Morphological and etiological analyses of C3 and non-C3 glomerulonephritis in primary membranoproliferative glomerulonephritis using periodic acid-methenamine silver stain electron microscopy: a retrospective multicentered study

This study elucidated the etiology of C3 glomerulonephritis (C3GN) and non-C3GN with primary membranoproliferative glomerulonephritis (MPGN) using transmission electron microscopy (TEM) and periodic acid-methenamine silver stain (PAM-EM). Thirty-one primary MPGN cases were analyzed by TEM and PAM-EM to distinguish among MPGN I, MPGN II, MPGN III Burkholder subtype (MPGN IIIB), and Anders and Strife subtype (MPGN IIIA/S). Each case was also classified into C3GN or non-C3GN according to the standard C3GN definition using immunostaining. Four cases of MPGN II met C3 glomerulopathy; whereas, four cases of MPGN IIIB did not meet C3 glomerulopathy. Seven of 11 cases (64%) of MPGN I without GBM disruption and 7 of 12 cases (58%) of MPGN IIIA/S with GBM disruption met the non-C3GN criteria with significant immunoglobulins' deposition. Regardless of the C3GN or non-C3GN diagnosis, the deposits in primary MPGN I and MPGN IIIA/S exhibited ill-defined, amorphous, and foggy characteristics similar to those found in postinfectious GN but were different from immune complex (IC) deposits seen in MPGN IIIB. Not only C3GN but also non-C3GN was due to mechanisms other than IC deposition as found in postinfectious GN. Consequently, GBM disruption of MPGN IIIA/S was not due to IC deposition.

A new approach to detecting sugar syrup addition to honey: Stable isotope analysis of hexamethylenetetramine synthesised from honey monosaccharides (fructose and glucose)

One of the most common types of adulteration of honey involves the addition of invert sugar syrups. A new method was developed to measure the stable isotope ratios of carbon and carbon-bound non-exchangeable (CBNE) hydrogen from specific molecular positions in fructose and glucose in honey. This was achieved through periodate oxidation of the sugars to produce formaldehyde, followed by reaction with ammonia to form hexamethylenetetramine (HMT). The preparation was simplified, optimized, and validated by isotopic analysis of replicate syntheses of HMT from fructose, glucose, sugar syrup and a representative authentic honey sample. The optimized method had a repeatability standard deviation from 1.5‰ to 3.0‰ and from 0.1‰ to 0.4‰ for δ2H and δ13C, respectively. This methodology has advantages over alternative isotopic methods, for measuring CBNE hydrogen isotope ratios in sugars, in terms of time, sensitivity and operability and offers a complementary method to differentiate authentic honey from invert sugar syrups.

Synthesis and Application of Carbon Quantum Dots Derived from Carbon Black in Bioimaging

Carbon quantum dots (CQDs) are a new type of fluorescent QDs that consists mainly of carbon atoms. In this research, CQDs were synthesized through harsh oxidizing conditions applied on carbon black and subsequent N-doping using hexamethylenetetramine (Hexamine) and polyethyleneimine (PEI). The synthesized CQDs were characterized using FTIR, AFM, UV-Visible spectroscopy, photoluminescence (PL) spectroscopy, and fluorescence imaging respectively. The AFM images showed that the dots are in the range of 2-8 nm. N-doping of the CQDs increased the PL intensity. The PL enhancement for the CQDs that were N-doped with PEI was higher compared to those N-doped with hexamine. The shift in PL by changing the excitation wavelength has been attributed to the nano-size of the CQDs, functional groups, defect traps, and quantum confinement effect. The in vitro fluorescence imaging revealed that N-doped CQDs can internalize into the cells and be used for fluorescent cell imaging.

Effective interactions and phase behavior of protein solutions in the presence of hexamine cobalt(III) chloride

It is well established that deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) exhibit a reentrant condensation (RC) phase behavior in the presence of the trivalent hexamine cobalt(III) cations (Hac) which can be important for their packing and folding. A similar behavior can be observed for negatively charged globular proteins in the presence of trivalent metal cations, such as Y3+ or La3+. This phase behavior is mainly driven by charge inversion upon an increasing salt concentration for a fixed protein concentration (cp). However, as Hac exhibits structural differences compared to other multivalent metal cations, with six ammonia ligands (NH3) covalently bonded to the central cobalt atom, it is not clear that Hac can induce a similar phase behavior for proteins. In this work, we systematically investigate whether negatively charged globular proteins β-lactoglobulin (BLG), bovine serum albumin (BSA), human serum albumin (HSA) and ovalbumin (OVA) feature Hac-induced RC. Effective protein-protein interactions were investigated by small-angle X-ray scattering. The reduced second virial coefficient (B2/B2HS) was obtained as a function of salt concentration. The virial coefficient analysis performed confirms the reentrant interaction (RI) behavior for BLG without actually inducing RC, given the insufficient strengths of the interactions for the latter to occur. In contrast, the strength of attraction for BSA, HSA and OVA are too weak to show RC. Model free analysis of the inverse intensity [Formula: see text] also supports this finding. Looking at different q-range by employing static (SLS) and dynamic light scattering experiments, the presence of RI behavior can be confirmed. The results are further discussed in view of metal cation binding sites in nucleic acids (DNA and RNA), where Hac induced RC phase behavior.

Efficacy of methenamine with methylthioninium in the treatment of dysuria: a randomized clinical study

INTRODUCTION AND HYPOTHESIS

Dysuria is a common symptom present in several urological and gynecological conditions. Management relies on the underlying disease but may require additional symptomatic treatment. This study evaluated the combination of methenamine 250 mg and methylthioninium chloride 20 mg in the treatment of dysuria versus phenazopyridine.

METHODS

This was a multicenter, single-blind, randomized, superiority clinical trial, including individuals over 18 with dysuria and a score ≥ 5 points on the pre-treatment categorical scale for pain. The primary outcome was the proportion of participants presenting excellent clinical response within 24 h after treatment. Improvement up to 72 h, time to reach improvement, sustained healing, investigators' opinion, and safety were also evaluated.

