A feasibility study of sequential doublet chemotherapy comprising carboplatin-doxorubicin and carboplatin-paclitaxel for advanced endometrial adenocarcinoma and carcinosarcoma.

BACKGROUND: Platinum compounds, taxanes and anthracyclines provide the major effective drug classes in the treatment of advanced and recurrent endometrial cancer and carcinosarcoma. PATIENTS AND METHODS: A total of 52 women with advanced or recurrent endometrial cancer and carcinosarcoma were treated with four cycles of carboplatin area under the curve (AUC) 5 and doxorubicin (50 mg/m(2)) for four cycles before or after four cycles of carboplatin AUC5 and paclitaxel (175 mg/m(2)) with each cycle administered at 21-day intervals. RESULTS: Thirty-seven patients (71.2%) completed all planned treatment. Excluding six patients who did not complete treatment for non-drug-related causes, 80.4% completed all planned treatment. Three hundred and seventy-one treatment cycles were administered and 303 (81.7%) occurred on time. Common Toxicity Criteria grade 3/4 haematological toxic effects, particularly neutropenia and thrombocytopenia, were the predominant cause of treatment delays and dose reductions. A low incidence of grade 3 neurotoxicity and no cardiac toxicity were observed. The overall response rates for patients with evaluable disease were 82.1% and 66.7% for endometrial and carcinosarcoma, respectively. At a median follow-up of 21 months, the median progression-free survival for the endometrial adenocarcinoma and carcinosarcoma cohorts were 15.3 and 12.0 months, respectively. CONCLUSION: This regimen is generally well tolerated with encouraging efficacy.

Tailoring nanostructure and bioactivity of 3D-printable hydrogels with self-assemble peptides amphiphile (PA) for promoting bile duct formation.

3D-printing has expanded our ability to produce reproducible and more complex scaffold architectures for tissue engineering applications. In order to enhance the biological response within these 3D-printed scaffolds incorporating nanostructural features and/or specific biological signaling may be an effective means to optimize tissue regeneration. Peptides amphiphiles (PAs) are a versatile supramolecular biomaterial with tailorable nanostructural and biochemical features. PAs are widely used in tissue engineering applications such as angiogenesis, neurogenesis, and bone regeneration. Thus, the addition of PAs is a potential solution that can greatly expand the utility of 3D bioprinting hydrogels in the field of regenerative medicine. In this paper, we firstly developed a 3D-printable thiolated-gelatin bioink supplemented with PAs to tailor the bioactivity and nanostructure which allows for the incorporation of cells. The bioink can be printed at 4 °C and stabilized to last a long time (>1 month) in culture at 37 °C by via a dual secondary crosslinking strategy using calcium ions and homobifunctional maleiminde-poly (ethylene glycol). Rheological properties of inks were characterized and were suitable for printing multi-layered structures. We additionally demonstrated enhanced functionality of ink formulations by utilizing a laminin-mimetic IKVAV-based PA system within a 3D-printable ink containing cholangiocytes. Viability and functional staining showed that the IKVAV PA nanofibers stimulated cholangioctyes to form functional tubular structures, which was not observed in other ink formulations.

3D-printing porosity: A new approach to creating elevated porosity materials and structures.

We introduce a new process that enables the ability to 3D-print high porosity materials and structures by combining the newly introduced 3D-Painting process with traditional salt-leaching. The synthesis and resulting properties of three 3D-printable inks comprised of varying volume ratios (25:75, 50:50, 70:30) of CuSO4 salt and polylactide-co-glycolide (PLGA), as well as their as-printed and salt-leached counterparts, are discussed. The resulting materials are comprised entirely of PLGA (F-PLGA), but exhibit porosities proportional to the original CuSO4 content. The three distinct F-PLGA materials exhibit average porosities of 66.6-94.4%, elastic moduli of 112.6-2.7 MPa, and absorbency of 195.7-742.2%. Studies with adult human mesenchymal stem cells (hMSCs) demonstrated that elevated porosity substantially promotes cell adhesion, viability, and proliferation. F-PLGA can also act as carriers for weak, naturally or synthetically-derived hydrogels. Finally, we show that this process can be extended to other materials including graphene, metals, and ceramics. STATEMENT OF SIGNIFICANCE: Porosity plays an essential role in the performance and function of biomaterials, tissue engineering, and clinical medicine. For the same material chemistry, the level of porosity can dictate if it is cell, tissue, or organ friendly; with low porosity materials being far less favorable than high porosity materials. Despite its importance, it has been difficult to create three-dimensionally printed structures that are comprised of materials that have extremely high levels of internal porosity yet are surgically friendly (able to handle and utilize during surgical operations). In this work, we extend a new materials-centric approach to 3D-printing, 3D-Painting, to 3D-printing structures made almost entirely out of water-soluble salt. The structures are then washed in a specific way that not only extracts the salt but causes the structures to increase in size. With the salt removed, the resulting medical polymer structures are almost entirely porous and contain very little solid material, but the maintain their 3D-printed form and are highly compatible with adult human stem cells, are mechanically robust enough to use in surgical manipulations, and can be filled with and act as carriers for biologically active liquids and gels. We can also extend this process to three-dimensionally printing other porous materials, such as graphene, metals, and even ceramics.

