Glycine rich segments adopt polyproline II helices: Implications for biomolecular condensate formation.

Many intrinsically disordered proteins contain Gly-rich regions which are generally assumed to be disordered. Such regions often form biomolecular condensates which play essential roles in organizing cellular processes. However, the bases of their formation and stability are still not completely understood. Based on NMR studies of the Gly-rich H. harveyi "snow flea" antifreeze protein, we recently proposed that Gly-rich sequences, such as the third "RGG" region of Fused in Sarcoma (FUS) protein, may adopt polyproline II helices whose association might stabilize condensates. Here, this hypothesis is tested with a polypeptide corresponding to the third RGG region of FUS. NMR spectroscopy and molecular dynamics simulations suggest that significant populations of polyproline II helix are present. These findings are corroborated in a model peptide Ac-RGGYGGRGGWGGRGGY-NH2, where a peak characteristic of polyproline II helix is observed using CD spectroscopy. Its intensity suggests a polyproline II population of 40%. This result is supported by data from FTIR and NMR spectroscopies. In the latter, NOE correlations are observed between the Tyr and Arg, and Arg and Trp side chain hydrogens, confirming that side chains spaced three residues apart are close in space. Taken together, the data are consistent with a polyproline II helix, which is bent to optimize interactions between guanidinium and aromatic moieties, in equilibrium with a statistical coil ensemble. These results lend credence to the hypothesis that Gly-rich segments of disordered proteins may form polyproline II helices which help stabilize biomolecular condensates.

Seven novel COL7A1 mutations identified in patients with recessive dystrophic epidermolysis bullosa from Mexico.

Recessive dystrophic epidermolysis bullosa (RDEB; OMIM #226600) is one of the most devastating subtypes of epidermolysis bullosa, a group of skin and mucous membrane blistering disorders often associated with extracutaneous manifestations. RDEB is caused by mutations in COL7A1, the gene encoding type VII collagen (C7), and to date over 700 different mutations in the 8835 nucleotides constituting the open reading frame or adjacent exon-intron boundaries of COL7A1 have been described. We used targeted next-generation sequencing to identify seven previously unreported mutations in a cohort of 17 Mexican patients who were diagnosed with RDEB based on clinical presentation and immunoepitope mapping. Our study expands the spectrum of mutations identified in this cohort, including those suitable for emerging therapies reliant on precise genotyping.

Comparison of the solar photocatalytic activity of ZnO-Fe2O3 and ZnO-Fe(0) on 2,4-D degradation in a CPC reactor.

In this work a comparative study of the catalytic activity of ZnO-Fe2O3 and ZnO-Fe(0) 0.5 wt% materials was carried out in the degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) as a commercial formulation Hierbamina®, using a compound parabolic collector (CPC) reactor. The catalysts were synthesized by the sol-gel method and characterized by X-ray diffraction, UV-Vis diffuse reflectance spectroscopy, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy. The textural properties of solids were determined from N2 adsorption isotherms using the Brunauer-Emmett-Teller (BET) method. The incorporation of Fe(0) onto ZnO was demonstrated by X-ray photoelectron spectroscopy analysis. The photocatalytic tests were performed at pH 7, using 10 mg L(-1) of herbicide and 0.5 g L(-1) of catalyst loading. The decay in herbicide concentration was followed by reversed-phase chromatography. A complete degradation of 2,4-D was achieved using ZnO-Fe(0) while 47% of herbicide removal was attained with ZnO-Fe2O3 mixed oxide for an accumulated energy QUV ≈ 2 kJ L(-1). The removal percentage of total organic carbon (TOC) during the solar photocatalytic process was superior using ZnO-Fe(0), achieving 45% compared to the 15% obtained with the mixed oxide catalyst.

Emerging Trichosporon asahii in elderly patients: epidemiological and molecular analysis by the DiversiLab system.

