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A Guthmann JM Fritschy OP Ottersen R Torp H Herbert 《Canadian Metallurgical Quarterly》1998,400(2):229-243
Enzymes are increasingly being used to perform regio- and enantioselective reactions in chemoenzymatic syntheses. To utilize enzymes for unphysiological reactions and to yield novel products, a broad substrate spectrum is desirable. Thiamin diphosphate (ThDP)-dependent enzymes vary in their substrate tolerance from rather strict substrate specificity (phosphoketolases, glyoxylate carboligase) to more permissive enzymes (transketolase, dihydroxyacetone synthase, pyruvate decarboxylase) and therefore differ in their potential to be used as biocatalysts. We give an overview of the known substrate spectra of ThDP-dependent enzymes and present examples of multi-enzyme or chemoenzymatic approaches which involve ThDP-dependent enzymes as biocatalysts to obtain pharmaceutical compounds as ephedrine and glycosidase inhibitors, sex pheromones as exo-brevicomin, 13C-labeled metabolites, and other intermediates as 1-deoxyxylulose 5-phosphate, a precursor of vitamins and isoprenoids. 相似文献
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AA Kruize OP van Bijsterveld RJ Hené PC de Wilde TE Feltkamp L Kater JW Bijlsma 《Canadian Metallurgical Quarterly》1997,81(6):435-438
The reliability and validity of a Confidence of Dental Hygienist in Child Management Scale were examined. Forty-eight dental hygiene students, nine dental staff, and thirty-one dentists were subjects for the reliability and validity scale. The acceptable level of the reliability on the Scale was shown by internal consistency and stability. The confidence scores of the clinician's group were significantly higher than the confidence scores of the students. The reliability and validity of the Confidence Scale were established. Next, we evaluated the effect of behavioral science training, using videotape feedback and role playing on twelve dental hygiene students. Six students received the training, the other six students, the controls, had no training. The confidence scores of the training group were significantly higher than those of the control group, demonstrating that the training was effective for dental hygiene students. 相似文献
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Controlled overproduction of proteins by lactic acid bacteria 总被引:2,自引:0,他引:2
OP Kuipers PG de Ruyter M Kleerebezem WM de Vos 《Canadian Metallurgical Quarterly》1997,15(4):135-140
Lactic acid bacteria are widely used in industrial food fermentations, contributing to flavour, texture and preservation of the fermented products. Here we describe recent advances in the development of controlled gene expression systems, which allow the regulated overproduction of any desirable protein by lactic acid bacteria. Some systems benefit from the fact that the expression vectors, marker genes and inducing factors can be used directly in food applications since they are all derived from food-grade lactic acid bacteria. These systems have also been employed for the development of autolytic bacteria, suitable for various industrial applications. 相似文献
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AA Kruize RJ Hené A van der Heide C Bodeutsch PC de Wilde OP van Bijsterveld J de Jong TE Feltkamp L Kater JW Bijlsma 《Canadian Metallurgical Quarterly》1996,39(2):297-303
OBJECTIVE: To assess long-term outcome in patients with isolated keratoconjunctivitis sicca (KCS), primary Sj?gren's syndrome (SS), and secondary SS. METHODS: In 112 patients referred because of dry eyes, an ophthalmologic diagnosis of KCS was made based on results of the Schirmer I test, the tear fluid lysozyme concentration, and rose bengal staining. Subsequent assessments, including sublabial salivary gland biopsy, were performed. Followup assessments were performed 10-12 years after initial diagnosis. RESULTS: Six patients were excluded because no biopsy specimen was available. Seventy-three percent of the remaining 106 patients were female, with a mean age of 53.5 years and a mean symptom duration of 3.9 years. Application of the 1987 classification criteria of Daniels and Talal revealed a diagnosis of isolated KCS in 56 patients, primary SS in 31, and secondary SS in 19. At baseline, 2 of 56 patients with isolated KCS and 8 of 31 with primary SS exhibited mild features of organ-specific autoimmune disease. At followup, 2 of 38 patients with isolated KCS and 4 of 21 with primary SS had developed new features related to autoimmune disease, not necessitating treatment with corticosteroids; none of the patients developed major glandular complications. Three of 30 patients with primary SS died of malignant lymphoma. In 1 of these patients, the possibility could not be excluded that sicca symptoms and infiltrates seen on sublabial salivary gland biopsy had occurred concomitantly with early stages of lymphoma. Malignant lymphoma did not develop in any of the patients with isolated KCS or secondary SS. CONCLUSION: Primary Sj?gren's syndrome is characterized by a stable and rather mild course of glandular and extraglandular manifestations, in marked contrast to the increased risk of development of malignant lymphoma in these patients. Since patients with isolated KCS do not have an increased risk for development of malignant lymphoma, a presumptive diagnosis of primary SS should be confirmed in patients with sicca syndrome. 相似文献
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OP Ivaniv 《Canadian Metallurgical Quarterly》1997,(5):93-98
Dysfunctions were recorded in 185 patients with hypotonic discirculatory encephalopathy of physiologic mechanisms of regulation of macro- and microcirculation. Derangement of the above mechanisms got aggravated because of impairement of hypothalamic and truncal formations, incompetence of suprasegmental control of adaptive and trophic functions. With the purpose of ensuring an adequate correction of the above disorders, studies were made to design a complex of integrative therapy aimed at influencing all links of the changed intercentral systemic regulation and securing enhancement of cerebral systems of bodily vital activity with coordination of interrelations of neurovascular centres with emotional-and-behavioral ones. 相似文献
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KI Fritz F Groenendaal JE McGowan OP Mishra M Delivoria-Papadopoulos 《Canadian Metallurgical Quarterly》1996,729(1):66-74
Thymic carcinoma is a rare malignant neoplasm of the thymic epithelium, distinguished from invasive thymoma by the presence of malignant cytology and a greater incidence of local invasion and embolic metastases. Some common features of thymic carcinomas include (a) large and highly aggressive anterior mediastinal mass; (b) areas of necrosis, hemorrhage, calcification, or cyst formation; (c) gross invasion of contiguous mediastinal structures and wide spread to involve distant intrathoracic sites; (d) high incidence of extrathoracic metastases; (e) broad age range, with an average of 46 years; (f) very low incidence of paraneoplastic syndromes; and (g) very poor prognosis. Three case reports are presented, followed by an overview of the disease with emphasis on the radiographic features. 相似文献
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Influences of pressure changes within the upper airway on respiratory frequency were studied in anesthetized rabbits. These reflex effects were investigated in two ways: (1) by applying sustained negative or positive pressures to isolated upper airway in vagally intact animals during tracheostomy breathing, and (2) by briefly occluding the nasal airways of vagotomized animals at end expiration. Negative pressure applied to isolated upper airway decreased the respiratory frequency (P less than 0.01). Decrease in respiratory frequency correlated with magnitude of pressure change. In contrast, positive pressures produced an increase in respiratory frequency (P less than 0.05). But, the increase in frequency correlated poorly with magnitude of positive pressure change. A post-stimulus effect lasting several breaths was seen following the release of both negative and positive pressures (P less than 0.01). Nasal occlusion in vagotomized animals was associated with an increase in Ti and Ttot of the first nasally occluded breath (P less than 0.05). Increase in Ti was not associated with an increase in peak diaphragmatic activity. This would result in decreased inspiratory load on the upper airway patency maintaining muscles by reducing the mean inspiratory pressure. Hence, these reflex responses to airway pressure could play a functional role in the maintenance of upper airway patency. 相似文献