Increased Hepato-Splanchnic Vasoconstriction in Diabetics during Regular Hemodialysis

BACKGROUND AND OBJECTIVES:Ultrafiltration (UF) of excess fluid activates numerous compensatory mechanisms during hemodialysis (HD). The increase of both total peripheral and splanchnic vascular resistance is considered essential in maintaining hemodynamic stability. The aim of this study was to evaluate the extent of UF-induced changes in hepato-splanchnic blood flow and resistance in a group of maintenance HD patients during regular dialysis. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS:Hepato-splanchnic flow resistance index (RI) and hepato-splanchnic perfusion index (QI) were measured in 12 chronic HD patients using a modified, non-invasive Indocyaningreen (ICG) dilution method. During a midweek dialysis session we determined RI, QI, ICG disappearance rate (kICG), plasma volume (Vp), hematocrit (Hct), mean arterial blood pressure (MAP) and heart rate (HR) at four times in hourly intervals (t1 to t4). Dialysis settings were standardized and all patient studies were done in duplicate. RESULTS:In the whole study group mean UF volume was 1.86 ± 0.46 L, Vp dropped from 3.65 ± 0.77L at t1 to 3.40 ± 0.78L at t4, and all patients remained hemodynamically stable. In all patients RI significantly increased from 12.40 ± 4.21 mmHg∙s∙m2/mL at t1 to 14.94 ± 6.36 mmHg∙s∙m2/mL at t4 while QI significantly decreased from 0.61 ± 0.22 at t1 to 0.52 ± 0.20 L/min/m2 at t4, indicating active vasoconstriction. In diabetic subjects, however, RI was significantly larger than in non-diabetics at all time points. QI was lower in diabetic subjects. CONCLUSIONS:In chronic HD-patients hepato-splanchnic blood flow substantially decreases during moderate UF as a result of an active splanchnic vasoconstriction. Our data indicate that diabetic HD-patients are particularly prone to splanchnic ischemia and might therefore have an increased risk for bacterial translocation, endotoxemia and systemic inflammation

Early detection and intervention using neutrophil gelatinase-associated lipocalin (NGAL) may improve renal outcome of acute contrast media induced nephropathy: A randomized controlled trial in patients undergoing intra-arterial angiography (ANTI-CIN Study)

<p>Abstract</p> <p>Background</p> <p>Patients with pre-existing impaired renal function are prone to develop acute contrast media induced nephropathy (CIN). Neutrophil gelatinase-associated lipocalin (NGAL), a new biomarker predictive for acute kidney injury (AKI), has been shown to be useful for earlier diagnosis of CIN; however, urinary NGAL values may be markedly increased in chronic renal failure at baseline. Results from those studies suggested that urinary NGAL values may not be helpful for the clinician. An intravenous volume load is a widely accepted prophylactic measure and possibly a reasonable intervention to prevent deterioration of renal function. The aim of our study is to evaluate NGAL as an early predictor of CIN and to investigate the clinical benefit of early post-procedural i.v. hydration.</p> <p>Methods/Design</p> <p>The study will follow a prospective, open-label, randomized controlled design. Patients requiring intra-arterial contrast media (CM) application will be included and receive standardized, weight-based, intravenous hydration before investigation. Subjects with markedly increased urinary NGAL values after CM application will be randomized into one of two study groups. Group A will receive 3-4 ml/kg BW/h 0.9% saline intravenously for 6 hours. Group B will undergo only standard treatment consisting of unrestricted oral fluid intake. The primary outcome measure will be CIN defined by an increase greater than 25% of baseline serum creatinine. Secondary outcomes will include urinary NGAL values, cystatin C values, contrast media associated changes in cardiac parameters such as NT-pro-BNP/troponin T, changes in urinary cytology, need for renal replacement treatment, length of stay in hospital and death.</p> <p>We assume that 20% of the included patients will show a definite rise in urinary NGAL. Prospective statistical power calculations indicate that the study will have 80% statistical power to detect a clinically significant decrease of CIN of 40% in the treatment arm if 1200 patients are recruited into the study.</p> <p>Discussion</p> <p>A volume expansion strategy showing a benefit from earlier intervention for patients with markedly elevated urinary NGAL values, indicating a CIN, might arise from data from this study.</p> <p>Trial registration</p> <p>ClinicalTrials.gov <a href="http://www.clinicaltrials.gov/ct2/show/NCT01292317">NCT01292317</a></p

Investigation of fibre surfaces using Atomic Force Microscopy (AFM)