Trichosporon asahii has been recognized as an emerging opportunistic agent for invasive infections, mainly in immunocompromised patients. Urinary tract infections by this pathogen may also occur, especially in patients with urinary obstruction or those undergoing vesical catheterization and antibiotic treatment. Many outbreaks of Trichosporon spp. have been detected after urinary catheter manipulations. We report the molecular-epidemiological characterization of T. asahii in our institution using the DiversiLab system for the molecular strain typing and compare three different methods for susceptibility testing. Our results present T. asahii as an emergent pathogen in elderly patients with urinary drainage devices that can be adequately treated with triazoles, with voriconazole being the most active. Broth dilution and Vitek 2 had good concordance, while Etest showed more discrepancies. In addition, the DiversiLab system for clonal strain typing may be a useful tool for fast and accurate management of nosocomial outbreaks.

High-throughput genotyping assay for the large-scale genetic characterization of Cryptosporidium parasites from human and bovine samples.

The epidemiological study of human cryptosporidiosis requires the characterization of species and subtypes involved in human disease in large sample collections. Molecular genotyping is costly and time-consuming, making the implementation of low-cost, highly efficient technologies increasingly necessary. Here, we designed a protocol based on MALDI-TOF mass spectrometry for the high-throughput genotyping of a panel of 55 single nucleotide variants (SNVs) selected as markers for the identification of common gp60 subtypes of four Cryptosporidium species that infect humans. The method was applied to a panel of 608 human and 63 bovine isolates and the results were compared with control samples typed by Sanger sequencing. The method allowed the identification of species in 610 specimens (90·9%) and gp60 subtype in 605 (90·2%). It displayed excellent performance, with sensitivity and specificity values of 87·3 and 98·0%, respectively. Up to nine genotypes from four different Cryptosporidium species (C. hominis, C. parvum, C. meleagridis and C. felis) were detected in humans; the most common ones were C. hominis subtype Ib, and C. parvum IIa (61·3 and 28·3%, respectively). 96·5% of the bovine samples were typed as IIa. The method performs as well as the widely used Sanger sequencing and is more cost-effective and less time consuming.

School-based individualised lifestyle intervention decreases obesity and the metabolic syndrome in Mexican children.

BACKGROUND: Currently, there is limited evidence about effective strategies to manage childhood obesity and the metabolic syndrome in school settings. The present study aims to analyse changes in the prevalence of being overweight/obese and having the metabolic syndrome in relation to a 10-month lifestyle intervention based on individualised face-to-face sessions and parental education in school settings. METHODS: The study sample comprised a cross-sectional sample of 96 overweight/obese Mexican children aged 6-12 years from eight schools. Clinical, anthropometric measurements and 24-h recalls were obtained during each of 13 visits. Laboratory measurements were determined at the beginning and end. The energy-reduced diet was based on dietary recommended intakes. Individualised structured daily meals and a physical activity plan, tailored-made for each child, were provided every 3 weeks at the schools. Parental attendance was required. Student's t-test, McNemar and Shapiro-Wilk tests and simple linear regression were used for the statistical analysis. RESULTS: The prevalence of metabolic syndrome fell significantly from 44% to 16% (P < 0.01), high blood pressure fell from 19% to 0%, hypertrigliceridaemia fell from 64% to 35%, high-density lipoprotein-cholesterol ≤ 40 fell from 60% to 41%, hyperglycaemia fell from 1% to 0%, and waist circumference ≥90th percentile fell from 72% to 57%. There was a 2.84 [95% confidence interval (CI) = -4.10 to -1.58; P < 0.01] significant decrease in body mass index percentile and in body-fat percentage (95% CI = -3.31 to -1.55; P < 0.01). Of the overweight children, 32% achieved normal-weight, whereas 24% of the obese ones converted to overweight and 1% reached normal-weight. Physical activity increased 16 min/day(-1) (P = 0.02) and 2 days/week(-1) . CONCLUSIONS: A school-setting lifestyle intervention led to a decreased prevalence of being overweight/obese and to a striking reduction in the prevalence of the metabolic syndrome in a sample of Mexican children.

Volumetric assessment of the sella turcica: a re-evaluation.

