Biomedical subjects

A Martin

Publications and source records attributed to A Martin.

At least 253 records · Page 14Linked to original sources

PubMed1999

Application of a DNA hybridization-hydrophobic-grid membrane filter method for detection and isolation of verotoxigenic escherichia coli.

Verotoxigenic Escherichia coli (VTEC) strains were isolated from food and animal fecal samples by using PCR to screen for the presence of VTEC after broth enrichment and then filtering VTEC-positive cultures through hydrophobic-grid membrane filters (HGMFs) which were incubated on MacConkey agar. The filters were probed with a digoxigenin-labeled PCR product generated by amplification of a conserved verotoxin gene sequence. Replication of the growth on filters allowed probe-positive colonies to be picked. When ground beef samples were inoculated with VTEC strains, 100% of the strains were recovered, and the detection limit was 0.1 CFU per g. Similar results were obtained with seven types of artificially contaminated vegetables. A survey of 32 packages of vegetables and 23 samples of apple cider obtained at the retail level did not reveal the presence of VTEC. However, the intestinal fecal contents of a moose, 1 of 35 wild mammals and birds examined, contained E. coli O157:H7. The DNA hybridization-HGMF method was also used in a prevalence survey of 327 raw and 744 ready-to-eat products; VTEC strains were recovered from 4.9% of the raw products and 0.7% of the ready-to-eat products. No serotype O157:H7 strains were detected. This method is particularly suited for surveys in which low numbers of VTEC-positive samples are expected and isolates are required.

Animals↗

PubMed1999

Conservation and accessibility of an inner core lipopolysaccharide epitope of Neisseria meningitidis.

We investigated the conservation and antibody accessibility of inner core epitopes of Neisseria meningitidis lipopolysaccharide (LPS) because of their potential as vaccine candidates. An immunoglobulin G3 murine monoclonal antibody (MAb), designated MAb B5, was obtained by immunizing mice with a galE mutant of N. meningitidis H44/76 (B. 15.P1.7,16 immunotype L3). We have shown that MAb B5 can bind to the core LPS of wild-type encapsulated MC58 (B.15.P1.7,16 immunotype L3) organisms in vitro and ex vivo. An inner core structure recognized by MAb B5 is conserved and accessible in 26 of 34 (76%) of group B and 78 of 112 (70%) of groups A, C, W, X, Y, and Z strains. N. meningitidis strains which possess this epitope are immunotypes in which phosphoethanolamine (PEtn) is linked to the 3-position of the beta-chain heptose (HepII) of the inner core. In contrast, N. meningitidis strains lacking reactivity with MAb B5 have an alternative core structure in which PEtn is linked to an exocyclic position (i.e., position 6 or 7) of HepII (immunotypes L2, L4, and L6) or is absent (immunotype L5). We conclude that MAb B5 defines one or more of the major inner core glycoforms of N. meningitidis LPS. These findings support the possibility that immunogens capable of eliciting functional antibodies specific to inner core structures could be the basis of a vaccine against invasive infections caused by N. meningitidis.

Animals↗

PubMed1999

Maturation of the hepatitis A virus capsid protein VP1 is not dependent on processing by the 3Cpro proteinase.

Most details of the processing of the hepatitis A virus (HAV) polyprotein are known. Unique among members of the family Picornaviridae, the primary cleavage of the HAV polyprotein is mediated by 3Cpro, the only proteinase known to be encoded by the virus, at the 2A/2B junction. All other cleavages of the polyprotein have been considered to be due to 3Cpro, although the precise location and mechanism responsible for the VP1/2A cleavage have been controversial. Here we present data that argue strongly against the involvement of the HAV 3Cpro proteinase in the maturation of VP1 from its VP1-2A precursor. Using a heterologous expression system based on recombinant vaccinia viruses directing the expression of full-length or truncated capsid protein precursors, we show that the C terminus of the mature VP1 capsid protein is located near residue 764 of the polyprotein. However, a proteolytically active HAV 3Cpro that was capable of directing both VP0/VP3 and VP3/VP1 cleavages in vaccinia virus-infected cells failed to process the VP1-2A precursor. Using site-directed mutagenesis of an infectious molecular clone of HAV, we modified potential VP1/2A cleavage sites that fit known 3Cpro recognition criteria and found that a substitution that ablates the presumed 3Cpro dipeptide recognition sequence at Glu764-Ser765 abolished neither infectivity nor normal VP1 maturation. Altered electrophoretic mobility of VP1 from a viable mutant virus with an Arg764 substitution indicated that this residue is present in VP1 and that the VP1/2A cleavage occurs downstream of this residue. These data indicate that maturation of the HAV VP1 capsid protein is not dependent on 3Cpro processing and may thus be uniquely dependent on a cellular proteinase.

