Phase IV head-to-head randomized controlled trial comparing ingenol mebutate 0·015% gel with diclofenac sodium 3% gel for the treatment of actinic keratosis on the face or scalp.

BACKGROUND: Ingenol mebutate (IngMeb) and diclofenac sodium (DS) are approved treatments for actinic keratosis (AK). OBJECTIVES: To compare the efficacy and safety of IngMeb 0·015% gel with DS 3% gel (NCT02406014). METHODS: Patients with 4-8 visible, discrete AK lesions on the face/scalp in a 25 cm2 contiguous area of skin were randomized 1:1 to IngMeb once-daily for three consecutive days or DS twice-daily for 90 days. Patients with AK lesions at Week 8 following IngMeb were offered a second IngMeb course. Primary end point was complete clearance of AK lesions (AKCLEAR 100) at end of first treatment course (Week 8, IngMeb; Week 17, DS). Secondary end points included AKCLEAR 100 at end of last treatment course and Week 17; adverse events (AEs) were assessed at these time points. Patients completed treatment satisfaction questionnaires for medication (TSQM; Week 17). RESULTS: AKCLEAR 100 at end of first treatment course was higher with IngMeb (34%) vs. DS (23%; P = 0·006). AKCLEAR 100 at end of last IngMeb course (53%) and Week 17 (45%) was higher than DS (both P < 0·001). The most frequent AE was application-site erythema (IngMeb 19%; DS 12%). Treatment-related AE (TRAE) duration was shorter with IngMeb. TRAE withdrawals were lower for IngMeb (2%) vs. DS (6%). TSQM scores for global satisfaction (P < 0·001) and effectiveness (P = 0·002) were higher with IngMeb, as was dosing instruction adherence (≥ 90% vs. 70%). CONCLUSIONS: AKCLEAR 100, patient treatment satisfaction and effectiveness were significantly higher with IngMeb compared with DS, demonstrating superiority of IngMeb for AK treatment on face/scalp.

Efficacy and safety of follow-up field treatment of actinic keratosis with ingenol mebutate 0·015% gel: a randomized, controlled 12-month study.

BACKGROUND: Ingenol mebutate (IngMeb) is a novel patient-applied topical field therapy for actinic keratosis. OBJECTIVES: To demonstrate the efficacy and safety of follow-up IngMeb field treatment of actinic keratoses (AKs) present at 8 weeks after initial treatment or emerging in a previously cleared field. METHODS: In this phase III, randomized, double-blind study in patients with 4-8 clinically visible AKs within a contiguous 25-cm(2) treatment area on the face or scalp, all patients were treated initially with IngMeb 0·015% gel for three consecutive days. If lesions were present in the field at 8 weeks, or emerged at weeks 26 or 44, patients were randomized (2 : 1) to follow-up IngMeb or vehicle gel for three consecutive days. The main outcome was complete clearance rates of AKs 8 weeks after randomization. RESULTS: Of 450 patients who received initial treatment with IngMeb, 61·6% demonstrated complete clearance at 8 weeks. Patients with AKs present at 8 weeks or emerging at weeks 26 or 44 were randomized to IngMeb (n = 134) or vehicle (n = 69). IngMeb achieved a higher complete clearance rate than vehicle 8 weeks after randomization in AKs present at 8 weeks (46·7% vs. 18·4%; P < 0·01) and in emergent AKs (59·5% vs. 25·0%; P = 0·01). Based on those who completed 12 months of follow-up (n = 340), the overall 12-month clearance rate was estimated at 50·0%. Follow-up IngMeb treatment was well tolerated. CONCLUSIONS: This study demonstrated the long-term benefit of IngMeb 0·015% gel for initial and follow-up therapy of AKs.

Dietary acid load, kidney function, osteoporosis, and risk of fractures in elderly men and women.