BACKGROUND: The sella turcica volume is widely measured by the Di Chiro-Nelson method. The purpose is to compare the fidelity of a proposed volumetry method vs. the Di Chiro-Nelson method, using computed tomography (CT) images. MATERIALS AND METHODS: Morphometric examination of 173 CT scans were included, of which 52.6% were female. The mean age was 53.2 ± 17.6 years. Considering the Di Chiro-Nelson method, two measurements were added for each axis in the CT evaluation: length (central, left, and right), width (central, anterior, and posterior), and height (central, left, and right). RESULTS: The mean measurements were length: central 10.11 ± 1.44, left 7.45 ± 1.67, right 7.53 ± 1.59; width: central 12.27 ± 2.11, anterior 10.99 ± 1.92, posterior 10.10 ± 1.74; height: central 7.68 ± 1.38, left 7.16 ± 1.35, right 7.40 ± 1.41. A statistically significant difference between sexes was found only in the anterior width (p = 0.01). Using the proposed method, the volume was 342.2 ± 88.5 and 378. 6 ± 113.9 mm³, respectively for females and males (p = 0.02) vs. 476.1 ± 132.4 and 523.8 ± 186.0 mm3 (p = 0.05) using the Di Chiro-Nelson's method. CONCLUSIONS: Women had significantly smaller sella turcica volume than men. This proposed method considers the sella turcica as a not strictly symmetrical structure and indicates reduced variation between the maximum and minimum values, compared to the Di Chiro-Nelson's. Our findings may be useful for reassessment the volume of the sella turcica as the measurements indicate a higher precision.

[Mycoplasma genitalium in Primary Care: Prevalence and azithromycin resistance in Santiago de Compostela Health Care Area]. / Mycoplasma genitalium en Atención Primaria: Prevalencia y resistencia a azitromicina en el Área Sanitaria de Santiago de Compostela.

OBJECTIVE: Mycoplasma genitalium is associated with persistent/recurrent sexually transmitted infections. The aim of this work was to estimate the prevalence and azithromycin resistance of M. genitalium in general population that was attended at Primary Care of Santiago de Compostela Health Care Area. METHODS: The study was carried out in 2019 in general population of Santiago de Compostela Health Care Area. Real-time multiplex PCR was used for screening of sexually transmitted infections associated pathogens and detection of mutations in the 23S rRNA gene. RESULTS: A total of 502 women and 532 men were studied. The prevalence of M. genitalium was 2,4% in men and 2,9% in women. Overall azithromycin resistance was 20% all of them detected in men. The mutations found were A2059G, A2058G and A2058T. CONCLUSIONS: Although the proportion of M. genitalium infection is low, the high percentage of azithromycin resistance detected supports the relevance of these data in order to the right management of the patients with sexually transmitted diseases and, so as, to avoid the emergence of resistance in other pathogens of the urogenital tract.

Morphometry of the aortic arch and its branches. A computed tomography angiography-based study.

BACKGROUND: The current study aims to determine the prevalence of variations of the aortic arch using computed tomography angiography (CTA), as well as morphometries and gender correlations. MATERIALS AND METHODS: A retrospective, transverse, observational and descriptive study of 220 CTA was performed. The branching pattern, most cranial vertebral level of the aortic arch, area of the proximal, middle and distal segments of the arch, area of each branch, and the path of atypical arteries were recorded. Results were analysed and stratified by gender. RESULTS: The typical aortic arch branching pattern was present in 77.7% without statistical significance between genders. The most common variant was a two-branch pattern with a common trunk and a left subclavian (13.6%), followed by a typical branching pattern with an added left vertebral artery (7.3%). T3 was the most frequent cranial level (32.3%), followed by T2-T3 (26.8%), and T3-T4 (23.2%). The mean areas of the aortic arch were 685.5 ± 183.9, 476.1 ± 124.1, and 445.0 ± 145.1 mm2 for the proximal, middle and distal segments, with statistical difference between men and women in the middle and distal segments. Three paths of atypical arteries were identified: bifurcated vertebral artery (0.5%), aberrant right subclavian artery (0.5%), and left subclavian ostium obstruction (0.5%). CONCLUSIONS: Mexican population has one of the highest prevalence of variations in the aortic arch branching pattern. The high probability of finding these should be taken into consideration when assessing patients. A standardised classification method would contemplate future un-reported findings, without causing confusion by the different numbers assigned by each author.

