Impression Disinfection and Its Effect on Dimensional Accuracy and Surface Detail in the Times of COVID-19: An In Vitro Study

Introduction The disinfection of impressions is crucial to eliminate the viral and other microbial loads to prevent the cross contamination of diseases. The aim of this study was to compare the effect of different virucidal disinfecting methods on the dimensional accuracy and surface detail reproduction (SDR) of impression materials. Methods A total of 160 samples were fabricated with different impression materials using zinc oxide eugenol (Group 1), alginate (Group 2), polyether (Group 3), and addition silicone (Group 4) impression materials, each containing 40 samples (n=40). These groups were further divided into Subgroups A, B, C, and D (n=10) based on the disinfecting method used. Disinfection was carried out using 0.2% peracetic acid (A), a natural polymer of glucosamine (B), ultraviolet (UV) radiation (C), and ozonated water (D). The disinfected impressions were poured in type IV gypsum, and the obtained casts were checked for dimensional accuracy and surface detail reproduction (SDR). For dimensional accuracy, a one-way analysis of variance (ANOVA) test and, for surface detail reproduction, the chi-square test were used to compare the different subgroups of each impression material separately. Results Zinc oxide eugenol samples showed the lowest mean dimensional change when disinfected with 0.2% peracetic acid (1A=154.1 µm), and alginate showed the lowest mean dimensional change when disinfected using ozonated water (2D=134.9 µm). On the other hand, the lowest mean dimensional change observed in polyether and addition silicone samples was those which were disinfected using UV radiation (3C=100.9 µm and 4C=113.5 µm). Surface detail was reproduced adequately in most of the samples. Conclusion A 0.2% peracetic acid could be used to disinfect zinc oxide eugenol impressions, ozonated water for alginate impressions, and UV radiation for polyether and addition silicone impressions.

Chemical torrefaction as an alternative to established thermal technology for stabilisation of sugar cane bagasse as fuel

Dry and chemical torrefaction of sugar cane bagasse was examined in this study with the aim of stabilising and upgrading the fuel properties of bagasse. Dry torrefaction was conducted at temperatures from 160°C to 300°C under inert conditions, whilst chemical torrefaction incorporated a H₂SO₄ pre-treatment of bagasse. Chemical torrefaction imparted superior chemical and physical properties inducing morphological transformation and textural development with the potential to address issues in handling, feeding and processing bagasse. It increased the energy density of the chars with maximum HHV_mass 21.5 MJ/kg and maximum HHV_volume of 7.4 GJ/m³. Chemically torrefied bagasse demonstrated resistance against microbiological attack for 18 months. These features demonstrate the practical value of chemical torrefaction in advancing the utilisation of bagasse as fuel.

Combustion of thermochemically torrefied sugar cane bagasse

This study compared the upgrading of sugar bagasse by thermochemical and dry torrefaction methods and their corresponding combustion behavior relative to raw bagasse. The combustion reactivities were examined by non-isothermal thermogravimetric analysis. Thermochemical torrefaction was carried out by chemical pre-treatment of bagasse with acid followed by heating at 160-300°C in nitrogen environment, while dry torrefaction followed the same heating treatment without the chemical pretreatment. The results showed thermochemical torrefaction generated chars with combustion properties that are closer to various ranks of coal, thus making it more suitable for co-firing applications. Thermochemical torrefaction also induced greater densification of bagasse with a 335% rise in bulk density to 340kg/m³, increased HHV_mass and HHV_volume, greater charring and aromatization and storage stability. These features demonstrate the potential of thermochemical torrefaction in addressing the practical challenges in using biomass such as bagasse as fuel.

Exposure to the common food additive carrageenan leads to glucose intolerance, insulin resistance and inhibition of insulin signalling in HepG2 cells and C57BL/6J mice

AIMS/HYPOTHESIS

The aim of this study was to determine the impact of the common food additive carrageenan (E407) on glucose tolerance, insulin sensitivity and insulin signalling in a mouse model and human hepatic cells, since carrageenan is known to cause inflammation through interaction with toll-like receptor (TLR)4, which is associated with inflammation in diabetes.

