Substrate specificities of three members of the human UDP-N-acetyl-alpha-D-galactosamine:Polypeptide N-acetylgalactosaminyltransferase family, GalNAc-T1, -T2, and -T3

Mucin-type O-glycosylation is initiated by UDP-N-acetylgalactosamine:polypeptide N-acetylgalactosaminyltransferases (GalNAc-transferases). The role each GalNAc-transferase plays in O-glycosylation is unclear. In this report we characterized the specificity and kinetic properties of three purified recombinant GalNAc-transferases. GalNAc-T1, -T2, and -T3 were expressed as soluble proteins in insect cells and purified to near homogeneity. The enzymes have distinct but partly overlapping specificities with short peptide acceptor substrates. Peptides specifically utilized by GalNAc-T2 or -T3, or preferentially by GalNAc-T1 were identified. GalNAc-T1 and -T3 showed strict donor substrate specificities for UDP-GalNAc, whereas GalNAc-T2 also utilized UDP-Gal with one peptide acceptor substrate. Glycosylation of peptides based on MUC1 tandem repeat showed that three of five potential sites in the tandem repeat were glycosylated by all three enzymes when one or five repeat peptides were analyzed. However, analysis of enzyme kinetics by capillary electrophoresis and mass spectrometry demonstrated that the three enzymes react at different rates with individual sites in the MUC1 repeat. The results demonstrate that individual GalNAc-transferases have distinct activities and the initiation of O-glycosylation in a cell is regulated by a repertoire of GalNAc-transferases.

cDNA cloning and expression of a novel human UDP-N-acetyl-alpha-D-galactosamine. Polypeptide N-acetylgalactosaminyltransferase, GalNAc-t3

The glycosylation of serine and threonine residues during mucin-type O-linked protein glycosylation is carried out by a family of UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (GalNAc-transferase). Previously two members, GalNAc-T1 and -T2, have been isolated and the genes cloned and characterized. Here we report the cDNA cloning and expression of a novel GalNAc-transferase termed GalNAc-T3. The gene was isolated and cloned based on the identification of a GalNAc-transferase motif (61 amino acids) that is shared between GalNAc-T1 and -T2 as well as a homologous Caenorhabditis elegans gene. The cDNA sequence has a 633-amino acid coding region indicating a protein of 72.5 kDa with a type II domain structure. The overall amino acid sequence similarity with GalNAc-T1 and -T2 is approximately 45%; 12 cysteine residues that are shared between GalNAc-T1 and -T2 are also found in GalNAc-T3. GalNAc-T3 was expressed as a soluble protein without the hydrophobic transmembrane domain in insect cells using a Baculo-virus vector, and the expressed GalNAc-transferase activity showed substrate specificity different from that previously reported for GalNAc-T1 and -T2. Northern analysis of human organs revealed a very restricted expression pattern of GalNAc-T3.

Cloning of a human UDP-N-acetyl-alpha-D-Galactosamine:polypeptide N-acetylgalactosaminyltransferase that complements other GalNAc-transferases in complete O-glycosylation of the MUC1 tandem repeat

A fourth human UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase, designated GalNAc-T4, was cloned and expressed. The genomic organization of GalNAc-T4 is distinct from GalNAc-T1, -T2, and -T3, which contain multiple coding exons, in that the coding region is contained in a single exon. GalNAc-T4 was placed at human chromosome 12q21.3-q22 by in situ hybridization and linkage analysis. GalNAc-T4 expressed in Sf9 cells or in a stably transfected Chinese hamster ovary cell line exhibited a unique acceptor substrate specificity. GalNAc-T4 transferred GalNAc to two sites in the MUC1 tandem repeat sequence (Ser in GVTSA and Thr in PDTR) using a 24-mer glycopeptide with GalNAc residues attached at sites utilized by GalNAc-T1, -T2, and -T3 (TAPPAHGVTSAPDTRPAPGSTAPPA, GalNAc attachment sites underlined). Furthermore, GalNAc-T4 showed the best kinetic properties with an O-glycosylation site in the P-selectin glycoprotein ligand-1 molecule. Northern analysis of human organs revealed a wide expression pattern. Immunohistology with a monoclonal antibody showed the expected Golgi-like localization in salivary glands. A single base polymorphism, G1516A (Val to Ile), was identified (allele frequency 34%). The function of GalNAc-T4 complements other GalNAc-transferases in O-glycosylation of MUC1 showing that glycosylation of MUC1 is a highly ordered process and changes in the repertoire or topology of GalNAc-transferases will result in altered pattern of O-glycan attachments.

