Two-step aggregation of gold nanoparticles based on charge neutralization for detection of melamine by colorimetric and surface-enhanced Raman spectroscopy platform.

A colorimetric and surface-enhanced Raman scattering (SERS) signal amplification platform based on 2-step aggregation of gold nanoparticles (AuNP) was constructed for the sensitive detection of melamine. In this study, the positively charged SYBR Green I was used for the first step of aggregation of AuNP, via charge neutralization, to obtain small-sized AuNP aggregates. The positively charged SYBR Green I decreased the negative charges of the surface of AuNP, which was beneficial to the aggregation of AuNP. In addition, the melamine could aggregate AuNP by decreasing the negative charges of the surface of AuNP and self-assemble with each other on the surface of AuNP by hydrogen bonds. Therefore, the second efficient aggregation of small-sized AuNP aggregates could be achieved with melamine at low concentration, resulting in significant signal changes of color and SERS. The sensitivity of a colorimetric (0.60 mg/L) and SERS (0.089 mg/L) platform, based on 2-step aggregation of AuNP, was 15 and 2.2 times higher than that based on 1-step aggregation of AuNP for detecting melamine.

Risk factors and mortality associated with multi-drug-resistant Gram-negative bacterial infection in adult patients following abdominal surgery.

BACKGROUND: Multi-drug-resistant (MDR) Gram-negative bacterial (GNB) infection remains a significant cause of morbidity and mortality among surgical patients. The objective of this study was to recognize the risk factors for MDR GNB infection in patients following abdominal surgery, and determine the predictors independently associated with death. METHODS: From 2010 to 2017, a retrospective cohort study was conducted among patients with abdominal surgery admitted to the surgical intensive care unit (ICU). Patients with GNB infection were included for analyses. RESULTS: In total, 364 patients experienced GNB infection following abdominal surgery. Of these, 117 (32.1%) were MDR GNB infection. Of 133 MDR GNB isolates, the most common isolate was Escherichia coli (45.1%). Patients with MDR GNB infection had significantly longer ventilator-days and hospital stay, as well as higher 30-day and in-hospital mortality compared with non-MDR GNB patients. Multi-variable analysis showed that longer length of pre-ICU stay, surgical re-exploration, receipt of group 2 carbapenems (e.g. imipenem, meropenem and doripenem) and fluoroquinolones, and higher total bilirubin were independent risk factors for the acquisition of MDR GNB infection. Predictors for 30-day mortality among patients with MDR GNB infection were chronic kidney disease, receipt of group 2 carbapenems and inappropriate empirical antimicrobial therapy. CONCLUSIONS: This study provides important information about the risk factors for MDR GNB infection and 30-day mortality among patients following abdominal surgery.

Optimal Culture Conditions for Mycelial Growth of Lignosus rhinocerus.

Lignosus rhinocerus is a macrofungus that belongs to Polyporaceae and is native to tropical regions. This highly priced mushroom has been used as folk medicine to treat diseases by indigenous people. As a preliminary study to develop a culture method for edible mushrooms, the cultural characteristics of L. rhinocerus were investigated in a range of culture media under different environmental conditions. Mycelial growth of this mushroom was compared on culture media composed of various carbon and nitrogen sources in addition to C/N ratios. The optimal conditions for mycelial growth were 30℃ at pH 6 and 7. Rapid mycelial growth of L. rhinocerus was observed on glucose-peptone and yeast extract peptone dextrose media. Carbon and nitrogen sources promoting mycelial growth of L. rhinocerus were glucose and potassium nitrate, respectively. The optimum C/N ratio was approximately 10 : 1 using 2% glucose supplemented as a carbon source in the basal media.

Low circulating level of CD133+KDR+cells in patients with systemic sclerosis.

