Weathering of Bi-bearing tennantite Keim, Maximilian F.; Staude, Sebastian; Marquardt, Katharina ...
Chemical geology,
11/2018, Letnik:
499
Journal Article
Recenzirano
The tennantite-tetrahedrite solid-solution series called fahlore; (Cu,Ag)6Cu4(Fe,Zn,Cu,Hg,Cd)2(Sb,As,Bi,Te)4(S,Se)13 is widespread in many geological environments. Since it incorporates heavy metals ...and toxic elements, a better understanding of its weathering behaviour and details of its weathering process is important to evaluate environmental risks (emerging mainly from the mobilization of As-Sb-Bi) and local and global metal fluxes in stream waters and oceans. In this study, weathering of Bi-rich members of this mineral group was investigated using microscopy, EMPA, SEM, TEM, LA-ICP-MS, Raman, μXRD, and MLA.
Observations reveal a succession of four distinct stages of weathering: During stage 1, irregular tubes within fahlore show an assemblage of nm- to μm-sized roméite group minerals, tripuhyite, crystalline Cu-oxides and Cu-sulfides. Stage 1 textures and secondary sulfides indicate a low redox-potential and a low fluid/rock ratio, typical of cementation zones. Mass balance calculations show that during this stage all Zn and the majority of As and S are released to the weathering fluids. Bismuth is immobile in this stage and Sb and Fe are immobile, if Bi is sufficiently available from fahlore, but both are partly released, if the fahlore did not contain sufficient Bi. During stage 2, amorphous and nano-crystalline arsenates replace fahlore as weathering fronts. Such assemblages indicate a higher redox-potential than in stage 1, typical for oxidation zones. Mass balance calculations reveal that Zn, Sb, S and partially Cu are lost. Arsenic and Bi are immobile. Stage 3 occurs only locally, dissolving former weathering stages and/or precipitating amorphous Cu-arsenates/silicates reflecting processes in micro-compartments, not characteristic for the general weathering process. Stage 4 is characterized by the formation of crystalline Bi-, Cu-, Ba-, Ca- or Al-bearing arsenates and Cu-carbonates, spatially independent of the precursor fahlore. Copper and As originate from older weathering assemblages, whereas many other elements are derived externally (Ca, Ba, Al). This stage reflects the increasing importance of the local host rock and gangue mineralogy, as it is typical in near-surface environments of oxidation zones or on mine dumps, where elements are highly mobile and a high fluid/rock ratio prevails (gossan mineralization).
The temporal evolution of fahlore weathering textures reflects the transition from fresh ore to cementation zone, oxidation zone and gossan assemblages in one hand specimen. Thus, one fahlore grain can record the uplift and erosion and the increasing fluid/rock interaction of a weathered ore deposit with time. Tube-like textures similar to the ones observed in stage 1 have been reported from other weathering environments and from a variety of element, oxide, arsenide, and sulfide phases. They also were produced during experimental work in ilmenite. This is clear evidence, that the diffusive process during the first contact with alteration fluids is a basic physical process and that it is not only valid for fahlore.
The importance of Bi to stabilize Sb-bearing supergene phases (and thereby for the immobilization of toxic Sb) shown in the present work, may stimulate further investigations on the environmental immobilization of toxic elements by “companion metals” during weathering processes.
Necrotizing fasciitis (NF) is a rare but lethal soft-tissue infection. There is still a paucity of information regarding the diagnostic tools and therapeutic strategies for the treatment of this ...devastating disease. This study aims to identify important perioperative parameters related to necrotizing fasciitis and to assess their relevance in terms of identifying NF.
We retrospectively analyzed patients who underwent surgical exploration for suspected necrotizing fasciitis at a tertiary referral center, to explore the clinical features and factors related to the presence of necrotizing fasciitis and mortality.
Between 2010 and 2017, 88 patients underwent surgical exploration for suspected NF. The infection occurred in the lower extremities in 48 patients, in the thoracocervical region in 18 patients, and the perineum and abdomen in 22 patients. Histological evidence of NF was present in 59 of 88 patients. NF was associated with a longer hospital stay and ICU stay (p = 0.05 and 0.019 respectively) compared to patients without NF. ROC analysis showed that only macroscopic fascial appearance could discriminate patients with histological evidence of NF. Moreover, multivariate logistic regression revealed, that liver failure (p = 0.019), sepsis (p = 0.011), positive Gram stain (p = 0.032), and macroscopic fascial appearance (p <0.001) were independent prognostic parameters for histological evidence of NF.
Intraoperative tissue evaluation by an experienced surgeon is the most important diagnostic tool in identifying necrotizing fasciitis. An intraoperative Gram stain is an independent prognostic tool and therefore its use can be recommended especially in case of clinical uncertainty.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In this paper, prediction models are proposed which allow the mineralogical characterization of particle systems observed by X-ray micro tomography (XMT). The models are calibrated using 2D image ...data obtained by a combination of scanning electron microscopy and energy dispersive X-ray spectroscopy in a planar cross-section of the XMT data. To reliably distinguish between different minerals the models are based on multidimensional distributions of certain particle characteristics describing, for example, their size, shape, and texture. These multidimensional distributions are modeled using parametric Archimedean copulas which are able to describe the correlation structure of complex multidimensional distributions with only a few parameters. Furthermore, dimension reduction of the multidimensional vectors of particle characteristics is utilized to make non-parametric approaches such as the computation of distributions via kernel density estimation viable. With the help of such distributions the proposed prediction models are able to distinguish between different types of particles among the entire XMT image.