Cloning and characterization of a close homologue of human UDP-N-acetyl-alpha-D-galactosamine:Polypeptide N-acetylgalactosaminyltransferase-T3, designated GalNAc-T6. Evidence for genetic but not functional redundancy

The UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase, designated GalNAc-T3, exhibits unique functions. Specific acceptor substrates are used by GalNAc-T3 and not by other GalNAc-transferases. The expression pattern of GalNAc-T3 is restricted, and loss of expression is a characteristic feature of poorly differentiated pancreatic tumors. In the present study, a sixth human UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase, designated GalNAc-T6, with high similarity to GalNAc-T3, was characterized. GalNAc-T6 exhibited high sequence similarity to GalNAc-T3 throughout the coding region, in contrast to the limited similarity that exists between homologous glycosyltransferase genes, which is usually restricted to the putative catalytic domain. The genomic organizations of GALNT3 and GALNT6 are identical with the coding regions placed in 10 exons, but the genes are localized differently at 2q31 and 12q13, respectively. Acceptor substrate specificities of GalNAc-T3 and -T6 were similar and different from other GalNAc-transferases. Northern analysis revealed distinct expression patterns, which were confirmed by immunocytology using monoclonal antibodies. In contrast to GalNAc-T3, GalNAc-T6 was expressed in WI38 fibroblast cells, indicating that GalNAc-T6 represents a candidate for synthesis of oncofetal fibronectin. The results demonstrate the existence of genetic redundancy of a polypeptide GalNAc-transferase that does not provide full functional redundancy.

A family of human beta4-galactosyltransferases. Cloning and expression of two novel UDP-galactose:beta-n-acetylglucosamine beta1, 4-galactosyltransferases, beta4Gal-T2 and beta4Gal-T3

BLAST analysis of expressed sequence tags (ESTs) using the coding sequence of the human UDP-galactose:beta-N-acetylglucosamine beta1, 4-galactosyltransferase, designated beta4Gal-T1, revealed a large number of ESTs with identical as well as similar sequences. ESTs with sequences similar to that of beta4Gal-T1 could be grouped into at least two non-identical sequence sets. Analysis of the predicted amino acid sequence of the novel ESTs with beta4Gal-T1 revealed conservation of short sequence motifs as well as cysteine residues previously shown to be important for the function of beta4Gal-T1. The likelihood that the identified ESTs represented novel galactosyltransferase genes was tested by cloning and sequencing of the full coding region of two distinct genes, followed by expression. Expression of soluble secreted constructs in the baculovirus system showed that these genes represented genuine UDP-galactose:beta-N-acetylglucosamine beta1, 4-galactosyltransferases, thus designated beta4Gal-T2 and beta4Gal-T3. Genomic cloning of the genes revealed that they have identical genomic organizations compared with beta4Gal-T1. The two novel genes were located on 1p32-33 and 1q23. The results demonstrate the existence of a family of homologous galactosyltransferases with related functions. The existence of multiple beta4-galactosyltransferases with the same or overlapping functions may be relevant for interpretation of biological functions previously assigned to beta4Gal-T1.

A family of human beta3-galactosyltransferases. Characterization of four members of a UDP-galactose:beta-N-acetyl-glucosamine/beta-nacetyl-galactosamine beta-1,3-galactosyltransferase family

