[Effects and Mechanisms of Polystyrene Microplastics on Extracellular Antibiotic Resistance Genes in Wastewater].

Microplastics (MPs) and antibiotic resistance genes (ARGs) are typical co-existing emerging pollutants in wastewater treatment plants. MPs have been shown to alter the distribution pattern of ARGs in sludge, but their effects on free extracellular ARGs (feARGs) in wastewater remain unclear. In this study, we used fluorescence quantitative PCR to investigate the dynamics of feARGs (including tetC, tetO, sul1, and sul2) in wastewater and their transition mechanisms after 60 d of exposure to typical MPs (polystyrene, PS). The results showed that the absolute abundance of tetracycline feARGs decreased by 28.4 %-76.0 % and 35.2 %-96.2 %, respectively, under nm-level and mm-level PS exposure and changed by -55.4 %-122.4 % under µm-level PS exposure. The abundance of sul1 showed a trend of nm-level > µm-level > mm-level upon PS exposure, and the changes in sul1 abundance was greater with ρ(PS)=50 mg·L-1 exposure. The relative abundance of sul2 was reduced by 25.4 %-42.6 % and 46.1 %-90.3 % after µm-level and mm-level PS exposure, respectively, and increased by 1.9-3.9 times after nm-level PS exposure, and the sul2 showed a higher reduction at ρ (PS)=50 mg·L-1 exposure than that at ρ (PS)=0.5 mg·L-1. The Pearson correlation analysis showed that the relative abundance of feARGs during PS exposure was positively correlated with cell membrane permeability and typical mobile genetic elements (intI1) abundance and negatively correlated with reactive oxygen species level. Our findings elucidated the effects and corresponding mechanisms of PS on the growth and mobility of feARGs in wastewater, providing a scientific basis for the control of the combined MPs and ARGs pollution in wastewater.

[Analysis on clinical characteristics, diagnosis and treatment of 13 cases of infant hairy polyp].

Objective: To explore and analyze the clinical characteristics, diagnosis and treatment of infant hairy polyp. Methods: A retrospective analysis was made on 13 cases of hairy polyp confirmed by pathology, who were admitted to the Children's Hospital of Hebei Province from January 2010 to September 2019, including 4 males and 9 females, with a male-female ratio of 1∶2.25. The age ranged from 3 hours to 1 year, and the median age was 1 month. Twelve of the 13 children were found to have difficulty breathing or feeding. All the children received coblation resection under general anesthesia. The root pedicle of the mass was found in the lateral nasopharyngeal wall in 8 cases, in the junction of palatine and palatopharyngeal arch of tonsil and the tongue and esophageal entrance in 1 case, respectively. Nasal septum was found in 2 cases, including 1 case located between two incisors. The wound at the root pedicle was ablated and the bleeding was stopped completely. Results: Postoperative follow-up lasted from 3 months to 2 years, and there was no recurrence in 12 cases. Fibrolaryngoscope showed a mass of the right eustachian tube and pharyngeal mouth in 1 case 2 years after the surgery, which was considered recurrence of hairy polyps and lost after that. Conclusion: Hairy polyps in infants is a rare clinical disease, and its main symptom is upper respiratory tract obstruction. Early diagnosis and radical surgery are the key to the treatment of the disease.

Parastomal hernia prevention using a novel collagen implant: a randomised controlled phase 1 study.

BACKGROUND: Parastomal hernias can be prevented or repaired using synthetic mesh; however, reported complications include infection, fibrosis and potential bowel erosion. The study aim was to assess the safety, feasibility and potential efficacy of using a prophylactic collagen implant. METHODS: Twenty patients undergoing defunctioning stomas were randomised to a conventional procedure or reinforcement with the implant. Follow-up included regular symptom questionnaires, clinical examination, stoma site ultrasound, and serum inflammatory markers. RESULTS: Ten patients (four males; mean BMI 26.3) had a conventional stoma, and ten (three males; mean BMI 26.3) received the implant. At a median of 6.5 months follow-up, a parastomal hernia was clinically evident in three of ten patients without the implant, and in none of ten patients with the implant. There were no clinical complications, ultrasound evidence of chronic seromas or serological evidence of a systemic inflammatory response. CONCLUSIONS: Xenogeneic collagen has been demonstrated to aid soft tissue reinforcement. In this study, in contrast to published data relating to the use of conventional synthetic mesh, there were no complications related to infection or the implant's proximity to the bowel. This trial demonstrates that the implant is safe, feasible to use and has the potential to prevent parastomal herniation.