BACKGROUND: Results of previous studies on the level of circulating endothelial progenitor cells (EPCs), which are involved in vascular repair, in scleroderma (SSc) patients have been controversial. OBJECTIVES: To enumerate circulating EPC subsets and to examine their relation with endothelial dysfunction, biochemical markers of endothelial injury and vascular outcome in SSc patients. METHODS: Enumeration of circulating CD34+KDR+ and CD133+ KDR+EPCs was performed by flow cytometry. Endothelium-dependent vasodilation was evaluated by changes in flow-mediated dilation (FMD%) in the brachial artery. Serum level of vascular endothelial growth factor (VEGF) was measured by enzyme linked immunosorbent assay. RESULTS: SSc patients (n=52) were found to have significantly lower CD133+KDR+EPCs (3.0 vs. 7.0/µl, p<0.001) as well as FMD% (4.8% vs. 7.8%, p<0.001) compared with age and sex-matched controls (n=52). Among patients who had no concomitant cardiovascular risk factors (n=28), CD133+KDR+ EPC level was significantly lower than controls (3.8 vs. 7.3/µl, p=0.001) and correlated modestly with FMD% (r=0.29, p=0.03). Disease duration was the only determining factor identified for circulating CD133+KDR+ EPCs (p=0.03) by logistic regression analysis. Levels of serum VEGF (p=0.92) and KDR expression were not different between patients who had early and intermediate/late disease. Circulating CD34+KDR+ EPCs was not different between SSc patients and controls and did not correlate with any clinical or biochemical parameter. CONCLUSIONS: Lower circulating CD133 +KDR+ EPC subset was found in SSc patients and correlated with impaired endothelium-dependent vasodilation in patients without cardiovascular risk factors suggesting a potential role of deficient EPC recruitment contributing to endothelial dysfunction in this disease.

A quasi-experimental study on a community-based behaviour change programme among injecting drug users in Sichuan, China.

The objective of this study is to explore an effective model of comprehensive intervention on HIV/AIDS among injecting drug users (IDUs) in communities located in urban areas and to evaluate its feasibility in Sichuan Province, China. A quasi-experimental study was designed so that various intervention measures were conducted in the intervention city but not in the control city. A Behaviour Surveillance Survey was introduced to evaluate intervention exposure and the effect of behaviour change. In the intervention city, services received by IDUs increased over time (P < 0.001). Awareness of HIV increased from 34.2% in 2003 to 58.3% in 2004, and to 67.4% in 2005 (P < 0.001). The proportion of IDUs surveyed who shared a needle the last time they injected drugs decreased from 17.1% in 2003 to 7.0% in 2005, and in terms of the past month from 42.4% in 2003 to 18.4% in 2005 (P < 0.001). Data from a multivariate logistic regression analysis showed that comprehensive intervention was a protective factor for behaviour change (odds ratio [OR] =0.561; 95% confidence interval [CI], 0.424-0.741). A well-designed and organized comprehensive intervention programme will effectively change the high-risk behaviour among IDUs in these communities. A more comprehensive, expanded and integrated response is needed when conducting an HIV/AIDS prevention programme.

Increase in plasma adrenomedullin in patients with heart failure characterised by diastolic dysfunction.