Feasibility of home delivery of pemetrexed in patients with advanced non-squamous non-small cell lung cancer.

OBJECTIVES: To evaluate the feasibility and adherence to home delivery (HD) of pemetrexed maintenance treatment in patients with advanced non-squamous non-small cell lung cancer (nsqNSCLC). MATERIALS AND METHODS: Exploratory, prospective, single-arm, Phase II study in advanced nsqNSCLC patients, with an Eastern Cooperative Oncology Group (ECOG) performance status of 0/1 that did not progress after 4 first-line induction cycles of a platinum doublet. The first cycle of pemetrexed (500mg/m(2)) was hospital administered, further cycles were HD until progressive disease or discontinuation. Feasibility was assessed by the adherence rate to HD (probability of reversion to hospital administration or treatment discontinuation due to HD) as primary endpoint, and by health-related quality-of-life (HRQoL: EQ-5D, lung cancer symptom scale [LCSS]), satisfaction with HD, overall survival (OS), and safety. RESULTS: 52 patients (UK & Sweden) received a median of 4 (range 1-19) pemetrexed maintenance cycles. Adherence rate up to Cycle 6 was 98.0% (95% confidence interval [CI]: 86.4%, 99.7%). All but 2 patients remained on HD. 1 patient discontinued after Cycle 1 (patient decision), and 1 after Cycle 6 (non-compliance with oral dexamethasone). 87% (33/38) of the patients preferred home to hospital treatment and in 90% (28/31) of cases, physicians were satisfied with distant management of patients. During HD Cycles 2-4 mean change from baseline ranged from 3.0 to 7.7 for EQ-5D visual analog scale. The 6-month OS rate was 73% (95% CI: 58%, 83%). 1 patient had an HD-related adverse event (device-related infection, Grade 2) and 1 patient died after Cycle 1, before HD, due to a possibly drug-related atypical pneumonia. CONCLUSION: HD of pemetrexed maintenance treatment in patients with advanced nsqNSCLC was feasible, safe, and preferred by patients, while maintaining HRQoL. Physicians were satisfied with distant patient management.

Follicular dendritic cell tumor presenting in the lung: a case report.

An example of extranodal follicular dendritic cell sarcoma (FDCS) presenting in the lung, a heretofore unreported site, is described. Macroscopically, a 9.5-cm, tan-white, dominant mass and multiple smaller parenchymal and pleural nodules were identified. Microscopically, the tumor was composed of spindled cells with uniform cytologic features arranged in short, intersecting fascicles and intermixed small lymphocytes and plasma cells. One of 4 peribronchial and hilar lymph nodes evaluated microscopically was focally involved by the process. Immunohistochemically, the neoplastic spindled cells expressed complement receptors CD21 and CD35 and low-affinity nerve growth factor receptor but did not express keratin (AE1/AE3 and CAM5.2), CD45 (leukocyte common antigen), CD20 (L26), S-100 protein, muscle-specific actin, or gp100 protein (HMB45). Ultrastructurally, the tumor cells have complex interdigitating cell surface processes and desmosomes. Epstein-Barr virus (EBV) was not detected in the tumor cells by in situ hybridization for EBV-encoded RNA or by polymerase chain reaction for viral DNA. FDCS should be considered in the differential diagnosis of any spindled-cell tumor with interspersed chronic inflammatory cells occurring in the lung. An immunohistochemical panel, including anti-CD21 and -CD35, can assist in its diagnosis, especially with small bronchial biopsy specimens. 2001 by W.B. Saunders Company.

Synthesis of di- and tri-saccharides with intramolecular NH-glycosidic linkages: molecules with flexible and rigid glycosidic bonds for conformational studies.