Change in surface hardness of enamel by a cola drink and a CPP-ACP paste.

OBJECTIVES: This in vitro study used surface microhardness to evaluate whether a paste containing casein phosphopeptide amorphous calcium phosphate (CPP-ACP) can reharden tooth enamel softened by a cola drink, and how different saliva-substitute solutions affect the enamel hardness. METHODS: Twenty-four bovine incisors, each tooth consisting of treatment and control halves, were immersed in a cola drink (Coke) for 8 min, then placed under a 0.4 mL/min drip with various saliva-substitute solutions. The saliva-substitute solutions were: saliva-like solution (SLS) with 1 ppm fluoride, SLS without fluoride, and Biotene mouthwash. CPP-ACP paste was applied to the treatment halves for 3 min at 0, 8, 24, and 36 h. Knoop microhardness measurements were performed at baseline, after the cola drink immersion, and after 24 and 48 h contact with saliva-substitute solution. RESULTS: Enamel hardness significantly decreased after immersion in cola drink (ANOVA, p<0.05). After contact with saliva-like solutions for 48 h, those treated with CPP-ACP paste were significantly harder than those untreated regardless of the presence of 1 ppm fluoride in the saliva-like solution (ANOVA, p<0.05). Biotene mouthwash significantly softened the enamel surface (ANOVA, p<0.05). Two-way ANOVA showed significant effects of the CPP-ACP paste application and types of saliva-substitute solutions on the changes in surface hardness of the softened enamel at a significance level of 0.05. CONCLUSION: The application of CPP-ACP paste with continuous replenishment of saliva-like solution for 48 h significantly hardened enamel softened by a cola drink. Biotene mouthwash softened enamel surface after 48 h contact.

Confocal imaging of mouse mandibular condyle cartilage.

Mice are commonly used to study the temporomandibular joint (TMJ) and to model human TMJ disease. However, evaluating TMJ pathology in mice using standard histologic methods is time consuming, labor intensive, and dependent upon investigators' expertise at consistently orienting and sectioning across tiny specimens. We describe a method that uses confocal microscopy to rapidly and reliably assess indicators of mandibular condyle cartilage pathology in mice. We demonstrate the utility of this method for detecting abnormalities in chondrocyte distribution in mice lacking lubricin (Prg4), the major boundary lubricant of articular cartilage. We further show that the method can provide information about recombination sites and efficiency in mandibular cartilage for Cre-driver strains. Because specimen preparation and data acquisition with confocal microscopy are simple and fast, the method can serve as a primary screening tool for TMJ pathology, before proceeding to complicated, time consuming, secondary analyses.

Microbiome Associated with Severe Caries in Canadian First Nations Children.

Young Indigenous children in North America suffer from a higher degree of severe early childhood caries (S-ECC) than the general population, leading to speculation that the etiology and characteristics of the disease may be distinct in this population. To address this knowledge gap, we conducted the first microbiome analysis of an Indigenous population using modern molecular techniques. We investigated the caries-associated microbiome among Canadian First Nations children with S-ECC. Thirty First Nations children <72 mo of age with S-ECC and 20 caries-free children were recruited in Winnipeg, Canada. Parents or caregivers completed a questionnaire on general and dental health, diet, and demographics. The plaque microbiome was investigated by sequencing the 16S rRNA gene. Sequences were clustered into operational taxonomic units and taxonomy assigned via the Human Oral Microbiome Database, then analyzed at the community level with alpha and beta diversity measures. Compared with those who were caries free, children with S-ECC came from households with lower income; they were more likely to live in First Nations communities and were more likely to be bottle-fed; and they were weaned from the bottle at a later age. The microbial communities of the S-ECC and caries-free groups did not differ in terms of species richness or phylogenetic diversity. Beta diversity analysis showed that the samples significantly clustered into groups based on caries status. Twenty-eight species-level operational taxonomic units were significantly different between the groups, including Veillonella HOT 780 and Porphyromonas HOT 284, which were 4.6- and 9-fold higher, respectively, in the S-ECC group, and Streptococcus gordonii and Streptococcus sanguinis, which were 5- and 2-fold higher, respectively, in the caries-free group. Extremely high levels of Streptococcus mutans were detected in the S-ECC group. Overall, First Nations children with S-ECC have a significantly different plaque microbiome than their caries-free counterparts, with the S-ECC group containing higher levels of known cariogenic organisms.