OBJECTIVE: To investigate the relation between plasma adrenomedullin and the severity of diastolic dysfunction in patients with heart failure. DESIGN: Prospective study. SETTING: University teaching hospital. PATIENTS: 77 patients (mean (SEM) age 66.3 (1.2) years; 75% male) who were being followed in the outpatient clinic after admission to hospital for acute heart failure. INTERVENTIONS: Same day echocardiography with Doppler studies; determination of venous adrenomedullin concentration by radioimmunoassay. MAIN OUTCOME MEASURES: Plasma adrenomedullin concentration and its correlation with systolic and diastolic function. RESULTS: 31 patients (40%) had isolated diastolic dysfunction (ejection fraction > 50%), and the remaining 46 had a depressed ejection fraction (< 50%). Of the patients with diastolic dysfunction, 17 had a restrictive filling pattern. In all but one of these there was coexisting systolic failure (chi(2) = 10.7, p = 0.001). Patients with systolic heart failure and a restrictive filling pattern (group 1, n = 16) had a higher plasma adrenomedullin than those with systolic failure and a non-restrictive filling pattern (group 2, n = 30) or with isolated diastolic heart failure and a non-restrictive filling pattern (group 3, n = 30) (mean (SEM): 91.7 (21.1) v 38.4 (8.8) v 34.0 (6.5) pmol/l, both p < 0.05). All heart failure values were higher (p < 0.01) than the control value (6.9 (1.2) pmol/l). Ejection fraction and left ventricular dimensions were similar in groups 1 and 2. Plasma adrenomedullin did not correlate with ejection fraction or New York Heart Association functional class. Stepwise multiple regression analysis showed that the presence of a restrictive filling pattern was the only independent variable associated with a high plasma adrenomedullin. CONCLUSIONS: Plasma adrenomedullin concentrations in patients with heart failure are determined by the presence of diastolic dysfunction, and are especially raised in the presence of a restrictive filling pattern. There appears to be no correlation with systolic dysfunction.

Making the framework try-in, altered-cast impression, and occlusal registration in one appointment.

Making a bilateral distal extension removable partial denture usually requires multiple appointments for metal-framework try-in, altered cast impression, and occlusal registration. This article describes an altered cast impression procedure that uses the prefabricated impression trays and record base for obtaining the jaw relation record. This method allows the framework try-in, altered cast impression, and jaw relation record to be efficiently completed in a single appointment.

The effects of methimazole on haematopoiesis in mice.

The effects of anti-thyroid drug, methimazole (MMI), on haematopoiesis in inbred C57BL/6 mice were studied. The in vitro proliferative response of bone marrow (BM) cells to interleukin-3 (IL-3) was significantly increased when mice were provided with 0.1% MMI in water (w/v) ad librium for 4 to 6 weeks. Using soft agar agar colony assay, the numbers of myeloid cell colonies were also significantly increased in mice treated with MMI. However, the proliferative response of BM cells to IL-3 was found to be greatly reduced 10 weeks after MMI treatment. In vitro studies showed that MMI alone at the concentrations of 500 microM or above inhibited both the growth of normal BM cells in liquid culture and the formation of macrophage (M)-/granulocyte (G)-colonies in soft agar culture in a dose dependent manner. Direct cytotoxic effect of MMI (0 - 1250 microM) to normal BM cells was not observed. Results from this study suggested that MMI can modulate the development of myeloid haematopoietic cells.

Association of the tyrosine phosphorylated epidermal growth factor receptor with a 55-kD tyrosine phosphorylated protein at the cell surface and in endosomes.

After the intraportal injection of EGF, the EGF receptor (EGFR) is rapidly internalized into hepatic endosomes where it remains largely receptor bound (Lai et al., 1989. J. Cell Biol. 109:2751-2760). In the present study, we evaluated the phosphotyrosine content of EGFRs at the cell surface and in endosomes in order to assess the consequences of internalization. Quantitative estimates of specific radioactivity of the EGFR in these two compartments revealed that tyrosine phosphorylation of the EGFR was observed at the cell surface within 30 s of ligand administration. However, the EGFR was also highly phosphorylated in endosomes reaching levels of tyrosine phosphorylation significantly higher than those of the cell surface receptor at 5 and 15 min after EGF injection. A 55-kD tyrosine phosphorylated polypeptide (pyp55) was observed in association with the EGFR at the cell surface within 30 s of EGF injection. The protein was also found in association with the EGFR in endosomes as evidenced by coprecipitation studies using a mAb to the EGFR as well as by coelution with the EGR in gel permeation chromatography. Limited proteolysis of isolated endosomes indicated that the tyrosine phosphorylated domains of the EGFR and associated pyp55 were cytosolically oriented while internalized EGF was intraluminal. The identification of pyp55 in association with EGFR in both hepatic plasma membranes and endosomes may be relevant to EGFR function and/or trafficking of the EGFR.