3C Viral Proteases↗

PubMed1999

Renal function in compensated hepatic cirrhosis: effects of an amino acid infusion and relationship with nitric acid.

AIMS: In order to assess the possible participation of nitric oxide (NO) in renal function during compensated hepatic cirrhosis, we studied renal function, the plasma and urinary levels of cGMP and the concentration of nitrates and nitrites, as markers of NO synthesis in blood and urine, in 10 patients with Child A hepatic cirrhosis as compared with 10 control subjects, both under basal conditions and during stimulation (amino acid-induced glomerular hyperfiltration). METHODS: To study renal function, the glomerular filtration rate (GFR), effective renal plasma flow (ERPF), renal functional reserve (RFR), renal venous resistance (RVR) and the filtration fraction (FF) were measured. Renin and aldosterone levels were determined to assess the possible involvement of these compounds in the renin-angiotensin-aldosterone axis. RESULTS: GFR and ERPF were significantly lower in the patients with cirrhosis than in the controls (mean GFR: 82+/-12.3 vs. 105+/-15 ml/min, p = 0. 01; ERPF 452+/-86 vs. 543+/-56 ml/min, p = 0.002). The RFR value was similar in both groups. In the basal situation cGMP levels were higher in plasma and urine in patients with cirrhosis than in the controls (plasma cGMP in cirrhosis 8.4+/-2.4 vs. 4.2+/-3.5 pmol/ml; urine cGMP in cirrhosis 1.2+/-2.1 vs. 0.68+/-0.1 pmol/ml). The NO levels were also higher in plasma and urine in patients with cirrhosis vs. controls (plasma NO in cirrhosis 45.5+/-9.2 vs. 30. 3+/-1.2 micromol/l; urinary NO in cirrhosis 6.2+/-1.3 vs. 3.1+/-2.3 micromol/ml). In both groups the amino acid perfusion increased GFR, ERPF, cGMP and NO levels in plasma and urine. In the patients with cirrhosis the RVR decreased significantly during perfusion and no noteworthy changes in FF were observed. The GFR values observed during amino acid perfusion were similar in patients with cirrhosis and portal hypertension to those observed in the controls (27.2+/-12 vs. 25.3+/-16%). However, the changes induced the ERPF were more marked in patients with cirrhosis (cirrhosis 35.3+/-15 vs. 22. 2+/-13%, p = 0.02). CONCLUSIONS: The present findings point to certain alterations in renal function in patients with hepatic cirrhosis and portal hypertension without ascitis, a clear difference being visible between the ERPF and GFR following amino acid-induced stimulation. The significant elevation in cGMP and NO levels in plasma and urine implies a maintained vasodilatory action that may at least partly compensate the vasoconstrictor effects of angiotensin II.

Adult↗

PubMed1999

Cortical regions associated with perceiving, naming, and knowing about colors.

Positron emission tomography (PET) was used to investigate whether retrieving information about a specific object attribute requires reactivation of brain areas that mediate perception of that attribute. During separate PET scans, subjects passively viewed colored and equiluminant gray-scale Mondrians, named colored and achromatic objects, named the color of colored objects, and generated color names associated with achromatic objects. Color perception was associated with activations in the lingual and fusiform gyri of the occipital lobes, consistent with previous neuroimaging and human lesion studies. Retrieving information about object color (generating color names for achromatic objects relative to naming achromatic objects) activated the left inferior temporal, left frontal, and left posterior parietal cortices, replicating previous findings from this laboratory. When subjects generated color names for achromatic objects relative to the low-level baseline of viewing gray-scale Mondrians, additional activations in the left fusiform/lateral occipital region were detected. However, these activations were lateral to the occipital regions associated with color perception and identical to occipital regions activated when subjects simply named achromatic objects relative to the same low-level baseline. This suggests that the occipital activations associated with retrieving color information were due to the perception of object form rather than to the top-down influence of brain areas that mediate color perception. Taken together, these results indicate that retrieving previously acquired information about an object's typical color does not require reactivation of brain regions that subserve color perception.

