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21.
Doris Kavanagh-Gray 《CMAJ》1964,90(26):1468-1471
Brachial artery and central aortic pressures were compared in 50 consecutive patients subjected to retrograde left heart catheterization in order to re-emphasize the fact that the two pressures are not necessarily identical. In 43 cases the systemic systolic pressure peaks exceeded those in the central aorta while in seven these pressures were equal. The average pressure difference was 22.6 mm. Hg. The greatest differences occurred in cases of aortic regurgitation and could be extreme, the brachial artery systolic pressure exceeding that in the aorta by more than 100 mm. Hg in some instances. The least differences occurred in cases of aortic stenosis but significant differences occasionally existed, leading to erroneous estimation of valve orifice size if the systemic rather than the aortic systolic pressure was used. 相似文献
22.
In the Panamanian iceryine coccid Icerya zeteki
Cockerell (Family Margarodidae
Morrison) all females become hermaphroditic early in the first instar; occasional males arise from unfertilized eggs, but self-fertilization is assured by the protandry of the hermaphrodite. In the development of the ovotestis, initiation of the male phase is brought about by haploidization of those germ cells destined for spermatogenesis. In both Icerya zeteki and Icerya purchasi this gonial reduction results from the degeneration and elimination of one genome during prophase. Except for minor variations in the coiling cycle of spermatocytes, the chromosomes (n=2) of I. zeteki correspond closely to those of all other haplo-diploid iceryines known. The present status of the species Icerya zeteki
Cockerell is reviewed, and on both taxonomicand cytological grounds is judged to be uncertain.Supported in part by National Science Foundation Grant GB — 1922. 相似文献
23.
The findings in and experiences with 19 consecutive patients subjected to open mitral valve surgery are described. All patients underwent a right-heart catheterization. In order to exclude multivalvular heart disease, a left-heart catheterization was performed in 10 patients and angiographic studies of the aortic valve area in 12. Pulmonary function studies were performed on 11 patients. The FEV (0.75 sec.) and the MMFR were found to correlate well with existing pulmonary reserves.Fourteen of the 19 patients subjected to open mitral valve surgery survived the operation and have been followed up for three months to 2½ years. Four patients had a mitral valvuloplasty. Three of these four have deteriorated and will require a valvular replacement. Ten of 15 patients subjected to a mitral valve replacement are alive; five of these 10 have had signs and symptoms indicating peripheral embolization. Mitral valvuloplasty is preferable to a valvular replacement as far as embolic complications are concerned, while valvular replacements result in a more perfect and lasting hemodynamic repair. The high incidence of peripheral embolization following valvular replacements focuses attention on the need for improved mitral valve prostheses. 相似文献
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25.
Protein-DNA conjugates produced by UV irradiation and their use as probes for hybridization. 下载免费PDF全文
Several proteins have been crosslinked to DNA by low dose uv irradiation. The principle of the method is based on an efficient and fast radiation induced reaction of amino acid residues with DNA at low pH. The method seems to be of general applicability for crosslinking proteins to DNA in a very simple one step procedure. Some of such DNA-protein conjugates have been used as probes for hybridization experiments. DNA-protein A probes were found to be most useful. 相似文献
26.
Ursula Meindl Doris Wittmann-Pinegger Oswald Kiermayer 《Plant Systematics and Evolution》1989,164(1-4):197-208
Cells ofMicrasterias denticulata
Bréb. were kept in nutrient solution of high osmolality (salt stress) for four weeks. In a special cell multiplication test it was established that cell division is gradually inhibited at increasing salt concentrations and totally arrested at the highest concentration (26 mosm/kg). Recovery studies proved that even cells from the highest concentration range start dividing immediately after being placed in aqua bidest. thus indicating the full reversibility of the inhibiting effect. — Cells of the highest concentration range show marked ultrastructural changes. Besides an enormous accumulation of starch and oil bodies and a condensed appearance of the ground plasma, a reduction of mitochondria, ER and the Golgi-system is found. The most striking effect occurs on the vacuolar system which appears extremely reduced and condensed. The cell wall is thickened by the formation of an additional cell wall layer with a spongy electron microscopical appearance. Through the cell wall many droplets of a probably fat-like substance are excreted. — In summary, salt stress induces growth-inhibited akinete cells in the sense ofFritsch; these can be reactivated by decreasing the salt concentration. The salt-induced akinete state seems to be an ecological adaption to unfavourable conditions rather than a degeneration of the cells.Dedicated to Prof. DrLothar Geitler on the occasion of his 90th birthday.23. 12. 1988 相似文献
27.