Intrauterine devices Wang S.S Cu 380 as compared to ML Cu 375, Nova T, T Cu 300, 7 Cu 200, Lippes Loop and Ohta Ring: clinical / physiopathological parameters.

PIP: IUDs are rigid and heavy thus irritating the endometrium. Their design accounts for many side effects and encourages pelvic infections. IUDs may even facilitate transmission of HIV. Since some health professionals and patients consider some IUDs to be harmful or unacceptable, researchers have worked on developing a newly designed IUD which meets the criteria for and ideal IUD. Some criteria include soft and flexible in nature and inside the uterus, safe, no migration, and light in weight. Taiwanese researchers have developed such an IUD. The silicone skeleton of the Wang SS (soft and safe) Copper 380 and 300 IUDs is bow-shaped with each arm of the bow tapering off from the middle and ending with a small rounded knob. Copper wire (0.31 mm x 380 sq mm or 0.31 mm x 300 sq mm) coils around the holeless vertical stem (3 cm). The monofilament nylon string is fixed in the middle of the stem by an enlarged top. Researchers designed the Wang SS Cu 300 for nulliparous women and the Wang SS Cu 380 for multiparous women. If physicians use a Wang IUD from a sterilized package, they can insert it without wearing sterile gloves. They need to clean the cervix. They must use a single tooth tenaculum to stabilize the uterus and to straighten the uterine axis. After placing the Wang IUD in the inserter, adjusting the flange, and putting the plunger on the inserter, they need to safely introduce the inserter into the uterine cavity to the point where the inserter touches the fundus or the flange touches the cervix. They then must push the plunger to insert the IUD. Insertion should be done immediately after menstruation. Clinicians need to conduct clinical trials to test the safety and effectiveness of the Wang Ss Cu IUDs.^ieng

Localization of epidermal growth factor receptors in cells of the enamel organ of the rat incisor.

Epidermal growth factor (EGF) is a peptide shown to effect precocious incisor tooth eruption in rat pups. Binding sites for EGF were visualized in the continuously erupting adult rat incisor by light and electron microscope radioautography after in vivo injection of 125I-EGF. These binding sites represented EGF receptors because of (i) competition between 125I-EGF binding at 2 min after injection and a coinjected excess of unlabeled EGF; (ii) the receptor-mediated endocytosis of 125I-EGF at 15 and 30 min after injection; and (iii) the demonstration of EGF receptor kinase activation in vivo. The stem and the mitotic cells in the epithelial odontogenic organ at the growing end of the tooth develop into two nondividing layers of the enamel organ: (i) ameloblasts which secrete enamel and are subsequently involved in the enamel maturation process, and (ii) papillary layer cells situated between the blood supply and the ameloblasts. Although few EGF receptors were present at the mitotic end, receptor density was highest at the mature end of the enamel organ. High levels of 125I-EGF binding were found on papillary layer cells and ruffle-ended, but not smooth-ended, ameloblasts. This implies a cyclical exteriorization and internalization of receptors during modulations between the two cell types. These data suggest that the EGF receptor mediates a major function of the enamel organ in the formation of enamel.

[Treatment of subgingival crown root fracture: forced eruption--case report].

The conventional treatment methods for a subgingival crown root fracture are (1) extract the residual root and restore with a fixed bridge; (2) crown restoration with a deep subgingival margin; and (3) exposure of the fracture line by a crown lengthening operation and restoration with a crown. However, these methods require reduction of either the tooth structure or the periodontal support. Improvements in endodontic and orthodontic therapy followed Heithersay in 1973 to combine the use of endodontic and orthodontic therapy to manage subgingival crown root fractures--the so-called forced eruption method. This method can save the tooth structure and periodontal tissue. We can now use this method with different appliances to treat subgingival fractures, subgingival caries, subgingival perforations, infrabony pockets, etc. In this report, we present three cases using forced eruption to manage a subgingival fracture and subgingival caries and in the follow-up examination after crown restoration.