Adult↗

PubMed1999

High expression of MDM2 protein and low rate of p21(WAF1/CIP1) expression in SCID mice Epstein Barr virus-induced lymphoproliferation.

To study the prevalence of p53 inactivation and MDM2/p21(WAFI/CIP1) expression in severe combined immunodeficient (SCID) mice Epstein-Barr virus (EBV)-induced lymphoproliferation, 19 samples obtained after ip injection of peripheral blood mononuclear cells (PBMCs) from EBV-seropositive donors or lymphoblastoid cell lines (LCL) were analyzed. In all samples tested, overexpression of Ki-67 antigen was shown by immunohistochemistry, indicating a high proliferative index of SCID mice EBV-induced lymphoproliferation. P53 mutations were screened by functional assay in yeast in 14 samples. With this test, a p53-inactivating mutation was found in only one case; the remaining cases exhibited a wild-type p53 pattern. However, an accumulation of p53 protein was detected by immunohistochemistry in six of 19 samples. P21 expression was found in seven of 19 samples but was not correlated with the rate of p53 protein in tumors. In contrast, high levels of nuclear accumulation of MDM2 were found in all samples by immunohistochemistry. These results suggest that a high Ki-67 proliferative index in SCID mice EBV-induced lymphoproliferation is not due to the inactivation of p53 by mutation, but could be associated with an overexpression of MDM2, which would act by a p53-independent mechanism.(J Histochem Cytochem 47:1315-1321, 1999)

Animals↗

PubMed1999

T-cell receptors and autoimmune thyroid disease--signposts for T-cell-antigen driven diseases.

The human autoimmune thyroid diseases (AITDs) are characterized by profuse infiltrates of both CD4+ and CD8+ T cells. The intrathyroidal T-cell-receptor repertoire in Graves' disease, more than in Hashimoto's disease, has been shown to be biased as evidenced by phenotypic analysis and by the use of a restricted T-cell-receptor variable (V) gene repertoire seen in both TCR alpha and beta chains. Evidence for a bias in the T-cell repertoire has also been observed in animal models of induced and spontaneous autoimmune thyroiditis. We found a similar phenomenon of autoimmune thyroid-related T-cell bias in thyroid-humanized scid mice. In these studies we transplanted lymphocyte-depleted thyrocytes and autologous peripheral lymphocytes from AITD patients with a basement membrane preparation which allowed the formation of an artificial thyroid which we have called an "organoid". T-cell clonal expansion was present in these artificial mixed-cell organoids which appeared to mimic the in vivo process. Such clonal expansion was suggestive of an antigen-driven immune response and could also be identified in thyroid tissue from patients with Graves' disease. Our data on scid mice grafted with human mixed-cell thyroid organoids, therefore, suggested that the major antigens driving T-cell selection in patients with AITD were most likely to be thyroid specific. These antigens include thyroglobulin, thyroid peroxidase, and the receptor for thyroid stimulating hormone (TSHR) on the surface of thyroid epithelial cells and we found significant T-cell proliferation to synthetic TSHR peptides in patients with AITD as compared with normals. Our search for a TCR recognition motif for the autoantigen TPO did not reveal any specific sequence motifs. Instead, analysis of the physico-chemical characteristics i.e. hydrophobicity of the amino acids in the CDR3 (N) region of the TCR alpha chain, revealed a strong negative linear correlation between strength of stimulation and the average hydrophobicity of N-region amino acids. This led us to hypothesize that lower affinity T-cell clones were commonly more hydrophobic in their CDR3 alpha region amino acids in keeping with potential crossreactivity of such T cells as a consequence of promiscuous, hydrophobic CDR3 regions. This phenomenon would be analogous to polyreactive, natural autoantibodies which tend to be crossreactive and 'sticky'. Thus, the physico-chemical characteristics of the TCR alpha CDR3 region supported the interaction with antigen/MHC by potentially cross-reactive T cells of low affinity. It would seem likely that such low-affinity autoreactive T-cell populations serve as a pool of potentially pathogenetic cells. These cells would be able to respond to an insult which, via a number of possible mechanisms such as molecular mimicry, would initiate a thyroid lymphocytic infiltration in an antigen-driven fashion with intrathyroidal T-cell expansion and a marked bias in the utilization of T-cell-receptor V genes.

