Ultrastructural changes in the mycelia of Actinomyces hygroscopicus var. var. enhygrus--a proteolytic enzyme producer--during submerged fermentation

Ultrastructural changes were found to occur in the mycelium of Actinomyces hygroscopicus, strain 33x, which produced an exocellular proteolytic enzyme during submerged fermentation, in both laboratory and semiindustrial conditions (in 100-1 fermenters). In the course of the enzyme accumulation, numerous vacuoles appeared in the hyphae, some hyphae became wider, and the cell walls were more loose. The greatest structural changes were found in the intracytoplasmic membrane systems. The ultrastructural changes of the mycelium are not presumably connected with the accumulation of the enzyme, but are the result of the differentiation of cellular structures during aging of the cells and their transition to the stage of autolysis.     

Oxygen determination in oxygen-supersaturated drinking waters by NMR relaxometry

In recent years, a rising number of different table waters supersaturated with oxygen have hit the market with claims of both positive health effects and an increase in athletic performance. In addition to research on the correctness of these claims and their possible physiological reasons, the appearance of oxygen supersaturation as a marketing promise also creates a need for appropriate analytical techniques allowing a rapid and reliable determination of oxygen contents in such waters. Here, we present NMR relaxometry as a possible analytical tool for such studies. NMR relaxation in oxygen supersaturated water is not only of interest in the context of monitoring the oxygen content in such drinking water products, but also might offer some interesting possibilities in medical and environmental science MRI applications. As a contact-less measuring method, NMR relaxometry avoids disturbance of the measurement due to outgassing. The method was applied in the concentration range from 10 mg l(-1) to over 100 mg l(-1) dissolved oxygen. In addition to freshly sampled drinking waters, also oxygen losses during storage of the water in open drinking vials was studied.     

Porous-coated total hip replacement

Fifteen years of clinical experience with porous-coated prostheses demonstrated the durability of this type of fixation. This experience was documented by clinical follow-up study of the 393 cases treated by the senior author before 1985. Only six of these femoral components have been revised: three for loosening, two for stem breakage, and one for infection. Thus, the revision rate for the porous-coated stems was 1.5%. Porous-coated acetabular components were used in 227 of the arthroplasties. Five of these porous-coated cups have been revised: four for malposition leading to dislocation and one for late loosening secondary to osteolysis. Thus, the revision rate for these porous-coated acetabular components was 2.2%. Twenty bipolar and 146 cemented acetabular components were used in the remaining 166 cases treated before 1985. Eleven (7.5%) of the cemented acetabular components were revised. Revisions of the porous-coated components were rare in the first ten postoperative years. The clinical data were supplemented with analysis of postmortem specimens from 15 patients. Mechanical testing of the femoral specimens showed the relative micromotion at the porous surface to be exceptionally small (less than 40 microns). Seven of these postmortem retrievals involved cases with unilateral arthroplasties. In these cases, the contralateral normal femur also was removed, and a prosthesis identical to that in the in vivo implanted side was inserted to simulate the immediate postoperative condition. Dual-energy X-ray absorptiometry (DEXA) of the seven paired femora demonstrated that bone remodeling can be expected to produce a 5%-52% loss of periprosthetic bone mineral content, with the greatest loss occurring in the more osteoporotic patients.(ABSTRACT TRUNCATED AT 250 WORDS)     

Iterative Antimicrobial Candidate Selection from Informed D‐/L‐Peptide Dimer Libraries

Growing resistance to antibiotics, as well as newly emerging pathogens, stimulate the investigation of antimicrobial peptides (AMPs) as therapeutic agents. Here, we report a new library design concept based on a stochastic distribution of natural AMP amino acid sequences onto half‐length synthetic peptides. For these compounds, a non‐natural motif of alternating D ‐ and L ‐backbone stereochemistry of the peptide chain predisposed for β‐helix formation was explored. Synthetic D ‐/L ‐peptides with permuted half‐length sequences were delineated from a full‐length starter sequence and covalently recombined to create two‐dimensional compound arrays for antibacterial screening. Using the natural AMP magainin as a seed sequence, we identified and iteratively optimized hit compounds showing high antimicrobial activity against Gram‐positive and Gram‐negative bacteria with low hemolytic activity. Cryo‐electron microscopy characterized the membrane‐associated mechanism of action of the new D ‐/L ‐peptide antibiotics.     

