Availability-adjusted X-factor

The notion of extended X-factor contribution has been proposed and evaluated recently as a tool to identify system capacity constraints based on machine group utilization and raw processing time. This provides a great convenience for factory-floor managers examining system capacity issues by using only local- or machine-level information. The purpose of this study is twofold: to study fundamental properties of the extended X-factor contribution measure augmented with availability, and to use this new measure to investigate resource allocation for optimizing mean cycle time. The availability-adjusted X-factor was first introduced in the context of local cycle time and its relation to allocation of personnel in individual machine groups. The availability-adjusted X-factor contribution measure developed and evaluated in the current study differs from the previous measure by its ability to identify capacity-constraining machines in the entire system. The measure presented herein is a more accurate indicator of capacity constraints than the extended X-factor contribution measures. With an objective to minimize cycle time or maximize throughput by properly allocating available resources, the results presented herein clearly demonstrate the effectiveness of this new measure to identify capacity-constraining machines. This study also uses availability as a decision variable for mean cycle time optimization.     

Detailed active site configuration of a new crystal form of methanol dehydrogenase from Methylophilus W3A1 at 1.9 A resolution

The three-dimensional structure of a new crystal form of methanol dehydrogenase from Methylophilus W3A1 has been obtained in the presence of substrate using data recorded at a synchrotron. The structure of this approximately 140 kDa heterotetramer, refined at 1. 9 A resolution, reveals the detailed configuration of its redox cofactor, pyrroloquinoline quinone (PQQ). C4, one of the oxygen-bearing atoms of this orthoquinone is in a planar configuration while C5, which bears the other quinone oxygen, is tetrahedral, suggesting that the PQQ is in the semiquinone redox state. The substrate binding site has been identified close to PQQ and to the side chain of Asp297, the putative active site base. The proximity of the hydroxyl of methanol to C5 of PQQ compared to the greater separation of the substrate methyl group from C5 supports the addition-elimination reaction mechanism involving a hemiketal intermediate.     

Biomonitoring using accessible human cells for exposure and health risk assessment

We describe a nonradioactive preembedding in situ hybridization protocol using digoxigenin-labeled RNA probes and tyramide signal amplification to increase the sensitivity of detection. The protocol is sensitive enough for electron microscopic localization of endogenous messenger RNAs encoding beta-actin and amphoterin. Three visualization methods were compared: diaminobenzidine enhanced by nickel, Nanogold enhanced by silver and gold toning, and fluorescently labeled tyramides. Diaminobenzidine and Nanogold can be used in both light and electron microscopy. The nickel-enhanced diaminobenzidine was the most sensitive visualization method. It is easy to accomplish but a drawback is poor spatial resolution, which restricts its use at high magnifications. Nanogold visualization has considerably better spatial resolution and is therefore recommended for electron microscopy. Fluorescent tyramides, especially TRITC-tyramide, offer a good detection method for fluorescence and confocal microscopy. The methods were used to localize amphoterin and beta-actin mRNAs in motile cells. Both mRNAs were found in the soma and cell processes. In double labeling experiments, beta-actin mRNA localized to filamentous structures that also contained ribosomal proteins. Especially in the cortical cytoplasm, beta-actin mRNA was associated with actin filaments. Direct localization to microtubules was only rarely seen. (J Histochem Cytochem 47:99-112, 1999)     

Segmental antigen challenge increases fibronectin in bronchoalveolar lavage fluid

Fibronectin may contribute to asthma pathogenesis by recruitment and activation of inflammatory cells, and by promotion of subepithelial fibrosis. Fibronectin is produced by several types of airway cells, including epithelial cells, fibroblasts, and alveolar macrophages. To test the hypothesis that antigen-induced airway inflammation is associated with increased local generation of fibronectin, segmental bronchoprovocation (SBP) with antigen and saline was performed in 17 atopic patients. Bronchoalveolar lavage (BAL) was performed at 5 min and 48 h after segmental challenge with saline or antigen. Fibronectin concentrations in BAL fluid, measured by enzyme-linked immunosorbent assay (ELISA), increased more than 5-fold 48 h after antigen challenge (65 [47 to 110] versus 407 [240 to 697] ng/ml, median and 25 to 75% interquartiles, p < 0.05). Fibronectin concentrations 48 h after antigen challenge correlated with histamine concentrations 5 min after antigen challenge and numbers of eosinophils, neutrophils, macrophages, and total cells in BAL fluid 48 h after antigen challenge. BAL was more enriched in fibronectin 48 h after challenge than would be predicted solely from increased permeability of plasma proteins. Western blot analysis showed that fibronectin in BAL fluid was largely intact and contained the extra domain-A (ED-A) splice variant of cellular fibronectin, indicative of local production. We conclude that antigen challenge in atopic subjects causes increased production of fibronectin by airway cells and speculate that this response may contribute to airway remodeling in allergic inflammation.     