Selective degradation of insulin within rat liver endosomes.

To characterize the role of the endosome in the degradation of insulin in liver, we employed a cell-free system in which the degradation of internalized 125I-insulin within isolated intact endosomes was evaluated. Incubation of endosomes containing internalized 125I-insulin in the cell-free system resulted in a rapid generation of TCA soluble radiolabeled products (t1/2, 6 min). Sephadex G-50 chromatography of radioactivity extracted from endosomes during the incubation showed a time dependent increase in material eluting as radioiodotyrosine. The apparent Vmax of the insulin degrading activity was 4 ng insulin degraded.min-1.mg cell fraction protein-1 and the apparent Km was 60 ng insulin.mg cell fraction protein-1. The endosomal protease(s) was insulin-specific since neither internalized 125I-epidermal growth factor (EGF) nor 125I-prolactin was degraded within isolated endosomes as assessed by TCA precipitation and Sephadex G-50 chromatography. Significant inhibition of degradation was observed after inclusion of p-chloromercuribenzoic acid (PCMB), 1,10-phenanthroline, bacitracin, or 0.1% Triton X-100 into the system. Maximal insulin degradation required the addition of ATP to the cell-free system that resulted in acidification as measured by acridine orange accumulation. Endosomal insulin degradation was inhibited markedly in the presence of pH dissipating agents such as nigericin, monensin, and chloroquine or the proton translocase inhibitors N-ethylmaleimide (NEM) and dicyclohexylcarbodiimide (DCCD). Polyethylene glycol (PEG) precipitation of insulin-receptor complexes revealed that endosomal degradation augmented the dissociation of insulin from its receptor and that dissociated insulin was serving as substrate to the endosomal protease(s). The results suggest that as insulin is internalized it rapidly but incompletely dissociates from its receptor. Dissociated insulin is then degraded by an insulin specific protease(s) leading to further dissociation and degradation.

Ligand-mediated internalization, recycling, and downregulation of the epidermal growth factor receptor in vivo.

EGF receptor internalization, recycling,a nd downregulation were evaluated in liver parenchyma as a function of increasing doses of injected EGF. The effect of ligand occupancy in vivo on the kinetics and extent of internalization was studied with changes in the receptor content of isolated plasmalemma and endosome fractions evaluated by direct binding, Scatchard analysis, and Western blotting. For all doses of injected EGF, receptor was lost from the plasmalemma and accumulated in endosomes in a time- and dose-dependent fashion. However, at doses of injected EGF equivalent to less than or equal to 50% surface receptor occupancy (i.e., less than or equal to 1 microgram/100 g body weight), receptor levels returned by 120 min to initial values. This return was resistant to cycloheximide and therefore did not represent newly synthesized receptor. Neither was the return due to replenishment by an intracellular pool of low-affinity receptors as such a pool could not be detected by Scatchard analysis or Western blotting. Therefore, receptor return was due to the recycling of previously internalized receptor. At doses of injected EGF greater than 50% receptor occupancy, net receptor loss-i.e., downregulation-was observed by evaluating the receptor content of total particulate fractions of liver homogenates. At the higher saturating doses of injected EGF (5 and 10 micrograms/100 g body weight), the majority of surface receptor content was lost by 15 min and remained low for at least an additional 105 min. As the kinetics of ligand clearance from the circulation and liver parenchyma were similar for all doses of EGF injected, then the ligand-mediated regulation of surface receptor content and downregulation were not a result of a prolonged temporal interaction of ligand with receptor. Rather, the phenomena must be a consequence of the absolute concentrations of EGF interacting with receptor at the cell surface and/or in endosomes.

Ligand-mediated autophosphorylation activity of the epidermal growth factor receptor during internalization.