RESULTS

Three hundred and fifteen participants were evaluated. Demographic characteristics and symptoms of dysuria were comparable between groups at baseline. The difference in the excellent response rate between treatments within 24 h was 12.7% (95% CI 6.16, 19.21) for pain, 9.4% (95% CI 3.32, 15.39) for burning, and 12.7% (95% CI 6.37, 18.99) for burning on urination, all in favor of the test drug, which was also superior from 36 to 48 h. Treatments were similar concerning time to reach the absence of symptoms and in the percentage of participants with sustained healing after 72 h.

CONCLUSIONS

The association of methenamine with methylthioninium is superior to phenazopyridine in the treatment of dysuria.

A biocatalytic platform for asymmetric alkylation of α-keto acids by mining and engineering of methyltransferases

Catalytic asymmetric α-alkylation of carbonyl compounds represents a long-standing challenge in synthetic organic chemistry. Herein, we advance a dual biocatalytic platform for the efficient asymmetric alkylation of α-keto acids. First, guided by our recently obtained crystal structures, we develop SgvMVAV as a general biocatalyst for the enantioselective methylation, ethylation, allylation and propargylation of a range of α-keto acids with total turnover numbers (TTNs) up to 4,600. Second, we mine a family of bacterial HMTs from Pseudomonas species sharing less than 50% sequence identities with known HMTs and evaluated their activities in SAM regeneration. Our best performing HMT from P. aeruginosa, PaHMT, displays the highest SAM regeneration efficiencies (TTN up to 7,700) among HMTs characterized to date. Together, the synergistic use of SgvMVAV and PaHMT affords a fully biocatalytic protocol for asymmetric methylation featuring a record turnover efficiency, providing a solution to the notorious problem of asymmetric alkylation.

[Efectividad de la suspensión bacteriana sublingual en la prevención de infecciones de vías aéreas de repetición en pediatría]

Background

Upper respiratory tract infections (URIs) are very common in the pediatric population. Most of these infections are mild, but due to their chronicity they affect quality of life (QoL), in addition to high costs for medical care. The use of bacterial extracts (BE) that stimulate general immunity can reduce its frequency and improve the QoL of the patient.

Objective

Evaluate the effectiveness of a BE in the prevention of ARVI in children from 1 to 6 years of age.

Methods

Children between the ages of 1 and 6 years, with a diagnosis of RAVI, were randomized into 3 different groups, with medical follow-up at 6 and 12 weeks after the start. The EB was administered with different doses to each group. An ANOVA test with a Tukey post hoc is used for multiple comparisons (maximum type I error of 0.05).

Results

33 children (12 girls) with a mean age of 3.11 years were included. The average frequency of RAVI prior to treatment was 2.2 events/month and 0.9 and 0.4 events/month at 6 and 12 weeks, respectively. The IVARS were reduced by 76.9% at 3 months of treatment. (Graph). No adverse effects were reported.

Conclusions

BE is safe and effective in reducing the frequency of RAVI in children, in agreement with the literature. There is not enough published scientific evidence, but the BE seems to have an application in the prevention and treatment of RAVI. Sublingual administration is comfortable in this age group.

Anthracite based activated carbon impregnated with HMTA as an effectiveness adsorbent could significantly uptake gasoline vapors

In this study, we synthesized and employed the amine impregnated activated carbon as an efficacious adsorbent for uptaking gasoline vapor. For this regard, anthracite as activated carbon source and hexamethylenetetramine (HMTA) as amine were selected and utilized. Physiochemical characterization of made sorbents were evaluated and investigated using SEM, FESEM, BET, FTIR, XRD, zeta potential, and elemental analysis. The synthesized sorbents provided an excellent textural features as compared with the literature and other activated carbon based sorbents and impregnated with amine. Our findings also suggested that in addition to high surface area (up to 2150 m² / g), the micro- meso pores created (Vmeso / V micro = 0.79 Cm ³ / g) surface chemistry may significantly affect the gasoline sorption capacity, which here the role of mesoporous is further highlighted. V meso for amine impregnated sample and free activated carbon was 0.89 and 0.31 Cm ³ / g, respectively. According to the results, the prepared sorbents have a potential capability in uptaking gasoline vapor and with line this, we report a high sorption capacity of 572.56 mg / g. After, four cycles used the sorbent had a high durability and about 99.11% of the initial uptake was maintained. Taking together the synthesized adsorbents as an activated carbon provided an excellent and unique features and enhanced gasoline uptake, therefore its applicability in uptaking gasoline vapor can be substantially considered.

Methenamine is as effective as antibiotics at preventing urinary tract infections

The studyHarding C, Mossop H, Homer T, et al. Alternative to prophylactic antibiotics for the treatment of recurrent urinary tract infections in women: multicentre, open label, randomised, non-inferiority trial. BMJ 2022;376:e068229.To read the full NIHR Alert, go to: https://evidence.nihr.ac.uk/alert/methenamine-as-good-as-antibiotics-preventing-urinary-tract-infections/.

Synthesis and Behavior of Hexamethylenetetramine-Based Ionic Liquids as an Active Ingredient in Latent Curing Formulations with Ethylene Glycol for DGEBA

The paper presents the preparation of new ionic liquids based on hexamethylenetetramine with bis(trifluoromethanesulfonyl)imide and dicyanamide anion, which were characterized in detail in terms of their purity (Ion Chromatography) and thermal properties (Differential Scanning Calorimetry), as well as stability. The obtained substances were used to develop curing systems with ethylene glycol, which were successfully tested for their application with bisphenol A diglycidyl ether molecule. In addition, the curing process and its relationship to the structure of the ionic liquid are characterized in detail. The research showed that hexamethylenetetramine-based new ionic liquids can be successfully designed using well-known and simple synthetic methods-the Delepine reaction. Moreover, attention was paid to their stability, related limitations, and the application of hexamethylenetetramine-based ionic liquids in epoxy-curing systems.