Frontal EMG-biofeedback training of athetoid cerebral palsy patients: a report of six cases

108 tendons of the m. extensor hallucis longus were examined with a tensile testing machine within 36 h after death. The specimen were kept at a resting length of 20 mm. After the "steady state" was reached by cyclic loading, the tendons were stretched up to a maximum load of 18 kp, then deloaded to a certain level and after that the elongation was kept constant. At high loading level the tension of the tendon decreases with time (relaxation). At medium and low loading level the tension increases slightly (mechanical recovery). Between that two regions there is a certain load, where the tension will not change with time (isorheological point). The position of the isorheological point depends on the velocity of the elongation. At low velocity (2 mm/min) the isorheological point is situated at 70%, at high velocity (12 mm/min) at 60% of the maximum load. One will find the maximum relaxation, when no deloading occurs. The mechanical recovery, however, has its maximum at 5--25% of the maximum load. But when the tendon is totally deloaded, there seems to occur no recovery. The maximum relaxation is 5 to 6 times larger than the maximum recovery. Supposingly the relaxation- and recovery-processses will happen at the same time but with different intensity depending on the loading level. At least the relaxation-process consists of different relaxation components with different relaxation times. This will explain the phenomenon of a "secondary relaxation": After a long time of registration the recovery will turn into a slight relaxation.     

The crystal structure of human procathepsin K

Cathepsin K is a cysteine protease present in human osteoclasts that plays an important role in bone resorption. Cathepsin K is synthesized as an inactive proenzyme and activated under conditions of low pH. Autoproteolytic processing of the N-terminal 99 amino acid propeptide produces the active, mature form of cathepsin K. It is presumed that the activation of procathepsin K in vivo occurs in the bone resorption pit, which has a low-pH environment. We have determined the structure of human procathepsin K at 2.8 A resolution. The structure of the mature enzyme domain within procathepsin K is virtually identical to that of mature cathepsin K. The fold of the propeptide of procathepsin K is similar to that observed in procathepsins B and L despite differences in length and sequence. A portion of the propeptide occupies the active site cleft of cathepsin K. Hydrophobic interactions, salt bridges, and hydrogen-bonding interactions are observed in the structure of the propeptide and between the propeptide and the mature enzyme of procathepsin K. These interactions suggest an explanation for the stability of the proenzyme. The structure of procathepsin K contributes to an understanding of the molecular basis of inhibition by the propeptide portion of the molecule and activation of this important member of the cysteine protease family.     

Brain proton magnetic resonance spectroscopy (1H-MRS) in Alzheimer's disease: changes after treatment with xanomeline, an M1 selective cholinergic agonist

OBJECTIVE: Higher than normal cellular levels of the phospholipid catabolic intermediate glycerophosphocholine have been found in postmortem brain tissue of persons with Alzheimer's disease. Proton magnetic resonance spectroscopy (1H-MRS) can detect a choline resonance that is largely due to glycerophosphocholine. The authors tested the hypothesis that treatment with xanomeline, an M1 selective muscarinic cholinergic agonist, would be associated with a decrease in the 1H-MRS choline resonance. METHOD: Patients with mild to moderate Alzheimer's disease received placebo or xanomeline for 6 months. 1H-MRS spectra were collected at baseline and after treatment discontinuation for 12 patients, two taking placebo and 10 taking xanomeline at a dose of 25 mg t.i.d. (N = 4), 50 mg t.i.d. (N = 3), or 75 mg t.i.d. (N = 3). RESULTS: For the combined group of patients taking xanomeline, there was a significant decrease in the choline/creatine ratio from baseline to endpoint. CONCLUSIONS: Treatment of Alzheimer's disease with a cholinergic agonist is associated with a decrease in the MRS choline resonance. Xanomeline may reduce breakdown of cholinergic neuron membranes by reducing the cellular requirement for free choline for acetylcholine synthesis.     

Stufentitration bei Weinessig

Ohne Zusammenfassung