Biomedical subjects
A Lauwers
Publications and source records attributed to A Lauwers.
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.
[Acute oligo-arthritis in a patient treated with BCG therapy for bladder carcinoma].
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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].
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.
Cauda equina syndrome due to a facet joint synovial cyst.
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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.
Bone manifestations of untreated hypothyroidism in adults.
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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.
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.
Electronic transport in metallic iron disilicide.
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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.
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.
Effect of electrolytes in the presence of some trace elements on the stability of all-in-one emulsion mixtures for total parenteral nutrition.
In a previous study we showed that the 'all-in-one' emulsion mixtures investigated for total parenteral nutrition are stable for 1 month when kept in ethylene vinyl acetate polymer (EVA) bags and refrigerated at 4 degrees C. Analogous experiments were performed with the addition of two different solutions of trace-elements: one was prepared in the pharmacy while the other was commercially obtained (Addamel, Kabi Vitrum). A Coulter counter TA II with a 30 microns orifice was used for globule size measurements. Particles with diameters ranging from 0.6 up to 16 microns were measured. No significant changes in particle size were noticed during storage and the routine addition of trace elements to the 'all-in-one' mixtures was thus possible. These emulsions can be stored without stability problems for at least 8 days.
Determination of average molecular weights of a polymeric substrate during enzymatic attack [proceedings].
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Differential spectrophotometric determination of tyrosine and tryptophan in pharmaceutical amino acid solutions.
A method is proposed for the simultaneous determination of tyrosine and tryptophan in solutions by differential spectrophotometry. The concentrations are calculated from the measurement of the absorbance of the amino acid mixture in an alkaline medium and from the differential absorbance of the alkaline solution against the acid solution at 294.4 nm. A comparison with three other well-known methods is discussed.