Mikroskopija atomskih sil (ang.: atomic force microscopy AFM) je ena od oblik mikroskopij, ki omogoča opazovanje neprevodnih površin v nanometrskem merilu. Razvila sta jo Nobelova nagrajenca s področja fizike, Binnig in Roher [5, 6]. Od izuma leta 1986 pa do danes je mikroskop atomskih sil postal zelo pomemben inštrument v laboratorijih za fiziko trdnih snovi, kemijskih, polimernih in bioloških laboratorijih, pojavlja pa se tudi že v industriji. Izredno uporaben je na področju tekstilstva, čeprav njegovih zmožnosti na tem področju do sedaj še niso intenzivneje raziskali. Struktura vlaken je zapletena. Večinoma je morfologija površine drugačna od tiste v notranjosti. Oblika površine vlaken vpliva na procese, ki se odvijajo na mejnih površinah. Zato je toliko bolj pomembno uvajanje novih metod na področje analize površinskih lastnosti vlaken. Mikroskop atomskih sil AFM nudi informacije o fibrilni strukturi vlaken, poleg tridimenzionalne analize površine vlaken omogoča tudi merjenje medmolekulskih in medatomskih sil velikostnega reda nekaj nN. V primerjavi z elektronskim mikroskopom je priprava vzorca mnogo enostavnejša. V prispevku je opisan princip delovanja AFM in predstavljeni rezultati analize PAG filamenta. Na površini PA6 monofilamenta je vidna fibrilna struktura. Najmanjši fibrili, ki jih je mogoče razločiti, imajo premer le nekaj 10 nm. Združujejo se v večje fibrilne snope, ki v najširših predelih merijo 1 do 2 μm. Praznine in vdolbine na površini so različno velike (30-200 nm) in so okrogle ali ovalne oblike, usmerjene v smeri osi vlakna. Površina filamenta je v smeri osi vlakna manj razbrazdanavišinska razlika med najnižjimi in najvišjimi področji znaša v prečni smeri do 70 nm, v vzdolžni smeri pa do 30 nm.Atomic force microscopy (AFM) is one of the most modem types of microscopy enabling nanoscale imaging of both conducting and insulating surfaces. It was developed by the Nobel Prize winners in physics, Binning and Roher. Since its invention in 1986 the atomic force microscope has become useful in industry and as a very important laboratory instrument in different fields of research such as physics, chemistry, polymers and biology. This method can also be applied in textile research although the researchers working in this field are few. The structure of fibres is very complex. In most cases the morphology of the fibre surface differs from the morphology of the core. The characteristics of the fibre surface influence the processes at the interfaces which makes any surface analysis of the fibres extremely important, and the introduction of new methods valuable. AFM gives a three-dimensional nanoscale image of the surface thus revealing additional information about the fibrillar structure of the fibres. It can also be used for intermolecular and intercolloidal force measurements sensing forces even smaller than 1 nN. A sample preparation prior to imaging is much simpler compared to electron microscopy. In this paper the basic AFM operation is discussed and the topography of PA6 filament is analysed using AFM. The fibrillar structure can be seen at the fibre surface. The smallest detectable fibrils are in the range of about 10 nm in width. They are congregated in bigger fibril bundles having up to 1-2 μm in diameter. Cavities and niches vary in width (30-200 nm) and shape (round or oblong). They are oriented in the direction of the fibre. The surface of the filament is less furrowed in the direction of the fibrethe difference in height between the highest and the lowest regions alongside is only up to 30 nm and transverse up to 70 nm

Eight Up-Coming Biotech Tools to Combat Climate Crisis

Biotechnology has a high potential to substantially contribute to a low-carbon society. Several green processes are already well established, utilizing the unique capacity of living cells or their instruments. Beyond that, the authors believe that there are new biotechnological procedures in the pipeline which have the momentum to add to this ongoing change in our economy. Eight promising biotechnology tools were selected by the authors as potentially impactful game changers: (i) the Wood-Ljungdahl pathway, (ii) carbonic anhydrase, (iii) cutinase, (iv) methanogens, (v) electro-microbiology, (vi) hydrogenase, (vii) cellulosome and, (viii) nitrogenase. Some of them are fairly new and are explored predominantly in science labs. Others have been around for decades, however, with new scientific groundwork that may rigorously expand their roles. In the current paper, the authors summarize the latest state of research on these eight selected tools and the status of their practical implementation. We bring forward our arguments on why we consider these processes real game changers

A Simple and Straightforward Method for Activity Measurement of Carbonic Anhydrases

Carbonic anhydrase (CA) is an enzyme of high interest due to its high implications relative to the medical and environmental sectors. In the current paper, an enzyme assay for the determination of CA activity is proposed and it is characterized by its simplicity and high practicability. It permits the straightforward comparison of CAs performance in physiological conditions. The methodology and the theoretical background of the evaluation method are explained in detail. Moreover, the presumed advantages over alternative assays are discussed. The assay has proven to be particularly useful for the screening of CA activity with respect to their application in CO2, capturing processes for further utilization or storage

Ethanol causes protein precipitation--new safety issues for catheter locking techniques.

OBJECTIVE: The ethanol lock technique has shown great potential to eradicate organisms in biofilms and to treat or prevent central venous catheter related infections. Following instillation of ethanol lock solution, however, the inherent density gradient between blood and ethanol causes gravity induced seepage of ethanol out of the catheter and blood influx into the catheter. Plasma proteins so are exposed to highly concentrated ethanol, which is a classic agent for protein precipitation. We aimed to investigate the precipitating effect of ethanol locks on plasma proteins as a possible cause for reported catheter occlusions. METHODS: Plasma samples were exposed in-vitro to ethanol (concentrations ranging from 7 to 70 v/v%) and heparin lock solutions. In catheter studies designed to mimic different in-vivo situations, the catheter tip was placed in a plasma reservoir and the material contained within the catheter was analyzed after ethanol lock instillation. The samples underwent standardized investigation for protein precipitation. RESULTS: Protein precipitation was observed in plasma samples containing ethanol solutions above a concentration of 28%, as well as in material retrieved from vertically positioned femoral catheters and jugular (subclavian) catheters simulating recumbent or head down tilt body positions. Precipitates could not be re-dissolved by dilution with plasma, urokinase or alteplase. Plasma samples containing heparin lock solutions showed no signs of precipitation. CONCLUSIONS: Our in-vitro results demonstrate that ethanol locks may be associated with plasma protein precipitation in central venous catheters. This phenomenon could be related to occlusion of vascular access devices locked with ethanol, as has been reported. Concerns should be raised regarding possible complications upon injection or spontaneous gravity induced leakage of such irreversibly precipitated protein particles into the systemic circulation. We suggest limiting the maximum advisable concentration of ethanol to 28 v/v% in catheter lock solutions