Health assessment of artisanal gold miners in Indonesia

Small scale miners use mercury to extract gold from ore in many countries. An environmental and health assessment was performed in Indonesia in two regions, Galangan in Central Kalimantan and Talawaan in Northern Sulawesi. The environmental assessment showed severe mercury contamination of the sediments, and increased mercury levels in local fish. For the health investigation 281 volunteers were recruited and examined by a standardized questionnaire, a neurological examination and neuro-psychological tests. A medical score was used consisting of significant factors of mercury intoxication. Mercury exposed workers showed typical symptoms of mercury intoxication, such as movement disorders (ataxia, tremor, dysdiadochokinesia, etc.). Blood, urine and hair samples were taken from any participant and analyzed for mercury. The mercury concentration in the biomonitors was high, partly extreme high in the working population, increased in the population living in the same habitat and low in the control group. By a standard protocol which includes a combination of threshold values of mercury in the biomonitors and a medical sum score the diagnosis of chronic mercury intoxication was made for highly burdened workers (amalgam smelters) in 55% in Sulawesi and in 62% in Kalimantan. Less exposed mineral processors and the general population in the mining areas were also intoxicated to a high percentage.     

Calibration of a Van de Graaf accelerator and determination of the threshold of the reaction 45Sc(p,n)45Ti using a covariance analysis

The resonances of the ²⁷Al(p, γ)²⁸Si reaction are used to determine the relation between the proton energy and the frequency of a nuclear magnetic resonance (NMR) meter controlling the magnetic induction of a 90° bending magnet used for proton energy analysis.The experimental results and their covariance matrix have been used to obtain a calibration function by a least-squares fit. In addition the threshold and the Q value of the reaction ⁴⁵Sc(p, n)⁴⁵Ti have been determined including all uncertainties and correlations in the analysis.     

Molecular dynamics-derived conformation and intramolecular interaction analysis of the N-acetyl-9-O-acetylneuraminic acid-containing ganglioside GD1a and NMR-based analysis of its binding to a human polyclonal immunoglobulin G fraction with selectivity for O-acetylated sialic acids

The influence of 9-O-acetylation of GD1a, yielding GD1a (eNeu5,9Ac2) with a 9-O-acetylated sialic acid moiety linked to the outer galactose residue, on the spatial extension and mobility of the carbohydrate chain and on recognition by a natural human antibody is analysed. To study a potential impact of the O-acetyl group on the overall conformation of the carbohydrate chain, molecular dynamics (MD) simulations of oligosaccharide chain fragments of increasing length starting from the non-reducing end have been carried out for the first time in this study. They revealed a considerable loss in chain flexibility after addition of the internal N-acetylneuraminic acid onto the chain. Besides MD calculations with different dielectric constants, the conformational behaviour of the complete oligosaccharide chain of the 9-O-acetylated GD1a ganglioside was simulated in the solvents water and dimethyl sulfoxide. These solvents were also used in NMR measurements. The results of this study indicate that 9-O-acetylation at the terminal sialic acid does not influence the overall conformation of the ganglioside. An extended interaction analysis of energetically minimized conformations of GD1a (eNeu5,9Ac2) and GD1a, obtained during molecular dynamics simulations, allowed assessment of the influence of the different parts of the saccharide chains on spatial flexibility. Noteworthy energetic interactions, most interestingly between the 9-O-acetyl group and the pyranose ring of N-acetylgalactosamine, were ascertained by the calculations. However, the strength of this interaction does not force the ganglioside into a conformation, where the 9-O-acetyl group is no longer accessible. Binding of GD1a (eNeu5,9Ac2) to proteins, which are specific for 9-O-acetylated sialic acids, should thus at least partially be mediated by the presence of this group. To experimentally prove this assumption, a NMR study of 9-O-acetylated GD1a in the presence of an affinity-purified polyclonal IgG fraction from human serum with preferential binding to 9-O-acetylated sialic acid was performed. The almost complete disappearance of the intensity of the 9-O-acetyl methyl signal of the GD1a (eNeu5,9Ac2) clearly indicates that the assumed interaction of the 9-O-acetyl group with the human protein takes place.     