BLAST analysis of expressed sequence tags (ESTs) using the coding sequence of a human UDP-galactose:beta-N-acetyl-glucosamine beta-1, 3-galactosyltransferase, designated beta3Gal-T1, revealed no ESTs with identical sequences but a large number with similarity. Three different sets of overlapping ESTs with sequence similarities to beta3Gal-T1 were compiled, and complete coding regions of these genes were obtained. Expression of two of these genes in the Baculo virus system showed that one represented a UDP-galactose:beta-N-acetyl-glucosamine beta-1, 3-galactosyltransferase (beta3Gal-T2) with similar kinetic properties as beta3Gal-T1. Another gene represented a UDP-galactose:beta-N-acetyl-galactosamine beta-1, 3-galactosyltransferase (beta3Gal-T4) involved in GM1/GD1 ganglioside synthesis, and this gene was highly similar to a recently reported rat GD1 synthase (Miyazaki, H., Fukumoto, S., Okada, M., Hasegawa, T., and Furukawa, K. (1997) J. Biol. Chem. 272, 24794-24799). Northern analysis of mRNA from human organs with the four homologous cDNA revealed different expression patterns. beta3Gal-T1 mRNA was expressed in brain, beta3Gal-T2 was expressed in brain and heart, and beta3Gal-T3 and -T4 were more widely expressed. The coding regions for each of the four genes were contained in single exons. beta3Gal-T2, -T3, and -T4 were localized to 1q31, 3q25, and 6p21.3, respectively, by EST mapping. The results demonstrate the existence of a family of homologous beta3-galactosyltransferase genes.

The lectin domain of UDP-N-acetyl-D-galactosamine: polypeptide N-acetylgalactosaminyltransferase-T4 directs its glycopeptide specificities

The initiation step of mucin-type O-glycosylation is controlled by a large family of homologous UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (GalNAc-transferases). Differences in kinetic properties, substrate specificities, and expression patterns of these isoenzymes provide for differential regulation of O-glycan attachment sites and density. Recently, it has emerged that some GalNAc-transferase isoforms in vitro selectively function with partially GalNAc O-glycosylated acceptor peptides rather than with the corresponding unglycosylated peptides. O-Glycan attachment to selected sites, most notably two sites in the MUC1 tandem repeat, is entirely dependent on the glycosylation-dependent function of GalNAc-T4. Here we present data that a putative lectin domain found in the C terminus of GalNAc-T4 functions as a GalNAc lectin and confers its glycopeptide specificity. A single amino acid substitution in the lectin domain of a secreted form of GalNAc-T4 selectively blocked GalNAc-glycopeptide activity, while the general activity to peptides exerted by this enzyme was unaffected. Furthermore, the GalNAc-glycopeptide activity of wild-type secreted GalNAc-T4 was selectively inhibited by free GalNAc, while the activity with peptides was unaffected.

Diagnosis and staging of head and neck cancer: a comparison of modern imaging modalities (positron emission tomography, computed tomography, color-coded duplex sonography) with panendoscopic and histopathologic findings

OBJECTIVE

To compare the clinical value of positron emission tomography (PET) using fludeoxyglucose F 18, computed tomography (CT), color-coded duplex sonography (CCDS), and panendoscopy in the detection and staging of head and neck cancer.

DESIGN

Prospective nonrandomized controlled study.

SETTING

Medical school.

PATIENTS

Convenience sample of 50 patients with suspected primary or recurrent head and neck cancer.

INTERVENTION

Biopsy, tumor surgery.

MAIN OUTCOME MEASURES

Information of diagnostic procedures compared with histopathologic features.

RESULTS

Both PET and panendoscopy had a sensitivity of 95% and 100% for detection of primary tumor or recurrent carcinomas, respectively. Specificity for PET and panendoscopy was 92% and 85% in primary tumors and 100% and 80% in recurrent carcinoma, respectively. Sensitivity of CCDS and CT was 74% and 68% in primary tumors and 67% and 63% in recurrent carcinomas, respectively. Specificity was 75% and 69% in primary tumors and 100% and 80% in recurrent neoplasms. When assessing neck nodes, all imaging procedures exhibited identical sensitivity (84%). Specificity was 90%, 96%, and 88% in PET, CT, and CCDS, respectively. In recurrent lymph node metastases, sensitivity was 100%, 67%, and 67% and specificity was 87%, 91%, and 87% for PET, CT, and CCDS, respectively.