Increased Young's modulus and hardness of Col1a2oim dentin.

Mice harboring the Col1a2(oim) mutation (oim) express dentinogenesis imperfecta. To determine the effect of Col1a2 genotype on tissue mechanical properties, we compared Young's modulus and hardness of dentin in the 3 Col1a2 genotypes. Upper incisors were tested by nanoindentation. Genotype had a significant effect on Young's modulus, but there was not a simple mutant allele dosage relationship. The effect of genotype on hardness did not reach significance. Hardness and Young's modulus were greater near the dento-enamel junction than near the pulp chamber. Greater hardness and Young's modulus values near the dento-enamel junction reflected continued mineralization of the dentin following its initial synthesis. Analysis showed the mechanical data to be consistent with Fourier transform infrared and backscattered electron microscopy studies that revealed increased mineralization in oim bone. Analysis of the data suggests that clinical fragility of teeth in oim mice is not due to deficiencies of hardness or Young's modulus, but may be due to defects in post-yield behavior or resistance to fatigue damage.

Prolonged circulation time and enhanced accumulation in malignant exudates of doxorubicin encapsulated in polyethylene-glycol coated liposomes.

In preclinical studies, a doxorubicin liposome formulation containing polyethylene-glycol (Doxil) shows a long circulation time in plasma, enhanced accumulation in murine tumors, and a superior therapeutic activity over free (unencapsulated) doxorubicin (DOX). The purpose of this study was to characterize the pharmacokinetics of Doxil in cancer patients in comparison with free DOX and examine its accumulation in malignant effusions. The pharmacokinetics of doxorubicin and/or liposome-associated doxorubicin were analyzed in seven patients after injections of equivalent doses of free DOX and Doxil and in an additional group of nine patients after injection of Doxil only. Two dose levels were examined, 25 and 50 mg/m2. When possible, drug levels were also measured in malignant effusions. The plasma elimination of Doxil followed a biexponential curve with half-lives of 2 and 45 h (median values), most of the dose being cleared from plasma under the longer half-life. Nearly 100% of the drug detected in plasma after Doxil injection was in liposome-encapsulated form. A slow plasma clearance (0.1 liter/h for Doxil versus 45 liters/h for free DOX) and a small volume of distribution (4 liters for Doxil versus 254 liters for free DOX) are characteristic of Doxil. Doxorubicin metabolites were detected in the urine of Doxil-treated patients with a pattern similar to that reported for free DOX, although the overall urinary excretion of drug and metabolites was significantly reduced. Doxil treatment resulted in a 4- to 16-fold enhancement of drug levels in malignant effusions, peaking between 3 to 7 days after injection. Stomatitis related to Doxil occurred in 5 of 15 evaluable patients and appears to be the most significant side effect in heavily pretreated patients. The results of this study are consistent with preclinical findings indicating that the pharmacokinetics of doxorubicin are drastically altered using Doxil and follow a pattern dictated by the liposome carrier. The enhanced drug accumulation in malignant effusions is apparently related to liposome longevity in circulation. Further clinical investigation is needed to establish the relevance of these findings with regard to the ability of liposomes to modify the delivery of doxorubicin to solid tumors and its pattern of antitumor activity.