SUMMARY: Because kidney dysfunction reduces the ability to excrete dietary acid excess, we hypothesized that underlying kidney function may have confounded the mixed studies linking dietary acid load with the risk of osteoporosis and fractures in the community. In a relatively large survey of elderly men and women, we report that dietary acid load did neither associate with DEXA-estimated bone mineral density nor with fracture risk. Underlying kidney function did not modify these null findings. Our results do not support the dietary acid-base hypothesis of bone loss. INTRODUCTION: Impaired renal function reduces the ability to excrete dietary acid excess. We here investigate the association between dietary acid load and bone mineral density (BMD), osteoporosis, and fracture risk by renal function status. METHODS: An observational study was conducted in 861 community-dwelling 70-year-old men and women (49% men) with complete dietary data from the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS). The exposure was dietary acid load as estimated from 7-day food records by the net endogenous acid production (NEAP) and potential renal acid load (PRAL) algorithms. Renal function assessed by cystatin C estimated glomerular filtration rate was reduced in 21% of the individuals. Study outcomes were BMD and osteoporosis state (assessed by DEXA) and time to fracture (median follow-up of 9.2 years). RESULTS: In cross-section, dietary acid load had no significant associations with BMD or with the diagnosis of osteoporosis. During follow-up, 131 fractures were validated. Neither NEAP (adjusted hazard ratios (HR) (95% confidence interval (CI)), 1.01 (0.85-1.21), per 1 SD increment) nor PRAL (adjusted HR (95% CI), 1.07 (0.88-1.30), per 1 SD increment) associated with fracture risk. Further multivariate adjustment for kidney function or stratification by the presence of kidney disease did not modify these null associations. CONCLUSIONS: The hypothesis that dietary acid load associates with reduced BMD or increased fracture risk was not supported by this study in community-dwelling elderly individuals. Renal function did not influence on this null finding.

A randomized trial comparing simultaneous vs. sequential field treatment of actinic keratosis with ingenol mebutate on two separate areas of the head and body.

BACKGROUND: Actinic keratoses (AKs) are precursors to invasive squamous cell carcinoma and can progress if untreated. Limited data support the use of ingenol mebutate to treat AKs on more than one area of the body simultaneously. OBJECTIVE: To investigate safety, efficacy and treatment satisfaction when treating separate areas simultaneously or sequentially with different concentrations of ingenol mebutate gel. METHODS: In this phase IIIb study (NCT01787383), patients with clinically visible, non-hyperkeratotic AKs on two separate treatment areas (face/scalp and trunk/extremities) were randomized to simultaneous or sequential treatment with ingenol mebutate gel (0.015% and 0.05%). Endpoints included composite local skin response (LSR) score 3 days after first application, complete AK clearance and percentage reduction in AKs at week 8. RESULTS: There were no statistically significant differences between simultaneous (n = 101) and sequential (n = 98) groups in composite LSR score (10.4 vs. 9.7), complete clearance (52.7% vs. 46.9%) or percentage reduction in AKs (83.4% vs. 79.1%). Mean composite LSR scores on face/scalp and trunk/extremities were similar for both groups. Adverse event (AE) incidence was comparable between groups, the most common treatment-related AEs being pruritus and pain at the application site. CONCLUSION: Treating AKs with ingenol mebutate simultaneously or sequentially gave similar results in terms of tolerability (LSR score, AEs) and efficacy (complete clearance). Therefore, the physician and patient can select the most convenient treatment regimen, with confidence in achieving a similar outcome.

Characterization of the neuropeptide Y system in the frog Silurana tropicalis (Pipidae): three peptides and six receptor subtypes.

Neuropeptide Y and its related peptides PYY and PP (pancreatic polypeptide) are involved in feeding behavior, regulation of the pituitary and the gastrointestinal tract, and numerous other functions. The peptides act on a family of G-protein coupled receptors with 4-7 members in jawed vertebrates. We describe here the NPY system of the Western clawed frog Silurana (Xenopus) tropicalis. Three peptides, NPY, PYY and PP, were identified together with six receptors, namely subtypes Y1, Y2, Y4, Y5, Y7 and Y8. Thus, this frog has all but one of the ancestral seven gnathostome NPY-family receptors, in contrast to mammals which have lost 2-3 of the receptors. Expression levels of mRNA for the peptide and receptor genes were analyzed in a panel of 19 frog tissues using reverse transcriptase quantitative PCR. The peptide mRNAs had broad distribution with highest expression in skin, blood and small intestine. NPY mRNA was present in the three brain regions investigated, but PYY and PP mRNAs were not detectable in any of these. All receptor mRNAs had similar expression profiles with high expression in skin, blood, muscle and heart. Three of the receptors, Y5, Y7 and Y8, could be functionally expressed in HEK-293 cells and characterized with binding studies using the three frog peptides. PYY had the highest affinity for all three receptors (K(i) 0.042-0.34 nM). Also NPY and PP bound to the Y8 receptor with high affinity (0.14 and 0.50 nM). The low affinity of NPY for the Y5 receptor (100-fold lower than PYY) differs from mammals and chicken. This may suggest a less important role of NPY on Y5 in appetite stimulation in the frog compared with amniotes. In conclusion, our characterization of the NPY system in S. tropicalis with its six receptors demonstrates not only greater complexity than in mammals but also some interesting differences in ligand-receptor preferences.