Animals↗

PubMed1999

For Mary.

Explore the source record for details and available documents.

Aged↗

PubMed1999

[Recurrent bilateral pleurisy in an 80-year-old man].

An 80-year-old man was admitted with recurrent asphyxiating pleurisy, first attributed to heart failure. During the recurrent episodes, the patient presented fever, signs of inflammation, no signs of heart failure, and subnormal cardiac function, prompting further investigations which disclosed that the patient was a homozygous carrier of the severe type of periodic disease mutation. The patient's age at symptom onset and the clinical features of this case of periodic disease are exceptional. These points emphasize the usefulness of available genetic tests in difficult diagnostic cases. It also reflects current difficulties in trying to establish correlations between genotype and phenotype in periodic disease.

Age of Onset↗

PubMed1999

Correlates of bone mineral density in nursing home residents.

PURPOSE: To explore correlates of bone mineral density (BMD) in nursing home residents, examining factors associated with BMD in community cohorts and factors prevalent among nursing home residents. METHODS: A cross sectional study of 2156 elderly residents from a representative state-wide sample of 47 nursing homes in Maryland. Data consisted of BMD scans of the distal radius and ulna; information on comorbidities, activities, behavior and medications abstracted from medical charts and interviews; and observation of cognitive and neuromuscular performance. RESULTS: Forty-two percent of the variance in BMD was explained by age, gender, race and weight. Fracture, use of steroids and seizure medications, and alcohol use were also related to low BMD. Other factors prevalent in nursing home populations, such as cognitive impairment and depressive symptomatology, were not strongly associated with low BMD. CONCLUSIONS: Despite the diversity of the nursing home population, their older age and greater dependency and comorbidity, the factors most closely related to low BMD in nursing home residents were comparable to those in community-dwellers. Demographic information, along with other clinical factors such as fracture and use of steroid and seizure medications, may aid health care providers in identifying high risk individuals in nursing homes.

Aged↗

PubMed1999

67Ga scintigraphy in B-cell non-Hodgkin's lymphoma: correlation of 67Ga uptake with histology and transferrin receptor expression.

UNLABELLED: 67Ga scintigraphy is routinely used in the management of non-Hodgkin's lymphomas (NHLs), but the heterogeneity of 67Ga uptake in the different NHL histological subtypes has not been clearly explained. The transferrin receptors (TfR/CD71) play an important role in the mechanisms of 67Ga uptake by tumor cells. However, the relationship between the 67Ga uptake in NHL and the TfR/CD71 expression in lymphomatous cells remains to be defined. The aim of this study was to determine the intensity of 67Ga uptake in different histological subtypes of B-cell NHL (B-NHL) and to compare this uptake with the expression of TfR/CD71 on lymphomatous cells. METHODS: 67Ga scintigraphy of 47 patients having histologically proven lymphomas was investigated. 67Ga uptake was semiquantitatively evaluated in regions of interest and was reported as 67Ga uptake index (GaUI). In all cases, biopsies were reviewed for classification of NHL. The expression of TfR/CD71 was determined on frozen sections and was semiquantitatively evaluated. The relationships between GaUI, histology and TfR/CD71 were investigated. RESULTS: The values of GaUI were significantly related to the different histological subtypes analyzed (P = 0.0007) and to the presence of a large cells component, thus demonstrating that 67Ga uptake rose with the grade of lymphoma. Moreover, the values of GaUI and TfR/CD71 were closely related in the tested cases (P = 0.0059). CONCLUSION: There were three factors influencing 67Ga uptake in NHL: histology, TfR/CD71 expression and the presence of a large cells component. This justifies the usefulness of 67Ga scintigraphy in staging the TfR/CD71-positive lymphomas.

Adolescent↗

PubMed1999

Experimental colitis increases small intestine permeability in the rat.