The association of EGF with its receptor in endosomes isolated from rat liver homogenates was assessed biochemically by polyethylene glycol precipitation and morphologically by electron microscope radioautography. The proportion of receptor-bound ligand in endosomes at 15 min after the injection of doses of 0.1 and 1 microgram EGF/100 g body weight was 57%. This value increased to 77% for the dose of 10 micrograms EGF injected. Quantitative electron microscope radioautography carried out on endosomes isolated at 15 min after the injection of 10 micrograms 125I-EGF demonstrated that most radiolabel was over the endosomal periphery thereby indicating that ligand-receptor complexes were in the bounding membrane but not in intraluminal vesicles of the content. EGF receptor autophosphorylation activity during internalization was evaluated in plasmalemma and endosome fractions. This activity was markedly but transiently reduced on the cell surface shortly after the administration of saturating doses of EGF. The same activity, however, was augmented and prolonged in endosomes for up to 30 min after EGF injection. The transient desensitization of cell surface activity was not due to prior in vivo phosphorylation since receptor dephosphorylation in vitro failed to restore autophosphorylation activity. Transient desensitization of cell surface autophosphorylation activity coincided with a diminished capacity for endocytosis of 125I-EGF with endocytosis returning to normal after the restoration of cell surface autophosphorylation activity. The inhibition of cell surface autophosphorylation activity and the activation of endosomal autophosphorylation activity coincident with downregulation suggest that EGF receptor traffic is governed by ligand-regulated phosphorylation activity.

[Access cavity preparation for mandibular incisors with suspected two canals].

One of the common reasons for endodontic failure is incomplete root canal obturation. According to previous studies, about 10-45% of all lower incisors have two canals. The purposes of this study were: 1. determine the incidence of double canals in the lower incisors among Chinese; 2. evaluate the usefulness of X rays for locating double canals in the lower incisors; and 3. propose a method of access cavity preparation for lower incisors when double canals are diagnosed. One hundred lower incisors were collected and checked by dental X ray, mesiodistally, buccolingually and at a 30 degrees mesial shift, in order to determine the incidence of double canals and evaluate their images on film. In addition, a method for drawing the pathway of the double canals from the apex to the incisal edge, as a reference for access cavity preparation, was proposed. The results of this study showed that 36 out of the 100 lower incisors had double canals and only two of them had two separate apical foramina. Clinically, when the X ray image of the lower incisor canal is obscure or missing at the middle third of the root, it is best to extend the access cavity to the incisal edge in order to find the lingual canal.

In vivo demonstration of cell types in bone that harbor epidermal growth factor receptors.

The binding and internalization of [125I]iodoepidermal growth factor (EGF) by bone cells of the rat was demonstrated in situ by quantitative radioautography. Specific binding sites were observed on a cell profile enriched in endocytic components, including lysosome-like structures, a rough endoplasmic reticulum-rich cell profile, and a cell profile that histologically resembles an undifferentiated precursor cell. By the criteria of gel filtration and precipitability by trichloroacetic acid, most of the bound [125I]iodo-EGF was considered intact. By morphological criteria none of the cell profiles that bound [125I]iodo-EGF corresponded to fully formed osteoclasts or osteoblasts. The endocytic cell was found in the epiphyseal plate between the invading capillary and the transverse and longitudinal cartilage septa as well as near osteoclasts in the zone of mixed spicules. The rough endoplasmic reticulum-rich cell was present in vacated chondrocyte lacunae of the epiphyseal plate close to the metaphysis, and the poorly differentiated cell was observed between the mixed spicules of the metaphysis. Similar cell types were also found in the alveolar bone surrounding the incisors. These cells may be the origin of established bone cell lines that harbor high concentrations of EGF receptors and may also be responsible for the humoral hypercalcemia in response to the reported actions of injected EGF or transforming growth factor-alpha as well as that of malignancy.