Gas chromatographic determination of acetic acid in industrial atmosphere and waste water.

A gas chromatographic (GC) method is presented for the specific determination of acetic acid in air and total ionic acetate (as acetic acid) in industrial waste water. Atmospheric air samples are collected in fritted midget bubblers containing aqueous sodium carbonate solution; wastewater samples are treated directly with sodium carbonate. Both air and water samples are concentrated by evaporation of water, and the acetic acid is regenerated by the addition of hydrochloric acid. The amount of acetic acid is determined quantitatively on a porous polymer packed column by internal standardization with propionic acid. GC conditions are described for the suppression of "ghosting" and "tailing" caused by adsorption phenomena associated with the GC behavior of organic acids.     

Extracorporal therapy with AN69 membranes in combination with ACE inhibition causing severe anaphylactoid reactions: still a current problem?

The negatively charged membrane AN69 is known to evoke anaphylactoid reactions both without and with concomitant ACE inhibition. Underlying reasons are mainly the induction of bradykinin release due to the negatively charged membrane and the reduced degradation of bradykinin due to ACE inhibition. This complication has been reported repeatedly, but anaphylactoid reactions still occur in clinical practice. We recently had to treat two patients who suffered anaphylactoid reactions during extracorporal therapy with an AN69 membrane and simultaneous ACE inhibition. The first incident occurred in a patient on hemodialysis, the second was in a patient on continuous venovenous hemofiltration. An anaphylactoid reaction induced by an AN69 membrane during continuous, extracorporal treatment in combination with ACE inhibition has not been reported so far. Our report intends to serve as a reminder that the potentially lethal combination of AN69 membranes with ACE inhibitor treatment should be avoided.     

Effects of bicarbonate- and lactate-buffered replacement fluids on cardiovascular outcome in CVVH patients

BACKGROUND: Bicarbonate-buffered replacement fluid (RF-bic) in continuous venovenous hemofiltration (CVVH) may be superior to lactate-buffered replacement fluid (RF-lac) in acute renal failure. In an open, randomized, multicenter study, we investigated the effects of RF-bic and RF-lac on cardiovascular outcome in patients requiring CVVH following acute renal failure. METHODS: One hundred seventeen patients between the age of 18 and 80 years were randomized to CVVH either with RF-bic (N = 61) or RF-lac (N = 56). Patients were treated with CVVH for five days or until either renal function was restored or the patient was removed from the study. Data were analyzed on day 5 or according to the "last observation carried forward" (LOCF) option. Adverse events were classified according to the WHO-Adverse Reaction Terminology system. RESULTS: Blood lactate levels were significantly lower and blood bicarbonate levels were significantly higher in patients treated with RF-bic than in those treated with RF-lac (lactate, 17.4 +/- 8.5 vs. 28.7 +/- 10.4 mg/dL, P < 0.05; bicarbonate, 23.7 +/- 0.4 vs. 21.8 +/- 0.5 mmol/L, P < 0. 01). The number of hypotensive crises was lower in RF-bic-treated patients than in RF-lac-treated patients (RF-bic 14 out of 61 patients, RF-lac in 29 out of 56 patients; 0.26 +/- 0.09 vs. 0.60 +/- 0.31 episodes per 24 h, P < 0.05). Nine out of 61 patients (15%) treated with RF-bic and 21 out of 56 patients (38%) treated with RF-lac developed cardiovascular events during CVVH therapy (P < 0. 01). A multiple regression analysis showed that the occurrence of cardiovascular events was dependent on replacement fluid and previous cardiovascular disease and not on age or blood pressure. Patients with cardiac failure died less frequently in the group treated with RF-bic (7 out of 24, 29%) than in the group treated with RF-lac (12 out of 21, 57%, P = 0.058). In patients with septic shock, lethality was comparable in both groups (RF-bic, 10 out of 27, 37%; RF-lac, 7 out of 20, 35%, P = NS). CONCLUSIONS: The results show that the administration of RF-bic solution was superior in normalizing acidosis of patients without the risk of alkalosis. The data also suggest that the use of RF-bic during CVVH reduces cardiovascular events in critically ill patients with acute renal failure, particularly those with previous cardiovascular disease or heart failure.     

Genetic determinants of plasma lipid response to dietary intervention: the role of the APOA1/C3/A4 gene cluster and the APOE gene

Polymorphisms at the APOA1/C3/A4 gene cluster and the APOE gene have been extensively studied in order to examine their potential association with plasma lipid levels, coronary heart disease risk and more recently with inter-individual variability in response to dietary therapies. Although the results have not been uniform across studies, the current research supports the concept that variation at these genes explains a significant, but still rather small, proportion of the variability in fasting and postprandial plasma lipid responses to dietary interventions. This information constitutes the initial frame to develop panels of genetic markers that could be used to predict individual responsiveness to dietary therapy for the prevention of coronary heart disease. Future progress in this complex area will come from experiments carried out using animal models, and from carefully controlled dietary protocols in humans that should include the assessment of several other candidate gene loci coding for products that play a relevant role in lipoprotein metabolism (i.e. APOB, CETP, LPL, FABP2, SRBI, ABC1 and CYP7).     