Thermal tolerance and potential distribution of Carvalhotingis visenda (Hemiptera: Tingidae), a biological control agent for cat's claw creeper, Macfadyena unguis-cati (Bignoniaceae).

The specialist tingid, Carvalhotingis visenda, is a biological control agent for cat's claw creeper, Macfadyena unguis-cati (Bignoniaceae). Cat's claw creeper is an invasive liana with a wide climatic tolerance, and for biological control to be effective the tingid must survive and develop over a range of temperatures. We evaluated the effect of constant temperatures (0-45 degrees C) on the survival and development of C. visenda. Adults showed tolerance for wider temperature ranges (0-45 degrees C), but oviposition, egg hatching and nymphal development were all affected by both high (>30 degrees C) and low (<20 degrees C) temperatures. Temperatures between 20 degrees C and 30 degrees C are the most favourable for adult survival, oviposition, egg hatching and nymphal development. The ability of adults and nymphs to survive for a few days at high (40 degrees C and 45 degrees C) and low (0 degrees C and 5 degrees C) temperatures suggest that extreme temperature events, which usually occur for short durations (hours) in cat's claw creeper infested regions in Queensland and New South Wales states are not likely to affect the tingid population. The potential number of generations (egg to adult) the tingid can complete in a year in Australia ranged from three to eight, with more generations in Queensland than in New South Wales.

Carbapenem-resistant Enterobacter cloacae and the emergence of metallo-beta-lactamase-producing strains in a third-level hospital (Santiago de Compostela, NW Spain).

The purpose of this paper was to investigate the occurrence of carbapenem-resistant Enterobacter cloacae in our institution, to detect the carbapenemase-associated resistance and to determine the genetic relatedness of the isolates. Species identification and antimicrobial susceptibility testing were performed using the Vitek 2 system and Etest. Multiplex polymerase chain reaction-enzyme linked immunosorbent assay (PCR-ELISA) was used for the detection of extended-spectrum beta-lactamase (ESBL)-producers. The bla (IMP) and bla (VIM) genes were amplified by PCR and sequenced. The DiversiLab System was used for strain-typing. During the period 2006-2008, 12 different isolates of carbapenem-resistant E. cloacae (2.3 %) were recovered in our laboratory. Only two positive isolates for the bla (VIM) gene were detected. The minimum inhibitory concentration (MIC) values were higher for all carbapenems in the group of non-metallo-beta-lactamase (MBL)-producers. All isolates showed MIC values

Endemic linezolid-resistant Staphylococcus epidermidis in a critical care unit.

The aim of this article was to report the emergence of patient infections with linezolid-resistant Staphylococcus epidermidis (LRSE) in a tertiary university hospital. Our objectives were to determine the molecular mechanism of the resistance, set up the genetic relationship among isolates, and analyze the relations between linezolid usage, period of treatment, and emergence of resistance in the hospital. The emergence of infection with linezolid-resistant S. epidermidis affecting 20 patients in a tertiary university hospital was investigated using repetitive sequence-based PCR (rep-PCR, DiversiLab System; BioMérieux, Inc., France). The presence of the G2576T mutation of 23S rRNA was screened by pyrosequencing. We determined the pattern of linezolid usage in the hospital as a whole and in the critical care unit that was most affected. G2576T mutation of 23S rRNA was detected in all linezolid-resistant S. epidermidis studied. Of these, 90% were genetically related and had been recovered from patients admitted to the same critical care unit. There had been an increase in linezolid usage in the hospital and in the critical care unit in the 2 years prior to the emergence of resistant strains. More strict control measures in hand washing and linezolid prescription were subsequently established, but no reduction in LRSE rates have yet been observed. Linezolid-resistant S. epidermidis emerged at our hospital, probably from a single strain originating in the critical care unit. The most likely explanation is that person-to-person spread of linezolid-resistant S. epidermidis led to skin colonization and, after linezolid treatment, this resistant staphylococci became the dominant cutaneous flora causing infection in some critical patients. In order to preserve the usefulness of this antibiotic as a therapeutic agent and to avoid a situation similar to methicillin-resistant Staphylococcus aureus, judicious use of antibiotics is essential.

