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61.
62.
63.
The susceptibility of Mycobacterium tuberculosis and Mycobacterium avium-intracellulare to the disinfections used for spillage and heat sensitive instruments has received much attention in recent years. The use of clinical isolates of M. tuberculosis and M. avium-intracellulare as test organisms is considered unsuitable for standard tests due to their hazardous nature (category 3 pathogens and slow growth rates). This has led to much debate in standards committees on the selection and use of a possible surrogate which would be safer and more practical to use and yet mimic the susceptibility of clinical isolates. This study compared the susceptibility of one possible surrogate Mycobacterium terrae NCTC 10856, with that of clinical isolates of M. tuberculosis H37 Rv and M. avium-intracellulare using a quantitative suspension test. The instrument and environmental disinfectants tested were a chlorine-releasing agent, sodium dichloroisocyanyurate (NaDCC) at 1000 ppm and 10,000 ppm av. Cl, chlorine dioxide at 1100 ppm av. ClO2 (Tristel, HayMan MediChem), 0.35% peracetic acid (NuCidex, Johnson & Johnson), 70% industrial methylated spirit (IMS), 2% alkaline glutaraldehyde (Asep, Galen), 10% succine dialdehyde and formaldehyde mixture (Gigasept, Schulke and Mayr). Results showed that the clinical isolate of M. avium-intracellulare was the most resistant of the three test organisms. M. terrae, which is not a category 3 pathogen, was slightly more resistant than M. tuberculosis and this would appear to be a suitable surrogate for establishing tuberculocidal activity. However, with an increase in the clinical significance of M. avium-intracellulare, particularly in human immunodeficiency virus (HIV) and immunocompromised patients, a more resistant surrogate is required. In the absence of such a surrogate, testing with M. avium-intracellulare in a clinical laboratory equipped for handling category 3 pathogens is still advised to establish mycobactericidal activity. 相似文献
64.
The diagnostic value of monitoring human cytomegalovirus (HCMV) late pp67 mRNA expression by nucleic acid sequence-based amplification (NASBA) after renal-allograft transplantation was evaluated. RNAs were isolated from 489 whole-blood specimens of 42 patients for the specific amplification of the late pp67 (UL65) mRNA. NASBA results were compared to results from the pp65 antigenemia assay, virus isolation by cell culture, and serology. The sensitivity value for NASBA proved to be higher than that for the antigenemia assay (50 versus 35%) for the detection of HCMV infection, while the sensitivity values of cell culture and NASBA were comparable (54 and 50%, respectively). NASBA detected the onset of HCMV infection simultaneously with cell culture and the antigenemia assay. Both the antigenemia assay and NASBA are very specific (100%) and highly predictive (100%) for the onset of HCMV infection. Antiviral therapy with ganciclovir resulted in negative results for cell culture, the antigenemia assay, and NASBA. In conclusion, monitoring HCMV pp67 mRNA expression by NASBA is a highly specific method for the detection of HCMV infection in renal-allograft recipients and is more sensitive than the antigenemia assay. Furthermore, NASBA can be used to monitor the progression of HCMV infections and the effect of antiviral therapy on viral activity. 相似文献
65.
66.
B Rehberg R Rüschner M Fischer BJ Ebeling A Hoeft 《Canadian Metallurgical Quarterly》1998,33(7):425-429
Despite improvement in early diagnosis, surgical techniques, and general patient care, most deaths of cancer patients result from metastases. Recent studies have revealed that cytokines produced by cancer cells or by stromal cells play an important role into development the cancer metastasis. The formation of a cancer metastasis involves several major steps: 1) extensive vascularization; 2) local invasion; 3) adherence either to capillary endothelial cells or to subendothelial basement membrane; 4) extravasation; and 5) proliferation. In colon cancer, several cytokines such as growth factors, inflammatory cytokines, and angiogenic factors have been confirmed to be involved in each step of metastasis. This paper summarizes the involvement of cytokines in the development of invasion and metastasis in colon cancer. 相似文献
67.
