Omega-3 Intake Improves Clinical Pregnancy Rate in Polycystic Ovary Syndrome Patients: A Double-Blind, Randomized Study

BACKGROUND

Omega-3 fatty acids promote fertility in males and females and constitute an important factor in the normal development of the fetus.

OBJECTIVES

We investigated the effect of omega-3 supplements during ovulation induction treatment in women with polycystic ovary syndrome (PCOS)-related infertility.

METHODS

A randomized, double-blind study was conducted for 60 treatment cycles in 34 women with PCOS-related oligo/anovulation referred to the fertility clinic at the Bikur Cholim/Shaare Zedek Medical Center in Jerusalem, who underwent ovulation induction with clomiphene citrate (50 mg). Seventeen women (mean age 33.9 ± 0.9 years) received omega-3 supplements (3 × 600 mg/day) and 17 received placebo capsules (mean age 32.7 ± 0.9 years) for a maximum of two cycles. We recorded their characteristics and data from their serial hormonal blood tests and ultrasound examinations. We also conducted both univariate and multivariate analyses. The primary endpoint was conception.

RESULTS

There were clinical pregnancies in 8/30 (26.7%) treatment cycles for women receiving omega-3 supplements versus 4/30 (13.3%) cycles with placebo. Among overweight/obese women (body mass index [BMI] 25-35), there were clinical pregnancies in 8/27 cycles (29.6%) versus 1/19 (5.3%) with placebo (P < 0.04). For overweight/obese PCOS women, omega-3, lower BMI rates, and higher values of the endometrium's thickness increased the odds of becoming pregnant. No harmful side effects from the omega-3 treatment were reported.

CONCLUSIONS

Omega-3 supplements demonstrated beneficial effects for fertility in women diagnosed with PCOS. Among the overweight/obese participants, the increased clinical pregnancy rate was significant.

Clinical outcome of planned oocyte cryopreservation at advanced age

PURPOSE

To report outcome of planned oocyte cryopreservation (POC) in the first 8 years of this treatment in our center.

METHODS

A retrospective study in a university-affiliated medical center.

RESULTS

A total of 446 women underwent POC during 2011-2018. Fifty-seven (13%) women presented to use these oocytes during the study period (until June 2021). POC was performed at a mean age of 37.9 ± 2.0 (range 33-41). Age at thawing was 43.3 ± 2.1 (range 38-49). A total of 34 (60%) women transferred their oocytes for thawing at other units. Oocyte survival after thawing was significantly higher at our center than following shipping to ancillary sites (78 vs. 63%, p = 0.047). Forty-nine women completed their treatment, either depleting their cryopreserved oocytes without conceiving (36) or attaining a live birth (13)-27% live birth rate per woman. Only one of eleven women who cryopreserved oocytes aged 40 and older had a live birth using thawed oocytes.

CONCLUSION

Women should be advised to complete planned oocyte cryopreservation before age 40, given low success rates in women who underwent cryopreservation at advanced reproductive age. In this study, oocyte shipping was associated with lower survival rate. These findings may be relevant for women considering POC and utilization of cryopreserved oocytes.

O-142 SARS-CoV-2 vaccination and IVF cycle outcomes

Study question

Does recent mRNA SARS-CoV-2 vaccination effect IVF pregnancy rate?

Summary answer

We observed no influence of mRNA SARS-CoV-2 vaccine on patients’ IVF cycle outcomes; vaccination did not change pregnancy rates.

What is known already

Two recent studies showed that the BNT162b2 mRNA SARS-COV-2 vaccine does not appear to have negative effects on oocytes during controlled ovarian stimulation. Assessment of follicular fluid after vaccination (1) concluded that there was no affect on the follicle quality or function. An additional study of 36 patients that underwent IVF both immediately before and immediately after vaccination found no change in ovarian yield or embryo quality (2).

Study design, size, duration

A retrospective case control study including 385 women from January 1, 2021 to May 31st of the same year.

Participants/materials, setting, methods

The study group included patients that received 2 doses of the Pfizer SARS-COV-2 vaccine between 7-180 days prior to starting IVF and without a history of COVID infection. Controls included unvaccinated patients from the same time period and historical age matched patients from our hospital from the same months in prior years. 385 patients under the age of 40 years met the inclusion criteria, 349 in the control and 36 in the vaccinated group.

