Validating a New Method for Ergonomic Evaluation of Human Computer Interfaces

Human Computer Interaction (HCI) is the basic component of using all kinds of information technological systems. This is why examination methods capable of assessing factors influencing users´ performance, current mental effort and well-being during HCI in a well established and scientifically sound way have got great importance. The `current´ attribute for mental effort means here that in addition to overall measures concerning a relatively longer period - several hours or a whole working day - such methods should also provide informative and valid data about users´ mental investments at the temporal resolution corresponding to users´ elementary actions as keystrokes, mouse clicks, etc. It has already been shown that under certain circumstances Heart Period Variability (HPV) could be a measure of momentary mental effort. This paper gives a short overview of applications of HPV in ergonomics in general, and based on empirical evidence intends to prove that this methodology, after a careful adaptation, could be an especially adequate and powerful technique for monitoring mental effort in HCI. The paper outlines the main principles of a new method and the related components of the integrated system (INTERFACE) developed by us for investigating HCI from several aspects with emphasis on assessing mental effort. A detailed application example is also provided

An improved technique for isolated perfusion of rat livers and an evaluation of perfusates

We have modified the apparatus for isolated rat liver perfusion (IPRL) in order to be able to perform two perfusions simultaneously. In addition, we studied the quality and stability of livers by comparison of five different perfusates: Blood (Group A), Original Krebs Henseleit buffer (Group B), Krebs buffer with glucose (Group C) or bovine serum albumin (BSA) added, (Group D). In a last group (E) albumin, glucose, and taurocholic acid were added to Krebs. After 180 min of perfusion, livers perfused with solutions including 2% albumin (Group D, E) had a significantly higher release of hepatocellular and endothelial cell (purine nucleoside phosphorylase) enzymes and lower bile production as compared to Groups A, B, and C (P < 0.0001). Increasing levels of purine nucleoside phosphorylase (PNP), a reflection of damage to the microvascular endothelium preceded the increases in hepatocellular enzymes. Histologically, damages of sinusoidal endothelial cells and hepatocytes are appreciated moderate to severe in Groups D and E, slight to mild in Groups A and B, and not significant in Group C. These results suggest that BSA may have toxic effects to the perfused rat liver. These data also confirm that the IPRL modified for simultaneous perfusion of two livers is efficient, and that with this technique the rat liver can be optimally perfused for up to 3 hr with oxygenated Krebs Henseleit buffer without additives (Group B) and without blood. These two improvements should allow those performing studies with perfused rat livers to obtain data in a more efficient, accurate, and inexpensive fashion. © 1992

Inhibition of free radical generation and improved survival by protection of the hepatic microvascular endothelium by targeted erythrocytes in orthotopic rat liver transplantation

The capacity of specifically targeted erythrocytes to inhibit free radical—mediated injury to the endothelial cell after cold preservation, and improve liver function was studied in two experimental models: An isolated perfused rat liver (IPRL) system and syngeneic orthotopic rat liver transplantation. In the IPRL model, livers were preserved in University of Wisconsin solution for 24 h at 4°C. At the end of the preservation period, livers were flushed with lactated Ringer’s (control), immu- noerythrocytes (IES), or blank intact erythrocytes prior to warm reperfusion for 2 h using an assanguinous Krebs-Henseleit buffer. Production of superoxide (O2-) anion during warm reperfusion in the IES-treated liver was reduced by 65% as compared with controls (P<0.001) and by 74% (P<0.001) when compared with blank erythrocyte—treated livers. Endothelial cell preservation, as assessed by levels of purine nucleoside phos- phorylase (PNP), was much better in the IES-treated group (P<0.001) when compared with untreated livers. Hepatocellular preservation was markedly improved in the IES-treated livers. In the syngeneic liver transplantation model, livers were preserved in UW solution for 24 h at 4°C. Prior to implantation, livers were flushed with 5 ml of cold lactated Ringer’s or immunoerythrocytes. Survival after three weeks was 60% in the IES-treated group and 30% in the untreated group. Survival in the IES-treated group was not significantly different from a control (no preservation) group. IES-treated livers in both models demonstrated better endothelial cell integrity and ultimate liver function. IES treatment therefore appears to protect the hepatic microvascular endothelial cell from reperfusion injury and could prove to be an easy reproducible method of donor organ preparation after cold preservation. © 1990 by Williams & Wilkins