Attempted dephthalimidation of the trisaccharide 1-O-acetyl-3,4-di-O-benzyl- 2,6-di-O-(3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-beta-D-glucopyranosyl )-alpha-D-mannopyranose (1) and its derivatives 2 and 3, as well as the disaccharide 1-O-acetyl-3,4,6-tri-O-benzyl-2-O-(3,4,6-tri-O-acetyl- 2-deoxy-2-phthalimido-beta-D-glucopyranosyl)-alpha-D-mannopyranose (13), with hydrazine hydrate in ethanol at 80 degrees C, produced the trisaccharide-6-O-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-beta-D- glucopyranosyl)-3,4-di-O-benzyl-beta-D-mannopyranose-3',4',6'-tri-O-a cet yl- beta-D-glucopyranose 1,2'-N:1',2-O-dianhydride (4) and 3,4,6-tri-O-benzyl-beta-D-mannopyranose 3',4',6'-tri-O-acetyl-beta-D-glucopyranose 1,2'-N:1',2-O-dianhydride (14), respectively, containing an intramolecular NH-glycosidic linkage. The conventional deblocking of compounds 4 and 14 gave the completely deblocked trisaccharide 6-O-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-beta-D-mannopyranose beta-D-glucopyranose 1,2'-N:1',2-O-dianhydride (6) and the disaccharide beta-D-mannopyranose beta-D-glucopyranose 1,2'-N:1',2-O-dianhydride (16), respectively, containing an intact intramolecular NH-glycosidic bond. The unusual intra NH-glycosyl character makes the linkage rigid, and therefore these compounds should not only be useful for NMR studies but also as substrates or inhibitors of GlcNAc-transferases.

Control of glycoprotein synthesis. Characterization of (1-->4)-N-acetyl-beta-D-glucosaminyltransferases acting on the alpha-D-(1-->3)- and alpha-D-(1-->6)-linked arms of N-linked oligosaccharides.

Hen oviduct membranes contain at least three N-acetyl-beta-D-glucosaminyltransferases (GlcNAc-T) that attach a beta GlcNAc residue in (1-4)-linkage to a D-Man p residue of the N-linked oligosaccharide core, i.e., (1-->4)-beta-D-GlcNAc-T III which adds a "bisecting" GlcNAc group to form the beta-D-GlcpNAc-(1-->4)-beta-D-Man p-(1-->4)-D-GlcNAc moiety; (1-->2)-beta-D-GlcNAc-T IV which adds a GlcNAc group to the (1-->3)-alpha-D-Man arm to form the beta-D-GlcpNAc-(1-->4)-[beta-D- GlcpNAc-(1-->2)]-alpha-D-Man p-(1-->3)-beta-D-Man p-(1-->4)-D-GlcpNAc component; and (1-->4)-beta-D-GlcNAc-T VI which adds a GlcNAc group to the alpha-D-Man p residue of beta-D-GlcpNAc-(1-->6)-[beta-D-GlcpNAc- (1-->2)]-alpha-D-Man p-R to form beta-D-GlcpNAc-(1-->6)-[beta-D-GlcpNAc-(1-->4)]-[beta-D-GlcpNAc- (1-->2)]-alpha-D-Man p-R. We now report a novel (1-->4)-beta-D-GlcNAc-T activity (GlcNAc-T VI') in hen oviduct membranes that transfers GlcNAc to beta-D-GlcpNAc-(1-->2)-alpha-D-Man p-(1-->6)-beta-D-Man p-R to form beta-D-GlcpNAc-(1-->4)-[beta-D-GlcpNAc-(1-->2)]-alpha-D-Man p-(1-->6)- beta-D-Man p-R. The structure of the enzyme product was confirmed by 1H NMR spectroscopy, FAB-mass spectrometry and methylation analysis. Previous work with GlcNAc-T IV was carried out with biantennary substrates; we now show that hen oviduct membrane GlcNAc-T IV can also transfer GlcNAc to monoantennary beta-D-GlcpNAc-(1-->2)-alpha-D-Manp-(1-->3)-beta-D-Man p-R to form beta-D-GlcpNAc-(1-->4)-[beta-D-GlcpNAc-(1-->2)]-alpha-D-Man p- (1-->3)-beta-D-Man p-R. The findings that GlcNAc-T VI' and IV have similar kinetic characteristics and that hen oviduct membranes can convert methyl beta-D-GlcpNAc-(1-->2)-alpha-D-Man p to methyl beta-D-GlcpNAc-(1-->4)-[beta-D-GlcpNAc-(1-->2)]-alpha-D-Man p suggest that these two activities may be due to the same enzyme. The R-group of the beta-D-GlcpNAc-(1-->2)-alpha-D-Man p-(1-->6)-beta-D-Man p (or Glcp)-R substrate has an important influence on GlcNAc-T VI' enzyme activity.(ABSTRACT TRUNCATED AT 400 WORDS)

Flexibility in a tetrasaccharide fragment from the high mannose type of N-linked oligosaccharides.