LDL-associated apolipoprotein J and lysozyme are associated with atherogenic properties of LDL found in type 2 diabetes and the metabolic syndrome.

OBJECTIVES: Exchangeable low-density lipoprotein (LDL)-associated proteins can affect the atherogenic properties of LDL. Our aim was to analyse the protein composition of LDL from individuals with or without type 2 diabetes and the metabolic syndrome (T2DM) in relation to other LDL particle characteristics, to assess whether certain proteins associate more with certain subclasses of LDL typical for T2DM, such as small, apoCIII-rich LDL. DESIGN: Low-density lipoprotein from two cohorts of 61-year-old men (n = 19 and 64) with or without T2DM was isolated using size-exclusion chromatography or deuterium oxide-based ultracentrifugation. LDL-associated proteins were identified using mass spectrometry and quantified using two-dimensional gel electrophoresis or enzyme-linked immunosorbent assay. Differently expressed LDL-associated proteins apolipoprotein (apo)J and lysozyme were also measured in serum from a third cohort of women (n = 71) with or without T2DM. Lysozyme binding to advanced glycation end product (AGE)-LDL was examined in vitro. RESULTS: ApoJ and lysozyme were increased in LDL particles with increased apoCIII content and decreased cholesterol content. When isolated with size-exclusion chromatography, LDL from individuals with T2DM contained more apoJ and lysozyme and less apoA1 than LDL from control individuals. LDL content of apoJ correlated with a smaller LDL particle size. Serum levels of lysozyme, but not apoJ, were increased in individuals with T2DM. In vitro, lysozyme associated more with AGE-LDL than with unmodified LDL. CONCLUSIONS: Our results indicate that apoJ and lysozyme are increased in LDL with characteristics of small dense LDL in T2DM. Small dense LDL is easily glycated, and the increased affinity of lysozyme for AGE-LDL provides a possible partial explanation for an increase lysozyme in LDL from those with type 2 diabetes.

Relation between fibroblast growth factor-23, body weight and bone mineral density in elderly men.

SUMMARY: We evaluated the relation between serum FGF23 and bone mineral density (BMD) in a community-based cohort of elderly men. There was a weak correlation between FGF23 and BMD, which was primarily dependent on body weight. INTRODUCTION: FGF23 is a hormonal factor produced in bone and regulates serum levels of phosphate (Pi) and vitamin D. FGF23 over-expression is associated with skeletal abnormalities, including rickets/osteomalacia. The relation between FGF23 and Bone Mineral Density (BMD) in the community remains unexplored. METHODS: We employed a large, population-based cohort of 3014 Swedish men aged 69-80 years, without known renal disease. BMD was measured with dual X-ray absorptiometry (DXA) in the hip and lumbar spine. Serum intact FGF23 was analyzed with a two-site monoclonal ELISA. RESULTS: There was a weak but significant correlation between FGF23 and BMD in femoral neck (r = 0.04, p < 0.05), femoral trochanter (r = 0.05, p = 0.004), total hip (r = 0.06, p = 0.0015) and lumbar spine (r = 0.07, p = 0.0004). The correlations remained significant when adjusting for biochemical covariates (Pi, calcium, PTH, 25(OH)D and renal function). However, the association became insignificant in all regions when adjusting for established confounding variables including age, height, weight and smoking. Further analysis confirmed a significant correlation between FGF23 and body weight (r = 0.13, p < 0.0001). CONCLUSIONS: The weak correlation between FGF23 and BMD in elderly male subjects is mainly due to an association between FGF23 and body weight. Therefore, FGF23 may not play a significant role in the hormonal regulation of BMD.

Birth and death of neuropeptide Y receptor genes in relation to the teleost fish tetraploidization.