CONCLUSIONS

Positron emission tomography was the most reliable imaging procedure in the detection of primary tumor and recurrent carcinomas localized in the head and neck region. Owing to its limited anatomical depiction, it cannot as yet replace other diagnostic procedures in preoperative planning but does contribute valuable complementary diagnostic information. Computed tomograpy may have difficulties in identifying recurrent carcinomas. For routine diagnosis of nodal spread in the neck, CCDS is recommended. Panendoscopy is a valuable diagnostic procedure that can provide key information in cases of superficial mucosal tumor involvement. Arch Otolaryngol Head Neck Surg. 2000;126:1457-1461

A novel human UDP-N-acetyl-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase, GalNAc-T7, with specificity for partial GalNAc-glycosylated acceptor substrates

A novel member of the human UDP-N-acetyl-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase gene family, designated GalNAc-T7, was cloned and expressed. GalNAc-T7 exhibited different properties compared to other characterized members of this gene family, in showing apparent exclusive specificity for partially GalNAc-glycosylated acceptor substrates. GalNAc-T7 showed no activity with a large panel of non-glycosylated peptides, but was selectively activated by partial GalNAc glycosylation of peptide substrates derived from the tandem repeats of human MUC2 and rat submaxillary gland mucin. The function of GalNAc-T7 is suggested to be as a follow-up enzyme in the initiation step of O-glycosylation.

Expression of polypeptide GalNAc-transferases in stratified epithelia and squamous cell carcinomas: immunohistological evaluation using monoclonal antibodies to three members of the GalNAc-transferase family

Mucin-type O-glycosylation is initiated by a large family of UDP-GalNAc: polypeptide N -acetyl-galactosaminyltransferases (GalNAc-transferases). Individual GalNAc-transferases appear to have different functions and Northern analysis indicates that they are differently expressed in different organs. This suggests that O-glycosylation may vary with the repertoire of GalNAc-transferases expressed in a given cell. In order to study the repertoire of GalNAc-transferases in situ in tissues and changes in tumors, we have generated a panel of monoclonal antibodies (MAbs) with well defined specificity for human GalNAc-T1, -T2, and -T3. Application of this panel of novel antibodies revealed that GalNAc- transferases are differentially expressed in different cell lines, in spermatozoa, and in oral mucosa and carcinomas. For example, GalNAc-T1 and -T2 but not -T3 were highly expressed in WI38 cells, and GalNAc-T3 but not GalNAc-T1 or -T2 was expressed in spermatozoa. The expression patterns in normal oral mucosa were found to vary with cell differentiation, and for GalNAc-T2 and -T3 this was reflected in oral squamous cell carcinomas. The expression pattern of GalNAc-T1 was on the other hand changed in tumors to either total loss or expression in cytological poorly differentiated tumor cells, where the normal undifferentiated cells lacked expression. These results demonstrate that the repertoire of GalNAc-transferases is different in different cell types and vary with cellular differentiation, and malignant transformation. The implication of this is not yet fully understood, but it suggests that specific changes in sites of O-glycosylation of proteins may occur as a result of changes in the repertoire of GalNAc-transferases.

Increase in proportion of hippocampal spine synapses expressing neural cell adhesion molecule NCAM180 following long-term potentiation

Neural recognition molecules such as the neural cell adhesion molecule (NCAM) have been implicated in synaptic plasticity, including long-term potentiation (LTP), sensitization, and learning and memory. The major isoform of NCAM carrying the longest cytoplasmic domain of all NCAM isoforms (NCAM180) is predominantly localized in postsynaptic membranes and postsynaptic densities of hippocampal neurons, with only a proportion of synapses carrying detectable levels of NCAM180. To investigate whether this differential expression of NCAM180 may correlate with distinct states of synaptic activity, LTP was induced by high-frequency stimulation of the perforant path and the percentage of NCAM180 immunopositive spine synapses determined in the outer third of the dentate molecular layer of the dentate gyrus by immunoelectron microscopy. Twenty-four hours following induction of LTP by high-frequency stimulation, the percentage of spine synapses expressing NCAM180 increases from 37% (passive control) to 70%. This increase was inhibited by the noncompetitive N-methyl-D-aspartate receptor antagonist MK801. Following repeated LTP induction at 10 consecutive days with one tetanization each day, 60% of all spine synapses were NCAM180 immunoreactive. Compared to passive control animals, the percentage of NCAM180 expressing synapses in low-frequency stimulated animals decreased from 37% to 28%. Spine synapses in the inner part of the dentate molecular layer not contacted by the afferents of the perforant path did not change the percentage of NCAM180-expressing synapses. The results obtained by the postembedding immunogold staining technique confirmed the difference in NCAM180 expression of spine synapses between passive control and potentiated animals. These observations suggest a role for NCAM180 in synaptic remodeling accompanying LTP.