An analysis has been carried out of the three-dimensional structure of a tetrasaccharide, Man(alpha 1-3)Man(alpha 1-6)Man(beta 1-4)GlcN Ac beta 1-OCD3, which is a fragment from the high mannose type of N-linked oligosaccharides. Although earlier work had suggested that this fragment might adopt a stable three-dimensional structure, both n.m.r. and conformational energy calculations support the existence of an ensemble of structures. The conformational entropy calculated from the ensemble and the distribution of distances between the terminal Man(alpha 1-3) and GlcN Ac residues, however, suggests that a significant fraction of the ensemble has the two terminal residues in close proximity.

Detection of internal motions in oligosaccharides by 1H relaxation measurements at different magnetic fields.

The effect of internal motions on proton relaxation data in oligosaccharides has been investigated experimentally. 1H steady-state and transient NOEs together with 13C T1's have been measured at two magnetic field strengths. The existence of internal motions leads to additional modulations of the dipolar interaction between proton pairs, thus producing a range of spectral density functions for these interactions. As a result, it is possible to show that protons relaxing through fixed distances have a different ratio of relaxation parameters, acquired at 500 and 300 MHz, compared to those relaxing through fluctuating distances. This approach has been used to unequivocally establish for two disaccharides the existence of internal motions on the time scale of the overall tumbling.

Pregnancy effects on nonhuman primate high density lipoprotein.

The concentration of cholesterol in high density lipoproteins (HDL) has been showed to be dramatically decreased during pregnancy in Macaca nemestrina. HDL were isolated from females of this species at various stages of pregnancy to determine if pregnancy also alters their composition and size. The chemical compositions of the HDL were determined nad found different in pregnant animals; the mass ratio of surface (coat) to center (core) constituents was higher, suggesting that the average size of HDL decreased during pregnancy. When measured chromatographically, the average size of HDL was found to decrease during pregnancy. This change in HDL size was accompanied by a minor alteration in apolipoprotein distribution.

Upper airways sarcoidosis presenting as obstructive sleep apnoea.

Sarcoidosis may present in a number of different ways, affecting many organ systems. The case history is presented of a 32 year old woman who presented with symptoms of severe obstructive sleep apnoea (OSA) due to infiltration of the upper airway by sarcoidosis. To our knowledge this presentation of sarcoidosis has not previously been described.

Influence of dietary fatty acid composition on the relationship between CETP activity and plasma lipoproteins in monkeys.

CETP activity, measured as transfer of cholesteryl ester from exogenous HDL to exogenous VLDL and LDL, reflecting CETP mass as determined by ELISA, was documented in three groups of St. Kitts vervet monkeys fed diets enriched in saturated (Sat), monounsaturated (Mono), or n-6 polyunsaturated (Poly) fatty acids. CETP activity was not different when comparing the three dietary fats. However, CETP activity was significantly higher when cholesterol was added to each of the diets. Significant positive associations between CETP activity and VLDL and LDL cholesterol concentrations were found whereas significant negative associations were seen between CETP activity and HDL cholesterol in each of the diet groups. The strength of these associations was highest in the Sat group. Cholesteryl ester (CE) fatty acid composition of lipoproteins varied widely among diet groups, with the more polyunsaturated CE of the Poly group being associated with a higher rate of CE transfer to endogenous acceptor apolipoprotein B-containing lipoproteins. Finally, only the Sat diet group showed significant positive correlations of CETP activity with LDL particle diameter (r = 0.76), cholesteryl ester percentage (r = 0.67), and a strong negative correlation (r = -0.86) with LDL receptor function, estimated as the difference between native and methylated LDL turnover rates. We speculate that strong associations between CETP and LDL metabolism may explain, at least in part, the increased atherogenicity of dietary saturated fat.

Characterization of molecularly imprinted polymers with the Langmuir-Freundlich isotherm.

