Effects of surface relaxation on convergent-beam electron diffraction analysis of stress in silicon.

Convergent-beam electron diffraction on cross-sectional transmission electron microscopy specimens can map strains in the silicon substrate of microelectronics devices with high spatial resolution. However, at shallow depths below the interface, most of the diffraction lines within a convergent-beam electron diffraction pattern are split, rendering pattern interpretation impossible in the classic way. The splitting effect was systematically analysed for a variety of materials, and the same qualitative behaviour that can be explained by stress relaxation at the surfaces of the thin transmission electron microscopy specimen was observed. The effects of surface relaxation are modelled by finite elements simulations. The results predict well the experimental magnitude of the splitting for a variety of diffraction lines at different positions below the interface, but fail to simulate the intensity of the secondary lines. Possible reasons for such discrepancies are discussed and assessed.

A case of Schnitzler's syndrome with nodular regenerative hyperplasia of the liver.

Schnitzler's syndrome is a rare condition of urticaria, macroglobulinemia, and sclerotic bone lesions. We report a case in a 70-year-old man in whom inflammatory polyarthralgia was followed by a nonpruritic urticarial eruption with a moderate decline in general health. Laboratory tests showed inflammation and a modest isolated peak of monoclonal IgM kappa. There was no evidence of Waldenström macroglobulinemia. Schnitzler's syndrome was considered. However, an ultrasound scan of the abdomen done because of mild gamma-glutamyl-transferase elevation disclosed multiple hepatic lesions. The liver histology showed incipient nodular regenerative hyperplasia. Only about 30 cases of Schnitzler's syndrome have been reported since the seminal description in 1972. Hepatic involvement was a common but nonspecific finding, and we found no cases with nodular regenerative hyperplasia. However, this abnormality is often found in patients with autoimmune or hematological disorders. The pathogenesis of Schnitzler's syndrome remains unknown, but the possibility of progression to a hematological malignancy requires prolonged follow-up.

Can an osteoporotic vertebral fracture cause compression of the spinal cord or cauda equina.

A 78-year-old woman developed an osteoporotic fracture of L2 followed two months later by spinal cord compression. Imaging study findings suggested a malignancy but a biopsy showed osteonecrosis, of which there was no evidence on the imaging studies. Osteonecrosis may be the cause of neurologic compromise associated with osteoporotic vertebral fractures.

[Fibromyalgia. A critical review]. / La fibromyalgie. Une revue critique.

Fibromyalgia is a chronic pain syndrome, more common in women. Its prevalence is estimated around 2% in the general population, and up to 20% among rheumatology outpatients. Besides musculoskeletal pain, symptoms as fatigue and sleep disturbance are considered characteristic. Research criteria have been set up, but their seemingly preciseness is unable to distinguish clearly between fibromyalgia and other functional somatic syndromes (chronic fatigue syndrome, irritable bowel syndrome) and psychiatric disorders (depression, anxiety), with which a striking comorbidity is documented. The diagnosis of fibromyalgia does not theoretically require the exclusion of muscle, joint, or metabolic diseases, but in clinical practice this problem proves to be of crucial importance. There are numbers of pathophysiological hypothesis for fibromyalgia, but none of them is fully satisfying: muscle is probably innocent; sleep disturbance, although sometimes considered a landmark of the syndrome, is unspecific; stress response studies show subtle anomaly; psychiatric disorders may represent factors of vulnerability and perpetuation rather than causes. We propose to include some of these etiological contributors in vicious circles leading to a "final common pathway" characterized by generalized hyperalgesia. Treatments of fibromyalgia, whether pharmacological (antidepressants) or psychological (cognitive-behavioral therapies) are of little efficacy, and the global prognosis of fibromyalgia is poor. However, the outcome might prove better outside the specialized clinics in which studies of chronic sufferers with severe abnormal illness behaviors are done. The social consequences of the popularization of the diagnosis of fibromyalgia should not be neglected.

Impact on bone of thyroid hormone therapy.

Results of recent cross-sectional and longitudinal studies of the effects on bone of thyroid hormone therapy are reviewed. Substantial discrepancies exist, perhaps because bone density is influenced by many factors, including the underlying disease, dietary factors and hormonal status. No effect on bone mineral density of the dose of thyroid hormones given as replacement or suppressive therapy was found. However, prospective studies demonstrated increased bone remodeling with transient bone loss early during treatment. Whether antiosteoclastic agents may prevent bone loss associated with thyroid hormone therapy is discussed.