Methenamine hippurate to prevent recurrent urinary tract infections in older women: protocol for a randomised, placebo-controlled trial (ImpresU)

INTRODUCTION

Methenamine hippurate is a urinary antiseptic used as preventive treatment for recurrent urinary tract infections (UTIs) in some Scandinavian countries. However, the scientific evidence for the preventive effect and safety for longer-term use is limited. The aim of this study is to assess whether methenamine hippurate can reduce the incidence of UTIs in older women with recurrent UTIs.

METHODS AND ANALYSIS

The ImpresU consortium is a collaboration between Norway, Sweden, Poland and the Netherlands. The study is a randomised, controlled, triple-blind phase IV clinical trial. Women ≥70 years with recurrent UTIs are screened for eligibility in a general practice setting. We aim to include 400 women in total, with 100 recruited from each collaborating country. The participants are randomised to treatment with methenamine hippurate 1 g or placebo tablets two times per day for a treatment period of 6 months, followed by a drug-free follow-up period of 6 months. The primary outcome is number of antibiotic treatments for UTIs during the treatment period. The secondary outcomes include number of antibiotic treatments for UTIs during the follow-up period and self-reported symptom of severity and duration of UTI episodes. Differences in complications between the treatment groups are measured as safety outcomes. We also aim to investigate whether strain characteristics or phylogenetic subgroups of Escherichia coli present in the urine culture at inclusion have a modifying effect on the outcomes.

ETHICS AND DISSEMINATION

Ethical approvals are obtained in all participating countries. The results will be communicated in peer-reviewed journals and at scientific conferences.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Registry (NCT04077580); EudraCT: 2018-002235-15.

Ultrasensitive and rapid colorimetric detection of urotropin boosted by effective electrostatic probing and non-covalent sampling

Leakage and contamination of hazardous chemical substances have been widely recognized as the critical issue in ensuring human health, maintaining environmental sustainability, and safeguarding public security. Urotropin as a crucial raw material in industrial holds a potential threat to aquatic/atmospheric environment with refractory degradation problem, hence, there remains a severe challenge to effectively and on-site monitor urotropin. Here, a general design with all-in-one strategy was presented, in which a highly integrated "pocket sensing chip" combining a sampling unit and a detecting unit together endows a rapid and ultrasensitive colorimetric detection without dead-zone towards urotropin. By loading fast blue B as sensing reagent in the detecting unit, a moderate and sensitive detection towards urotropin via electrostatic interaction was achieved with detection limits of 9 μM for liquid and 17.19 ng for particulates. Furthermore, an expandable sensing chip for the purpose of simultaneously screening on multi-target exhibited remarkable applicability for examining suspicious objects with all sorts of surface in real scenes, being unacted on environmental complexity. We expect this design would provide a universal strategy and the high referential value to propel the development of handy and portable sensing device to efficiently screen the environmental relevant critical substance on-site.

3DG Functionalized Magnetic Solid Phase Extraction Materials for the Efficient Enrichment of Hexamethylenetetramine in Vermicelli

Solid phase extraction (SPE) is regarded as the most effective purification method for complex matrix samples owing to its simplicity of operator, time-saving, high accuracy, and environmental friendliness. SPE technology is still affected by the high cost of commercial SPE columns and poor adsorption selectivity. Hence, the development of low-cost and highly selective adsorbents is quite challenging and demanding in SPE. In this study, a novel 3DG functionalized magnetic solid phase extraction materials was prepared based on “thiol-ene” click chemistry. The structure, morphology, thermal stability, and magnetic properties of the magnetic composites were studied by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM). Then the adsorption performance of composite was determined by static adsorption experiments, which showed fast binding kinetics (100 min) and good adsorption performance (Q_e= 65.34 mg/g). Moreover, these magnetic nanoparticles were used as adsorbents for magnetic solid phase extraction (MSPE) and coupled with high-performance liquid chromatography (HPLC) for separation and detection of illegally added hexamethylenetetramine in vermicelli. As for practical application, the recoveries for the spiked samples in the concentration range of 8–40 μg/g were between 83.24–92.69%, and the RSD was between 0.20–2.07%.

Core-Shell Au@Metal-Organic Frameworks for Promoting Raman Detection Sensitivity of Methenamine

Abuse of methenamine in foodstuff is harmful to the health of people. Routine methods recommended by the national standard are indirect assays with complicated pretreatment of samples or less sensitivity. In this work, core-shell Au nanoparticles@inositol hexaphosphate@MIL-101(Fe) nanoparticles, designated as Au@MIL-101, are successfully synthesized by layer-by-layer assembly. Metal-organic framework (MOF; MIL-101)-modified AuNPs could narrow the distance between neighboring Au@MIL-101, which increases the amount of "hot spots" and contributes excellent enhancement of Raman scattering. In addition, certain target molecules could access the proximity to the "hot spots" by the strong interaction capability of MOF with -COOH groups. Taking the syngeneic effect of "hot spots" and chemical enhancement via specific binding, Au@MIL-101-based Raman protocol with huge sensitivity is developed to achieve direct detection of methenamine. It has good linearity of dynamic concentration from 3.16 × 10^-6 to 1.0 × 10^-8 M with correlation coefficient ( R²) of 0.9908. The limit of detection reaches 5.0 × 10^-10 M. As a practical application, such an Au@MIL-101-based Raman protocol could be used for the direct determination of trace methenamine in vermicelli, which meets the requirements of the national standard.

A SILVER STAIN FOR DEOXYRIBONUCLEIC ACID

By hydrolyzing tissue sections with 1 M citric acid for 30 minutes at 60°C and subsequently treating the sections with methenamine silver for 60 minutes at 60°C (5% silver nitrate in 3% aqueous methenamine), a stain has been developed which is extremely intense and specific for nuclear deoxyribonucleic acid. This has been tested in a number of ways including deoxyribonuclease, trichloroacetic and perchloric acid extraction. The reaction has been successful with fresh frozen cryostat sections as well as with paraffin-embedded material. The stain is likewise satisfactory with tissue fixed in neutral formalin, Carnoy's solution, or formalin-phosphate-sucrose mixture. Because the silver precipitate is precisely localized it may be useful in visualizing chromatin with the electron microscope.