Liposomes and hyperthermia in mice: increased tumor uptake and therapeutic efficacy of doxorubicin in sterically stabilized liposomes.

We have shown that sterically stabilized (Stealth) liposomes (SL), can accumulate in the extracellular space within tumors, and may improve pharmacokinetics and therapeutic efficacy of encapsulated doxorubicin (SL-DOX). When SL-DOX were incubated in vitro at different temperatures with 50% bovine serum, approximately 20% of the encapsulated DOX was released at 42 degrees C within 1 min, compared with less than 1% DOX released at 37 degrees C. In vivo, mice were implanted s.c. with C-26 colon carcinoma in both flanks to produce matched tumors 6-10 mm in diameter. Topical hyperthermia treatment consisting of 42 degrees C minimum tumor temperature for 30 min was applied with a microwave device to the tumor on one side only at 1 h after i.v. injection of SL-DOX or free DOX. Tumor DOX concentration in the group which was given injections of SL-DOX and sacrificed 2 h after drug injection was 1.5-fold higher compared with the nonheated tumor in mice given injections of SL-DOX. At 24 h after injection the thermal enhancement ratio for DOX accumulation in tumor remained at 1.5. In addition, there was a 15-fold higher concentration of DOX in tumor from the group given injections of SL-DOX compared to mice given injections of free doxorubicin. To assess therapeutic efficacy, we treated mice with hyperthermia for 15 min either at 1, or at 24 h or at both time points after injection of SL-DOX. We have found that the life span of the group of mice treated with SL-DOX and two 15-min hyperthermia treatments increased 51% compared with control groups receiving the same dosage of SL-DOX but without hyperthermia, and 59% compared to those receiving two hyperthermia treatments but with free DOX. A single hyperthermia treatment either at 1 or 24 h was less effective in increasing life span compared with two treatments, but all groups treated with SL-DOX and single hyperthermia were still superior to the control groups, showing a 27-38% increase in life span.

An improved method for covalent attachment of antibody to liposomes.

A rapid and simple method is described for the incorporation of monoclonal antibody coupled with palmitic acid into liposomes prepared by the reverse-phase evaporation method (Szoka, F. and Papahadjopoulos, D. (1978) Proc. Natl. Acad. Sci. U.S.A. 75, 4194-4198). Palmitoyl antibody in 0.15% deoxycholate is added to a liposome suspension after the majority of the organic solvent has been removed by evaporation. Efficient incorporation (over 80%) of palmitoyl antibody occurred without leakage of the encapsulated drug. Native, unmodified antibody did not incorporate under identical conditions. About 50% of the incorporated antibodies could be readily digested by protease, while most of an internal protein marker was not, suggesting that about half of the antibodies were exposed on the outer surfaces of liposomes. Target-specific binding of antibody-liposomes has also been demonstrated in vitro with the RDM-4 lymphoma cells. This method offers a rapid and highly efficient attachment of functional antibody molecules to liposomes with high capture efficiency of drugs, and therefore should be useful in target-specific delivery of drugs mediated by liposomes.

Immunoliposome labeling: a sensitive and specific method for cell surface labeling.

A simple, one-step procedure for fluorescence labeling of cultured cells with high sensitivity and specificity is described. We term this method immunoliposome labeling. Monoclonal IgG antibody was first covalently coupled with palmitic acid. The palmitoyl IgG was then incorporated into unilamellar liposomes (about 100 nm diameter) containing either N-(4-nitrobenzo-2-oxa-1,3-diazole)- or N-(fluorescein isothiocyanyl)-phosphatidylethanolamine by a detergent-dialysis procedure. A monoclonal antibody to the mouse major histocompatibility antigen, H-2k, was tested as a model system. Fluorescent liposomes with covalently coupled anti-H-2k specifically labeled the mouse L-929 cells (H-2k type), but not the A-31 cells (H-2d type). The degree of labeling was quantitated by a microscope photometer. Cells labeled with fluorescent liposomes showed 4--6-fold stronger fluorescence than cells labeled with either fluorescein-conjugated antibody or with primary antibody followed by fluorescein-conjugated secondary antibody (indirect immunofluorescence). Since different types of label (fluorescent, radioactive, etc.) can be incorporated into liposomes, this specific and sensitive method is potentially very versatile.