Targeted disruption of GAP-43 in P19 embryonal carcinoma cells inhibits neuronal differentiation. As well as acquisition of the morphological phenotype

GAP-43 is expressed in proliferating neuroblasts in vivo and in vitro, but its role during early neurogenesis has not been investigated. Here we show that neuroectodermal differentiation stimulated by retinoic acid (RA) in the embryonal carcinoma (EC) line P19 is accompanied by upregulation of GAP-43 expression in neuroepithelial precursor cells. In contrast, when upregulation of GAP-43 expression was prevented in 3 independent P19 lines because of a targeted insertion into the gene, generation of neuroepithelial precursors was inhibited. Consequently, neuronal number was significantly decreased, neuronal morphology was abnormal and fewer than 20% of all neurons were able to initiate neuritogenesis. Extracellular matrix (ECM) was unable to rescue initiation of neuritogenesis in the mutant cells, however those neurites that were extended responded normally to ECM-stimulated neurite outgrowth-promoting signals. These data suggest that GAP-43 function is required for commitment to a neuronal phenotype as well as initiation of neurite extension. However, stimulation of neurite outgrowth by ECM in P19s occurs independently of GAP-43.     

A quality assessment tool to evaluate tocolytic studies

Over the past 15 years, the use of β-agonists has declined worldwide. Following the Royal College of Obstetricians and Gynaecologists guidelines in 2002, clinicians in the UK and beyond were faced with the dilemma of continuing to use β-agonists, desist from using tocolytic therapy completely or choosing to change to atosiban or calcium channel blockers (CCBs). While grade A level 1 evidence exists to show that atosiban is significantly more efficacious than placebo and significantly safer than β-agonists for the treatment of spontaneous preterm labour, the evidence for CCBs, such as nifedipine, is much less robust and no placebo-controlled trials have been performed. Published studies on nifedipine are largely investigator-led studies of small sample size, which lack sufficient power. As a result, most of the evidence has been based on meta-analyses of these studies, which look retrospectively at pooled data and are only as good as the quality of the studies included. In light of this, a tool was developed to produce a systematic review of studies on tocolytic effectiveness, which can and should be applied to all tocolytics and which considered both method- and topic-specific markers of quality. In the process of applying this tool to nifedipine, an extensive literature search identified 31 studies for a systematic review of the quality of nifedipine studies assessed by eight paired reviewers with wide experience in the subject of spontaneous preterm labour and preterm birth. Forty topic- and method-specific items of quality were assessed. The paucity of good quality studies of nifedipine used for the treatment of spontaneous preterm labour should be highlighted in meta-analyses or systematic reviews, which measure efficacy and should limit and influence the degree to which recommendations and guidelines are made on the basis of such studies.     

The human epidermis models EpiSkin, SkinEthic and EpiDerm: an evaluation of morphology and their suitability for testing phototoxicity, irritancy, corrosivity, and substance transport.

The commercially available reconstructed human epidermis models EpiSkin, SkinEthic and EpiDerm demonstrate reasonable similarities to the native human tissue in terms of morphology, lipid composition and biochemical markers. These models have been identified as useful tools for the testing of phototoxicity, corrosivity and irritancy, and test protocols have been developed for such applications. For acceptance of these tests by the authorities, prevalidation or validation studies are currently in progress. Furthermore, first results also indicate their suitability for transport experiments of drugs and other xenobiotics across skin. Still, however, the barrier function of these reconstructed human epidermis models appears to be much less developed compared to native skin. Further adaptation of the models to the human epidermis, especially concerning the barrier function, therefore remains an important challenge in this area of research.     

The role of bone scintigraphy in patients with Erdheim-Chester disease

Erdheim-Chester disease (ECD) is a rare disorder that has been reported fewer than 60 times in the literature. Although clinical findings seem to be specific at first sight, histologic classification remains unclear. It has not been decided whether ECD is part of the spectrum of histiocytoses or whether it may be a lipid storage disorder or even a primary macrophage cell disorder, although it does show a distinct histologic pattern. However, the clinical appearance alone shows several typical features, rendering the diagnosis very probable if present. This article illustrates the importance of bone scanning in ECD, because the scintigraphic pattern of involved skeletal sites may in themselves lead to the diagnosis. Several differential diagnoses are considered. The importance of bone scintigraphy as an imaging method in patients with an unclear diagnosis is discussed, as exemplary in ECD, as is its role for the detection of sites of skeletal involvement in other diseases.