Assessment of home care aides' respiratory exposure to total volatile organic compounds and chlorine during simulated bathroom cleaning: An experimental design with conventional and "green" products.

Home care (HC) aide visits to clients' homes often involve cleaning and disinfecting (C&D) bathrooms. Some ingredients in C&D household products are associated with respiratory illness, including sodium hypochlorite (bleach) and quaternary ammonium compounds (quats). "Green" products may be safer for the environment, however there are limited quantitative evaluations of their respiratory risks. This study assessed airborne concentrations and time profiles of total volatile organic compounds (TVOC) and chlorine generated during typical bathroom cleaning performed by aides using conventional and green products. Aides performed cleaning tasks in a simulated residential bathroom constructed in an environmental air sampling laboratory. A balanced experimental design involved each aide coming to the lab for four visits during which she performed two 20-min cleaning sessions using one of three C&D products (bleach-based, 1-5% sodium hypochlorite by weight; quats-based, 0.1-1% by weight quaternary ammonium compounds; and "green," 0.05% by weight thymol, a component of botanical thyme oil) or distilled water as a control. TVOC and chlorine direct reading instruments were attached to aides with sample inlets located in the breathing zone. Ten-second averages of TVOC and chlorine gas concentrations and instantaneous peak concentrations were recorded for the sessions' duration. TVOC concentrations by methods of C&D application (spraying, streaming, wiping) also were evaluated. The study completed 169 air sampling sessions with 22 aides. The quats-based product generated more than twice the average TVOC concentrations (mean = 1,210 ppb) than the bleach-based (mean = 593 ppb) or green (mean = 498 ppb) products. Each product generated TVOC concentrations that rose rapidly within the first few minutes of application. Spraying produced the highest TVOC exposures, wiping the lowest. Thirteen aides (65%) experienced peak chlorine exposures above the OSHA PEL ceiling limit (1 ppm) when using the bleach-based product. HC aides may experience respiratory hazards from use of conventional or green C&D products formulated with bleach or other respiratory irritants and sprayed in small, poorly ventilated spaces typical of bathrooms. Spraying should be avoided.

Elastin-like hydrogel stimulates angiogenesis in a severe model of critical limb ischemia (CLI): An insight into the glyco-host response.

Critical limb ischemia (CLI) is characterized by the impairment of microcirculation, necrosis and inflammation of the muscular tissue. Although the role of glycans in mediating inflammation has been reported, changes in the glycosylation following muscle ischemia remains poorly understood. Here, a murine CLI model was used to show the increase of high mannose, α-(2, 6)-sialic acid and the decrease of hybrid and bisected N-glycans as glycosylation associated with the ischemic environment. Using this model, the efficacy of an elastin-like recombinamers (ELR) hydrogel was assessed. The hydrogel modulates key angiogenic signaling pathways, resulting in capillary formation, and ECM remodeling. Arterioles formation, reduction of fibrosis and anti-inflammatory macrophage polarization wa also induced by the hydrogel administration. Modulation of glycosylation was observed, suggesting, in particular, a role for mannosylation and sialylation in the mediation of tissue repair. Our study elucidates the angiogenic potential of the ELR hydrogel for CLI applications and identifies glycosylation alterations as potential new therapeutic targets.

Hagen Bræ: A Surging Glacier in North Greenland-35 Years of Observations.

We use remotely sensed ice velocities in combination with observations of surface elevation and glacier area change to investigate the dynamics of Hagen Bræ, North Greenland in high detail over the last 35 years. From our data, we can establish for the first time that Hagen Bræ is a surge-type glacier with characteristics of both Alaskan- and Svalbard-type surging glaciers. We argue that the observed surge was preconditioned by the glacier geometry and triggered by englacially stored meltwater. At present, the glacier is in a transitional state between active and quiescence phases and is not building up to its pre-surge geometry. We suggest that the glacier is adjusting to the loss of its floating section, general thinning, and changes in fjord conditions that occurred over the study period which are unrelated to the surge behavior. The high temporal resolution of the ice velocity data gives insight to the sub-annual glacier flow.

Cartilage oligomeric matrix protein forms protein complexes with synovial lubricin via non-covalent and covalent interactions.