Main results and the role of chance

Demographic and clinical characteristics were comparable between groups. The pregnancy rate was 33.3% (n = 12) in the vaccinated group vs 31.8% (n = 111) in the control group (p > 0.1). There were no statistically significant differences between the control and vaccine groups with a small non-significant trend to higher pregnancy rates in vaccinated patients: pregnancy rate OR for vaccination group was 1.17 (95% CI 0.56-2.44). 

Limitations, reasons for caution

Our study size was small and was observational leaving it open to confounding and selection bias regarding who chose to receive the vaccine and those in high risk groups for COVID infection. Additionally, longterm effect of the vaccine and booster were not assessed.

Wider implications of the findings

We did not observe any effect of this vaccine regimen on IVF outcomes or pregnancy rates. This underscores worldwide data and physiologic reasoning that there should not be significant effects of this COVID vaccine on developing gametes quality and function and is a good option for those trying to conceive.

Trial registration number

LND 0031-21

Loss of heterochromatin and retrotransposon silencing as determinants in oocyte aging

Mammalian oocyte quality reduces with age. We show that prior to the occurrence of significant aneuploidy (9M in mouse), heterochromatin histone marks are lost, and oocyte maturation is impaired. This loss occurs in both constitutive and facultative heterochromatin marks but not in euchromatic active marks. We show that heterochromatin loss with age also occurs in human prophase I-arrested oocytes. Moreover, heterochromatin loss is accompanied in mouse oocytes by an increase in RNA processing and associated with an elevation in L1 and IAP retrotransposon expression and in DNA damage and DNA repair proteins nuclear localization. Artificial inhibition of the heterochromatin machinery in young oocytes causes an elevation in retrotransposon expression and oocyte maturation defects. Inhibiting retrotransposon reverse-transcriptase through azidothymidine (AZT) treatment in older oocytes partially rescues their maturation defects and activity of the DNA repair machinery. Moreover, activating the heterochromatin machinery via treatment with the SIRT1 activating molecule SRT-1720, or overexpression of Sirt1 or Ezh2 via plasmid electroporation into older oocytes causes an upregulation in constitutive heterochromatin, downregulation of retrotransposon expression, and elevated maturation rates. Collectively, our work demonstrates a significant process in oocyte aging, characterized by the loss of heterochromatin-associated chromatin marks and activation of specific retrotransposons, which cause DNA damage and impair oocyte maturation.

P–448 Clinical outcome of social oocyte cryopreservation at advanced age

Study question

What are the success rates of social oocyte cryopreservation (SOC) at advanced age?

Summary answer

In this study, one in four women who underwent SOC above age 35 had a delivery.

What is known already

While SOC is gaining popularity, reports on delivery rates are limited due to low utilization rates.

Study design, size, duration

Retrospective data collection of all woman who underwent SOC between 2011–2018, and presented for treatment using cryopreserved oocytes until January 2021. Participants/materials, setting, methods: Review of patient records (including both IVF and antenatal/postnatal) and laboratory data in a university affiliated hospital-based IVF unit. Main results and the role of chance: A total of 448 women underwent SOC during 2011–2018. 50 (11.2%) women returned to use these oocytes until the end of January 2021. Women who returned to use their oocytes underwent cryopreservation at mean age of 38.2±2.2. 46 (92%) of participants were above 35 at time of cryopreservation. Number of oocytes cryopreserved was 11.3±9.7. Mean time from cryopreservation to thawing was 5.5±1.8years (range 1–9 years). and age at thawing was 43.4±2.1 (range 40–49). Nearly half of patients initially attempted to conceive before using their cryopreserved oocytes, mostly by ART using fresh oocytes. Mean number of oocytes thawed and oocytes survived per women was 9.7±6.2 and 6.1±4.9 respectively (post thawing survival rate 65.4±35%).