Extensive evidence exists for a genome duplication in the fish lineage leading to the species-rich clade of the teleosts, comprising > 99% of the known actinopterygian (ray-finned) fish species. Our previous studies of the neuropeptide Y receptor (NPYR) gene family suggested an ancestral gnathostome repertoire of 7 genes in 3 subfamilies. However, studies in the zebrafish have earlier identified only 5 NPYR genes, despite the expected increase in gene number due to the teleost tetraploidization. Notably, receptors Y(1), Y(5) and Y(6) were missing in the zebrafish genome database and only Y(8) had been duplicated. We report here an investigation of the evolutionary history of the Y(1) subfamily (Y(1), Y(4), Y(6) and Y(8)) and the Y(5) receptor. Seven basal actinopterygian species and a shark were investigated and a total of 22 gene fragments were cloned and analyzed. Our results show that subtypes Y(1), Y(5) and Y(6) still exist in species representing basal actinopterygian lineages (bichir, sturgeon, gar and bowfin) as well as in some basal teleost lineages. Surprisingly we identified a zebrafish Y(1) receptor, the first Y(1) receptor found in euteleosts. Thus, these findings confirm the ancestral gnathostome repertoire of 7 NPYR genes and show that many of these receptors are present in basal actinopterygians as well as some basal teleosts. NPYR losses seem to have occurred relatively recently in euteleosts because Y(1), Y(5) and Y(6) are absent in the genome databases of two pufferfishes as well as medaka and stickleback and Y(5) and Y(6) are absent in the zebrafish database. A duplicate of Y(8) seems to be the only remaining receptor gene resulting from the teleost tetraploidization. The unexpected absence of the two appetite-stimulating receptors Y(1) and Y(5) in some euteleosts, along with our discovery of duplicates of the peptide ligands NPY and PYY, has implications for the role of the NPY system in euteleost feeding behavior.

Mathematical optimization of high dose-rate brachytherapy-derivation of a linear penalty model from a dose-volume model.

High dose-rate brachytherapy is a method for cancer treatment where the radiation source is placed within the body, inside or close to a tumour. For dose planning, mathematical optimization techniques are being used in practice and the most common approach is to use a linear model which penalizes deviations from specified dose limits for the tumour and for nearby organs. This linear penalty model is easy to solve, but its weakness lies in the poor correlation of its objective value and the dose-volume objectives that are used clinically to evaluate dose distributions. Furthermore, the model contains parameters that have no clear clinical interpretation. Another approach for dose planning is to solve mixed-integer optimization models with explicit dose-volume constraints which include parameters that directly correspond to dose-volume objectives, and which are therefore tangible. The two mentioned models take the overall goals for dose planning into account in fundamentally different ways. We show that there is, however, a mathematical relationship between them by deriving a linear penalty model from a dose-volume model. This relationship has not been established before and improves the understanding of the linear penalty model. In particular, the parameters of the linear penalty model can be interpreted as dual variables in the dose-volume model.

Expression and functional analysis of fibulin-1 (Fbln1) during normal and abnormal placental development of the mouse.

The extracellular matrix protein fibulin-1 (FBLN1) is an important component of blood vessel walls, as shown by the lethality of mice with homozygous targeted deletion of the Fbln1 gene. Here, we show that a murine placental overgrowth phenotype is associated with elevated Fbln1 transcript levels, suggesting that the gene and its product have a functional role in placentation. Fbln1 exhibits a specific expression pattern in the mouse placenta. Transcripts could not be detected prior to day 12. In subsequent stages, Fbln1 was expressed strongly in the spongiotrophoblast. Other sites of expression were endothelia of large fetal blood vessels, a tissue type reported to not express this gene. In addition, a subset of giant cells expressed the gene. This giant cell specific expression was strongly increased in hyperplastic placentas. Analysis of the placentation in fibulin null mice did not show any abnormality. Attempts to rescue the placental phenotypes of a congenic model of interspecies hybrid placental dysplasia (IHPD) by normalizing expression of Fbln1 proved that Fbln1 alone is not the key cause of phenotypes in these models of placental hyperplasia.

Thermodynamic stability and crystal structures for polymorphs and solvates of formoterol fumarate.

Polymorph screening of formoterol fumarate was performed in 12 solvents, followed by evaluations of thermodynamic stability. Three anhydrates, a dihydrate, a diethanolate, a diisopropanolate, and a dibensylalcoholate were found. The crystal structure of three solvated modifications and of the most stable anhydrate was investigated. This indicated that solvation is needed to get a stable and well packed crystal structure. Thermodynamic testing suggests that five crystal modifications are thermodynamically stable, at different conditions, since they are all reversibly related to each other.

Effect of systemically increasing human full-length Klotho on glucose metabolism in db/db mice.