The majority of binding models that have been applied to molecularly imprinted polymers (MIPs) have been homogeneous models. MIPs, on the other hand, are heterogeneous materials containing binding sites with a wide array of binding affinities and selectivities. Demonstrated is that the binding behavior of MIPs can be accurately modeled by the heterogeneous Langmuir-Freundlich (LF) isotherm. The applicability of the LF isotherm to MIPs was demonstrated using five representative MIPs from the literature, including both homogeneous and heterogeneous MIPs. Previously, such comparisons required the use of several different binding models and analyses, including the Langmuir model, the Freundlich model, and numerical approximation techniques. In contrast, the LF model enabled direct comparisons of the binding characteristics of MIPs that have very different underlying distributions and were measured under different conditions. The binding parameters can be calculated directly using the LF fitting coefficients that yield a measure of the total number of binding sites, mean binding affinity, and heterogeneity. Alternatively, solution of the Langmuir adsorption integral for the LF model enabled direct calculation of the corresponding affinity spectrum from the LF fitting coefficients from a simple algebraic expression, yielding a measure of the number of binding sites with respect to association constant Finally, the ability of the LF isotherm to model MIPs suggests that a unimodal heterogeneous distribution is an accurate approximation of the distribution found in homogeneous and heterogeneous MIPs.

Expression of Das-1 in primary lung adenocarcinomas represents reactivation of an oncofetal pulmonary antigen.

OBJECTIVE: The monoclonal antibody (mAb) designated as mAb Das-1 was generated against a colonic epithelial protein. It reacts with bronchiolar epithelium and submucosal glands and weakly with alveolar lining cells of fetal lung. Adult alveolar epithelium is, however, nonreactive for mAb Das-1. The present study was designed to evaluate the immunoexpression of Das-1 and to correlate it with the histomorphology of primary lung adenocarcinomas and intestinal metaplasia. METHODS: Eighty-four cases of primary lung adenocarcinomas were reviewed and categorized according to histologic grade and subtype. Immunohistochemical staining with mAb Das-1 was performed with normal colon as control. RESULTS: Expression of Das-1 in the submucosal bronchial glands also served as internal control. Strong and diffuse staining was seen in 33 of the 84 cases of adenocarcinomas (39%). CONCLUSIONS: Expression of Das-1 was seen in primary lung adenocarcinomas even though adult alveolar epithelium is negative. Staining with mAb Das-1 was seen regardless of the grade or histological subtype of the lung adenocarcinomas. As most primary lung adenocarcinomas are not of bronchial gland origin, expression of Das-1 represents activation of oncofetal antigens.

Control of glycoprotein synthesis. Detection and characterization of a novel branching enzyme from hen oviduct, UDP-N-acetylglucosamine:GlcNAc beta 1-6 (GlcNAc beta 1-2)Man alpha-R (GlcNAc to Man) beta-4-N-acetylglucosaminyltransferase VI.

Hen oviduct membranes were shown to contain high activity of a novel enzyme, UDP-GlcNac:GlcNAc beta 1-6(GlcNAc beta 1-2) Man alpha-R (GlcNAc to Man) beta 4-GlcNAc-transferase VI. The enzyme was shown to transfer GlcNAc in beta 1-4 linkage to the D-mannose residue of GlcNAc beta 1-6 (GlcNAc beta 1-2) Man alpha-R where R is either 1-6Man beta-(CH2)8COOCH3 or methyl. Radioactive enzyme products were purified by several chromatographic steps, including high performance liquid chromatography, and structures were determined by proton nmr, fast atom bombardment-mass spectrometry, and methylation analysis to be GlcNAc beta 1-6 ([14C]GlcNAc beta 1-4) (GlcNAc beta 1-2) Man alpha-R. The enzyme is stimulated by Triton X-100 and has optimum activity at a relatively high MnCl2 concentration of about 100 mM; Co2+, Mg2+, and Ca2+ could partially substitute for Mn2+. A tissue survey demonstrated high GlcNAc-transferase VI activity in hen oviduct and lower activity in chicken liver and colon, duck colon, and turkey intestine. No activity was found in mammalian tissues. Hen oviduct membranes cannot act on GlcNAc beta 1-6Man alpha-R but have a beta 4-GlcNAc-transferase activity that converts GlcNAc beta 1-2Man alpha-R to GlcNAc beta 1-4(GlcNAc beta 1-2) Man alpha-R where R is either 1-6Man beta-(CH2)8COOCH3 or 1-6Man beta methyl. The latter activity is probably due to GlcNAc-transferase IV which preferentially adds GlcNAc in beta 1-4 linkage to the Man alpha 1-3 arm of the GlcNAc beta 1-2Man alpha 1-6(GlcNAc beta 1-2Man alpha 1-3)Man beta 1-4GlcNAc beta 1-4GlcNAc-Asn core structure of asparagine-linked glycans. The minimum structural requirement for a substrate of beta 4-GlcNAc-transferase VI is therefore the trisaccharide GlcNAc beta 1-6(GlcNAc beta 1-2) Man alpha-; this trisaccharide is found on the Man alpha 6 arm of many branched complex asparagine-linked oligosaccharides. The data suggest that GlcNAc-transferase VI acts after the synthesis of the GlcNAc beta 1-2Man alpha 1-3-, GlcNAc beta 1-2Man alpha 1-6-, and GlcNAc beta 1-6 Man alpha 1-6-branches by GlcNAc-transferases I, II, and V, respectively, and is responsible for the synthesis of branched oligosaccharides containing the GlcNAc beta 1-6(GlcNAc beta 1-4)(GlcNAc beta 1-2)Man alpha 1-6Man beta moiety.