Mean number of embryos transferred, at one or more attempts was 2.6±2.1 per women. Eleven women gave birth or had an ongoing pregnancy &gt; 20 weeks at time of analysis. All deliveries resulted from cryopreservation at age 36 and older (delivery rate 23.9% per women). Limitations, reasons for caution: We report our initial experience of women who underwent SOC at a single center. Most women who returned to use their oocytes had undergone SOC at advanced age, therefore not necessarily reflecting outcome for younger patients attempting to preserve fertility using this technology. Wider implications of the findings: Considering modest success rates of SOC in our cohort, women considering SOC are advised to do so at an earlier age.

Trial registration number

Not applicable

'Luckily, I don't believe in statistics': survey of women's understanding of chance of success with futile fertility treatments

RESEARCH QUESTION

Why are women who face poor prognoses for success in assisted reproductive technology (ART) treatment choosing to pursue procedures using their own eggs, despite receiving information that their chances of success are very low.

DESIGN

Cross-sectional study based on an anonymous questionnaire distributed to women aged between 43 and 45 years, undergoing ART using their own oocytes, at six public outpatient fertility clinics and three public in-hospital IVF units in Israel between 2015 and 2016. The main outcome measure was personal estimation of chance to achieve a live birth after the current ART treatment cycle and the cumulative estimated rate after all the treatment cycles the patient intended to undergo.

RESULTS

Response rate was 70.0%, with 91 participants of mean age 43.8 ± 0.7 years. Participants estimated their delivery rates after the next ART treatment cycle at 49.0 ± 31.8% (response rate 93.4%) and their cumulative delivery rates after all the ART treatments they would undergo at 57.7 ± 36.3% (response rate 90.1%). This is significantly higher than the predicted success rates of 5% and 15%, respectively (both P < 0.001), which are based on national register data. Nearly one-half of patients rated themselves as having a better than average chance of conception (47.3%).

CONCLUSION

Women do not pursue futile treatments because they lack information. Despite being informed of the low success rates of conception using ART treatments, many patients of advanced maternal age have unrealistically high expectations from ART, essentially ignoring their estimated prognosis when deciding on treatment continuation. Future work should examine the psychological reasons behind continuing futile fertility treatments.

Anti-Mullerian Hormone (AMH) Determinations in the Pediatric and Adolescent Endocrine Practice

Anti-Mullerian hormone (AMH), secreted by immature testicular Sertoli-cells, triggers the regression of male fetal Mullerian ducts. During puberty, AMH is downregulated by intratesticular testosterone. In females, AMH is secreted from granulosa cells of immature ovarian follicles from late prenatal life until menopause; serum concentration is 5-20 times lower in females than in males through lifetime. In boys, AMH determination is useful in the clinical setting as a marker of Sertoli cell function. Serum AMH is low in infants with hypogonadotrophic hypogonadism (and increases with FSH treatment), in patients with primary hypogonadism from early postnatal life and in Klinefelter syndrome from midpuberty. In boys with nonpalpable gonads, AMH determination is useful to distinguish between cryptorchidism and anorchism, as well as differentiating the dysgenetic causes of disorders of sexual development from those due to defective androgen synthesis or action. AMH can be used as a marker of sertoli/granulosa cell tumors and primary ovarian insufficiency in girls with delayed puberty, Turner Syndrome and after treatment with gonadotoxic agents.

Analysis of effects of MCB3681, the antibacterially active substance of prodrug MCB3837, on human resident microflora as proof of principle

The water-soluble prodrug MCB3837 is rapidly converted to MCB3681, active against Gram-positive bacterial species, after intravenous infusion. The aim of this study was to prove the principle that MCB3681 is efficacious in vivo by demonstrating its effect on the resident microflora or colonizers of the human skin, nose, oropharynx and intestine. MCB3837 was infused at a daily dose of 6 mg/kg for 5 days. MCB3681 was active against clostridia, bifidobacteria, lactobacilli, enterococci and Staphylococcus aureus, thus proving the principle that MCB3681 is antibacterially efficacious in vivo without affecting the Gram-negative microflora.