Preoperative fibrinogen/CRP score predicts survival in upper urothelial tract carcinoma patients undergoing radical curative surgery

Purpose Upper tract urothelial carcinoma (UTUC) represents an often aggressive malignancy associated with poor prognosis. Therefore, finding reliable prognostic biomarkers in patients undergoing curative surgery for improved risk stratification is crucial. We evaluated the prognostic value of the Fibrinogen/C-reactive protein (FC)-score in a cohort of surgically treated UTUC patients. Methods 170 patients with radiologically and histologically verified UTUC who underwent radical curative surgery between 1990 and 2020, were included. The FC-score was calculated for each patient, with patients receiving 1 point each if Fibrinogen and/or CRP levels were elevated above the 25th or 75th percentile, respectively. Patients were divided into three subgroups according to their FC-score of 0, 1 or 2 point(s). Kaplan–Meier analysis, uni- and multivariable Cox proportional hazard models were implemented. We determined cancer-specific survival (CSS) as primary endpoint, whereas overall survival (OS) and recurrence-free survival (RFS) were considered secondary endpoints. Results High FC-score (2 points) was significantly associated with adverse histological features such as vascular invasion (OR = 4.08, 95%CI 1.18–14.15, p = .0027) and tumour necrosis (OR = 6.67, 95%CI 1.35–32.96, p = 0.020). Both, uni- and multivariable Cox proportional hazard models showed the FC-score as a significant predictor for CSS (univariable analysis: FC-score = 1: HR = 1.90, 95%CI 0.92–3.93, p = 0.085 | FC-score = 2: HR = 2.86, 95%CI 1.22–6.72, p = 0.016). Furthermore, in univariable analysis, patients with higher FC-score had significantly shorter OS (FC-score = 1: HR = 1.32, 95%CI 0.70–2.49, p = 0.387 | FC-score = 2: HR = 2.19, 95%CI 1.02–4.67, p = 0.043). However, this did not prevail in multivariable analysis. Conclusion The FC-score represents a novel potential biomarker in patients with UTUC undergoing radical curative surgery

A modified apparatus for dual, sterilized, isolated perfusion of the rat liver

The isolated perfused rat liver (IPRL) has proven to be a useful model for the study of physiology and pathology of the liver. For research in nonparenchymal cell (NPC) function that includes measurement of cytokine production (eg, TNF), it is necessary to have a sterilized perfusion system. We have modified the IPRL apparatus so as to be able to perform sterile perfusions of two livers simultaneously. The perfusion apparatus is a recirculating closed system in which the oxygenator is a plastic container separated into two chambers by a fenestrated plastic wall. A disposable macropore filter functions as both a bubble trap and perfusate filter. The sterilization process is done by immersing the various components in Benz-All solution. The tubing is disinfected by irrigation with 10% Clorox followed by 0.9% sodium chloride solution. The perfusate used is filter-sterilized Krebs buffer solution containing 0.5 g Mandol/250 mL perfusate. Not only can two organs be conveniently perfused simultaneously, but the entire system can be reliably sterilized for up to 20 consecutive perfusions. Bile production is higher and more stable with less leakage of intracellular enzymes. Many of the components are disposable and can be altered to suit the needs of a particular experiment. © 1990 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted

Impact of perioperative chemotherapy on survival in patients with advanced primary urethral cancer: results of the international collaboration on primary urethral carcinoma

This is the first series that suggests a prognostic benefit of neoadjuvant treatment in a consecutive series of patients who underwent perioperative chemotherapy plus surgery for advanced primary urethral carcinoma. Further studies should yield a better understanding of how perioperative chemotherapy exerts a positive effect on survival in order to selectively advocate its use in advanced primary urethral carcinom