Identification of mosquito avian-derived blood meals by polymerase chain reaction-heteroduplex analysis

A polymerase chain reaction (PCR) heteroduplex assay (HDA) was developed to identify avian derived mosquito blood meals to the species level. The assay used primers amplifying a fragment of the cytochrome B gene from vertebrate but not invertebrate species. In Culex tarsalis fed on quail, PCR products derived from the quail cytochrome B gene were detected seven days post-engorgement. In an analysis of wild-caught mosquitoes, 85% of blood-fed mosquitoes produced detectable PCR products. Heteroduplex patterns obtained from bird-derived PCR products were found to permit the unambiguous identification of all species examined. No intraspecific variation in HDA patterns was found. The PCR-HDA was used to characterize blood meals in wild caught Cx. tarsalis. Of the 67 blood meals analyzed, 60% were derived from avian sources. Of the avian blood meals, 65% were derived from a single host, the common grackle.

Analysis of endoscopic ultrasound elastography used for characterisation and differentiation of benign and malignant lymph nodes

PURPOSE

Ultrasound elastography is a new imaging procedure which allows the reconstruction of elasticity distribution by characterising the difference of hardness between pathological and normal tissue.

MATERIALS AND METHODS

The aim of our study was to apply real-time elastography during endoscopic ultrasound (EUS) examinations and to consequently characterise benign versus malignant lymph nodes. The pattern of real-time EUS elastography images was compared with the conventional EUS aspects of lymph nodes and with the final diagnosis obtained by EUS-FNA cytology analysis and/or by surgical pathology.

RESULTS

Patients diagnosed by EUS with cervical, mediastinal or abdominal lymph nodes were prospectively included, with a total number of 42 lymph nodes examined by EUS elastography. By using a qualitative pattern analysis, we were able to differentiate between benign and malignant lymph nodes with a high sensitivity, specificity and accuracy (91.7 %, 94.4 % and 92.86 %, respectively), based on five pre-defined patterns obtained on EUS elastography. A quantitative analysis based on histograms of the EUS elastography images also allowed an excellent discrimination between benign and malignant lymph nodes. Based on separate RGB channel histogram values, an "elasticity ratio" was further defined and yielded a sensitivity, specificity and accuracy for the differential diagnosis of 95.8 %, 94.4 % and 95.2 % respectively, based on a cut-off level of 0.84.

CONCLUSION

EUS elastography is a promising method which allows characterisation and differentiation of benign and malignant lymph nodes with a high sensitivity, specificity and accuracy, offering complementary information added to conventional EUS imaging.

Recent progress on biomass co-pyrolysis conversion into high-quality bio-oil

Co-pyrolysis of biomass with abundantly available materials could be an economical method for production of bio-fuels. However, elimination of oxygenated compounds poses a considerable challenge. Catalytic co-pyrolysis is another potential technique for upgrading bio-oils for application as liquid fuels in standard engines. This technique promotes the production of high-quality bio-oil through acid catalyzed reduction of oxygenated compounds and mutagenic polyaromatic hydrocarbons. This work aims to review and summarize research progress on co-pyrolysis and catalytic co-pyrolysis, as well as their benefits on enhancement of bio-oils derived from biomass. This review focuses on the potential of plastic wastes and coal materials as co-feed in co-pyrolysis to produce valuable liquid fuel. This paper also proposes future directions for using this technique to obtain high yields of bio-oils.

Oral or vaginal misoprostol for induction of labor

OBJECTIVE

To compare vaginal versus oral misoprostol for induction of labor.

METHOD

Induction of labor was carried out in 40 women near term in two equal and randomized groups (according to a computer generated table) using misoprostol. Group I received vaginal misoprostol (100 micrograms) every 3 h while group II patients were given the same dose via the oral route. The dose was doubled if no response was detected under continuous cardiotocographic (CTG) tracings.