METHODS

Male C57BL/6J mice were given carrageenan (10 mg/l) in their drinking water, and underwent a glucose tolerance test (GTT), an insulin tolerance test (ITT) and an ante-mortem intraperitoneal insulin injection. HepG2 cells were exposed to carrageenan (1 mg/l × 24 h) and insulin. Levels of phospho(Ser473)-protein kinase B (Akt), phospho(Ser307)-IRS1, phosphoinositide 3-kinase (PI3K) activity and phospho(Ser32)-inhibitor of κB (IκBα) were determined by western blotting and ELISA.

RESULTS

Glucose tolerance was significantly impaired in carrageenan-treated 12-week-old mice compared with untreated controls at all time points (n = 12; p < 0.0001). Baseline insulin and insulin levels at 30 min after taking glucose during the GTT were significantly higher following carrageenan treatment. During the ITT, glucose levels declined by more than 80% in controls, but not in carrageenan-treated mice. Carrageenan exposure completely inhibited insulin-induced increases in phospho-(Ser473)-Akt and PI3K activity in vivo in mouse liver and in human HepG2 cells. Carrageenan increased phospho(Ser307)-IRS1 levels, and this was blocked when carrageenan-induced inflammation was inhibited.

CONCLUSION

This is the first report of the impact of carrageenan on glucose tolerance and indicates that carrageenan impairs glucose tolerance, increases insulin resistance and inhibits insulin signalling in vivo in mouse liver and human HepG2 cells. These effects may result from carrageenan-induced inflammation. The results demonstrate extra-colonic manifestations of ingested carrageenan and suggest that carrageenan in the human diet may contribute to the development of diabetes.

Evolutionary conservation of alternative splicing in chicken

Alternative splicing represents a source of great diversity for regulating protein expression and function. It has been estimated that one-third to two-thirds of mammalian genes are alternatively spliced. With the sequencing of the chicken genome and analysis of transcripts expressed in chicken tissues, we are now in a position to address evolutionary conservation of alternative splicing events in chicken and mammals. Here, we compare chicken and mammalian transcript sequences of 41 alternatively-spliced genes and 50 frequently accessed genes. Our results support a high frequency of splicing events in chicken, similar to that observed in mammals.

Detection of vascular complications after liver transplantation: early experience in multislice CT angiography with volume rendering

OBJECTIVE

Our objective was to investigate the usefulness of three-dimensional multislice CT angiography for the evaluation of liver transplant recipients presenting with clinical or sonographic findings suggestive of hepatic vascular complications.

CONCLUSION

Our early results indicate that three-dimensional multislice CT angiography with volume rendering can reveal common and potentially lethal vascular complications in patients who have undergone liver transplantation.

Prognostic significance of arterial phase CT for prediction of response to transcatheter arterial chemoembolization in unresectable hepatocellular carcinoma: a retrospective analysis

OBJECTIVE

The purpose of this study was to use hepatic arterial phase helical CT to assess tumor vascularity and predict the likelihood of response to transcatheter arterial chemoembolization in patients with hepatocellular carcinoma.

MATERIALS AND METHODS

Helical CT findings for 57 patients with hepatocellular carcinoma were classified into one of three patterns of vascularity on the basis of the degree of tumor or liver enhancement during the hepatic arterial phase. Cases in which hypervascular lesions predominated were classified as a type 1 pattern. Cases in which hypovascular lesions predominated were classified as a type 2 pattern. Patients were classified as responders or nonresponders on the basis of the changes of tumor size revealed on CT after three transcatheter arterial chemoembolization treatments.

RESULTS

We classified the 57 patients as 37 responders (65%) and 20 nonresponders (35%). A statistically significant correlation between the type 1 hypervascular pattern and response to transcatheter arterial chemoembolization was seen; conversely, the type 2 hypovascular pattern correlated with nonresponse to transcatheter arterial chemoembolization (chi-square = 7.85, p = 0.02). Patients classified as responders lived significantly longer than those classified as nonresponders with 12-, 24-, and 36-month survival rates of 90%, 67%, and 36%, respectively, for responders and 70%, 17%, and 10%, respectively, for nonresponders.