The incorporation was studied of the gluconeogenic substrates lactate, alanine, aspartate and glutamate into glycogen of astroglial primary cultures derived from mouse brain. The incorporation was inhibited by 3-mercaptopicolinate, an inhibitor of one of the characteristic gluconeogenic enzymes, phosphoenolpyruvate carboxykinase. Only the mitochondrial isoenzyme of phosphoenolpyruvate carboxykinase was detectable in the astroglial primary cultures. After the incubation of glucose-starved cells with medium containing a mixture of [6-3H]glucose and [U-14C]glucose, the newly synthesized glycogen showed a 3H/14C ratio which was approximately 15% less than the isotope ratio for the medium. The decrease of the isotope ratio was not significantly inhibited by 3-mercaptopicolinate, indicating a cycling of approximately 15% of the glucose to the level of the triose phosphates before its incorporation into astroglial glycogen. During the initial phase of glycogen resynthesis, the contribution of the gluconeogenic substrates appeared to be higher. This was in agreement with the accumulation of fructose 2,6-bisphosphate during refeeding. A participation of gluconeogenic substrates in glycogen metabolism was also detectable when the glycogen content was not changing significantly. 相似文献
68.
Trimethylaminuria, also called fish-odour syndrome, is an inherited disorder caused by deficient N-oxidation and increased excretion of trimethylamine. This study reports on two unrelated and otherwise healthy children with transient trimethylaminuria, a hitherto unknown abnormality, without N-oxidation deficiency. This demonstrates that a diagnosis of fish-odour syndrome should include the analysis of urinary excretion not only of trimethylamine but also of trimethylamine-N-oxide. Since transient trimethylaminuria may be a common condition and no cause for it can presently be recognized, such patients will require careful follow-up. 相似文献
69.
F. Minami A. Brückner-Foit D. Munz B. Trolldenier 《International Journal of Fracture》1992,54(3):197-210
The local approach was recently proposed by Beremin and Mudry for evaluating the statistical behaviour of toughness results of materials. This approach introduces a stress parameter
w
, termed the Weibull stress, as a measure of the fracture resistance of materials instead of the conventional toughness parameters such as K
c,
c
and J
cl (critical stress intensity factor, CTOD and J-integral, respectively). The Weibull stress
w
obeys the Weibull distribution with the two parameters m and
u
(the shape and the scale parameter, respectively). The first parameter m is normally estimated to be 22 irrespective of the kind of material. In this paper a procedure for the determination of the Weibull parameters m and
u
is developed. This procedure consists of the determination of the plastic zone ahead of the crack tip, from which cleavage fracture originates, and of the maximum likelihood estimation of the parameters m and
u
based on the stress distribution in the plastic zone. Calculations using this procedure confirm that the distribution of the Weibull stress
w
is a material property independent of specimen thickness, and in particular that the shape parameter m depends on the material, e.g. m12 for a German reactor pressure vessel steel (20 Mn Mo Ni 5 5). Using these parameters for the distribution of the Weibull stress the size effect in fracture toughness values is predicted and an improved agreement between theory and experiments is obtained compared to the Weakest Link model. 相似文献
70.
Jürgen Heym 《Journal of Low Temperature Physics》1992,89(5-6):869-884
Fluctuation-induced corrections to the NMR relaxation rate T
1
–1
in dirty two-dimensional superconductors above the superconducting transition (T>Tc) are re-investigated including dynamic fluctuations. Static fluctuations, as discussed by Kuboki and Fukuyama,1 dominate the fluctuation terms near Tc. We find that dynamic fluctuations become important for T/Tc1.05, and might even reverse the sign of the total fluctuation-induced contributions to T
1
–1
. We observe that (T1T)–1 has a minimum at T=Tmin (·) for ·/Tc0.1 which depends on the pair-breaking parameter ·. Furthermore, we show that the fluctuation contributions to T
1
–1
can be obtained numerically with very high accuracy from multipoint Padé approximants. 相似文献