RESULT

The vaginal route of administration induced a higher success rate in a shorter time interval using a lower dose but was associated with more abnormal FHR patterns and instances of uterine hyperstimulation.

CONCLUSION

It is recommended to use the vaginal approach with cardiotocographic monitoring.

Fermentation of dietary starch in humans

OBJECTIVE

Dietary starch that escapes digestion in the small intestine may be quantitatively more important than dietary fiber as a substrate for fermentation. The products of fermentation have important implications in the pathogenesis of colorectal cancer and other diseases of the large bowel, which are uncommon in Africans but have a high prevalence in Western populations.

METHODS

Maize porridge is a staple of most blacks in South Africa. Stale maize porridge (high-resistant starch [HRS]) seems to induce greater fermentation in the large bowel than fresh maize porridge (low-resistant starch [LRS]).

RESULTS

In the present study, healthy colostomy subjects fed stale maize porridge had significantly more production of short-chain fatty acids (SCFA) (mean SCFA, HRS = 182.6; mean SCFA, LRS = 116.1; p < 0.05) in their colostomy effluent together with a significant drop in stool pH (mean pH, HRS = 5.91; mean pH, LRS = 6.70; p < 0.001). The SCFA butyrate (mean, HRS = 35.1; mean, LRS = 17.6; p < 0.05) and acetate (mean, HRS = 93.9; mean, LRS = 65.8; p < 0.05) were significantly elevated on the stale maize porridge diet when compared with consumption of fresh maize porridge. SCFA propionate (mean, HRS = 43.1; mean, LRS = 24.8; p = 0.05), also increased with stale maize porridge, but was not statistically significant.

CONCLUSION

A high-resistant starch diet and its resultant increase in fermentation products may be partly responsible for protecting the black population against colorectal cancers and other large bowel diseases.

Dynamic epigenetic regulation of initial O-glycosylation by UDP-N-Acetylgalactosamine:Peptide N-acetylgalactosaminyltransferases. site-specific glycosylation of MUC1 repeat peptide influences the substrate qualities at adjacent or distant Ser/Thr positions

In search of possible epigenetic regulatory mechanisms ruling the initiation of O-glycosylation by polypeptide:N-acetylgalactosaminyltransferases, we studied the influences of mono- and disaccharide substituents of glycopeptide substrates on the site-specific in vitro addition of N-acetylgalactosamine (GalNAc) residues by recombinant GalNAc-Ts (rGalNAc-T1, -T2, and -T3). The substrates were 20-mers (HGV20) or 21-mers (AHG21) of the MUC1 tandem repeat peptide carrying GalNAcalpha or Galbeta1-3GalNAcalpha at different positions. The enzymatic products were analyzed by MALDI mass spectrometry and Edman degradation for the number and sites of incorporated GalNAc. Disaccharide placed on the first position of the diad Ser-16-Thr-17 prevents glycosylation of the second, whereas disaccharide on the second position of Ser-16-Thr-17 and Thr-5-Ser-6 does not prevent GalNAc addition to the first. Multiple disaccharide substituents suppress any further glycosylation at the remaining sites. Glycosylation of Ser-16 is negatively affected by glycosylation at position -6 (Thr-10) or -10 (Ser-6) and is inhibited by disaccharide at position -11 (Thr-5), suggesting the occurrence of glycosylation-induced effects on distant acceptor sites. Kinetic studies revealed the accelerated addition of GalNAc to Ser-16 adjacent to GalNAc-substituted Thr-17, demonstrating positive regulatory effects induced by glycosylation on the monosaccharide level. These antagonistic effects of mono- and disaccharides could underlie a postulated regulatory mechanism.