Metabolism is a critical basis for immune cell functionality. It was recently shown that NK cell subsets from peripheral blood modulate their expression of nutrient receptors following cytokine ...stimulation, demonstrating that NK cells can adjust to changes in metabolic requirements. As nutrient availability in blood and tissues can significantly differ, we examined NK cells isolated from paired blood-liver and blood-spleen samples and compared expression of the nutrient transporters Glut1, CD98 and CD71. CD56bright tissue-resident (CXCR6+) NK cells derived from livers and spleens expressed lower levels of Glut1 but higher levels of the amino acid transporter CD98 following stimulation than CD56bright NK cells from peripheral blood. In line with that, CD56dim NK cells, which constitute the main NK cell population in the peripheral blood, expressed higher levels of Glut1 and lower levels of CD98 and CD71 compared to liver CD56bright NK cells. Our results show that NK cells from peripheral blood differ from liver- and spleen-resident NK cells in the expression profile of nutrient transporters, consistent with a cell-adaptation to the different nutritional environment in these compartments.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
To determine whether a new surgical method using a flexible endoscope (FlexVATS) to perform sparing debridement and apply negative-pressure therapy without extensive decortication may be an ...alternative treatment option for empyema. Surgical treatment of pleural empyema is associated with considerable postoperative complications and mortality rates, and alternative treatment options are being explored to improve patient outcomes. This was a prospective case series. Seventeen consecutive patients treated with FlexVATS between February 2021 and August 2022 were included in the study. Only patients for whom FlexVATS was the first therapeutic intervention for pleural empyema were included. Treatment success, defined as infection resolution, was the primary endpoint of the study. The secondary endpoints were length of hospital stay, 90-day mortality, and empyema cavity volume reduction. Patients who had previously been treated for pleural empyema by either drainage or surgery were excluded. The trial was performed as a single-centre study at a tertiary medical centre in Germany. In total, 17 patients with pleural empyema were included in the study. The median (IQR) duration of vacuum treatment was 15 days (8-35 days). Twelve of the 17 (71%) patients were successfully treated, and a significant reduction in the empyema cavity volume was observed. 41% of the dressing changes were performed outside the operating room. Compared with a historic cohort of conventionally treated patients (decortication via VATS or thoracotomy), the 90-day mortality rates tended to be lower without reaching statistical significance. Three patients (18%) died in hospital during treatment. No negative pressure-therapy-related complications were observed. FlexVATS therapy is a promising alternative therapy for both healthy and debilitated patients with pleural empyema. Larger randomised trials are required to validate this treatment option.
Introduction
Lysophosphatidylcholine acyltransferase 1 (LPCAT1) has repeatedly been suggested to be associated with tumorigenesis. To evaluate the role of LPCAT1 in esophageal cancer, LPCAT1 ...immunostaining was analyzed on a tissue microarray containing samples from esophageal cancer patients.
Results
In benign esophageal tissue, LPCAT1 staining was detectable in low intensities. LPCAT1 staining was increased in malignant as compared to benign esophageal tissue and was found in high intensity in 26.4% of 288 interpretable esophageal adenocarcinomas (EACs) and in 23.2% of 211 squamous cell carcinomas (ESCCs). Increased LPCAT1 staining was linked to undifferentiated tumor grading in both subtypes of EACs and ESCCs (
p
= 0.0273 and
p
= 0.0085).
Conclusion
However, LPCAT1 was not associated with prognosis of EAC and ESCC patients (
p
= 0.6838 and
p
= 0.4695) and thus cannot be considered a prognostic biomarker in esophageal cancers.
Severe acute pancreatitis is still a potentially life threatening disease with high mortality. The aim of this study was to evaluate the therapeutic effect of thoracic epidural anaesthesia (TEA) on ...survival, microcirculation, tissue oxygenation and histopathologic damage in an experimental animal model of severe acute pancreatitis in a prospective animal study.
In this study, 34 pigs were randomly assigned into 2 treatment groups. After severe acute pancreatitis was induced by intraductal injection of glycodesoxycholic acid in Group 1 (n = 17) bupivacaine (0.5%; bolus injection 2 ml, continuous infusion 4 ml/h) was applied via TEA. In Group 2 (n = 17) no TEA was applied. During a period of 6 hours after induction, tissue oxygen tension (tpO2) in the pancreas and pancreatic microcirculation was assessed. Thereafter animals were observed for 7 days followed by sacrification and histopathologic examination.
Survival rate after 7 days was 82% in Group 1 (TEA) versus 29% in Group 2: (Control) (P <0.05). Group 1 (TEA) also showed a significantly superior microcirculation (1,608 ± 374 AU versus 1,121 ± 510 AU; P <0.05) and tissue oxygenation (215 ± 64 mmHg versus 138 ± 90 mmHG; P <0.05) as compared to Group 2 (Control). Consecutively, tissue damage in Group 1 was reduced in the histopathologic scoring (5.5 (3 to 8) versus 8 (5.5 to 10); P <0.05).