The metabolic effects of antiaging Klotho were previously investigated in vivo by genetic manipulation. We have here studied the metabolic effect of physiologic levels of circulating full length Klotho in db/db mice. Increasing the full-length human Klotho levels has a positive effect on blood glucose through increasing insulin secretion.

Binding of GTP and GDP induces a significant conformational change in the GTPase domain of Ffh, a bacterial homologue of the SRP 54 kDa subunit.

The bacterial Ffh protein is homologous to the SRP54 subunit of the signal recognition particle. Ffh plays a key role in the targeting of proteins to the membrane and it is composed of a N-terminal domain (N), a middle GTPase (G) domain and a C-terminal M domain which has binding sites for SRP RNA and signal peptide. The GTP binding and hydrolysis of Ffh is critical to its function. We have used protease digestion to probe the conformation of the Mycoplasma mycoides Ffh N+G domain. In the absence of nucleotide the protein was comparatively sensitive to protease cleavage and we identified sites particularly prone to cleavage in a region near the C-terminus of the GTPase domain. However, in the presence of GTPgammaS or GDP this region is stabilized and the protein adopts a more ordered structure. The pattern of cleavage with GTPgammaS was indistinguishable from that when GDP was bound, indicating that the conformation of the nucleotide-free form is distinct from that when either GTPgammaS or GDP is bound to the protein. The possible functional role of this significant conformational change is discussed.

Use of an affinity proteomics approach for the identification of low-abundant bacterial adhesins as applied on the Lewis(b)-binding adhesin of Helicobacter pylori.

Microbial attachment to host cell surfaces is considered to be the first essential step for colonization and infection. In most known cases, attachment is mediated by a specific protein-carbohydrate interaction. We have used a carbohydrate-containing crosslinking probe to select bacterial surface adhesins for trypsin digestion, MALDI-TOF mass spectrometry and identification against genome sequence. The present paper describes this functional proteomics approach for identification of the recently cloned low-abundant Lewis(b)-binding adhesin of Helicobacter pylori. Protein identification was obtained through the enrichment of approximately 300 fmol of adhesin from solubilized cells.

The efflux of spin label entrapped in human erythrocyte ghosts when suspended in hyposmolar solutions. The effect of chlorpromazine, trifluoperazine, nicardipine and some other membrane active substances.

Human erythrocyte ghosts were loaded with the spin label tempocholine . Once entrapped in the ghosts, this spin label, carrying a positive charge, is not able to penetrate through intact ghost membranes. The ghosts were loaded with spin label to a concentration high enough to introduce exchange broadening of the electron spin resonance (ESR) signal with a relatively small signal amplitude. The efflux of the spin label brought about by hyposmolar stress was studied. The appearance of the label in the relatively large external volume gave rise to an increase of the ESR signal amplitude since the concentration of the spin label outside the ghosts was in the range in which exchange broadening can be excluded. The duration of the efflux following hyposmolar stress was less than half a minute. After this time, the ghosts resealed spontaneously and without restoration of the normal osmolarity. A number of membrane active substances were studied for possible influence on the efflux of spin label induced by hyposmolar stress. The drug substances chlorpromazine, trifluoperazine and nicardipine were found to increase the hyposmolar efflux of spin label. It was suggested that these substances, classified as calcium-antagonists and inhibitors of the calmodulin system, exert their action on the efflux of spin label by interaction with membrane proteins which maintain shape and tension of the erythrocytes.

Entrapping of the spin label tempocholine into human erythrocytes by resealing after hyposmolar stress. Comparison with haemolysis. The effects of some membrane-active substances.

Human erythrocytes were subjected to a sudden hyposmolar stress by suspension in solutions of varying salt concentrations in the presence of the spin label tempocholine. The enlarged pores in the erythrocyte membranes produced by the influx of water, followed by stretching, allowed the passage of the spin label, so that a certain amount of tempocholine was entrapped when the erythrocytes spontaneously resealed with closing of the pores. The excess of spin label in the external solution was then reduced to a diamagnetic species by the addition of ascorbic acid. The positively charged tempocholine and the ascorbic acid did not penetrate properly resealed erythrocytes, so that the electron spin resonance (ESR) signal from the entrapped spin label constituted a measure of the effective resealing of the pores and rifts in the membrane subsequent to hyposmolar stress. Some drug substances were found to influence the entrapping curves obtained when the amount of entrapped spin label was plotted against the osmolarity. Chlorpromazine, trifluoperazine, nicardipine, amperozide and haloperidol gave rise to a dose-dependent decrease of the entrapping of tempocholine, especially at low osmolarities. The exclusion of Ca2+ and Mg2+ ions from the solutions increased the action of chlorpromazine. The protective action against haemolysis brought about by a number of membrane-active substances at low concentrations [2] had its counterpart in the entrapping curve observed with chlorpromazine at 0.1 mM. It is suggested that the substances in this series exerted their action on the resealing process by interaction with the calmodulin system.