A microdeletion of less than 250 kb, including the proximal part of the FMR-1 gene and the fragile-X site, in a male with the clinical phenotype of fragile-X syndrome 下载免费PDF全文
Doris Whrle Dieter Kotzot Mark C. Hirst Antonella Manca Bernhard Korn Angela Schmidt Gotthold Barbi Hans-Dieter Rott Annemarie Poustka Kay E. Davies Peter Steinbach 《American journal of human genetics》1992,51(2):299-306
A gene designated "FMR-1" has been isolated at the fragile-X locus. One exon of this gene is carried on a 5.1-kb EcoRI fragment that exhibits length variation in fragile-X patients because of amplification of or insertion into a CGG-repeat sequence. This repeat probably represents the fragile site. The EcoRI fragment also includes an HTF island that is hypermethylated in fragile-X patients showing absence of FMR-1 mRNA. In this paper, we present further evidence that the FMR-1 gene is involved in the clinical manifestation of the fragile-X syndrome and also in the expression of the cellular phenotype. A deletion including the HTF island and exons of the FMR-1 gene was detected in a fragile X-negative mentally retarded male who presented the clinical phenotype of the fragile-X syndrome. The deletion involves less than 250 kb of genomic DNA, including DXS548 and at least five exons of the FMR-1 gene. These data support the hypothesis that loss of function of the FMR-1 gene leads to the clinical phenotype of the fragile-X syndrome. In the fragile-X syndrome, there are pathogenetic mechanisms other than amplification of the CGG repeat that do have the same phenotypic consequences. 相似文献
28.
29.
Inci Arisan-Atac Regina Hodits Doris Kristufek Christian P. Kubicek 《Applied microbiology and biotechnology》1993,39(1):58-62
Trichoderma reesei was studied for its ability to produce -mannanase activity on a variety of carbon sources. The highest -mannanase activity was produced on cellulose, whereas -mannan-containing carbon sources (such as kojac powder or locust bean gum) gave lower enzyme titres. The enzyme responsible for the major -mannanolytic activity from T. reesei was purified to physical homogeneity by preparative chromatofocusing and anion exchange fast protein liquid chromatography. This -mannanase is a glycoprotein, with a molecular mass of 46 (±2) kDa and an isoelectric point of 5.2. It has an optimal pH at 5.0 and broad pH stability (2.5–7.0). It is stable for 60 min at 55° C, and has an optimal temperature for activity at 75° C. During incubation with locust bean gum, the enzyme releases mainly tri- and disaccharides.
Correspondence to: C. P. Kubicek 相似文献
30.
Substrate specificity and product inhibition of different forms of fructokinases and hexokinases in developing potato tubers 总被引:10,自引:0,他引:10
The substrate dependence and product inhibition of three different fructokinases and three different hexokinases from growing potato (Solanum tuberosum L.) tubers was investigated. The tubers contained three specific fructokinases (FK1, FK2, FK3) which had a high affinity for fructose K
m=64, 90 and 100 (M) and effectively no activity with glucose or other hexose sugars. The affinity for ATP (K
m=26, 25 and 240 M) was at least tenfold higher than for other nucleoside triphosphates. All three fructokinases showed product inhibition by high fructose (K
i=5.7, 6.0 and 21 mM) and were also inhibited by ADP competitively to ATP. Sensitivity to ADP was increased in the presence of high fructose, or fructose-6-phosphate. In certain conditions, the K
i (ADP) was about threefold below the K
m (ATP). All three fructokinase were also inhibited by fructose-6-phosphate acting non-competitively to fructose (K
i=1.3 mM for FK2). FK1 and FK2 showed very similar kinetic properties whereas FK3, which is only present at low activities in the tuber but high activities in the leaf, had a generally lower affinity for ATP, and lower sensitivity to inhibition by ADP and fructose. The tuber also contained three hexokinases (HK1, HK2, HK3) which had a high affinity for glucose (K
m=41, 130 and 35 M) and mannose but a poor affinity for fructose (K
m=11, 22 and 9 mM). All three hexokinases had a tenfold higher affinity for ATP (K
m=90, 280 and 560 M) than for other nucleoside triphosphates. HK1 and HK2 were both inhibited by ADP (K
i=40 and 108 M) acting competitively to ATP. HK1, but not HK2, was inhibited by glucose-6-phosphate, which acted non-competitively to glucose (K
i=4.1 mM). HK1 and HK2 differed, in that HK1 had a narrower pH optimum, a higher affinity for its substrate, and showed inhibition by glucose-6-phosphate. The relevance of these properties for the regulation of hexose metabolism in vivo is discussed.Abbreviations FK
fructokinase
- Fru6P
fructose-6-phosphate
- Glc6P
glucose-6-phosphate
- HK
hexokinase
- NTP
nucleoside triphosphate
- Pi
inorganic phosphate
- UDPGlc
uridine-5-diphosphoglucose
This work was supported by the Deutsche Froschungsgemeinschaft (SFB 137). We are grateful to Professor E. Beck (Lehrstuhl für Pflanzenphysiologie, Universität Bayreuth, FRG) for providing laboratory facilities. 相似文献