Prevalence of genital Mycoplasma and response to eradication treatment in patients undergoing assisted reproductive techniques.

OBJECTIVE: Several studies have reported greater success of fertilisation by ART in couples who were not infected by Ureaplasma. Increased semen quality and better results have also been observed in couples who were treated with antibiotics to eradicate the infection. The aim of this study was to determine the prevalence of genital mycoplasmas in urine samples from male partners enrolled in the Assisted Reproduction Program (ARP) in our healthcare area so that, positive cases can be treated prior to the use of ART in order to increase the quality of semen, improve the embryo implantation rates and minimize the risk of adverse effects during pregnancy. METHODS: This study included couples enrolled in the ARP during 2016. Mycoplasma detection was made using real-time PCR. In positive cases, both members of the couple were treated with antibiotics until eradication of the microorganism. The antibiotics used were: azithromycin, doxycycline, levofloxacin, moxifloxacin, and clindamycin. RESULTS: Of the 205 men studied, 33 were positive: Ureaplasma urealyticum 15.1%, Mycoplasma hominis 3.9%. Eradication treatment with azithromycin failed in 50% compared to 10.2% for doxycycline. Of the 5 cases treated with levofloxacin, only 2 achieved elimination of U. urealyticum. CONCLUSIONS: We consider that genital mycoplasma routine screening could be useful in order to increase the quality of semen which could simplify the in vitro fertilisation procedures and raise the success rate of embryo implantation and pregnancy, especially when fast, sensitive and specific technics as real time PCR are used.

Sex-related differences in muscle size explained by amplitudes of higher-threshold motor unit action potentials and muscle fibre typing.

AIM: To investigate the relationships between motor unit action potential amplitudes (MUAPAMP ), muscle cross-sectional area (mCSA) and composition (mEI), per cent myosin heavy chain (%MHC) areas and sex in the vastus lateralis (VL). METHODS: Ten males and 10 females performed a submaximal isometric trapezoid muscle action that included a linearly increasing, steady torque at 40% maximal voluntary contraction, and linearly decreasing segments. Surface electromyographic decomposition techniques were utilized to determine MUAPAMPS in relation to recruitment thresholds (RT). Ultrasound images were taken to quantify muscle mCSA and mEI. Muscle biopsies were collected to calculate %MHC areas. Y-intercepts and slopes were calculated for the MUAPAMP vs RT relationships for each subject. Independent-samples t tests and ANOVA models examined sex-related differences in mCSA, mEI, slopes and y-intercepts for the MUAPAMP vs RT relationships and %MHC areas. Correlations were performed among type IIA and total type II %MHC area, mCSA and the slopes and y-intercepts for the MUAPAMP vs RT relationships. RESULTS: Males exhibited greater slopes for the MUAPAMP vs RT relationships (P = .003), mCSA (P < .001) and type IIA %MHC (P = .011), whereas females had greater type I %MHC area (P = .010) and mEI (P = .024). The mCSA, type IIA and total II %MHC area variables were correlated (P < .001-.015, r = .596-.836) with the slopes from the MUAPAMP vs RT relationships. CONCLUSION: Sex-related differences in mCSA and MUAPAMPS of the higher-threshold MUs were likely the result of larger muscle fibres expressing type II characteristics for males.

[Comparison between Phoenix system and agar-based methods for antimicrobial susceptibility testing of Streptococcus spp]. / Comparación entre el sistema Phoenix y métodos basados en agar para el ensayo de sensibilidad a antibióticos en Streptococcus spp.