OBJECTIVE: Understanding the cartilage surface structure, lost in arthritic disease, is essential for developing strategies to effectively restore it. Given that adherence of the lubricating protein, lubricin, to the cartilage surface is critical for boundary lubrication, an interaction with cartilage oligomeric matrix protein (COMP) was investigated. COMP, an abundant cartilage protein, is known to be important for matrix formation. DESIGN: Synovial fluid (SF) from arthritic patients was used to detect possible COMP-lubricin complexes by immunological methods. Recombinant (RC) COMP and lubricin fragments were expressed to characterize this bonding and mass spectrometry employed to specifically identify the cysteines involved in inter-protein disulfide bonds. RESULTS: COMP-lubricin complexes were identified in the SF of arthritic patients by Western blot, co-immunoprecipitation and sandwich ELISA. RC fragment solid-phase binding assays showed that the C-terminal (amino acids (AA) 518-757) of COMP bound non-covalently to the N-terminal of lubricin (AA 105-202). Mass spectrometry determined that although cysteines throughout COMP were involved in binding with lubricin, the cysteines in lubricin were primarily focused to an N-terminal region (AA 64-86). The close proximity of the non-covalent and disulfide binding domains on lubricin suggest a two-step mechanism to strongly bind lubricin to COMP. CONCLUSION: These data demonstrate that lubricin forms a complex network with COMP involving both non-covalent and covalent bonds. This complex between lubricin and the cartilage protein COMP can be identified in the SF of patients with arthritis conditions including osteoarthritis (OA) and rheumatoid arthritis (RA).

Characterisation of lubricin in synovial fluid from horses with osteoarthritis.

REASON FOR PERFORMING STUDY: The glycoprotein lubricin contributes to the boundary lubrication of the articular cartilage surface. The early events of osteoarthritis involve the superficial layer where lubricin is synthesised. OBJECTIVES: To characterise the glycosylation profile of lubricin in synovial fluid from horses with osteoarthritis and study secretion and degradation of lubricin in an in vitro inflammation cartilage model. STUDY DESIGN: In vitro study. METHODS: Synovial fluid samples collected from horses with joints with normal articular cartilage and structural osteoarthritic lesions; with and without osteochondral fragments, were analysed for the lubricin glycosylation profiles. Articular cartilage explants were stimulated with or without interleukin-1ß for 25 days. Media samples collected at 3-day intervals were analysed by quantitative proteomics, western blot and enzyme-linked immunosorbent assay. RESULTS: O-glycosylation profiles in synovial fluid revealed both Core 1 and 2 O-glycans, with Core 1 O-glycans predominating. Synovial fluid from normal joints (49.5 ± 1.9%) contained significantly lower amounts of monosialylated Core 1 O-glycans compared with joints with osteoarthritis (53.8 ± 7.8%, P = 0.03) or joints with osteochondral fragments (57.3 ± 8.8%, P = 0.001). Additionally, synovial fluid from normal joints (26.7 ± 6.7%) showed higher amounts of disialylated Core 1 O-glycan than from joints with osteochondral fragments (21.2 ± 4.9%, P = 0.03). A C-terminal proteolytic cleavage site in lubricin was found in synovial fluid from normal and osteochondral fragment joints and in media from interleukin-1ß stimulated and unstimulated articular cartilage explants. CONCLUSIONS: This is the first demonstration of a change in the glycosylation profile of lubricin in synovial fluid from diseased equine joints compared with that from normal joints. We demonstrate an identical proteolytic cleavage site of lubricin both in vitro and in vivo. The reduced sialation of lubricin in synovial fluid from diseased joints may affect the boundary lubricating ability of the superficial layer of articular cartilage and could be one of the early events in the progression of osteoarthritis.

Impact of a fast-track surgery programme for pancreaticoduodenectomy.