Elimination of isobaric interference and signal-to-noise ratio enhancement using on-line mobile phase filtration in liquid chromatography/tandem mass spectrometry

RATIONALE

Liquid chromatography/tandem mass spectrometry (LC/MS/MS) instruments are selective and sensitive but can still be affected by isobaric interference or chemical noise arising from multiple sources such as the mobile phase. In this study, a high-performance liquid chromatography (HPLC) on-line mobile phase filtration setup is described and used to remove interference to allow better detection of the analyte of interest.

METHODS

For instance, a filtration device containing a chemical sorbent is installed at the HPLC outlet of the aqueous solvent pump A or the organic solvent pump B. This manuscript reports different case scenarios under reversed-phase and HILIC separations either in positive (ESI(+)) or negative electrospray ionization (ESI(-)) mode using selected reaction monitoring (SRM) scans as well as additional Q1 MS scans.

RESULTS

The filtration of the aqueous effluent of the mobile phase using a porous graphitic carbon filter eliminated the isobaric interferences and improved the detectability of gestodene and perindopril-D4. Also, a strong cation-exchange guard column installed at the acetonitrile outlet pump was found helpful on reducing the baseline intensity and improving significantly the signal-to-noise ratio (S/N) of methenamine. Moreover, the on-line mobile phase filtration was efficient at removing chemical background ions in full scan mode.

CONCLUSIONS

This strategy demonstrated its usefulness by removing co-eluting isobaric interference, and reducing chemical background ions from the mobile phase, while drastically improving S/N.

Identification of fungi in fungal ball sinusitis: comparison between MUC5B immunohistochemical and Grocott methenamine silver staining

CONCLUSION

MUC5B immunohistochemical staining was a valuable method for identifying fungi in fungal ball sinusitis, especially in distinguishing aspergillus and mucor. Combined infection with Aspergillus and Mucor fungi was the most common pattern in fungal ball sinusitis.

OBJECTIVE

To assess the value of MUC5B immunohistochemical staining in identifying fungi in fungal ball sinusitis by comparing it with conventional Grocott methenamine silver (GMS) staining.

METHODS

GMS staining and MUC5B immunohistochemical staining were used to identify fungi in mucopurulent cheesy or clay-like tissues from sinuses in 180 fungal ball sinusitis patients, and the examination results were compared.

RESULTS

In 180 samples of fungal ball sinusitis, GMS staining showed Aspergillus in 130, Mucor in 88, and Candida albicans in 6, while MUC5B immunohistochemical staining identified Aspergillus in 166, Mucor in 172, and Candida albicans in 16. The fungal detection rate for MUC5B immunohistochemical staining was markedly greater than that for GMS staining (p < 0.01). This implies that MUC5B immunohistochemical staining was more sensitive than GMS staining in identifying fungi in fungal ball sinusitis. Mixed infection of Aspergillus and Mucor was present in 146 of 180 patients (81.1%).

Morphological changes of the human purkinje cells and deposition of neuritic plaques and neurofibrillary tangles on the cerebellar cortex of Alzheimer's disease

Alzheimer's disease is a neurodegenerative disorder, characterized by progressive decline in memory and in social performance. The morphological hallmarks of the disease are neuronal loss, loss of dendritic spines, neurofibrillary degeneration and neuritic plaques mainly in the hippocampus and the cortex of the cerebral hemispheres. This study is based on the morphological analysis of the cerebellar cortices of eight brains, 4 patients suffered from Alzheimer's disease and 4 normal controls, by Golgi method, as well as Nissl, Gallyas', Bielschowsky's, Methenamine Silver staining and Congo red methods. Although typical neuritic plaques were not seen in the cerebellar cortex and the diffuse plaques found in the cerebellum in far smaller proportion than plaques in the prefrontal and parietal cortices of the same cases, Golgi impregnation technique revealed a loss of Purkinje cells and a marked decrease in the density of dendritic arborization.

Significance of PAM histochemical reaction in delineating macrophages

Periodic acid methenamine silver staining has been used for proof of the existence of carbohydrates in both paraffin and resin embedded tissues. The staining was applied to delineate macrophages that have been well known as cells of mononuclear phagocyte system by stainable nature for lysosomes, and it is found to be useful method for detection of macrophage. Fetal macrophage, which is often observed in placental villi, is called the highly vacuolated cell. Vacuoles in the cytoplasm seem to be empty with light microscopic staining, but it is clarified that they contain a full amount of carbohydrate. The present result leads us to the necessity of reconsidering the functional aspect of fetal macrophage.

Quantitative Digital Histochemistry With Methenamine Silver Staining in Renal Allograft Biopsies Excluding Pure Chronic Allograft Nephropathy Cases

Deterioration of renal function is correlated with irreversible damage in chronic diseases. Recently we described a digital quantitative histochemistry method, relying on periodic acid methenamine silver (PAMS) staining to determine the chronic renal lesions. This index was strongly correlated with progressive deterioration of renal function in grafts with chronic allograft nephropathy (CAN). Herein the method has been applied to a cohort of renal allografts which were biopsied for various reasons, we sought to highlight its value to quantify chronic graft damage. Forty-four renal allograft biopsies from 37 patients with elevated serum creatinine values (SCr) underwent light microscopic image analysis (Mediscope, Dokuz Eylül University, Clinical Engineering Department, Izmir, Turkey) of the PAMS-stained area percentage (SAP). SCr was recorded at four intervals to overcome acute effects: the under SCr value before (SCr1) and after a biopsy within 3 months (SCr3), SCr at the time of the biopsy (SCr2), and the latest value (SCr4). The PAMS-SAP scores were strongly associated with increased interstitial fibrosis and tubular atrophy Banff scores (Kruskal-Wallis test, P = .006 and P = .003, respectively). There was a moderate positive correlation between PAMS and SCr3 (Pearson correlation test, P = .04, r = .312), and a strong positive correlation between time from transplantation to biopsy (Pearson correlation test, P << .000, r = .532). The present results show that PAMS-SAP seems to be of value to quantify renal scarring in allograft biopsies, reflecting four compartments. The strong correlation with time is noteworthy especially as a probable reflection of aging of the renal allograft.