CONCLUSION

We found that patients who responded to transcatheter arterial chemoembolization had prolonged survival (p < 0.01). Response correlated closely with tumor vascularity as shown on hepatic arterial phase helical CT.

Extrahepatic metastases of hepatocellular carcinoma

PURPOSE

To determine the relative frequency, incidence, and locations of metastases of hepatocellular carcinoma (HCC), correlate extrahepatic metastatic disease with intrahepatic tumor staging, and determine the computed tomographic (CT) manifestations of HCC metastases.

MATERIALS AND METHODS

CT findings in 403 consecutive patients with HCC at our institution since 1992 were reviewed retrospectively. One hundred forty-eight patients with extrahepatic metastatic HCC were identified, and the locations, sizes, and attenuation and enhancement characteristics of the lesions were recorded.

RESULTS

A majority (128 [86%] of 148) of patients with extrahepatic HCC foci had either intrahepatic stage IVA tumor (112 [76%] patients) or an intrahepatic stage III tumor (16 [11%] patients) at the occurrence of metastases. The most frequent site of the first detectable metastasis was the lung (58 [39%] patients). Tabulation of all extrahepatic metastatic sites showed the most common to be the lung in 81 (55%) patients, the abdominal lymph nodes in 60 (41%) patients, and the bone in 41 (28%) patients.

CONCLUSION

The lung, abdominal lymph nodes, and bone are the most common sites of extrahepatic metastatic HCC. Most extrahepatic HCC occurs in patients with advanced intrahepatic tumor stage (stage IVA). Incidental extrahepatic lesions at CT in patients with stage I or II intrahepatic HCC are unlikely to represent metastatic HCC.

Expression of the human hepatocyte growth factor cDNA in primary cultures of rat hepatocytes

Hepatocyte growth factor (HGF) and epidermal growth factor (EGF) are primary mitogens for hepatocytes in culture. hepatocytes express the HGF-receptor MET but not HGF itself. To investigate the influence of autocrine HGF expression on the proliferative potential of hepatocytes, primary cultures were submitted to retrovirus-mediated transduction of the human hgf (huHGF) cDNA. Expression of the transduced cDNA revealed a minimum 2-fold increase in HGF-mRNA, whereas expression of the Escherichia coli beta-galactosidase gene remained even. Estimation of huHGF copy numbers showed there was a minimum 4-fold increase, suggesting an increase in the population of transduced cells. Immunoprecipitation of excreted huHGF and growth bioassays proofed that HGF was present and functional. HGF is excreted into the medium and therefore, by diffusion, available to transduced and non-transduced cells. The increase in huHGF-transduced cells suggests that the autocrine pathway as opposed to the paracrine pathway, which are both present at the same time, confers a growth advantage to these cells.

Expression of HGF and cMet in the developing and adult brain

Hepatocyte growth factor (HGF) was recently recognized as a potential neurotrophic factor in the developing brain. We studied expression of HGF and its receptor using Northern blot analysis and in situ hybridization for mRNA and double immunofluorescent laser confocal microscopy. HGF and cMet messages were abundant in the hippocampus of both human and rat brains. In this region, both messages were localized in the neuronal layer. Segregation of HGF predominantly in the hippocampal CA3-4 and cMet in CA1 supports the hypothesis that HGF may mediate important neurotrophic functions in both developing and adult brains.

Population expansion, clonal growth, and specific differentiation patterns in primary cultures of hepatocytes induced by HGF/SF, EGF and TGF alpha in a chemically defined (HGM) medium