BACKGROUND: Fast-track (FT) programmes are multimodal, evidence-based approaches to optimize patient outcome after surgery. The aim of this study was to evaluate the safety, clinical outcome and patients' experience of a FT programme after pancreaticoduodenectomy (PD) in a high-volume institution in Sweden. METHODS: Consecutive patients undergoing PD were studied before and after implementation of the FT programme. FT changes included earlier mobilization, standardized removal of the nasogastric tube and drain, and earlier start of oral intake. Patient experience was evaluated with European Organization for Research and Treatment of Cancer QLQ-C30 and QLQ-PAN26 questionnaires 2 weeks before and 4 weeks after surgery. RESULTS: Between 2011 and 2014, 100 consecutive patients undergoing PD were studied, of whom 50 received standard care (controls), followed by 50 patients treated after implementation of the FT programme. The nasogastric tube was removed significantly earlier in the FT group, and these patients were able fully to tolerate fluids and solid food sooner after PD. Delayed gastric emptying was significantly reduced in the FT group (26 versus 48 per cent; P = 0.030). Overall morbidity remained unchanged and there were no deaths in either group. Postoperative length of hospital stay was reduced from 14 to 10 days and hospital costs were decreased significantly. Health-related quality-of-life questionnaires showed similar patterns of change, with no significant difference between groups before or after surgery. CONCLUSION: The FT programme after PD was safe. Delayed gastric emptying, hospital stay and hospital costs were all reduced significantly. Although patients were discharged 4 days earlier in the FT group, this did not influence health-related quality of life compared with standard care.

Detection of pulsed gamma rays above 100 GeV from the Crab pulsar.

We report the detection of pulsed gamma rays from the Crab pulsar at energies above 100 giga-electron volts (GeV) with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) array of atmospheric Cherenkov telescopes. The detection cannot be explained on the basis of current pulsar models. The photon spectrum of pulsed emission between 100 mega-electron volts and 400 GeV is described by a broken power law that is statistically preferred over a power law with an exponential cutoff. It is unlikely that the observation can be explained by invoking curvature radiation as the origin of the observed gamma rays above 100 GeV. Our findings require that these gamma rays be produced more than 10 stellar radii from the neutron star.

Development and validation of the Capacity of Daily Living during the Morning questionnaire and the Global Chest Symptoms Questionnaire in COPD.

This report concerns the development and validation of two patient-reported outcomes questionnaires developed to assess chronic obstructive pulmonary disease (COPD) patients' ability to perform morning activities and to evaluate their morning symptoms. Based on interviews with COPD patients, the Capacity of Daily Living during the Morning (CDLM) questionnaire and the Global Chest Symptoms Questionnaire (GCSQ) were developed, linguistically validated and incorporated into two multicentre, randomised trials involving a total of 1,100 COPD patients; those trials were registered at ClinicalTrials.gov (NCT00496470 and NCT00542880). Data from these trials were used to determine the reliability, validity and responsiveness of the questionnaires and to derive estimates of minimal important differences (MIDs). Both questionnaires displayed good-to-high reliability (Cronbach's alpha 0.75-0.93). Analysis of convergent validity showed that CDLM and GCSQ scores correlated significantly (p<0.001) with symptoms, health-related quality of life (HRQoL) and use of rescue medication. In both trials, CDLM and GCSQ scores discriminated between patients with different levels of HRQoL, as assessed by the St George's Respiratory Questionnaire for COPD patients (SGRQ-C), but not with disease severity, as assessed by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria. A significant improvement in CDLM and GCSQ scores occurred in response to treatment. Estimations of MID scores, corresponding to an SGRQ-C MID of 4, were 0.20 for the CDLM questionnaire and 0.15 for the GCSQ. Both the CDLM questionnaire and the GCSQ are easy-to-use, reliable, responsive, self-administered questionnaires that report on patients' symptoms and ability to perform morning activities.

Radio imaging of the very-high-energy gamma-ray emission region in the central engine of a radio galaxy.

The accretion of matter onto a massive black hole is believed to feed the relativistic plasma jets found in many active galactic nuclei (AGN). Although some AGN accelerate particles to energies exceeding 10(12) electron volts and are bright sources of very-high-energy (VHE) gamma-ray emission, it is not yet known where the VHE emission originates. Here we report on radio and VHE observations of the radio galaxy Messier 87, revealing a period of extremely strong VHE gamma-ray flares accompanied by a strong increase of the radio flux from its nucleus. These results imply that charged particles are accelerated to very high energies in the immediate vicinity of the black hole.