Use of antimicrobial containing acrylic strips in the treatment of chronic periodontal disease. A three month follow-up study

Local antimicrobial therapy has been considered for use in the treatment of chronic periodontal disease. This study evaluated chlorhexidine, metronidazole, and tetracycline delivered into periodontal pockets in an acrylic resin vehicle and compared the results with root planed and untreated sites over a three-month follow-up period. One site per patient where pocketing greater than or equal to 6 mm associated with a single rooted tooth was randomly allocated to one of the five possible regimens. Baseline and follow-up measurements included probing depth, loss of attachment, bleeding on probing, crevicular fluid flow, and dark-field microscopy of a subgingival plaque sample. Intratreatment evaluations revealed no significant changes in any parameter for untreated sites. Significant improvements in many parameters occurred with all four therapies although the magnitude and duration were greater in metronidazole and root planing groups. The more important intertreatment comparisons indicated that most treatments produced significant benefits compared with the control group; however, again these were greater with metronidazole and root planing. Furthermore, significantly greater effects were noted for metronidazole and root planing compared with tetracycline and more particularly chlorhexidine. It is concluded that some locally delivered antimicrobials alone may be useful in the treatment of chronic periodontal disease. However, at this time local antimicrobial therapy should be considered as adjunctive to conventional debridement techniques.

Endoscopic ultrasonography in detection of cholelithiasis in patients with biliary pain and negative transabdominal ultrasonography

BACKGROUND

The aim of the study was to evaluate endoscopic ultrasonography (EUS) as a single method for diagnosing cholecystolithiasis in patients with a clinical suspicion of cholecystolithiasis, but with a normal transabdominal ultrasonography (TUS).

METHODS

A prospective study was performed on patients with biliary type of colic and normal US of the gallbladder. All patients had at least one normal TUS examination (mean 2.1, range 1-5) performed by an experienced radiologist. All patients were subsequently examined with EUS. EUS examination was performed with either a mechanical radial scanning echo-endoscope (Olympus GF-UM20) or a linear echo-endoscope (Pentax FG32-UA or FG34-UA). Patients in whom EUS demonstrated cholecystolithiasis were offered laparoscopic cholecystectomy within 2 weeks.

RESULTS

A total of 35 patients (31 F and 4 M) were included. In 18 out of 35 (52.4%) patients cholecystolithiasis was diagnosed by EUS. In 15 out of 17 patients the EUS diagnosis was verified by surgery. At follow-up after 12 months, 13 of the 15 patients (87%) with verified gallbladder stones had no abdominal discomfort, whereas 2 patients (13%) complained of persistent and unchanged abdominal pain.

CONCLUSION

EUS seems to be a promising imaging method in the detection of microlithiasis in the gallbladder in patients with clear biliary colic and normal transabdominal US.

The effects of irbesartan and telmisartan on metabolic parameters and blood pressure in obese, insulin resistant, hypertensive patients

Obesity, hypertension, dyslipidemia and glucose intolerance cluster in the insulin resistance syndrome. Angiotensin II receptor blockers (ARB) are able to reduce insulin resistance. Furthermore, among ARB, telmisartan displays the property of stimulating PPARgamma. The aim of the study was to examine if and to what extent treatment with irbesartan and telmisartan induces variations in metabolic parameters in insulin resistant, hypertensive subjects. Forty-six non diabetic, obese, insulin-resistant, hypertensive patients took part in the study. They were divided into 2 groups. Group A (23) was submitted to irbesartan 150 mg/day, Group B (23) to telmisartan 80 mg/day for 6 months. Adiponectin, glucose, cholesterol, triglycerides, free fatty acids (FFA), steady-state plasma insulin and glucose (SSPG), 24-hBP were determined at the beginning and at the end of the study. Both irbesartan or telmisartan reduced blood pressure and ameliorated the insulin sensitivity, with increased adiponectin values; in Group B, the amelioration of metabolic parameters was greater than in Group A and the reduction of blood pressure was related with variation of adiponectin levels. Data obtained showed that the antihypertensive action of telmisartan and irbesartan is associated with the amelioration of the metabolic picture. The greater impact on the improvement of the metabolic profile showed by telmisartan and the inverse correlation between adiponectin levels and blood pressure may be partly due to the action as partial PPARgamma agonist displayed by telmisartan.

Mass spectrometric determination of O-glycosylation sites using beta-elimination and partial acid hydrolysis

The present study demonstrates that treating O-glycosylated peptides with methylamine vapor followed by partial acid hydrolysis is an effective means for locating O-glycosylation site(s). The reaction with methylamine transforms the glycosylated Ser and Thr residues into stable methylamine derivatives with a mass increment of +13 Da relative to nonglycosylated Ser and Thr residues. Peptide sequencing based on partial acid hydrolysis followed by mass spectrometric analysis or in favorable cases by CID-MS/MS enables the determination of the formerly O-glycosylated sites.