New international F.I.P. method for the determination of the activity of Aspergillus oryzae proteases.

Proteases of Aspergillus oryzae are used as a drug in the therapy of digestive disorders. To standardize these enzyme the Enzyme Commission of the Fédération Internationale Pharmaceutique (F.I.P.) has tested a new determination method, which will be described below. The standard preparation of a mixture of Aspergillus oryzae proteases used in this test is characterized.

Organic sulfur compounds resulting from the interaction of iron sulfide, hydrogen sulfide and carbon dioxide in an anaerobic aqueous environment.

The reaction of iron sulfide (FeS) with H2S in water, in presence of CO2 under anaerobic conditions was found to yield H2 and a variety of organic sulfur compounds, mainly thiols and small amounts of CS2 and dimethyldisulfide. The same compounds were produced when H2S was replaced by HCl, in the H2S-generating system FeS/HCl/CO2. The identification of the products was confirmed by GC-MS analyses and the incorporation of H2 in the organic sulfur compounds was demonstrated by experiments in which all hydrogen compounds were replaced by deuterium compounds. Generation of H2 and the synthesis of thiols were both dependent upon the relative abundance of FeS and HCl or H2S, i.e. the FeS/HCl- or FeS/H2S-proportions. Whether thiols or CS2 were formed as the main products depended also on the FeS/HCl-ratio: All conditions which create a H2 deficiency were found to initiate a proportional increase in the amount of CS2. The quantities of H2 and thiols generated depended on temperature: the production of H2 was significantly accelerated from 50 degrees C onward and thiol synthesis above 75 degrees C. The yield of thiols increased with the amount of FeS and HCl (H2S), given a certain FeS/HCl-ratio and a surplus of CO2. A deficiency of CO2 results in lower thiol synthesis. The end product, pyrite (FeS2), was found to appear as a silvery granular layer floating on the aqueous surface. The identity of the thiols was confirmed by mass spectrometry, and the reduction of CO2 demonstrated by the determination of deuterium incorporation with DCl and D2O. The described reactions can principally proceed under the conditions comparable to those obtaining around submarine hydrothermal vents, or the global situation about 4 billion years ago, before the dawn of life, and could replace the need for a reducing atmosphere on the primitive earth.

Arthritis, hypercalcemia, and lytic bone lesions after hepatitis B vaccination.

We report a case of arthritis, hypercalcemia, and lytic bone lesions that occurred shortly after repeated administration of recombinant hepatitis B virus (HBV) vaccine in a 44-year-old man who had had myasthenia gravis 20 years earlier. He presented with ankle and knee arthritis and hypercalcemia. Radiographs revealed small lytic lesions and densitometry showed severe osteopenia. Quantimetric bone biopsy confirmed major bone loss and showed dramatic increase in bone turnover, as well as an unusual periosteal apposition of woven bone. Short term treatment with prednisone and furosemide and longterm treatment with clodronate allowed rapid improvement. After one year, the patient remains clinically asymptomatic. Despite negative immunologic investigations to sustain the hypothesis of HBV vaccination as a causal factor, we believe the bone lesions could be attributed to unusual bone "hyperremodeling" triggered by an immune process in a predisposed individual.

Kinetic investigation of the action of hyaluronidase on hyaluronan using the Morgan-Elson and neocuproine assays.

In this paper we describe kinetic investigations of the action of testicular hyaluronidase on hyaluronan. We have compared the use of two spectrophotometric assays, the first based on the Morgan-Elson reaction and the second on the neocuproine reaction. With the neocuproine reaction Km was found to be 0.46 mg/ml and Vmax to be 126 nmol l-1 s-1. Because of a low sensitivity and the production of interfering precipitates, the Morgan-Elson assay cannot be used for kinetic investigation of the enzyme. Furthermore this assay is prone to interference from compounds such as disodium cromoglycate, (+)-catechine, penicillamine, CaCl2 and acetate buffer.

Kinetic constants for the hydrolysis of aggrecan by the papaya proteinases and their relevance for chemonucleolysis.