Ionic, Structural, and Temperature Effects on DNA Nanoparticles Formed by Natural and Synthetic Polyamines

We synthesized analogues of spermine and studied the effects of chemical structure, ionic strength, and temperature on lambda-DNA nanoparticle formation. Effective concentration of polyamines for DNA condensation (EC50) was lowest for hexamines (0.2 microM) and highest for spermine (tetramine, 4.2 microM). The EC50 value increased with [Na+]. Dynamic light scattering showed nanoparticles with hydrodynamic radii (R(h)) of 40-50 nm. Effect of temperature on R(h) was measured between 20 and 70 degrees C. For spermine, R(h) remained relatively stable until 50 degrees C and increased significantly at >60 degrees C. In contrast, the hexa- and penta-valent analogues exhibited a gradual increase in R(h) between 20 and 70 degrees C. The nanoparticles were mainly toroidal, as revealed by electron microscopy (EM). EM studies showed changes in morphology and size of condensed structures with an increase in temperature. A possible mechanism for the differential effects of temperature on DNA nanoparticles might involve different modes of DNA-polyamine interactions.

Methenamine silver staining quantitative digital histochemistry in chronic allograft nephropathy

Renal function and final outcome of renal allografts have been correlated with irreversible damage. This study describes a quantitative histochemical method relying on periodic acid methenamine silver (PAMS) staining of all renal compartments. Among 60 renal allograft biopsies from 43 patients, 15 biopsies showing pure chronic allograft nephropathy were selected to determine PAMS-stained area percentage (SAP), using image analysis with quantitative histochemistry. Of the 15 cases, 9 (60%) were grade I and 6 (40%) were grade II chronic allograft nephropathy (CAN). The mean serum creatinine (sCr) value was 1.86 +/- 0.47 for allograft biopsies. The mean (+/-SD) SAP for the implantation biopsies was 10.58 +/- 1.87%, and for allograft biopsies 25.26 +/- 9.67 (P <<.000). The serum creatinine (sCr) values for grade I versus II CAN were 1.63 +/- 0.24 versus 2.20 +/- 0.54 mg/dL, respectively (P=.019), and SAP values were 18.97 +/- 0.24 versus 34.7 +/- 5.89 (P=.003). There was a strong positive correlation between sCr values and SAP (P=.005; r=0.64). These findings show the PAMS approach to be a useful alternative method for reflecting damage in more than one compartment of the renal tissue. Also, the method can discriminated implantation and allograft biopsies as well as grade I and II CAN cases. The series is small for a multivariate analysis of the value of SAP measurements in PAMS-stained sections as a prognosticator, but the data support its use.

Evaluation of silver methenamine method for nanoleakage

OBJECTIVES

The aim of this study was to evaluate nanoleakage patterns following silver methenamine staining of restorations bonded with a total-etch single bottle system, a self-etching primer system and a total-etch single bottle system after collagen depletion.

METHODS

The dentin bonding systems used in this study were Prime and bond 2.1 (PB) and Clearfil SE Bond (CSEB). Cavities were made in grounded labial surfaces of 15 extracted bovine lower incisors, randomly divided into 3 Groups. Group 1 (PB), Group 2 (CSEB) and Group 3 (PB/SH) PB after collagen depletion with sodium hypochlorite (SH). The specimens were restored, sectioned and submitted to silver methenamine staining, polished and observed with low-vacuum back-scattered SEM. One way ANOVA and multiple-comparison Tukey's test were used for statistical analysis of the leakage scores.

RESULTS

PB presented significantly greater silver deposition and a distinct pattern when compared to CSEB. No silver deposition was detected for PB after collagen depletion.

SIGNIFICANCE

The dentine bonding systems tested were unable to prevent nanoleakage when used according to the manufacturers' instructions; however, CSEB presented a lower level of silver deposition. Collagen depletion prior to PB application may prevent nanoleakage occurrence in dentine walls. Silver methenamine staining may be a useful method for detection of nanoleakage in dentine when the collagen fibrils remain exposed within the hybrid layers.

[Comparison of the methenamine silver staining, direct fluorescent antibody and nested-polymerase chain reaction methods in the diagnosis of Pneumocystis carinii pneumonia]

Pneumocystis carinii is one of the most common causative agents of pneumonia in immunocompromised patients, but the problems in the laboratory diagnosis of the disease frequently leads to diagnosis according to the response to medical treatment. In this study, the presence of P. carinii was investigated in immunocompromised patients who were presenting with the clinical symptoms of atypical pneumonia, by Gomori methenamine silver staining (GMS), direct fluorescent antibody (DFA) test and nested-polymerase chain reaction (nPCR) methods. Fifty-three samples of 49 patients were included in the study. Twelve of the samples (22.6%) were found to be positive by nPCR, 6 of them (11.3%) were found to be positive by DFA, while only one of them (1.8%) was positive by GMS staining method. As a result, for the appropriate treatment and prophylaxis of P. carinii infections, PCR which is a rapid and reliable diagnostic test should be used for diagnosis.

Immunofluorescence of the epizootic ulcerative syndrome pathogen, Aphanomyces invadans, using a monoclonal antibody

A monoclonal antibody (MAb), designated 3gJC9, was raised against a protein antigen of Aphanomyces invadans, the oomycete pathogen that causes epizootic ulcerative syndrome (EUS). The antigen was expressed on the surface of hyphae and secreted extracellularly. MAb 3gJC9 did not cross-react with other oomycete or fungal pathogens of fish, although it did react to the crayfish plague pathogen A. astaci. The MAb was used for immunofluorescent staining on histological sections of fish infected with EUS, and was found to be more sensitive than conventional staining methods for detecting A. invadans. It thus has utility in confirming the case definition of EUS. It also revealed very small filamentous structures, the significance of which is unclear, but they may represent an early stage of infection, thus allowing earlier detection of the disease, since they are not detected using conventional staining methods.