Small intestine permeability is frequently altered in patients with Crohn's disease and is thought to play a pathogenic role. The aim of this study was to investigate the permeability and structure of small intestine tight junctions (TJ) in an animal model of chronic distal colitis. Seven days after colitis induction with trinitrobenzenesulfonic acid/ethanol, the duodenal and ileal TJ were studied by means of transmission electron microscopy using lanthanum nitrate, freeze fractures, and immunohistochemistry of occludin, ZO-1, and cingulin. Animals treated with intrarectal ethanol alone served as controls. In controls, 7.5% of duodenal and 9.6% of ileal TJ were permeable to lanthanum, whereas in colitis, permeability increased significantly (79.5% and 72.9%, respectively; p < 0.001, both segments compared with controls). In colitis, the percentage of "leaky" junctions in duodena as well as in terminal ilea correlated positively with the macroscopic colon damage score (p < 0.02 and p < 0.005, respectively). Freeze-fracture analysis and immunohistochemistry of cingulin and ZO-1 did not reveal any difference between control and treated animals, whereas the signal of the transmembrane protein occludin was found to be disrupted and irregular in both small intestine segments. Distal colitis induces an increase of TJ permeability throughout the entire small intestine, and the extent of alterations correlates with colonic damage. Alterations in the transmembrane protein occludin seem to be responsible for the observed changes. Further investigation is needed to elucidate the mechanism of TJ alterations by a remote focus of inflammation.

Animals↗

PubMed1998

Cerebrospinal fluid levels of oxytocin in Prader-Willi syndrome: a preliminary report.

BACKGROUND: Prader-Willi syndrome (PWS) is a genetic disorder characterized by mental retardation, appetite dysregulation, and a high risk for obsessive-compulsive disorder (OCD). Microscopic abnormalities of the hypothalamus have been described in PWS, and oxytocin has been implicated in both appetite regulation and OCD. METHODS: Oxytocin and arginine vasopressin (AVP) were measured in the cerebrospinal fluid of 5 subjects with PWS (2 male, 3 female) and in 6 normal control subjects (all female). RESULTS: CSF oxytocin was elevated in PWS (9.2 +/- 3.9 pmol/L) as compared to normal control subjects (5.1 +/- 0.9 pmol/L, p = 0.045), a finding that was more significant when excluding male subjects from analysis (p = 0.02). AVP was not significantly different between the groups as a whole. CONCLUSIONS: These data provide further evidence for hypothalamic and oxytocinergic dysfunction in PWS. The associations between oxytocin, appetite regulation, and obsessive compulsive symptomatology in PWS warrant further investigation.

Adolescent↗

PubMed1998

Long-term dietary strawberry, spinach, or vitamin E supplementation retards the onset of age-related neuronal signal-transduction and cognitive behavioral deficits.

Recent research has indicated that increased vulnerability to oxidative stress may be the major factor involved in CNS functional declines in aging and age-related neurodegenerative diseases, and that antioxidants, e.g., vitamin E, may ameliorate or prevent these declines. Present studies examined whether long-term feeding of Fischer 344 rats, beginning when the rats were 6 months of age and continuing for 8 months, with diets supplemented with a fruit or vegetable extract identified as being high in antioxidant activity, could prevent the age-related induction of receptor-mediated signal transduction deficits that might have a behavioral component. Thus, the following parameters were examined: (1) oxotremorine-enhanced striatal dopamine release (OX-K+-ERDA), (2) cerebellar beta receptor augmentation of GABA responding, (3) striatal synaptosomal 45Ca2+ clearance, (4) carbachol-stimulated GTPase activity, and (5) Morris water maze performance. The rats were given control diets or those supplemented with strawberry extracts (SE), 9.5 gm/kg dried aqueous extract (DAE), spinach (SPN 6.4 gm/kg DAE), or vitamin E (500 IU/kg). Results indicated that SPN-fed rats demonstrated the greatest retardation of age-effects on all parameters except GTPase activity, on which SE had the greatest effect, whereas SE and vitamin E showed significant but equal protection against these age-induced deficits on the other parameters. For example, OX-K+-ERDA enhancement was four times greater in the SPN group than in controls. Thus, phytochemicals present in antioxidant-rich foods such as spinach may be beneficial in retarding functional age-related CNS and cognitive behavioral deficits and, perhaps, may have some benefit in neurodegenerative disease.

Aging↗

PubMed1998

Selective loss of substrate recognition induced by the tumour-associated D294G point mutation in protein kinase Calpha.