Microvascular free-flap correction of severe hemifacial atrophy

Romberg's disease is a progressive hemifacial atrophy of unknown etiology. Microsurgical reconstruction, focusing on the correction of facial asymmetry and restoration of contour, has become the "gold standard." We report our experience with 15 patients involving 16 free-tissue transfers with a minimum of 1 year of follow-up who were treated from July of 1989 to January of 1993. All patients were classified as having severe atrophy. There were 7 males and 8 females in the series. Distribution of disease was a coup de sabre type or segmental pattern in 6 patients, whereas 9 patients had a hemifacial distribution. Fourteen patients had unilateral disease (7 right and 7 left), and 1 patient had bilateral atrophy. The average age of onset of disease was 11.9 years. The average duration of atrophy was 6.7 years. No patient was operated on with a quiescent interval of less than 2 years. Average age at operation was 28.7 years, with a range from 6 to 46 years. Follow-up ranged from 1 to 4.5 years. Two patients had facial hematomas as the only complication. No flaps were lost. Flap revisions consisting of minor contour corrections were performed in 10 patients. Limited recurrence of facial atrophy was seen in a single patient 2 years postoperatively. All patients rated their improvement as excellent. The deepithelialized extended parascapular flap with large fascial extensions of dorsal thoracic fascia is our procedure of choice. This fascia can be folded into variable thicknesses to correct subtle contour defects of the upper lip, medial canthus, eyelids, and ear that have reportedly been difficult to reconstruct.(ABSTRACT TRUNCATED AT 250 WORDS)     

A numerical study of persistence length effects on DNA conformation in sequencing electrophoresis

We have developed a program to evaluate the influence of DNA stiffness on molecular mobility and conformation during electrophoresis. This (currently) two-dimensional numerical study models DNA as a chain of uniformly charged beads connected to one another by elastic segments, of finite mean size, in the presence of fixed obstacles representing gel fibers. Contrary to the standard biased reptation model (BRM), our Langevin-type dynamics for the chain are microscopic and warrant studies of fine effects such as inner chain orientation. Using this model, we show that the introduction of a persistence length decreases the (saturated) mobility at high electric fields, providing strong evidence that the gel generates a friction force and not only a (dissipation-free) constraint force. We also show that the persistence length leads to an increase of the chain orientation in the field direction. This suggests that DNA stiffness causes the saturation plateau value to be reached for smaller chain sizes than those predicted by the BRM model.     

Crosstalk of Diabetic Conditions with Static Versus Dynamic Flow Environment—Impact on Aortic Valve Remodeling

Type 2 diabetes mellitus (T2D) is one of the prominent risk factors for the development and progression of calcific aortic valve disease. Nevertheless, little is known about molecular mechanisms of how T2D affects aortic valve (AV) remodeling. In this study, the influence of hyperinsulinemia and hyperglycemia on degenerative processes in valvular tissue is analyzed in intact AV exposed to an either static or dynamic 3D environment, respectively. The complex native dynamic environment of AV is simulated using a software-governed bioreactor system with controlled pulsatile flow. Dynamic cultivation resulted in significantly stronger fibrosis in AV tissue compared to static cultivation, while hyperinsulinemia and hyperglycemia had no impact on fibrosis. The expression of key differentiation markers and proteoglycans were altered by diabetic conditions in an environment-dependent manner. Furthermore, hyperinsulinemia and hyperglycemia affect insulin-signaling pathways. Western blot analysis showed increased phosphorylation level of protein kinase B (AKT) after acute insulin stimulation, which was lost in AV under hyperinsulinemia, indicating acquired insulin resistance of the AV tissue in response to elevated insulin levels. These data underline a complex interplay of diabetic conditions on one hand and biomechanical 3D environment on the other hand that possesses an impact on AV tissue remodeling.     

Modeling-Assisted Design of Thermostable Benzaldehyde Lyases from Rhodococcus erythropolis for Continuous Production of α-Hydroxy Ketones

Enantiopure α-hydroxy ketones are important building blocks of active pharmaceutical ingredients (APIs), which can be produced by thiamine-diphosphate-dependent lyases, such as benzaldehyde lyase. Here we report the discovery of a novel thermostable benzaldehyde lyase from Rhodococcus erythropolis R138 (ReBAL). While the overall sequence identity to the only experimentally confirmed benzaldehyde lyase from Pseudomonas fluorescens Biovar I (PfBAL) was only 65 %, comparison of a structural model of ReBAL with the crystal structure of PfBAL revealed only four divergent amino acids in the substrate binding cavity. Based on rational design, we generated two ReBAL variants, which were characterized along with the wild-type enzyme in terms of their substrate spectrum, thermostability and biocatalytic performance in the presence of different co-solvents. We found that the new enzyme variants have a significantly higher thermostability (up to 22 °C increase in T₅₀) and a different co-solvent-dependent activity. Using the most stable variant immobilized in packed-bed reactors via the SpyCatcher/SpyTag system, (R)-benzoin was synthesized from benzaldehyde over a period of seven days with a stable space-time-yield of 9.3 mmol ⋅ L^-1 ⋅ d⁻¹. Our work expands the important class of benzaldehyde lyases and therefore contributes to the development of continuous biocatalytic processes for the production of α-hydroxy ketones and APIs.