Measuring gluconeogenesis using a low dose of 2H2O: advantage of isotope fractionation during gas chromatography

The contribution of gluconeogenesis to glucose production can be measured by enriching body water with (2)H(2)O to approximately 0.5% (2)H and determining the ratio of (2)H that is bound to carbon-5 vs. carbon-2 of blood glucose. This labeling ratio can be measured using gas chromatography-mass spectrometry after the corresponding glucose carbons are converted to formaldehyde and then to hexamethylenetetramine (HMT). We present a technique for integrating ion chromatograms that allows one to use only 0.05% (2)H in body water (i.e., 10 times less than the current dose). This technique takes advantage of the difference in gas chromatographic retention times of naturally labeled HMT and [(2)H]HMT. We discuss the advantage(s) of using a low dose of (2)H(2)O to quantify the contribution of gluconeogenesis.

A simple method for the specific detection of Ren-1 renin

BACKGROUND

Ren-1 and Ren-2 renin are expressed in the kidneys of all mice and in the submandibular gland of several mouse strains. The present study determined the usefulness of modified periodic acid silver-methenamine (PAM) staining for the specific detection of Ren-1 renin.

METHODS

Conventional paraffin sections were prepared from kidneys of ICR, BALB/cA, C57BL/6Cr, C3H/HeN, DBA/2Cr, angiotensin II type 1a receptor gene knockout (AT1aKO) mice, Wistar rats and a human, and submandibular glands of C57BL/6Cr and DBA/2Cr mice. Sections were analyzed for the presence of renin using PAM and immunohistochemistry. PAM reactions were terminated at generally or weakly intense (weak PAM staining; W-PAM). In addition, kidneys of DBA/2Cr mice were fixed using various fixatives (formalin, PFA, PLP, Zamboni's, Bouin's, or Carnoy's) and treated using identical procedures.

RESULTS

Although PAM-positive reactions were observed in juxtaglomerular (JG) cells, W-PAM reactions were particularly specific for these cells. These findings were observed in all mouse strains. Immunohistochemistry using mirror sections suggested that a W-PAM-positive reaction detected renin. This hypothesis was confirmed by the results from AT1aKO mice. Briefly, W-PAM detected an expansion of renin-positive areas in AT1aKO mice. Rat and human kidneys and mouse submandibular glands were negative for W-PAM. Levels of JG cell detection by W-PAM were similar in samples fixed in formalin, PFA, PLP, or Zamboni's.

CONCLUSIONS

The present findings show that W-PAM can identify Ren-1 renin, but not Ren-2, rat or human renin. The W-PAM method is useful for the specific detection of Ren-1 renin.

Usefulness for scanning electron microscopy]

Prostheses implanted in hard tissues cannot be processed for electron microscopic examination or microanalysis in the same way as those in other tissues. For these reasons, we have developed a method allowing light and electron microscopic studies as well as microanalysis of the interface between bone and biomaterials after the sections glycoproteins have been stained with silver methenamine. Silver can be evidenced by SEM in back scattered mode.

MATERIALS AND METHODS

Tranverse sections of a human femur containing an HA-coated prostheses were obtained with a diamond saw and ground to a thickness of 50-100 microns. The sections were stained in a microwave oven using a 1% silver methenamine solution. They have been examined by back-scatter SEM operated at 25 KV. EDS has been performed on cellular inclusions and extracellular bone matrix.

RESULTS

Type I and III collagen fibers, and reticulin fibers were stained. The mineralized matrix was heavily colored. At the cell level, the nuclear and cytoplasm membranes, the chromatin and ribosomes were shown. The characteristic peaks of the Ag spectrum are distinct from those of the elements used in orthopaedic biomaterials and did not impair their identification.

Degeneration of Pick bodies visualized by methenamine-silver staining and immunohistochemistry

The degeneration process of Pick's bodies (PB) was investigated using methenamine-silver (MS) staining and immunohistochemistry. Methenamine-silver staining sensitively detected extracellular PB as well as intracellular PB in the granular cell layer of the dentate gyrus. Extracellular PB appeared as granular masses with ill-defined boundaries in the neuropil. For MS electron microscopy, the extracellular PB were composed of randomly oriented fibrillary components measuring 9-12 nm in diameter with astroglial processes and degenerated organelles. Tau immunoreactivity of extracellular PB was reduced or abolished. These findings indicate that MS staining is a convenient method for detecting extracellular PB. In addition, it was shown that microglial involvement was associated with PB-bearing neurons at the late stage of the degeneration process and that extracellular PB remained in the neuropil with astroglial reaction.

Comparison of staining methods and a nested PCR assay to detect Histoplasma capsulatum in tissue sections

To optimize diagnosis of histoplasmosis in tissue sections, 30 spleen specimens from mice, experimentally infected with Histoplasma capsulatum, were examined by H&E, Grocott stain, anti-bacille Calmette-Guerin antibody immunostain, Fungiqual A fluorochrome stain (Drs Reinehr and Rembold, Kandern, Germany), and a nested polymerase chain reaction (PCR) assay. Results were compared with the tissue burden determined by quantitative culture. By applying logistic regression, the nested PCR assay was the most sensitive method, but not significantly more sensitive than the Grocott stain. The 50% quantile to achieve a positive result was determined to be 3 colony-forming units per milligram of spleen tissue for the PCR assay, 11 for the Grocott stain, 27 for the fluorochrome stain, 190 for immunostaining, and 533 for the H&E stain. The Grocott and fluorochrome stains did not differ significantly in detecting fungal elements. The PCR assay unambiguously identified H. capsulatum in tissue sections.

