously mixing 3 ml of normal saline with 3 ml of 20% Intralipid, 3 ml of 20% albumin or 3 ml of the patient's own blood. In all patients, CO2 US angiography revealed equal or superior tumor detectability as compared with CT, conventional US and angiography. For demonstrating the inner structure of HCC, the image of CO2 microbubbles mixed with Intralipid was better than that of CO2 microbubbles mixed with albumin. In 9 of 23 patients, CO2 US angiography depicted nodules that had not been seen in the other images. TAE was performed in 21 patients with HCC who showed hypervascularity. In one patient in whom it was difficult to clearly depict the small lesion of HCC by conventional angiography and US, PEIT was successful under CO2 US angiography. The detectability of HCC was higher in CO2 US angiography than in CT, conventional US or angiography. The distribution of blood supply to HCC was observed easily by CO2 US angiography. In TAE of HCC, CO2 US angiography was useful to determine the dose of embolization materials without having to perform repeated angiography. It was possible to perform PEIT easily for non-detectable tumors without CO2 US angiography. CO2 US angiography was useful to evaluate the stage of HCC and to perform TAE and PEIT.

Infrahyoid spread of deep neck abscess: anatomical consideration.

The aim of this study was to determine the pathway of infrahyoid extension of the oropharyngeal abscess considering the anatomy of the fascial spaces by cross-sectional imaging. CT scans and MR images were retrospectively reviewed in ten patients with known infrahyoid extension of oropharyngeal abscesses (eight with acute tonsillitis, two with acute phlegmonous oropharyngitis). In seven of eight patients tonsillar abscesses descended along the deep cervical fascia converging on the hyoid bone and further accumulated in the anterior cervical space through which extension to the mediastinum took place in four patients. In seven patients the abscesses involved the retropharyngeal space at the infrahyoid neck. In two of these seven patients the abscesses directly extended down into the upper mediastinum through the retropharyngeal space. In one patients of the seven mediastinal spread of an abscess occurred through the posterior cervical space, not through the retropharyngeal space. Cross-sectional imaging is valuable in the evaluation of deep neck abscesses and the pathway of spread. The anterior cervical space in the infrahyoid neck is important for mediastinal extension of pharyngeal abscesses.

Poly-N-acetyllactosamine synthesis in branched N-glycans is controlled by complemental branch specificity of I-extension enzyme and beta1,4-galactosyltransferase I.

Poly-N-acetyllactosamine is a unique carbohydrate that can carry various functional oligosaccharides, such as sialyl Lewis X. It has been shown that the amount of poly-N-acetyllactosamine is increased in N-glycans, when they contain Galbeta1-->4GlcNAcbeta1-->6(Galbeta1-->4GlcNAcbeta1 -->2)Manalpha1-->6 branched structure. To determine how this increased synthesis of poly-N-acetyllactosamines takes place, the branched acceptor was incubated with a mixture of i-extension enzyme (iGnT) and beta1, 4galactosyltransferase I (beta4Gal-TI). First, N-acetyllactosamine repeats were more readily added to the branched acceptor than the summation of poly-N-acetyllactosamines formed individually on each unbranched acceptor. Surprisingly, poly-N-acetyllactosamine was more efficiently formed on Galbeta1-->4GlcNAcbeta1-->2Manalpha-->R side chain than in Galbeta1-->4GlcNAcbeta1-->6Manalpha-->R, due to preferential action of iGnT on Galbeta1-->4GlcNAcbeta1-->2Manalpha-->R side chain. On the other hand, galactosylation was much more efficient on beta1,6-linked GlcNAc than beta1,2-linked GlcNAc, preferentially forming Galbeta1-->4GlcNAcbeta1-->6(GlcNAcbeta1-->2)Manalph a1-->6Manbeta -->R. Starting with this preformed acceptor, N-acetyllactosamine repeats were added almost equally to Galbeta1-->4GlcNAcbeta1-->6Manalpha-->R and Galbeta1-->4GlcNAcbeta1-->2Manalpha-->R side chains. Taken together, these results indicate that the complemental branch specificity of iGnT and beta4Gal-TI leads to efficient and equal addition of N-acetyllactosamine repeats on both side chains of GlcNAcbeta1-->6(GlcNAcbeta1-->2)Manalpha1-->6Manbet a-->R structure, which is consistent with the structures found in nature. The results also suggest that the addition of Galbeta1-->4GlcNAcbeta1-->6 side chain on Galbeta1-->4GlcNAcbeta1-->2Man-->R side chain converts the acceptor to one that is much more favorable for iGnT and beta4Gal-TI.