Solution conformation of the branch points of N-linked glycans: synthetic model compounds for tri'-antennary and tetraantennary glycans.

The solution conformation of model compounds for the tri'-antennary and tetraantennary (six-arm) branch point of N-linked glycans has been determined through the use of chemical shift, relaxation, and nuclear Overhauser enhancement data. The object was to establish the conformation about the glycosidic linkages in the N-linked substructure GlcNAc(beta 1,6) [GlcNAc(beta 1,2)] Man(alpha)- by estimation of values for the appropriate glycosidic torsional angles. The GlcNAc(beta 1,6) linkage in a trisaccharide model compound was found to be constrained to a narrow rotameric subpopulation about the substituted Man C5-C6 bond (omega = -60 degrees) and a narrow range of possible phi - psi values. Free rotation about the Man C5-C6 bond was obstructed by unfavorable steric interactions between the GlcNAc(beta 1,6) and GlcNAc(beta 1,2) residues. A phi, psi value of 55 degrees, 190 degrees was found to be consistent with the NMR data for the GlcNAc(beta 1,6) linkage. However, the value of psi appears to be "virtual" in that the molecule is in equilibrium between two different values (90 degrees and 252 degrees). For the GlcNAc(beta 1,2) linkage, complete agreement between all the observed NMR parameters and all the calculated ensemble average values could only be obtained with a set of potential energy functions which included hydrogen bonding. Other choices of potentials yielded calculated values that disagreed with at least two of the observed quantities. As a result, we infer that an interresidue hydrogen bond is formed, and we find it to be between the GlcNAc(beta 1,2) ring oxygen and the Man C3 hydroxyl.(ABSTRACT TRUNCATED AT 250 WORDS)

Substrate specificity and inhibition of UDP-GlcNAc:GlcNAc beta 1-2Man alpha 1-6R beta 1,6-N-acetylglucosaminyltransferase V using synthetic substrate analogues.

UDP-GlcNAc:GlcNAc beta 1-2Man alpha 1-6R (GlcNAc to Man) beta 1,6- N-acetylglucosaminyltransferase V (GlcNAc-T V) adds a GlcNAc beta 1-6 branch to bi- and triantennary N-glycans. An increase in this activity has been associated with cellular transformation, metastasis and differentiation. We have used synthetic substrate analogues to study the substrate specificity and inhibition of the partially purified enzyme from hamster kidney and of extracts from hen oviduct membranes and acute myeloid leukaemia leukocytes. All compounds with the minimum structure GlcNAc beta 1-2Man alpha 1-6Glc/Man beta-R were good substrates for GlcNAc-T V. The presence of structural elements other than the minimum trisaccharide structure affected GlcNAc-T V activity without being an absolute requirement for activity. Substrates with a biantennary structure were preferred over linear fragments of biantennary structures. Kinetic analysis showed that the 3-hydroxyl of the Man alpha 1-3 residue and the 4-hydroxyl of the Man beta- residue of the Man alpha 1-6(Man alpha 1-3)Man beta-R N-glycan core are not essential for catalysis but influence substrate binding. GlcNAc beta 1-2(4,6-di-O-methyl-)Man alpha 1-6Glc beta-pnp was found to be an inhibitor of GlcNAc-T V from hamster kidney, hen oviduct microsomes and acute and chronic myeloid leukaemia leukocytes.