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61.
HeLa cells were established as a model system to study the invasiveness and biology of Legionella pneumophila. In this model, invasion could be distinguished from adherence; virulent strains of L. pneumophila were adherent and invasive, whereas nonvirulent strains were adherent but poorly invasive. Invasion was rapid and did not require de novo bacterial protein synthesis, suggesting that the invasion factor is constitutively expressed by virulent strains. Entry into HeLa cells required actin polymerization and an intact microtubule cytoskeleton and was only moderately inhibited by the presence of 100 mM glucose or galactose. Intracellular replication of virulent L. pneumophila took place in ribosome-studded complex endosomes and led to the formation of free bacteria-laden vesicles presumably released from lysed HeLa cells. These free vesicles (referred to as mature vesicles) were isolated in continuous density gradients of Percoll. The bacteria contained in the isolated mature vesicles had a unique envelope structure and were highly adherent to HeLa cells, characteristics that correlated with a bright red appearance after the Giménez stain (Giménez positive). Plate-grown legionellae and replicating legionellae, harboured in complex endosomes, displayed a typical Gram-negative envelope and stained green after the Giménez stain (Giménez negative). Chronically infected cultures of HeLa cells were also established that may be a useful tool for studying long-term interactions between virulent L. pneumophila and mammalian cells. HeLa cells constitute a valuable model system that offers unique opportunities to study parasite-directed endocytosis, as well as stage specific-parasite interactions. 相似文献
62.
CM Schneider D Huzly C Vetter BU von Specht FD Daschner 《Canadian Metallurgical Quarterly》1997,16(6):467-471
OBJECTIVE: The purpose of this study was to determine the depth that implants may be safely placed into the distal femoral epiphysis (DFE) for the repair of distal femoral physeal fractures. STUDY DESIGN: The depth of the DFE was related to the radiographic thickness of the patella in this experimental study. ANIMALS OR SAMPLE POPULATION: Twenty immature canine cadavers. METHODS: Patella thicknesses were measured from lateral radiographs. Actual DFE depths were determined for pins driven in normograde fashion and for pins driven retrograde from the central depression between the metaphyseal pegs and from the cranial pegs. The association of DFE depth and patella thickness was evaluated using linear regression analysis. Using 95% confidence intervals, rules for estimating the safe depth of implant placement into the DFE were determined. RESULTS: DFE depth had significant correlation with patella thickness for pins placed in retrograde fashion from the central depression between the metaphyseal pegs (r2 = .83) and from the cranial pegs (r2 = .82) and for pins placed in normograde fashion (r2 = .65). CONCLUSIONS: Based on 95% confidence intervals, pins placed in retrograde fashion from the central depression between the metaphyseal pegs may be safely driven into the DFE a distance equal to 140% of patella thickness. Pins placed from the cranial metaphyseal pegs may be driven to a depth equal to 80% of patella thickness, and pins placed in normograde fashion may be driven to a depth equal to 30% of patella thickness. CLINICAL RELEVANCE: Measurement of patella thickness assists the surgeon in determining the approximate depth that pins may be driven into the DFE without penetrating the articular surface of the stifle joint. 相似文献
63.
S Diallo O Ndir Y Dieng FD Ba IB Bah BM Diop O Gaye T Dieng 《Canadian Metallurgical Quarterly》1995,40(2):123-128
One hundred ASA I orthopaedic surgical patients (four randomized groups) were anaesthetized using continuous propofol and intermittent fentanyl (TIVA), with controlled ventilation via a tracheal tube in groups 1 and 2, and a laryngeal mask airway (LMA) in groups 3 and 4. Neuromuscular blockers were used in groups 1 and 3 only. There were no significant differences between groups in total anaesthetic requirements, as assessed by cardiovascular variables and movement. Coughing interfered with surgery and made controlled ventilation difficult to manage. In contrast, movement not associated with coughing did not impair surgery or ventilation. Patients in group 2 (tracheal tube, no neuromuscular blocker) required more interventions for coughing than the other groups, while patients in group 4 (LMA, no neuromuscular blocker) needed more boluses for movement than groups 1 and 3. Groups 1 and 2 (tracheal tube) had significantly higher heart rates and mean arterial pressures than groups 3 and 4 for varying periods up to 5 min after insertion of the airway management device. There was no correlation between mean arterial pressure and plasma concentrations of catecholamines related to insertion of either the tracheal tube or LMA. The LMA was found to be a highly effective device for controlled ventilation in TIVA and easier to manage than the tracheal tube in the absence of neuromuscular blockers. 相似文献
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SM de Matta FD Monache F Ferrari GB Marini-Bettolo 《Canadian Metallurgical Quarterly》1976,31(7):527-535
The direct and indirect effects of staphylococcal enterotoxins A and C on the flux of water, sodium, and potassium have been studied in paired Thiry Vella fistulae in dogs. Administration of toxin resulted in a significant decrease in absorption, both in the loop to which the toxin had been administered and its pair. This decrease in absorption was associated with a decrease in movement out of the lumen, movement into the lumen remaining relatively unchanged. The mechanism of action of staphylococcal enterotoxins is discussed, and comparisons made with other enterotoxins. 相似文献
67.
A filtration technique was employed to trap 14CO2 continuously for liquid scintillation counting. Devices for delivering scintillator and ethanolamine solutions were combined symmetrically with two fritted-glass aspirators for alternating operation. The collector was regulated by a fraction collector timer. Trial and animal tests indicated that the described method was efficient, reliable, and more convenient for frequent collection over long periods than alternative methods. The automatic collector was used for metabolic studies of [1-14C] arachidonic acid in rats kept in metabolic cages and the results were processed by multicompartmental analysis. 相似文献
68.
FD Goldberg 《Canadian Metallurgical Quarterly》1977,28(10):759-763
Insurance companies and administrators of group insurance plans have accepted the premise that coverage for mental illness must be different from coverage for other health problems, and thus insurers continue to limit their liability through various exclusions and restrictions. For several years providers and consumers of services have worked for the enactment of state laws that mandate or regulate certain kinds of coverage for mental illness; as of January 1, 1977, a total of 22 states had such statutes. The author presents a state-by-state summary of the provisions. He also classifies many of the provisions into six categories and discusses the probable basis for their enactment. 相似文献
69.
FD Burg RC Brownlee FH Wright H Levine CW Daeschner VC Vaughan JA Anderson 《Canadian Metallurgical Quarterly》1976,51(10):824-828
In 1972 the American Board of Pediatrics (ABP) initiated studies leading to a report which identifies the important components of competency needed in the practice of pediatrics. The development of the report involved a group process engaging ABP board members and examiners. The outcome has been (a) the delineation of a process for establishing definitions of competency in a medical discipline; (b) the development of a framework for specifying the abilities needed to perform the tasks required of pediatricians; (c) an elaboration of samples of pediatric subjects to which these abilities and tasks are relevant; and (d) the development of a basis for choice of methods to use for purposes of certification. 相似文献
70.
Thyroid scans were performed at 4 and 24 hr after administration of Na123I solution in 124 examinations. The 4-hr and 24-hr scans were found to be of equal diagnostic value. Thus, in individuals with structural thyroid abnormalities, one can effectively reduce the time required for scan evaluation from the standard 24 hr to 4 hr. 相似文献