Stereoselective binding of 3-acetoxy-, and 3-hydroxy-1,4-benzodiazepine-2-ones to human serum albumin. Selective allosteric interaction with warfarin enantiomers.

Stereoselective binding of oxazepam, lorazepam, temazepam and methyl lorazepam as well as of their acetates to human serum albumin was investigated by different techniques. The 2'-chlorine and the N(1)-methyl substitution exert opposite effects on the antipodes. Enantiomers of oxazepam acetate (OAc) and lorazepam acetate (LAc) displace diazepam. Allosteric interactions with warfarin were manifested by either mutually increased or decreased binding depending on the structure of benzodiazepine and on the configuration of both benzodiazepine and warfarin. The most remarkable effect could be observed in the simultaneous binding of (S)-lorazepam acetate and (S)-warfarin.

Diagnosis of a patient with oncogenic osteomalacia using a phosphate uptake bioassay of serum and magnetic resonance imaging.

A previously healthy man with no family history of fractures presented with muscle pain, back pain and height loss. Investigations revealed hypophosphataemia, phosphaturia, undetectable serum 1,25-dihydroxyvitamin D and severe osteomalacia on bone biopsy, suggestive of a diagnosis of oncogenic osteomalacia. Thorough physical examination did not locate a tumour. Support for the diagnosis was obtained by detection of phosphate uptake inhibitory activity in a blinded sample of the patient's serum using a renal cell bioassay. On the basis of detection of this bioactivity, a total body magnetic resonance (MR) examination was performed. A small tumour was located in the right leg. Removal of the tumour resulted in the rapid reversal of symptoms and the abnormal biochemistry typical of oncogenic osteomalacia. Inhibitory activity was also demonstrated using the bioassay in serum from two other patients with confirmed or presumptive oncogenic osteomalacia, but not in serum from two patients with hypophosphataemia of other origin. This is the first case to be reported in which the diagnosis of oncogenic osteomalacia was assisted by demonstration of inhibitory activity of the patient's serum in a renal cell phosphate bioassay that provided an impetus for total body MR imaging.

Isolectins from Solanum tuberosum with different detailed carbohydrate binding specificities: unexpected recognition of lactosylceramide by N-acetyllactosamine-binding lectins.

Glycosphingolipid recognition by two isolectins from Solanum tuberosum was compared by the chromatogram binding assay. One lectin (PL-I) was isolated from potato tubers by affinity chromatography, and identified by MALDI-TOF mass spectrometry as a homodimer with a subunit molecular mass of 63,000. The other (PL-II) was a commercial lectin, characterized as two homodimeric isolectins with subunit molecular masses of 52,000 and 55,000, respectively. Both lectins recognized N-acetyllactosamine-containing glycosphingolipids, but the fine details of their carbohydrate binding specificities differed. PL-II preferentially bound to glycosphingolipids with N-acetyllactosamine branches, as Galbeta4GlcNAcbeta6(Galbeta4GlcNAcbeta3)Galbeta4Glcbeta1C er. PL-I also recognized this glycosphingolipid, but bound equally well to the linear glycosphingolipid Galbeta4GlcNAcbeta3Galbeta4GlcNAcbeta3Galbeta4Glcbeta1Cer. Neolactotetraosylceramide and the B5 pentaglycosylceramide were also bound by PL-I, while other glycosphingolipids with only one N-acetyllactosamine unit were non-binding. Surprisingly, both lectins also bound to lactosylceramide, with an absolute requirement for sphingosine and non-hydroxy fatty acids. The inhibition of binding to both lactosylceramide and N-acetyllactosamine-containing glycosphingolipids by N-acetylchitotetraose suggests that lactosylceramide is also accomodated within the N-acetylchitotetraose/N-acetyllactosamine-binding sites of the lectins. Through docking of glycosphingolipids onto a three-dimensional model of the PL-I hevein binding domain, a Galbeta4GlcNAcbeta3Galbeta4 binding epitope was defined. Furthermore, direct involvement of the ceramide in the binding of lactosylceramide was suggested.