The origin of endodontic Enterococcus faecalis explored by comparison of virulence factor patterns and antibiotic resistance to that of isolates from stool samples, blood cultures and food

AIM

To elucidate the origin of Enterococcus faecalis isolated from secondary root canal infections and the possibility for a foodborne transmission by comparing them to strains recovered from food, blood and stool regarding putative virulence factors and antibiotic susceptibility profiles, where strains from common origin were hypothesized to harbour similar characteristics.

METHODOLOGY

A total of 108 E. faecalis strains recovered in the county of Stockholm, Sweden, were screened using PCR for putative virulence factors esp, cylA, gelE/gelatinase-negative phenotype (ef1841/fsrC), efaA, ace and asa1. The minimum inhibitory concentration (MIC) for ampicillin, piperacillin-tazobactam, imipenem, gentamicin, vancomycin, ciprofloxacin and linezolid was determined using the agar dilution method.

RESULTS

Next to strains from blood, the food isolates presented the highest average number of virulence determinants and were frequently enriched with asa1 coding for aggregation substance. None of the endodontic strains carried cylA, and the gelatinase-negative phenotype caused by a deletion dominated the group. Altogether, the most prevalent genes were gelE, efaA and ace, and a combination of them was equally present in approximately 80% of the strains from food, stool and root canals in comparison with 43.3% of the blood isolates. High-level resistance to ciprofloxacin and gentamicin was observed in 30% of the blood isolates, whereas the isolates from other origins, with single exceptions, were susceptible to all tested antibiotics.

CONCLUSIONS

Evidence for a foodborne transmission, explaining the high reported prevalence of E. faecalis in root filled teeth, could not be determined based on the similarities in virulence factor patterns and antibiotic susceptibility. The only linkage between isolates from food and root canals consisted of a shared common combination of the genes gelE, efaA and ace. The high occurrence of putative virulence traits in food isolates questions the safety of E. faecalis in food products.

Antibiotic resistance patterns of Escherichia coli isolates from different aquatic environmental sources in León, Nicaragua

Antibiotic-resistant bacteria have emerged due to the selective pressure of antimicrobial use in humans and animals. Water plays an important role in dissemination of these organisms among humans, animals and the environment. We studied the antibiotic resistance patterns among 493 Escherichia coli isolates from different aquatic environmental sources collected from October 2008 to May 2009 in León, Nicaragua. High levels of antibiotic resistance were found in E. coli isolates in hospital sewage water and in eight of 87 well-water samples. Among the resistant isolates from the hospital sewage, ampicillin, chloramphenicol, ciprofloxacin, nalidixic acid, trimethoprim-sulphamethoxazole was the most common multi-resistance profile. Among the resistant isolates from the wells, 19% were resistant to ampicillin, ceftazidime, ceftriaxone, cefotaxime, chloramphenicol, ciprofloxacin, gentamicin, nalidixic acid and trimethoprim-sulphamethoxazole. E. coli producing ESBL and harbouring bla(CTX-M) genes were detected in one of the hospital sewage samples and in 26% of the resistant isolates from the well-water samples. The bla(CTX-M-9) group was more prevalent in E. coli isolates from the hospital sewage samples and the bla(CTX-M-1) group was more prevalent in the well-water samples.

Antibiotic resistance patterns in gram-negative and gram-positive bacteria causing septicemia in newborns in León, Nicaragua: correlation with environmental samples

The aim of this study was to identify the bacteria causing neonatal septicemia in a neonatal intensive care unit (NICU) in León, Nicaragua and its relation with bacteria isolated from the environment at the NICU. Our data showed that 74% (34/46) of the bacteria related to newborns with septicemia were Gram-negative and highly resistant to beta-lactams (>85%) and aminoglycosides (80%), leading to treatment failure in 10 neonates with fatal outcome. Although, the prevalence of Gram-positive bacteria (26%) was lower than Gram-negative bacteria, Staphylococcus epidermidis was related to the death of three newborns. No clonal similarity was found among Enterobacter cloacae , Escherichia coli and Serratia liquefaciens isolated from the neonates with septicemia and the NICU environment. However, in order to improve the outcome for neonates with septicemia, infection control practices and appropriate empirical therapy should be considered to reduce the high prevalence of extended-spectrum beta-lactamase (ESBL)-producing Gram-negative bacteria isolated from neonates with septicemia (80%) and from the NICU environment (34%).