Mature adult parenchymal hepatocytes, typically of restricted capacity to proliferate in culture, can now enter into clonal growth under the influence of hepatocyte growth factor (scatter factor) (HGF/SF), epidermal growth factor (EGF), and transforming growth factor alpha (TGFalpha) in the presence of a new chemically defined medium (HGM). The expanding populations of hepatocytes lose expression of hepatocyte specific genes (albumin, cytochrome P450 IIB1), acquire expression of markers expressed by bile duct epithelium (cytokeratin 19), produce TGFalpha and acidic FGF and assume a very simplified morphologic phenotype by electron microscopy. A major change associated with this transition is the decrease in ratio between transcription factors C/EBPalpha and C/EBPbeta, as well as the emergence in the proliferating hepatocytes of transcription factors AP1, NFkappaB. The liver associated transcription factors HNFI, HNF3, and HNF4 are preserved throughout this process. After population expansion and clonal growth, the proliferating hepatocytes can return to mature hepatocyte phenotype in the presence of EHS gel (Matrigel). This includes complete restoration of electron microscopic structure and albumin expression. The hepatocyte cultures however can instead be induced to form acinar/ductular structures akin to bile ductules (in the presence of HGF/SF and type I collagen). These transformations affect the entire population of the hepatocytes and occur even when DNA synthesis is inhibited. Similar acinar/ductular structures are seen in embryonic liver when HGF/SF and its receptor are expressed at high levels. These findings strongly support the hypothesis that mature hepatocytes can function as or be a source of bipotential facultative hepatic stem cells (hepatoblasts). These studies also provide evidence for the growth factor and matrix signals that govern these complex phenotypic transitions of facultative stem cells which are crucial for recovery from acute and chronic liver injury.

Pulsatile perfusion system for ex vivo investigation of biochemical pathways in intact vascular tissue

We have constructed and performed initial validation of an innovative perfusion system that allows exposure of intact segments of vascular tissue to realistic physiological and hemodynamic environments ex vivo. Computer-controlled opening and closing of an in-line gate valve allows generation of arterial pressure waveforms. The control algorithm predicted resultant pressure waveforms with a high degree of accuracy (Pearson correlation coefficient > 0.97). To document vascular homeostasis ex vivo, vasomotor bioassays and morphological studies were performed. The bioassays consisted of injecting epinephrine (2 x 10(-3) mg/ml) into the perfusion system followed by acetylcholine (100 microM) while concurrently measuring vessel diameter with a laser micrometer, significant vasomotion was measured for canine carotid arteries (n = 4) bioassayed after 1, 24, and 48 h of perfusion (P < 0.03). Additionally, human saphenous vein segments were perfused for 24 h (n = 4) and viewed with laser confocal scanning microscopy and transmission electron microscopy; photomicrographs show typical vascular morphology. We conclude that the vascular perfusion system described herein is well suited for investigating the response of intact vascular tissue to hemodynamic variables.

Fusion of immunoscintigraphy single photon emission computed tomography (SPECT) with CT of the chest in patients with non-small cell lung cancer

In non-small cell lung cancer (NSCLC), accurate staging is critical in deciding between potentially curative surgery and palliative treatment. Image registration, or fusion, combines the unique functional information provided by SPECT imaging with the excellent anatomic detail offered by computed tomography (CT) or magnetic resonance imaging to better characterize the information provided by each separate modality. In this study, we explored the role of fusion of immunoscintigraphy SPECT with CT in the staging of NSCLC. We fused chest CT with 99mTc-labeled IMMU-4 anti-carcinoembryonic antigen Fab' antibody fragment SPECT in 14 patients with NSCLC using a landmark-based algorithm. The algorithm's accuracy was a measure from the center-to-center distance and the percentage overlap of two regions of interest: one drawn on CT and warped onto SPECT, the other drawn directly on the SPECT. We found that the average center-to-center distance was 1.3 +/- 0.8 pixels. Average overlap was 46 +/- 20%. CT-SPECT fusion helped differentiate tumor from normal blood pool, necrotic areas within viable tumor, tumor recurrence from scar, and malignant lymphadenopathy from hyperplasia. We conclude that fusion of CT and SPECT augments the information provided by each separate modality. Future clinical applications of fusion in NSCLC staging using immunoscintigraphy appear promising.

Crystallization and preliminary X-ray study of rat Clara cell 10,000 Mr protein

Single crystals of Clara cell 10,000 Mr protein have been grown by vapour diffusion in the presence of ammonium sulphate. The space group is P4(1)32 or P4(3)32 with unit cell dimension a = 156.9 A. Crystals diffract to about 3.8 A resolution.