Hyperthermia induces doxorubicin release from long-circulating liposomes and enhances their anti-tumor efficacy.

PURPOSE: To examine the possibility that hyperthermia would accelerate drug release from long-circulating liposomes, and enhance their antitumor activity. METHODS AND MATERIALS: Liposomes were prepared by thin film hydration technique. Hyperthermia was induced by ultrasound apparatus and a water bath heating system. The antitumor efficacy of treatment against RIF-1 tumor in C3H mice was evaluated by the tumor growth delay assay. RESULTS: In vitro drug release experiments demonstrated that increase in temperature from 37 degrees C to 41 degrees C resulted in about a sixfold increase in doxorubicin (DOX) release in a 1-h period. Increasing the temperature to 43 degrees C, resulted in only a modest additional drug release. Drug uptake studies showed that local hyperthermic treatment immediately following the drug administration dramatically enhanced Stealth liposome-encapsulated doxorubicin (S-DOX) uptake by tumors, but did not do so for free DOX. At 42 degrees C and at a dose of 10 mg/kg, the accumulation of S-DOX was about 10-fold and 2.5-fold higher than that with free drug and S-DOX at 37 degrees C, respectively. The antitumor efficacy study confirmed our hypothesis that the addition of hyperthermia to the treatment of RIF-1 tumors with doxorubicin encapsulated in long-circulating liposomes would enhance antitumor effects. Two hyperthermia treatments given at 24-h intervals appeared to be the most promising method of combining heat and long-circulating liposomes. The increased antitumor activity was not accompanied by increased toxicity, as determined by the body weight of the mice. CONCLUSION: Local hyperthermic treatment is able to accelerate DOX release from long-circulating liposomes, increase tumor uptake, and enhance their antitumor efficacy. The combination of local hyperthermia and long-circulating liposomes appears to show considerable promise in the treatment of localized diseases.

Paracellular permeability of corneal and conjunctival epithelia.

The paracellular permeability of normal rabbit cornea and conjunctiva was studied in vivo and in vitro. After intravenous administration, horseradish peroxidase was found to percolate to the intercellular space of conjunctival epithelia and was restricted by the tight junctions of the superficial epithelium. Only minimal tracer was present in the limbus and cornea. The difference between corneal and conjunctival paracellular pathways was further compared in vitro by tissue perfusion studies using various tracers from subepithelial space to apical surface. The intact full-thickness cornea was permeable to mannitol (MW 182) but not to inulin or dextran. The conjunctiva was permeable to mannitol, inulin and FITC-dextran (MW 20,000). The quantitative permeability to 3H-mannitol (X10(-8) cm/sec) of adult rabbit cornea was 0.12 +/- 0.02, which is about 55-fold and 50-fold lower than that of conjunctiva (6.78 +/- 0.21) and peritoneum (6.12 +/- 0.63), respectively. Removal of the corneal epithelium increased the permeability 40-fold; however, removal of the endothelium had little effect on the solute permeation. When both corneal epithelium and endothelium were debrided, the bare stroma became edematous and the permeability increased 70-fold. The permeability of 1-week-old rabbit cornea was 1.32 +/- 0.18, which decreased to 0.46 +/- 0.06 in 2-week-old rabbits, and became similar to the adult level at 4 weeks of age. When Tenon's capsule was included in the perfusion, the conjunctival permeability decreased 2.5-fold. With the apposition of bare corneal stroma to the conjunctiva and Tenon's capsule, the permeability decreased further (4-fold).(ABSTRACT TRUNCATED AT 250 WORDS)

Fluoride profiles in dental calculus from Japanese, Chinese and British residents.