Distinct ribotypes and rates of antimicrobial drug resistance in Clostridium difficile from Shanghai and Stockholm

Seventy-five clinical isolates of Clostridium difficile from Shanghai and 80 from Stockholm were investigated. The prevalence of toxin A-negative, toxin B-positive isolates of C. difficile among isolates from Shanghai (33.3%) was significantly higher than among isolates from Stockholm (0%). Both sets of isolates were fully susceptible to metronidazole and vancomycin. However, the MICs of fluoroquinolones, erythromycin-clindamycin, tetracycline, rifampin and fusidic acid were significantly higher for the Shanghai isolates than for the Stockholm isolates. Thirty-three PCR ribotypes were identified; a dominant clone, 017, accounted for 18.7% of Shanghai isolates, whereas clone 005 dominated among Stockholm isolates, accounting for 11.3%. Strains 027 and 078 were not detected. No outbreak occurred during the study period.

Identification of Bacteroides fragilisby a modified immuno polymerase chain reaction (mIPCR), using a specific monoclonal antibody

Bacteroides fragilis is the anaerobic species most commonly isolated from human clinical specimens, and is resistant to many antimicrobial agents. A monoclonal antibody, mAb4H8 (IgG3), reacting with a specific epitope in the lipopolysaccharide (LPS) isolated from most of the B. fragilis strains, was produced and employed with modified Immuno Polymerase Chain Reaction (mIPCR) for identification of B. fragilis with a detection limit of 10(4) cfu/mL bacterial suspension. A number of bacterial strains were examined, including B. fragilis, Bacteroides spp. other than B. fragilis and other genera. All the B. fragilis strains with the immunodominant (beta1,6-linked D-galactosyl chain) epitope were positive. None of the other strains showed the positive reaction. The results indicate that mIPCR assay with mAb4H8 has a high specificity and high sensitivity.

Plasmid-mediated quinolone resistance determinant qnrS in Enterobacter cloacae

PCR was used to investigate the occurrence of the plasmid-encoded quinolone resistance determinants qnrA and qnrS among diarrhoeagenic enterobacterial isolates recovered from Hanoi, Vietnam, during the period March 2001 to April 2002. In total, 162 Escherichia coli isolates, 28 Shigella isolates and three Enterobacter cloacae isolates were negative for qnrA, while a single Ent. cloacae isolate harboured a 50-kb qnrS-positive conjugative plasmid. Cloning and sequencing identified a qnrS gene bracketed by open reading frames identical to those surrounding the qnrS gene of a Shigella flexneri isolate from Japan, thereby suggesting a common mechanism of acquisition.

The dental student as a technician: preclinical and clinical laboratory programs in fixed prosthodontics

PURPOSE

A 2-part survey of United States dental schools was conducted. The first part of the survey was published in 1998 and determined the curricular structure, techniques taught, and materials used in predoctoral fixed prosthodontics courses. The purpose of the second part of the survey was to ascertain the delegation of laboratory procedures in preclinical and clinical fixed prosthodontic programs.

MATERIALS AND METHODS

The survey was mailed to the course directors of predoctoral fixed prosthodontic programs at 53 US dental schools. Of these, 42 schools returned the completed survey, resulting in a response rate of 79%.

RESULTS

Results from this survey show that certain laboratory procedures in preclinical and clinical fixed prosthodontics are completed by dental laboratories (either in-house or commercially available laboratories).

CONCLUSIONS

For the preclinical programs of fixed prosthodontics, there is more student involvement in the completion of laboratory procedures in the dental schools surveyed. In clinical fixed prosthodontic programs, there is a high emphasis on patient care and less on laboratory techniques that can be delegated to laboratory technicians.