Modeling metal bioaccumulation in a deposit-feeding polychaete from labile sediment fractions and from pore water

Estuarine sediments are often highly enriched in particle-reactive metal contaminants and because aquatic animals have often been shown to acquire metals predominantly from their diet, benthic animals feeding on deposited or resuspended sediments may also accumulate metals through this uptake pathway. Laboratory experiments were performed in which the surface deposit-feeding polychaete, Nereis succinea, was exposed to As(+ 5), Cd, and Cr(+ 3) in pore water or in estuarine sediments with and without enrichment with algal debris. These experiments generated metal uptake parameters (assimilation efficiency of ingested metal [AE], uptake rate constant of dissolved metal, efflux rate constants following dietary or aqueous metal exposures) used in a kinetic model of metal bioaccumulation. The model showed that > 97% of the body burden of these metals is accumulated through ingested sediment. The kinetic model was further modified to consider the geochemical fractionation of the metals in the sediments because metals bound to some fractions were shown to be unavailable to these polychaetes. The modified model substituted the AE term for each metal by the percentage of metal extracted in neutral and weak acid exchangeable fractions (termed “carbonex” fraction) multiplied by the slope of the regression between the metal AE and its fractionation in carbonex. The modified model generated predictions of As, Cd, and Cr body burdens in polychaetes at three different estuarine sites that matched independent field observations at these sites (r² = 0.84 for sediments without organic enrichment, r² = 0.87 with organic enrichment). Model predictions that relied on total metal concentrations showed weaker relationships (r² = 0.11-0.50). This study adds to the evidence for the dominance of dietary uptake of metals in aquatic animals and identifies a key sedimentary fraction of metals that can account for bioavailability of sediment-bound metals.     

Die Cocosfett- und Milchfettbestimmung nach Bertram, Bos und Verhagen

Ohne Zusammenfassung     

Relationship between haemodynamics and morphology in pulmonary hypertension. A quantitative intravascular ultrasound study

BACKGROUND: Intravascular ultrasound imaging of the pulmonary arteries has been demonstrated to be a reliable method of quantifying vessel diameter, luminal area and pulsatility. Simultaneous measurement of flow velocity and its response to vasodilators allows the relationship between morphology and functional compromise to be studied, especially endothelial dysfunction. METHODS: In 51 patients (mean age = 49.8 +/- 12.6 years, 17 female) we performed right heart catheterization and simultaneous intravascular ultrasound of pulmonary artery branches. The patients were divided in two groups: group 1 with normal pulmonary artery pressure and pulmonary vascular resistance, and group 2 with pulmonary hypertension (peak pulmonary artery pressure > 30 mmHg and/or mean pulmonary artery pressure > 20 mmHg). Vessel wall and lumen were studied using a 2.9 F intravascular ultrasound catheter with a 30 MHz phased array transducer. Measurement of blood flow velocity was accomplished by a Doppler flow wire (0.018 inch). The maximal flow change during acetylcholine infusion (adjusted to 10(-6); 10(-5), and 10(-4) M concentration in the blood vessel) was measured. RESULTS: There were no significant differences between groups 1 and 2 with respect to age (48.5 +/- 14.3 years vs 50.3 +/- 12.3 years; P = ns), gender (4 female/8 male vs 13 female/26 male; P = ns), luminal area of the vessel segment in which the intravascular ultrasound measurements were obtained (11.8 +/- 6.1 mm2 vs 16.7 +/- 14.3 mm2; P = ns), internal diameter (3.9 +/- 1.2 mm vs 4.2 +/- 1.7 mm; P = ns), and external diameter (6.1 +/- 1.3 mm vs 6.9 +/- 2.1 mm; P = ns). Cross-sectional images of the pulmonary artery wall demonstrated a single ring with high echodensity with a thin inner layer regarded as intima in group 1. In contrast, the majority of patients (n = 35/39) in group 2 demonstrated a thickening of the intimal layer and/or a disturbance of layering of the echogenic arterial wall. The relative wall thickness was higher in group 2 than in group 1 (22.5 +/- 10.4% vs 15.3 +/- 6.5%; P < 0.05). There were no significant correlations between pulmonary artery pressure and wall thickness pulmonary artery pressure and area change in the cardiac cycle, acetylcholine-dependent increase in pulmonary flow and morphological changes in the vessel wall. CONCLUSION: We conclude that intravascular ultrasound is capable of detecting morphological changes in the pulmonary vessel wall in pulmonary hypertension and that vessel wall hypertrophy of small pulmonary segment arteries, as detected by intravascular ultrasound, is not predictive of functional vasodilatory response of resistance vessels of the same vessel area.     

Characterization of an Invertebrate-Type Dopamine Receptor of the American Cockroach,Periplaneta americana

We have isolated a cDNA coding for a putative invertebrate-type dopamine receptor (Peadop2) from P. americana brain by using a PCR-based strategy. The mRNA is present in samples from brain and salivary glands. We analyzed the distribution of the PeaDOP2 receptor protein with specific affinity-purified polyclonal antibodies. On Western blots, PeaDOP2 was detected in protein samples from brain, subesophageal ganglion, thoracic ganglia, and salivary glands. In immunocytochemical experiments, we detected PeaDOP2 in neurons with their somata being located at the anterior edge of the medulla bilaterally innervating the optic lobes and projecting to the ventro-lateral protocerebrum. In order to determine the functional and pharmacological properties of the cloned receptor, we generated a cell line constitutively expressing PeaDOP2. Activation of PeaDOP2-expressing cells with dopamine induced an increase in intracellular cAMP. In contrast, a C-terminally truncated splice variant of this receptor did not exhibit any functional property by itself. The molecular and pharmacological characterization of the first dopamine receptor from P. americana provides the basis for forthcoming studies focusing on the significance of the dopaminergic system in cockroach behavior and physiology.