Mucins in the mucosal barrier to infection.

The mucosal tissues of the gastrointestinal, respiratory, reproductive, and urinary tracts, and the surface of the eye present an enormous surface area to the exterior environment. All of these tissues are covered with resident microbial flora, which vary considerably in composition and complexity. Mucosal tissues represent the site of infection or route of access for the majority of viruses, bacteria, yeast, protozoa, and multicellular parasites that cause human disease. Mucin glycoproteins are secreted in large quantities by mucosal epithelia, and cell surface mucins are a prominent feature of the apical glycocalyx of all mucosal epithelia. In this review, we highlight the central role played by mucins in accommodating the resident commensal flora and limiting infectious disease, interplay between underlying innate and adaptive immunity and mucins, and the strategies used by successful mucosal pathogens to subvert or avoid the mucin barrier, with a particular focus on bacteria.

Risk factors for acute graft-versus-host disease grades II-IV after reduced intensity conditioning allogeneic stem cell transplantation with unrelated donors: a single centre study.

We analysed factors associated with moderate to severe acute GVHD in 111 patients treated with fludarabin-based reduced intensity conditioning (RIC) and allogeneic haematopoietic stem cell transplantation (HSCT). Most patients had a haematological malignancy. Donors were 97 HLA-A, -B and -DRbeta1 identical unrelated and 14 HLA-A, -B or -DRbeta1 allele mismatched unrelated donors. In the univariate analysis, we found ten factors associated with acute GVHD. These were diagnosis (P=0.06), GVHD prophylaxis with combinations other than CsA+MTX (P=0.006), graft nucleated (P<0.001) and CD34 (P<0.001) cell-dose, bidirectional ABO mismatch (P=0.001), conditioning (P=0.002), hospital vs home-care (P=0.06), ATG dose (P<0.001), donor herpes virus serology (P=0.07) and an immunized female donor to male recipient (P=0.05). In the multivariate analysis, three factors remained significant: a high CD34 cell dose (P<0.001), low dose (4 mg/kg) ATG (P<0.001), and an immunized female donor to male recipient (P<0.01). Patients receiving a CD34 cell dose > or =17.0 x 10(6) per kg had a higher incidence of GVHD, 53.7%, compared to 22.3% in patients receiving a lower dose (P=0.002). In patients without any of these risk factors (n=70), the incidence of acute GVHD was 14.1%, while it was 38.0 and 85.0% in patients with one (n=29) or two (n=10) risk factors (P<0.001). We concluded that risk factors for acute GVHD using RIC are similar as using myeloablative conditioning.

Rhinitis in the menstrual cycle, pregnancy, and some endocrine disorders.

By clinical experience, rhinitis has been suggested as caused by some endocrine disorders, but the evidence for this is vague, and the few descriptions almost anecdotal. Rhinitis of the menstrual cycle has been more described, although a solid picture is still lacking. Pregnancy rhinitis is therefore so far the only clearly defined "hormonal rhinitis." However, the cause of pregnancy rhinitis is not simply estrogen or progesterone, but seems multifactorial, and may possibly be associated with the PGH. Treatment consists mainly of information, physiological measures, and nasal saline washings.

Impact of social standing on sports injury prevention in a WHO safe community: intervention outcome by household employment contract and type of sport.

OBJECTIVES: As physical activity is promoted as part of a healthy lifestyle, sports injuries are becoming an important public health concern in many countries. The objective of this study is to investigate rates of sports injuries before and after implementation of a WHO Safe Community program. METHODS: Sports injury data were collected pre- and post-implementation from all individuals below 65 years of age during 1 year in the targeted municipality (population 41,000) and in a control municipality (population 26,000). A quasi-experimental design was used and individuals were divided into three categories based on household relationship to the labour market. RESULTS: There were no differences between socio-economic categories regarding pre-intervention injury rates. No statistically significant post-intervention changes in injury rate were observed in the control area or among any females in either area. In the intervention area, a statistically significant (p = 0.011) decrease in injury rate was observed among male members of households in which the vocationally important member was employed. A statistically significant decrease was observed in injuries sustained in team sports among male members of households in which the vocationally important member was employed (p = 0.001) and among members of households in which the vocationally important member was self employed (p<0.05). CONCLUSIONS: The study indicates areas for improvement in the civic network based WHO Safe Community model. The results show that females, participants in individual sports, and members of non-vocationally active households were less affected by the interventions. These facts have to be addressed in planning future community based sports injury prevention programmes and their evaluations.