Peripheral neuropathy in burn patients

Neuropathy in burn patients is frequently overlooked. This study aimed at looking for neuropathies among burn patients. It included 55 burn patients, whether symptomatic or asymptomatic, with variable depths of burn at different stages. Their ages ranged from 8 to 55 years with a mean age of 23.6 +/- 11.1 years. All patients were submitted to clinical examination, electromyographic and motor conduction velocities of burned and unburned limbs. Serum electrolyte, blood urea and creatinine were measured for all patients. Sixteen patients (29 per cent) had peripheral neuropathy. Only six had symptoms and signs of peripheral neuropathy. The most frequently diagnosed neuropathy in this study was mononeuritis multiplex in nine patients (56 per cent), then generalized distal axonal neuropathy in five patients (31 per cent) and entrapment neuropathy in two patients (13 per cent). In patients with mononeuritis, 29 nerves were affected, 24 nerves related to the site of the burn and five nerves were away from the site of the burn. All the entrapment neuropathy developed after wound healing. Age above 20 years, electric burns burns involving full thickness of the skin and a surface area of more than 20 per cent were associated with a significantly higher prevalence of neuropathy. Other parameters were not found to be significant in the development of neuropathy.

Effect of treatment with Ginkgo biloba extract EGb 761 (oral) on unilateral idiopathic sudden hearing loss in a prospective randomized double-blind study of 106 outpatients

OBJECTIVE

Test of dose-response relationship for Ginkgo biloba extract EGb 761 (oral) in outpatients with acute idiopathic sudden sensorineural hearing loss (ISSHL) of at least 15 dB at one frequency within the speech range occurring less than 10 days before study inclusion.

DESIGN

Multicentre, randomized, double-blind phase III study comparing dosages of 120 mg twice daily and 12 mg twice daily over 8 weeks. MAIN ENDPOINT: Recovery (in dB) of the auditory threshold from the initial measurement to the value on the last day of treatment, averaged over those frequencies from 0.25, 0.5, 1, 2, and 3 kHz for which the initial hearing loss amounted to 15 dB or more compared to the level on the opposite side.

PATIENTS

106 patients with an average age of 44+/-16 years and with hearing loss at affected frequencies 26 dB +/- 9 dB included between December 1995 and July 1997.

RESULTS

Large majorities of both treatment groups recovered completely. In exploratory analyses of the 96 patients included according to the protocol, patients given the higher dose had less risk of not recovering well (< or =10 dB residual hearing loss) (one-sided Fisher test: P = 0.0061), especially if they had no tinnitus (n = 44, P = 0.00702).

CONCLUSION

A higher dosage of EGb 761 (oral) appears to speed up and secure the recovery of ISSHL patients, with a good chance that they will recover completely, even with little treatment. This was already observed after one week of treatment. We find it justified to treat patients who have unilateral ISSHL of less than 75 dB and neither tinnitus nor vertigo with 120 mg oral EGb 761 twice daily.

Successful treatment of normeperidine neurotoxicity by hemodialysis

Normeperidine, a major metabolite of meperidine, is half as potent as meperidine as an analgesic but two to three times more potent as a convulsant. Renal failure significantly increases the plasma half-life of normeperidine. The intensity of the central nervous system excitation is highly correlated with the plasma concentration of normeperidine. Moreover, normeperidine toxicity is not reversed by naloxone, which may exacerbate it. We report a patient with end-stage renal disease undergoing maintenance continuous cycler peritoneal dialysis who had been receiving meperidine for pain control. The patient subsequently developed myoclonic contractions and a grand mal seizure. The patient was successfully treated with hemodialysis (using an F8 dialyzer) for presumed normeperidine-induced seizure. During hemodialysis, normeperidine average blood clearance was 73 mL/min, average plasma clearance was 50 mL/min, and average percentage of plasma extraction was 24%. There also was a 26% reduction in plasma concentration of normeperidine over 3 hours of hemodialysis. In conclusion, our findings suggest that hemodialysis may be used effectively for treating patients with suspected normeperidine-induced neurotoxicity.