Influence of calcium hydroxide dressing on the obturation of simulated lateral canals

The purpose of this in vitro study was to evaluate what influence an interappointment dressing with calcium hydroxide might have on the ability to subsequently obturate simulated lateral canals. Twenty extracted single-rooted human teeth were instrumented at the working length to a #35 file before creating three simulated lateral canals on the mesial and distal surfaces of the root, one in each third, using a #15 engine reamer. After enlarging the root canals to a #45 file, the teeth were randomly divided into two groups of 10. In both groups AH26 was used as the sealer. In group A, the obturation was performed immediately using Ultrafil. In group B, root canals were filled with calcium hydroxide and incubated for 7 days. The teeth were then reinstrumented, irrigated with 2.5% sodium hypochlorite solution, dried with paper points, and obturated as in group A. Teeth in group A showed a larger number of filled lateral canals compared with those in group B. Statistical significant differences were observed when comparing the same third in the two groups (apical third p < 0.05, middle third p < 0.01, and coronal third p < 0.01). No differences were found among the different thirds in the same group (p > 0.05).

Evaluation of lectin staining in the diagnosis of fungal keratitis in an experimental rabbit model

PURPOSE

To assess the sensitivity, specificity, and reliability of peroxidase labeled lectin staining in the diagnosis of fungal keratitis in an experimental rabbit model.

METHODS

Fungal keratitis by Candida albicans, Aspergillus fumigatus, and Fusarium solani was induced in rabbits. WGA-peroxidase staining of 660 corneal sections was performed. Fungal staining was evaluated independently by two observers. The test sensitivity, specificity, and reliability indexes were calculated.

RESULTS

The sensitivity of the lectin staining test for Candida albicans was 100% (95% CI: 93.51-100.00), and specificity was 100% (95% CI: 93.51-100.00). The sensitivity of the test for Aspergillus fumigatus was 96.36% (95% CI: 86.46-99.35), and specificity was 100% (95% CI: 93.51-100.00). The sensitivity of the test for Fusarium solani was 96.36% (95% CI: 86.46-99.35) and specificity was 96.15% (95% CI: 85.74-99.31). There was also a high degree of test-retest and inter-rater concordance for all three fungi tested. The test-retest k reliability indexes were 0.9455, 0.9636, and 0.8879, for Candida albicans, Aspergillus fumigatus, and Fusarium solani, respectively. The inter-rater k reliability indexes were 0.9636, 0.9818, and 0.9252, for Candida albicans, Aspergillus fumigatus, and Fusarium solani, respectively.

CONCLUSIONS

WGA-peroxidase staining is a very sensitive, specific, and reliable test for the identification of fungi in an experimental rabbit model of fungal keratitis.

Developmental changes in the fine structure and histochemical properties of mucous cells in the parotid gland of the infant Japanese macaque

Mucous cells have been known to occur in the terminal portions of the parotid gland in a few species of mammals during a limited period of their development. The aim of this study was to examine the occurrence and features of mucous cells in the parotid gland of the infant Japanese macaque. Light microscopy revealed that mucous cells in the macaque parotid gland were present in the terminal clusters and acini at postnatal day 15, were less prevalent at day 30, and continued to decrease in number over 3 months. Mucous cells were no longer recognized in the parotid gland in 6-month-old macaques. Electron microscopy showed that the mucous cells contained electron-lucent secretory granules and bipartite or tripartite secretory granules. By 3 months of age, there was a scarcity of mucous cells and a concomitant increase in transitional cells. These transitional cells were intermediate in structure between mucous and serous cells, and contained three types of granules: electron-lucent, bipartite or tripartite, and electron-dense. None of the cells showed apoptotic figures. Lectin histochemistry indicated that the mucous cells in the early postnatal period had sugar residues identical in nature to those seen in the granules from mature serous cells in the glands of 3-month-old macaques. Immunohistochemistry using an antibody against human alpha-amylase showed a weakly positive reactivity in the secretory granules of the mucous cells, starting from day 15. In the transitional cells, the electron-dense granules showed a stronger immunoreactivity than either the electron-lucent granules or the heterogeneously structured granules. These results suggest that the secretory granules of mucous cells have characteristics in common with those of serous cells, and that during the transitional period the mucous granules change from the initial electron-lucent to hetorogenous forms, finally becoming the electron-dense granules. The mucous cells in the parotid gland of the juvenile Japanese macaque are therefore suggested to be converted into serous cells.

Effects of chlorhexidine gluconate as an endodontic irrigant on the apical seal: short-term results

The aim of this study was to ascertain whether chlorhexidine gluconate (0.12%), used as an endodontic irrigating solution would affect the apical seal obtained when using three different root canal cements. One hundred extracted human single-canal teeth were divided into 9 experimental groups of 10 teeth each and a positive and negative group of 5 teeth each. The teeth were decoronated at the level of the cementoenamel junction, then accessed, instrumented to a Master Apical File #50, irrigated with either sterile saline, 5.25% NaOCl or 0.12% chlorhexidine gluconate, and dried using paper points. Obturation was accomplished using lateral condensation and 1 of 3 endodontic sealers: Roth's 811, AH26, or Sealapex. At 90 and 180 days after obturation apical leakage was measured using the fluid filtration method. Using the ANOVA test the results showed no significant difference in seal related to the irrigant at both the 90- and 180-day observation periods.

A scanning electron microscopic evaluation of root surfaces and the gutta-percha interface following root-end resection in vitro

AIM

The aim of this study was to evaluate the effects that various commonly used instruments have on root surface morphology, the obturating material, and the interface between the obturation and the root canal walls following root-end resection in vitro.

METHODOLOGY

Sixty human single-rooted teeth with fully formed apices were collected and decoronated. The root canals were instrumented, and then obturated with thermoplasticized gutta-percha using AH-26 as the sealer. The roots were randomly divided into 12 different groups, and apical root-end resections were performed using eight different instrument configurations, and two different directions in which the bur moved across the root face in relation to its direction of rotation. Epoxy resin replicas of the resected root ends were examined using scanning electron microscopy.

RESULTS

Each instrument produced a characteristic surface finish on the resected root end that mirrored its cutting profile. Irrespective of the design of the bur used, smearing and shredding of the gutta-percha across the root face occurred only when the handpiece was moved across the root face in reverse direction in relation to the direction of rotation of the bur.

CONCLUSIONS

To ensure minimal disruption and distortion of the root filling and to prevent shredding of the gutta-percha interface, care should be taken to ensure that the final pass of the bur across the root canal is in the correct direction in relation to its direction of rotation.