Introduction. Antibiotic resistance is an emerging problem among streptococcal species, especially for severe infections. Automated diagnostic systems for antimicrobial susceptibility testing, such as BD Phoenix, is a recently available instruments that makes it possible to obtain results within 12 h. Methods. Antimicrobial susceptibility testing results of the BD Phoenix system were compared to those obtained from Clinical Laboratory Standards Institute (CLSI) disk-diffusion method. Two-hundred different clinical isolates of streptococci were assayed: beta-hemolytic (n=65), viridans (n=87), S. penumoniae (n=48). Results. Overall, there was categorical agreement greater than 96.7% (94.8% for beta-hemolytic and 97.9% for viridans group) in relationship to the disk-diffusion method. The minor error rates were less than 10% for all the antibiotics. The greatest percentage of serious errors corresponded to erythromycin and clindamycin within the beta-hemolytic group (14.7%). Overall percentage of very serious errors was less 0.5%. The results for penicillin in viridans streptococci and S. pneumoniae results showed 89.7% and 91.7% of categorical agreement, respectively, using the Etest as reference. Conclusions. The automated BD Phoenix system is a very useful and effective diagnostic tool for quantitative testing of sensitivity to antibiotics in the streptococci group.

The change in motor unit firing rates at de-recruitment relative to recruitment is correlated with type I myosin heavy chain isoform content of the vastus lateralis in vivo.

AIM: To investigate the change in motor unit (MU) firing rates (FR) at de-recruitment relative to recruitment and the relation to % type I myosin heavy chain isoform content (type I %MHC) of the vastus lateralis (VL) in vivo. METHODS: Ten subjects performed a 22-s submaximal isometric trapezoid muscle action that included a linearly increasing, steady force at 50% maximal voluntary contraction, and linearly decreasing segments. Surface electromyographic signals were collected from the VL and were decomposed into constituent MU action potentials trains. A tissue sample from the VL was taken to calculate type I %MHC. The y-intercepts and slopes were calculated for the changes (Δ) in FR at de-recruitment (FRDEREC ) relative to FR at recruitment (FRREC ) vs. FRREC relationship for each subject. Correlations were performed between the y-intercepts and slopes with type I %MHC. RESULTS: The majority of MUs had greater FRDEREC than FRREC . The y-intercepts (r = -0.600, P = 0.067) were not significantly correlated, but the slopes (r = -0.793, P = 0.006) were significantly correlated with type I %MHC. CONCLUSION: The majority of the motoneuron pool had greater FRDEREC than FRREC , however, individuals with higher type I %MHC had a greater propensity to have MUs with FRREC > FRDEREC as indicated by the slope values. Overall, the contractile properties of the muscle (MHC) could partially explain the differences in MU firing rates at de-recruitment relative to recruitment. Thus, suggesting the fatigability of the muscle influences the alterations in MU firing rates from recruitment to de-recruitment.

Stochastic resonance in the synaptic transmission between hair cells and vestibular primary afferents in development.

The stochastic resonance (SR) is a phenomenon of nonlinear systems in which the addition of an intermediate level of noise improves the response of such system. Although SR has been studied in isolated hair cells and in the bullfrog sacculus, the occurrence of this phenomenon in the vestibular system in development is unknown. The purpose of the present study was to explore for the existence of SR via natural mechanical-stimulation in the hair cell-vestibular primary afferent transmission. In vitro experiments were performed on the posterior semicircular canal of the chicken inner ear during development. Our experiments showed that the signal-to-noise ratio of the afferent multiunit activity from E15 to P5 stages of development exhibited the SR phenomenon, which was characterized by an inverted U-like response as a function of the input noise level. The inverted U-like graphs of SR acquired their higher amplitude after the post-hatching stage of development. Blockage of the synaptic transmission with selective antagonists of the NMDA and AMPA/Kainate receptors abolished the SR of the afferent multiunit activity. Furthermore, computer simulations on a model of the hair cell - primary afferent synapse qualitatively reproduced this SR behavior and provided a possible explanation of how and where the SR could occur. These results demonstrate that a particular level of mechanical noise on the semicircular canals can improve the performance of the vestibular system in their peripheral sensory processing even during embryonic stages of development.