Impact of social standing on injury prevention in a World Health Organization Safe Community--intervention outcome by household employment contract.

BACKGROUND: Although social inequality in health has been an argument for community-based injury prevention programmes, intervention outcomes with regard to differences in social standing have not been analysed. The objective of this study was to investigate rates of injuries treated in health-care among members of households at different levels of labour market integration before and after the implementation of a WHO Safe Community programme. METHODS: A quasi-experimental design was used with pre- and post-implementation data collection covering the total populations <65 years of age during one year in the programme implementation municipality (population 41 000) and in a control municipality (population 26 000). Changes in injury rates were studied using prospective registration of all acute care episodes with regard to social standing in both areas during the study periods. RESULTS: Male members of households categorized as not vocationally active displayed the highest pre-intervention injury rates. Also after the intervention, males in households classified as not vocationally active displayed notably elevated injury rates in both the control and study areas. Households in the study area in which the significant member was employed showed a post-intervention decrease in injury rate among both men (P < 0.001) and women (P < 0.01). No statistically significant change was observed in households in which the significant member was self-employed or not vocationally active. In the control area, only an aggregate-level decrease (P < 0.05) among members of households in which the significant member was employed was observed. CONCLUSIONS: The study displayed areas for improvement in the civic network-based WHO Safe Community model. Even though members of non-vocationally active households, in particular men, were at higher pre-intervention injury risk, they were not affected by the interventions. This fact has to be addressed when planning future community-based injury prevention programmes.

Proteomic analysis of the genetic premature aging disease Hutchinson Gilford progeria syndrome reveals differential protein expression and glycosylation.

Proteomics has revealed differential protein expression and glycosylation in membrane proteins from premature aging Hutchinson-Gilford progeria syndrome fibroblasts (progeria). Progeria is a rare autosomal dominant genetic disorder of premature aging characterized by marked growth retardation and specific, progressive, premature senescent changes of the skin and other tissues. Affected children live to an average age of 13 years. The 1q20-24 region of chromosome 1 which codes for one of these proteins, lamin A/C, has previously been implicated by Brown et al. (1990) who described identical twins with progeria, where cytogenetic analysis showed an inverted insertion in the long arm of the chromosome in 70% of cells. Luengo et al. (2002) similarly reported an interstitial deletion of chromosome 1q23, in a 9-year-old patient with a classic clinical picture of progeria.

Fluticasone propionate aqueous nasal spray in pregnancy rhinitis.

Pregnancy rhinitis is a common condition with longstanding nasal congestion; troublesome for the mother, possibly also affecting the fetus. There is need for a safe, effective treatment. Nasal corticosteroids, indisputable in other types of rhinitis, have not been evaluated in pregnancy rhinitis. In this placebo-controlled, randomized, double-blind study with parallel groups, we evaluated the effect of 8 weeks of treatment with fluticasone propionate aqueous nasal spray in 53 women with pregnancy rhinitis. Daily symptom scores and nasal peak expiratory flow, as well as acoustic rhinometry before and after treatment, did not show any difference between the groups. Placebo resulted in 6/27 responders, compared with 5/26 for active treatment. There was no detectable influence on maternal cortisol as measured by morning S-cortisol and overnight 12-h-U-cortisol, or any difference in ultrasound measures of fetal growth or pregnancy outcome. Altogether, our study indicates no significant effects of the treatment described here.

Neutralization of pH in the Golgi apparatus causes redistribution of glycosyltransferases and changes in the O-glycosylation of mucins.