Whether the fluoride concentrations and profiles differ in human dental calculus obtained from different countries was investigated. A total of 203 dental calculus deposits on 203 permanent teeth from residents (mean age, 52.1 years) of Nagoya (Japan), Shanghai (China), Leeds (Great Britain) and the Wuhan mountainous area (China, fluoridated area) were analysed. An abrasive microsampling procedure was used to examine fluoride distribution. There were five types of fluoride profiles in dental calculus in each area/country (designated types L, J, U, T, W). In supragingival calculus, type L (highest in the outermost layers) and type J (highest in the innermost layers) both had significantly higher values than type U (high in the surface and innermost layers) but were relatively identical. In subgingival calculus, type W (high in the outermost, mid and innermost layers) was characteristics. Calculus from the Wuhan mountainous area (fluoridated) had the highest fluoride concentration, followed by Leeds (non-fluoridated), and Nagoya and Shanghai (non-fluoridated) calculus had the lowest. Fluoride concentrations in supragingival calculus were higher in teeth extracted because of periodontal diseases than dental caries. It is concluded that fluoride concentrations and distribution in dental calculus differ from country to country, probably due to different fluoride environments.

Fluoride profiles of perikymata in enamel surfaces of human premolars.

Twenty-five premolars (from Nagoya, Japan < 0.1 parts/10(-6)F in drinking water) were sampled to determine the fluoride content in imbrication lines of Retzius between the grooves and ridges of perikymata on the enamel surface. Eight small windows were formed on each surface in groove and ridge regions using an etched microsampling technique. By using a regression curve, y = ax(-b), fluoride concentrations were compared at depths of 1, 3, 5, 10, 20, 30 and 50 microm in the perikymata regions. Fluoride concentrations increased gradually from the age of 10 to 12 years on the premolar surfaces, but were significantly higher in 12-year-olds or older (erupted teeth) than in 10-year-olds or younger (unerupted teeth). No obvious difference in fluoride concentrations was found between males and females. In the outermost enamel ( < 5 microm depth), fluoride concentrations were significantly higher in the grooves than the ridges of the perikymata. Comparison of the exponential regression coefficients (-b) of the fluoride profiles showed a significant difference between the grooves and ridges. It was concluded that fluoride concentrations and profiles were higher in grooves than in ridges of perikymata, probably because they are naturally porous and are stagnation areas attracting dental plaque.

External pelvic rectal suspension (the Express procedure) for full-thickness rectal prolapse: evolution of a new technique.

OBJECTIVE: The Délorme's operation for rectal prolapse is a safe procedure but has a high recurrence rate. We aimed to develop an operation akin to it, but designed to reduce this deficit. PATIENTS AND METHODS: Thirty-one consecutive patients with rectal prolapse were included in the study. Initially, a conventional Délorme's procedure was performed and sutures or strips of Gore-Tex were attached circumferentially to the apex of the prolapse, tunneled subcutaneously, and anchored to the external surface of the pelvis. Subsequently, the procedure was modified. Acellular porcine collagen strips were used and buried within the apex without plication of the denuded rectal musculature. Patients were formally assessed preoperatively and four months postoperatively by symptom and quality of life questionnaires and subsequently by regular clinical review. RESULTS: In the Gore-Tex group (N = 11; males:females = 10:1; mean age, 61 years) three patients underwent suture repair and eight had strip fixation. All suture repairs developed sepsis and one patient had a recurrence. Seven of the strip fixations (88 percent) developed sepsis that resulted in implant extrusion. There was one full-thickness and one mucosal recurrence after a median follow-up of 25 months. In the collagen group (N = 20; males:females = 2:18; mean age, 63 years), sepsis occurred in four patients, requiring surgical intervention in one patient (5 percent) (cf Gore-Tex group, P = 0.002). There was one mucosal and three full-thickness (15 percent) recurrences after a median follow-up of 14 months (cf Gore-Tex group, P = not significant). Significant improvements in symptom and quality of life scores were recorded in both groups at four months. CONCLUSION: A new, minimally invasive perineal procedure for rectal prolapse has been developed and initial data testify to its relative safety provided collagen is used. It remains to be seen whether long-term recurrence rates will be lower than those of conventional perineal procedures.