Clinical features of gingival lesions in patients with dystrophic epidermolysis bullosa: a cross-sectional study.

BACKGROUND: Gingival lesions in patients with dystrophic epidermolysis bullosa (DEB) are a common manifestation. However, their clinical features, frequency and severity are currently unknown. METHODS: Forty-five DEB patients were assessed by an oral medicine specialist, who analysed the presence/absence of four clinical signs (erythema, erosion/ulcer, atrophy, blister) on free and attached gingiva, using the Epidermolysis Bullosa Oropharyngeal Severity score. RESULTS: Twenty-eight (62.2%) out of 45 DEB patients showed different types of gingival lesions, whose presence/absence and total frequency/distribution were not significantly different between males and females (p=0.087 and p=0.091, respectively). Erythema was the most prevalent lesion (66.2%) and the recessive DEB severe generalized (RDEB-sev gen) reached the highest median disease activity score. A significant correlation was observed between the DEB subtypes and the disease activity median score (p<0.001), but not between age and total disease activity score in each group of DEB (p>0.05). Lastly, logistic regression showed that only gender (p=0.031) and RDEB-sev gen (p=0.001) were risks factors for the presence of gingival lesions. CONCLUSIONS: Gingival lesions in DEB patients are a relatively common entity and may have multiple clinical aspects, emphasizing the need for thorough attention and awareness among dentists.

Contribution of capillary zone electrophoresis to the analysis of cecal mucins.

The ability of capillary electrophoresis to perform the separation of mucin glycoforms has been investigated. Adsorption of mucins to the capillary was observed in most cases, leading to unreproducible results. This was due in part to the characteristic structure of mucin (highly charged, large size) and also to its poor solubility. Various buffers were therefore investigated; it was found that a zwitterionic electrolyte, such as a (3-[cyclohexylamino]-1-propanesulfonic acid) (CAPS) buffer, pH 8.8, greatly improved the separation. Using this buffer, mucin was resolved into five main fractions. The use of several additives, such as cationic molecules (1,4-diaminobutane [DAB]) or hydrophilic polymers (hydroxypropylmethylcellulose [HPMC], polyethylene glycol [PEG]) was also investigated. PEG and HPMC did not affect the separation and the electroosmotic flow (EOF) in the same manner. The favorable effect of the addition of PEG was clearly demonstrated and it was postulated that some interaction of this polymer with the mucins occurred. Finally, the application of the method to the comparison of glycoform patterns of mouse cecal mucins showed a marked difference for mucins derived from two sources: germ-free and gnotobiotic mice. These results indicate that mucins from gnotobiotic mice have been degraded due to the glycosidic activity of the bacterial strains present in these mice.

Simultaneous bleaching of vital teeth and an open-chamber nonvital tooth with 10% carbamide peroxide.

OBJECTIVE: The purpose of this study was to evaluate the effectiveness of bleaching a nonvital tooth with an open pulp chamber while simultaneously bleaching the other vital teeth with 10% carbamide peroxide. METHOD AND MATERIALS: Ten discolored nonvital teeth were treated. Each nonvital tooth was prepared as in the conventional "walking bleaching" fashion, so that the gutta-percha was sealed from the pulp chamber. The 10% carbamide peroxide was injected into the chamber of the nonvital tooth and loaded into the custom-fitted tray for all teeth. The nonvital teeth were bleached from both the inside and the outside. The patient closed the orifice with a cotton pellet during the day and changed the cotton pellet after meals. The patient applied fresh solution nightly. RESULTS: All teeth were successfully lightened. The time required to lighten the nonvital tooth was related to the duration of the discoloration. CONCLUSION: With proper patient selection and education, this technique can provide an effective way to lighten nonvital and vital teeth simultaneously, especially where extended treatment time may be required for difficult discolorations.