The tumour-associated D294G mutant of protein kinase Calpha (PKCalpha) was recently shown not to be translocated to the plasma membrane on stimulation with PMA, in contrast with the wild-type enzyme. Using recombinant wild-type and mutant PKCalpha, we establish here that, although the PKCalpha intrinsic lipid-dependent catalytic activity remains unaltered by the D294G mutation, the mutant enzyme exhibits a selective loss of substrate recognition. Indeed, whereas the mutant enzyme is still able to phosphorylate histone IIIS with comparable efficiency to that of the wild-type enzyme, it exhibits a lack of kinase activity towards the previously cloned 35F and 35H substrates for PKC. Overlay experiments demonstrate that this selective loss of kinase activity is correlated with a decrease in binding of D294G PKCalpha to the 35F and 35H proteins compared with that of the wild-type enzyme. Because the 35H and 35F proteins are predicted to be PKCalpha-anchoring proteins, these findings suggest a selective loss of PKCalpha-protein interactions that might fail to stabilize the location of the PKCalpha mutant at the plasma membrane.

Amino Acid Sequence↗

PubMed1998

Development of an on-line preconcentration method for the analysis of pathogenic lipopolysaccharides using capillary electrophoresis-electrospray mass spectrometry. Application to small colony isolates.

The present investigation describes the use of on-line chromatographic preconcentration coupled to capillary zone electrophoresis-electrospray mass spectrometry (cPC-CZE-ES-MS) for trace level analysis of negatively charged lipopolysaccharides (LPS) obtained from pathogenic strains of Haemophilus influenzae. The analytical performance of two different types of adsorption media [i.e., C18 irregular particles and poly(styrene-divinylbenzene) membrane] for anionic analytes was first evaluated using a mixture of peptide standards to determine the overall sensitivity of this approach. These chromatographic preconcentrators provided an enhancement of sample loadings of up to 5 microliters with good linear response and low nM concentration detection limits for most peptides investigated. The application of cPC-CZE-ES-MS is further demonstrated for extracts of O-deacylated LPS obtained from H. influenzae strain Eagan. In combination with novel enzymatic releasing methods using proteinase K, this technique provides unparalleled sensitivity and enabled the identification of LPS surface antigens from as little as five bacterial colonies.

Amino Acid Sequence↗

PubMed1998

The pyruvate dehydrogenase multi-enzyme complex from Gram-negative bacteria.

Pyruvate dehydrogenase multi-enzyme complexes from Gram-negative bacteria consists of three enzymes, pyruvate dehydrogenase/decarboxylase (E1p), dihydrolipoyl acetyltransferase (E2p) and dihydrolipoyl dehydrogenase (E3). The acetyltransferase harbors all properties required for multi-enzyme catalysis: it forms a large core of 24 subunits, it contains multiple binding sites for the E1p and E3 components, the acetyltransferase catalytic site and mobile substrate carrying lipoyl domains that visit the active sites. Today, the Azotobacter vinelandii complex is the best understood oxo acid dehydrogenase complex with respect to structural details. A description of multi-enzyme catalysis starts with the structural and catalytic properties of the individual components of the complex. Integration of the individual properties is obtained by a description of how the many copies of the individual enzymes are arranged in the complex and how the lipoyl domains couple the activities of the respective active sites by way of flexible linkers. These latter aspects are the most difficult to study and future research need to be aimed at these properties.

Acetyltransferases↗

PubMed1998

Structure of an alpha-2,6-sialylated lipooligosaccharide from Neisseria meningitidis immunotype L1.

The recent cloning of the lipooligosaccharide (LOS) a-2,3-sialyltransferase from Neisseria meningitidis immunotype L3 permitted us to examine other immunotypes for this structural gene. We identified the gene and measured the enzyme activity in the L1 immunotype strain which had previously been reported to lack sialic acid in its LOS because it contains a terminal alpha-linked galactose which was thought not to be an acceptor for the sialyltransferase. This finding prompted us to re-examine the structure of the LOS from the L1 immunotype, which revealed the presence of sialic acid on the terminal alpha-linked galactose. Oligosaccharides derived from the LOS were shown to be sialylated by composition and methylation analysis, mass spectrometry and nuclear magnetic resonance. The detailed structural analysis showed the sialic acid to occur only at 06 of the terminal a-D-galactopyranose residue of the alpha-D-Gal-1,4-beta-D-Gal-1,4-beta-D-glc trisaccharide (Pk epitope) chain of the LOS, in the alpha-D configuration. These data are the first report of a alpha-2,6-linked sialic acid in a bacterial LOS or lipopolysaccharide, and also the first report of a sialylated Pk epitope.

Carbohydrate Conformation↗