The four known proteinases from papaya latex, namely papain (EC 3.4.22.2), chymopapain (EC 3.4.22.6), caricain (EC 3.4.22.30), and glycyl endopeptidase (EC 3.4.22.25), were purified to homogeneity and fully characterized by single radial immunodiffusion and active-site titration. A modified HPLC gel permeation assay was used to determine the kinetic constants for aggrecan hydrolysis by the papaya proteinases. The disappearance of intact aggrecan monomer was first-order, indicating that for the four enzymes studied the Km was much larger than 0.5 microM and that kcat/Km = 1.2 +/- 0.1 x 10(6) M-1 s-1 for chymopapain, 1.20 +/- 0.08 x 10(6) M-1 s-1 for caricain, 0.90 +/- 0.02 x 10(6) M-1 s-1 for papain, and 0.120 +/- 0.005 x 10(6) M-1 s-1 for glycyl endopeptidase. Chymodiactin, the chymopapain preparation used for chemonucleolysis, consists of a mixture of chymopapain (70%), caricain (20%), and glycyl endopeptidase (4%). The rate constant for the aggrecan hydrolysis by such a mixture was not significantly different from the rate constant for pure chymopapain. As a result of these observations, we predict that pure chymopapain could replace partially purified chymopapain preparations for chemonucleolysis.

Absolute and empirical determination of the enzymatic activity and kinetic investigation of the action of hyaluronidase on hyaluronan using viscosimetry.

We describe an investigation of the action of hyaluronidase on hyaluronan using viscosimetry. A new viscosimetric approach was developed for determining the activity of the enzyme in katal units. This approach requires knowledge of several parameters (e.g. Mark-Houwink constants) which were determined by combining viscosimetric measurement and gel-permeation chromatography analysis. Using all the necessary parameters we determined the kinetic parameters of the enzyme and found that 250 i.u. correspond to 1 nkat. An empirical viscometric was used to estimate the activity of the enzyme, and the Km was determined using the kinetic dilution method. The estimates produced by the absolute and empirical approaches were in good agreement. We demonstrate that the empirical estimation of the reaction rate is related to the rate of reaction expressed in absolute units and thus provides a good estimate of enzyme activity. Furthermore, we have found an empirical relationship which enables investigation of the kinetics of the enzyme in a simple and sensitive way by viscosimetry.

Transferability of lipase titrimetric assays: deductions from an interlaboratory study.

Following the selection of the most appropriate method for emulsification and the optimization of the reaction medium, interlaboratory studies were conducted to check the effect of preparing substrates and measuring the catalytic concentration of lipase at different sites as well as the effect of transport on emulsion. The determinations of lipase activity in an abnormal chemistry control against emulsions prepared by two laboratories (and used by both laboratories) and, also, against five separate emulsions prepared by one laboratory (and used by five different laboratories) resulted in average enzyme activity values (2234 +/- 125 and 2263 +/- 204 U/l respectively) which are not statistically different. Standard preparations of lipase, control sera and reference materials can therefore be titrated according to the procedure followed by at least two laboratories for at least 3 days against two separate emulsions.

Kinetic investigation of the degradation of hyaluronan by hyaluronidase using gel permeation chromatography.

A gel permeation chromatography (GPC) system for the analysis of hyaluronan was set up and calibrated by means of the universal calibration method. Using GPC, a kinetic assay of the action of hyaluronidase on hyaluronan has been developed. Applying Michaelis-Menten theory and the direct linear plot we have estimated the kinetic constants of the enzyme. By evaluating the decrease of the various molecular mass averages during the enzymatic reactions, we have given a demonstration of the at random degradation of hyaluronan by hyaluronidase in the initial stage of the reaction.

Fractionation and purification of the thiol proteinases from papaya latex.

Three cysteine proteinases, i.e. chymopapain, papaya proteinase IV and proteinase III, were purified to homogeneity from papaya latex using a combination of ion-exchange chromatography and hydrophobic interaction chromatography. During the purification procedure, the thiol-groups of the active center were reversibly blocked as mixed disulfides with 2-thiopyridone. Homogeneity was proved electrophoretically by native polyacrylamide gel electrophoresis (PAGE), sodium dodecyl sulfate (SDS)-PAGE and rechromatography on a Mono S 5/5 column at pH 5.0.