Depolymerization of the capsular polysaccharide from Vibrio cholerae O139 by a lyase associated with the bacteriophage JA1

We have studied the interaction between the Vibrio cholerae O139 specific phage JA1, belonging to the Podoviridae family, and the capsular polysaccharide (CPS) of the parent strain from which the phage was isolated. Upon incubation of the JA1 phage with the CPS, oligosaccharides were isolated and purified. The oligosaccharides derived from one (shown below) and two repeating units of the CPS were characterized using NMR spectroscopy, mass spectrometry and sugar analysis (structure: see text). The cleavage was found to occur by beta-elimination at the 4-substituted alpha-linked galacturonic acid, which results in a 4-deoxy-beta-L-threo-hex-4-enopyranosyl uronic acid group (Sug). The enzyme associated with the JA1 phage responsible for the depolymerization of the V. cholerae O139 CPS is thus a lyase.

Structural studies of the O-polysaccharide from the Escherichia coli O77 lipopolysaccharide

The structure of the O-antigen polysaccharide (PS) from Escherichia coli O77 has been determined. Sugar and methylation analysis together with 1H and 13C NMR spectroscopy were the main methods used. The PS is composed of tetrasaccharide repeating units with the following structure:-->2)-alpha-D-Manp-(1-->2)-beta-D-Manp-(1-->3)-alpha-D-GlcpNAc-(1-->6)-alpha-D-Manp-(1-->

Structure of the O-specific polysaccharide of Vibrio cholerae O9 containing 2-acetamido-2-deoxy-d-galacturonic acid

The O-specific polysaccharide (OPS) was isolated by mild-acid degradation of the lipopolysaccharide of Vibrio cholerae O9 and studied by carboxyl reduction, sugar and methylation analyses, Smith degradation, and two-dimensional NMR spectroscopy, including COSY, TOCSY, NOESY, and H-detected 1H,(13)C HMQC experiments. The following structure of the pentasaccharide-repeating unit of the OPS was established:

Enthalpic barriers to the hydrophobic binding of oligosaccharides to phage P22 tailspike protein

The structural thermodynamics of the recognition of complex carbohydrates by proteins are not well understood. The recognition of O-antigen polysaccharide by phage P22 tailspike protein is a highly suitable model for advancing knowledge in this field. The binding to octa- and dodecasaccharides derived from Salmonella enteritidis O-antigen was studied by isothermal titration calorimetry and stopped-flow spectrofluorimetry. At room temperature, the binding reaction is enthalpically driven with an unfavorable change in entropy. A large change of -1.8 +/- 0.2 kJ mol(-1) K(-1) in heat capacity suggests that the hydrophobic effect and water reorganization contribute substantially to complex formation. As expected from the large heat-capacity change, we found enthalpy-entropy compensation. The calorimetrically measured binding enthalpies were identical within error to van't Hoff enthalpies determined from fluorescence titrations. Binding kinetics were determined at temperatures ranging from 10 to 30 degrees C. The second-order association rate constant varied from 1 x 10(5) M(-1) s(-1) for dodecasaccharide at 10 degrees C to 7 x 10(5) M(-1) s(-1) for octasaccharide at 30 degrees C. The first-order dissociation rate constants ranged from 0.2 to 3.8 s(-1). The Arrhenius activation energies were close to 50 and 100 kJ mol(-1) for the association and dissociation reactions, respectively, indicating mainly enthalpic barriers. Despite the fact that this system is quite complex due to the flexibility of the saccharide, both the thermodynamic and kinetic data are compatible with a simple one-step binding model.

A randomized, double-blind, placebo-controlled trial of single-dose intravenous secretin as treatment for children with autism

OBJECTIVE

To determine whether a single injection of intravenous secretin results in measurable improvements in socialization and/or communication skills in children with autism.

STUDY DESIGN

Sixty subjects with autism were randomly selected and assigned to either treatment or placebo group. Subjects in the treatment group received 2.0 clinical units of secretin per kilogram of body weight as a single intravenous dose. Subjects in the placebo group received normal saline solution. Neurodevelopmental and behavioral assessments were performed for all subjects before injection and at 3 and 6 weeks after injection.

RESULTS

Assessment of language skills and parents' behavioral assessments revealed no significant differences between the treatment and placebo groups. Raters' assessments of severity of autistic symptoms did not differ for the 2 groups at 6 weeks after injection. A marginally statistically significant improvement in autistic behaviors was seen in the treatment group at 3 weeks after injection (P =.051).