TEA led to improved survival, enhanced microcirculatory perfusion and tissue oxygenation and resulted in less histopathologic tissue-damage in an experimental animal model of severe acute pancreatitis.
Despite improvements in diagnosis, intensive-care medicine and surgical technique, the mortality of patients with secondary peritonitis is still high. Early and aggressive empiric antibiotic ...treatment has strong impact on the outcome. This retrospective study investigates bacterial and fungal pathogens and their antibiotic sensitivity in patients with secondary peritonitis. All patients that underwent emergency laparotomy due to secondary peritonitis at the Department of Surgery, University Medical Center Hamburg-Eppendorf between 2005 and 2015 were reviewed and overall 414 patients were included. We correlated the intra-abdominal localization of the organ perforation with intraoperative microbiological findings and corresponding sensitivities to relevant antibiotics. Overall, the most common findings were Escherichia coli (39%) and other Enterobacterica (24%). Depending on the location of the perforation, Cefuroxime/Metronidazole and Cefutaxime/Metronidazole were effective (based on in vitro susceptibility testing) in only 55-73% of the patients, while Meropenem/Vancomycin was able to control the peritonitis in more than 98% of the patients; independent of the location. Besides early source control, appropriate empiric treatment plays a pivotal role in treatment of secondary peritonitis. We are able to show that the frequently used combinations of second or third generation Cephalosporins with Metronidazole are not always sufficient, which is due to the biological resistance of the bacteria. Further clinical studies are needed to determine whether calculated use of broad-spectrum antibiotics with a sensitivity rate > 99%, such as Carbapenem plus Vancomycin, can improve overall survival rates in critically ill patients with secondary peritonitis.
Introduction
The role of CD147 as an important indicator of tumor prognosis remains controversially discussed in literature. We focused on the prognostic significance of CD147 expression in ...esophageal cancer patients. While some studies report that CD147 is an unfavorable prognostic factor in esophageal squamous cell carcinoma, others showed no significant correlation. However, only one study draws attention to the significance of CD147 in esophageal adenocarcinoma, which is one of the most rapidly increasing neoplasms in the western world.
Methods
To finally clarify the impact of CD147 as a prognostic factor, especially for esophageal adenocarcinomas, we analyzed CD147 expression in a tissue microarray of 359 esophageal adenocarcinomas and 254 esophageal squamous cell cancer specimens. For the immuno-histochemical analysis, we used a primary antibody specific for CD147. Staining intensity and proportion of positive tumor cells were scored (negative, weak, moderate, strong staining). These findings were compared to normal esophageal tissue and correlated to the histopathological tumor phenotype and survival data.
Results
CD147 expression was detectable in weak intensities in benign esophageal tissue (85.78%) and expressed in predominately moderate to strong intensities in esophageal cancer (88.34%). Strong CD147 immunostaining was linked to increased infiltration depth (
p
= 0.015) and differentiation (
p
= 0.016) in esophageal squamous cell cancer but revealed no significant correlation with histopathology of adenocarcinoma. Moreover, CD147 intensity was unrelated to overall survival in this collective for both subtypes of esophageal cancer.
Conclusion
Thus, our data show that CD147 has no prognostic value, neither in esophageal adenocarcinoma nor squamous cell carcinoma.
Objectives
Diverting esophagectomies in cases of benign esophageal perforations remain rare but potentially life saving procedures. Usually, an esophagostoma and a feeding jejunostomy or gastrostomy ...are created, and patients are given time to recover from the emergency situation. However, little is known about morbidity and mortality as well as the optimal timing for a staged reconstruction.
Methods
Patients with benign esophageal perforations were selected from our retrospective database. Perforations in esophageal malignancies were excluded to avoid bias on patients’ general outcome. Clinical parameters and especially, the influence of the nutritional status indicated by the BMI (Body Mass Index) as well as serum albumin levels (g/l) were analyzed.
Results
A total of 24 patients with diverting esophagectomies were identified. Of these, 13 (54.2%) patients received a staged reconstruction after a median of 143.0 days. Patients presenting for their staged reconstruction demonstrated a significantly decreased level of their BMI (
p
= 0.026) as compared to their prior hospitalization. Interestingly, the relative decrease of BMI (8.5 kg/m
2
vs. 4.3 kg/m
2
) and albumin levels (6.5 g/l vs. 0.0 g/l) was significantly different in patients with or without anastomotic leaks between both surgeries (
p
= 0.021;
p
= 0.034, respectively). In addition, higher rates of overall complications were associated with an increased rate of malnutrition.
Conclusions
The relative amount of malnutrition indicated by BMI or serum albumin levels influences the rate of anastomotic leaks and general complications in patients with staged reconstruction after diverting esophagectomy for non-malignant esophageal perforations. Hence, reconstruction should be done as fast as possible to reduce the amount of malnutrition and a frequent assessment of the nutritional status must be done during recovery from the emergency surgery.
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