Addition of the weak base ammonium chloride (NH4Cl) or the proton pump inhibitor bafilomycin A1 to cultured HeLa and LS 174T cells effectively neutralized the pH gradient of the secretory pathway. This resulted in relocalization of the three studied glycosyltransferases, N-acetylgalactosaminyltransferase 2, beta1,2 N-acetylglucosaminyltransferase I, and beta1,4 galactosyltransferase 1, normally localized to the Golgi stack, the medial/trans-Golgi and the trans-Golgi/TGN, respectively. Indirect immunofluorescence microscopy, immunoelectron microscopy, and subcellular fractionation of the tagged or native glycosyltransferases showed that NH4Cl caused a relocalization of the enzymes mainly to vesicles of endosomal type, whereas bafilomycin A1 gave mainly cell surface staining. The general morphology of the endoplasmic reticulum and Golgi apparatus was retained as judged from immunofluorescence and electron microscopy studies. When the O-glycans on the guanidinium chloride insoluble gel-forming mucins from the LS 174T cells were analyzed by gas chromatography-mass spectrometry after neutralization of the secretory pathway pH by NH4Cl over 10 days shorter O-glycans were observed. However, no decrease in the number of oligosaccharide chains was indicated. Together, the results suggest that pH is a contributing factor for proper steady-state distribution of glycosyltransferases over the Golgi apparatus and that altered pH may cause alterations in glycosylation possibly due to a relocalization of glycosyltransferases.

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.

Identification of transient glycosylation alterations of sialylated mucin oligosaccharides during infection by the rat intestinal parasite Nippostrongylus brasiliensis.

The sialylation of the oligosaccharides from small-intestinal mucins during a 13-day infectious cycle was studied in Sprague-Dawley rats with the parasite Nippostrongylus brasiliensis. Sialic acid analysis and release, permethylation and analysis by GC-MS of the sialylated oligosaccharides isolated from the 'insoluble' mucin complex revealed a relative decrease (4-7-fold) of N-glycolylneuraminic acid compared with N-acetylneuraminic acid just before parasite expulsion. Northern blots showed that this effect was due to the decreased expression of a hydroxylase converting CMP-N-acetylneuraminic acid into CMP-N-glycolylneuraminic acid. Analysis of other rat strains showed that this parasite infection also caused the same effect in these animals. Detailed analysis of infected Sprague-Dawley rats revealed four sialylated oligosaccharides not found in the uninfected animals. These new oligosaccharides were characterized in detail and all shown to contain the trisaccharide epitope NeuAc/NeuGcalpha2-3(GalNAcbeta1-4)Galbeta1 (where NeuGc is N-glycolyl neuraminic acid). This epitope is similar to the Sd(a)- and Cad-type blood-group antigens and suggests that the infection causes the induction of a GalNAcbeta1-4 glycosyltransferase. This model for an intestinal infection suggests that the glycosylation of intestinal mucins is a dynamic process being modulated by the expression of specific enzymes during an infection process.

Novel carbohydrate binding site recognizing blood group A and B determinants in a hybrid of cholera toxin and Escherichia coli heat-labile enterotoxin B-subunits.

The B-subunits of cholera toxin (CTB) and Escherichia coli heat-labile enterotoxin (LTB) are structurally and functionally related. However, the carbohydrate binding specificities of the two proteins differ. While both CTB and LTB bind to the GM1 ganglioside, LTB also binds to N-acetyllactosamine-terminated glycoconjugates. The structural basis of the differences in carbohydrate recognition has been investigated by a systematic exchange of amino acids between LTB and CTB. Thereby, a CTB/LTB hybrid with a gain-of-function mutation resulting in recognition of blood group A and B determinants was obtained. Glycosphingolipid binding assays showed a specific binding of this hybrid B-subunit, but not CTB or LTB, to slowly migrating non-acid glycosphingolipids of human and animal small intestinal epithelium. A binding-active glycosphingolipid isolated from cat intestinal epithelium was characterized by mass spectrometry and proton NMR as GalNAcalpha3(Fucalpha2)Galbeta4(Fucalpha3)Glc NAcbeta3Galbeta4Glc NAcbeta3Galbeta4Glcbeta1Cer. Comparison with reference glycosphingolipids showed that the minimum binding epitope recognized by the CTB/LTB hybrid was Galalpha3(Fucalpha2)Galbeta4(Fucalpha3)GlcNAc beta. The blood group A and B determinants bind to a novel carbohydrate binding site located at the top of the B-subunit interfaces, distinct from the GM1 binding site, as found by docking and molecular dynamics simulations.