CONCLUSIONS

A single dose of intravenous secretin does not appear to have significant effects on either parents' perception of autistic behaviors or language skills at 6 weeks after injection. Transient, marginally significant improvements in autistic behaviors may occur in some children.

Structural analysis of the O-antigen polysaccharide from the Shiga toxin-producing Escherichia coli O172

The structure of the O-antigen polysaccharide from Escherichia coli O172 has been determined. In combination with sugar analysis, NMR spectroscopy shows that the polysaccharide is composed of pentasaccharide repeating units. Sequential information was obtained by mass spectrometry and two-dimensional NMR techniques. An O-acetyl group was present as 0.7 equivalent per repeating unit. Treatment of the O-deacetylated polysaccharide with aqueous 48% hydrofluoric acid rendered cleavage of the phosphodiester in the backbone of the polymer and the pentasaccharide isolated after gel permeation chromatography was structurally characterized. Subsequent NMR experiments on polymeric materials revealed the structure of the repeating unit of the O-polysaccharide from E. coli O172 as:-->P-4)-alpha-D-Glcp-(1-->3)-alpha-L-FucpNAc-(1-->3)-alpha-D- GlcpNAc-(1-->3)-alpha-L-FucpNAc-(1-->4)-alpha-D-Glcp6Ac-(1-->

Complement activation by Proteus mirabilis negatively charged lipopolysaccharides

Proteus mirabilis strains are human pathogens responsible for urinary tract infections and bacteremias and may be involved in rheumatoid arthritis. Lipopolysaccharide (LPS, bacterial endotoxin), the major component of the cell wall, is one of the virulence factors of Proteus. In the presented studies, we have investigated complement activation by LPSs isolated from P. mirabilis O10, O23, O30, and O43 strains, which differ in the number of negative COO- groups on their polysaccharide components. Four P. mirabilis strains studied were sensitive to complement-mediated killing, despite complement binding by their LPSs. The optimal complement binding by LPSs was detected in serum with functional assays for both the classical and alternative pathways. Complement activation in 80% serum by the smooth, uronic acid, and hexosamine containing P. mirabilis LPSs was not critically determined by the structure of their O-chain polysaccharides. One of four LPSs used as a model, P. mirabilis O10 LPS, fragmented C3 in an LPS dose- and time-dependent manner. It was detected by crossed-immunoelectrophoresis and capture ELISA with anti-C3c antibodies. The lower complement activation by 023 LPS correlates with its reduced C3 fragmentation, compared with three other Proteus LPSs studied. Rabbit anti-O antibodies enhanced the complement binding and factor C3 fragmentation by O10, O23, O30, and O43 P. mirabilis LPSs.

Structural studies of the O-specific polysaccharide of Vibrio cholerae O8 using solvolysis with triflic acid

The O-specific polysaccharide (OPS) of Vibrio cholerae 08 was isolated by mild acid degradation of the lipopolysaccharide and studied by two-dimensional NMR spectroscopy, including NOESY and heteronuclear multiple-bond correlation (HMBC) experiments. The OPS was found to have a tetrasaccharide repeating unit with the following structure: --> 4)-beta-D-Glcp NAc3NAcylAN-(1 --> 4)-beta-D-Manp NAc3NAcAN-(1 --> 4)-alpha-L-Gulp NAc3NAcA-(1 --> 3) -beta-D-QuipNAc4NAc-(1 --> where QuiNAc4NAc is 2,4-diacetamido-2,4,6-trideoxyglucose, GlcNAc3NAcylAN is 2-acetamido-3-(N-formyl-L-alanyl)amino-2,3-dideoxyglucuronamide, ManNAc3NAcAN is 2,3-diacetamido-2,3-dideoxymannuronamide, and GulNAc3NAcA is 2,3-diacetamido-2,3-dideoxyguluronic acid. The OPS was stable towards acid hydrolysis and solvolysis with anhydrous hydrogen fluoride, but could be cleaved selectively with trifluoromethanesulfonic (triflic) acid by the glycosidic linkages of beta-QuiNAc4NAc and alpha-GulNAc3NAcA. The structures of the oligosaccharides obtained that were elucidated by electrospray ionization (ESI) MS and NMR spectroscopy, confirmed the OPS structure.