Bacterial leakage versus dye leakage in obturated root canals

AIM

The aim of this study was to compare in vitro bacterial and dye leakage tests, commonly used to determine the seal of root canal fillings.

METHODOLOGY

Ninety-six single-rooted teeth had their crowns removed at the cemento-enamel junction and their roots instrumented to ISO size 60 within 1 mm of the apex. Three groups of 30 roots were obturated by lateral condensation using gutta-percha and one or other of the sealers. AH26, Ketac Endo, or Roth's 801 sealer. Three roots were used as negative controls and three roots as positive controls. The roots were then exposed at their coronal end first for 38 days to soy broth containing Staphylococcus epidermidis and thereafter for 48 h to basic fuchsin. Bacterial leakage was recorded when the challenging organism could be recovered from the apical end. Dye leakage was checked by microscopy of transverse sections of the apical tip at the end of the experiment.

RESULTS

For the bacterial experiment, there was no significant difference amongst the three sealer groups. The dye experiment showed significantly greater leakage in the AH26 compared to the Ketac Endo group. No correlation between the results of the two tests could be seen.

CONCLUSIONS

The results of this study suggest that the molecular size of the penetrating agent may not be the relevant parameter when attempting to determine an appropriate test for the sealability of root canal fillings.

Leakage associated with single or multiple increment backfill with the Obtura II gutta-percha system

The purpose of this in vitro study was to compare dye leakage between canals backfilled in a single increment and canals backfilled in multiple increments using the Obtura II system with two different sealers. Sixty extracted single canal teeth were decoronated, cleaned, and shaped. After master cone fit and placement of either Roth 801 or AH26 sealers, the canals were down-packed to 4 mm from working length. The teeth were then divided into 4 groups of 15: group 1--Roth 801 sealer with 1 increment of Obtura II back-fill; group 2--Roth 801 sealer backfilled in 4- to 5-mm increments; group 3--AH26 sealer with 1 increment of backfill; and group 4--AH26 sealer backfilled in 4- to 5-mm increments. After sealer set, the teeth were apicected 5 mm from working length. The apices were discarded. The coronal segments were coated with two layers of fingernail polish, except for the resected apical end. The teeth were immersed in Pelikan ink for 5 days. The teeth were then decalcified, dehydrated, and rendered transparent in methylsalicylate. Dye penetration was measured on four surfaces of each root. The mean measurements of each tooth were averaged for each group. Leakage of group 1 was 6.69; group 2, 5.39; group 3, 5.71; and group 4, 5.02. Differences were not statistically significant (p > 0.05). This study suggests that it may be clinically acceptable to backfill canals up to 10 mm in a single increment using sealer and the Obtura II gutta-percha system.

Leakage of five root canal sealers

AIM

The aim of this study was to examine the apical sealing ability of five root canal sealers using a fluid transport model.

METHODOLOGY

A comparison of root canal scalers AH26, AH Plus, Diaket, Apexit, and Ketac-Endo were tested on 60 single-rooted teeth. The coronal part of each tooth was removed at the amelo-cemento junction, and also 3 mm of the root tip. Root canals were instrumented using the 'step-back' technique with Gates Glidden drills and irrigated with 2.5% NaOCl. The specimens were divided into five groups of 10 samples each and filled with test materials and gutta-percha points by the cold lateral condensation technique. Ten teeth were used as a control group, out of which five served as negative and five as positive controls. The leakage was measured by the movement of an air bubble in a capillary glass tube connected to the experimental root section.

RESULTS

The differences in leakage amongst Ketac-Endo (0.318 microL: SD 0.084), AH26 (0.319 microL; SD 0.075), AH Plus (0.330L; SD 0.085) Apexit (0.360 microL; SD 0.127) and Diaket (0.387 microL; SD 0.140) were not statistically significant (P > 0.05).

CONCLUSIONS

Under the conditions of this study, all five sealers produced a satisfactory seal.

Dentinal tubule penetration of root canal sealers after root canal dressing with calcium hydroxide

The purpose of this study was to evaluate the dentinal tubule penetration of root canal sealers after root canal dressing with calcium hydroxide (Ca(OH)2). Forty-two single-rooted teeth were instrumented to size 60. Six teeth served as the control group, and the remaining teeth were assigned to two groups. Root canals of the first group were filled with the Ca(OH)2 paste; the second group was filled with TempCanal, and all were incubated for 7 days. The samples were either irrigated with only NaOCl or with EDTA, followed by NaOCl to remove Ca(OH)2. All of the teeth were obturated with CRCS, AH26, and Ketac Endo by a lateral condensation technique. The specimens were then kept at the same conditions for another 7 days, and then all of the roots were prepared for scanning electron microscopic evaluation. Scanning electron microscopic examination revealed that Ca(OH)2 was not completely removed from the root canal surfaces, and root canal sealers did not penetrate into the dentinal tubules when only NaOCl was used. EDTA followed by NaOCl irrigation resulted in complete removal of Ca(OH)2 and root canal sealers penetrated into the dentinal tubules.

An evaluation of plaster of Paris barriers used under various materials to repair furcation perforations (in vitro study)

The present study was undertaken to evaluate the effect of plaster of Paris barriers on the sealing ability of various materials when used to repair furcation perforations. The study was conducted on 90 human permanent molars with well developed, nonfused roots. Access openings and furcation perforations were prepared in the pulp chamber floor. The teeth were divided into one control and five experimental groups of 15 teeth each. In the experimental group, plaster of Paris barriers were created in the perforations and then sealed with silver amalgam, glass ionomer (GI), self-cured composite resin, IRM, or AH26. Access openings were filled with composite resin. The teeth were submerged in a solution of 2% methylene blue dye for 2 wk. Finally, the samples were sectioned and evaluated for linear dye leakage and analyzed statistically. Maximum dye penetration was observed in amalgam followed in a decreasing order by GI, composite, IRM, and AH26. AH26 showed the best sealing ability in the presence of plaster of Paris barriers followed by IRM, composite resin, and GI. Amalgam showed the poorest sealing ability when used to repair furcation perforations.