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21.
Discriminant analysis was used to explore multivariate associations with ABO blood types in a biracial sample of 898 Bogalusa youths. Dependent variables included blood pressure (systolic and diastolic), serum lipid and lipoprotein levels (total cholesterol, alpha-, beta-, and pre-beta-lipoprotein cholesterol, and triglycerides), and anthropometric variables (height, weight, right arm length, triceps skinfold thickness, and a computed ponderal index). Analyses performed within race showed that several variables including beta-lipoprotein cholesterol, systolic blood pressure, and the ponderal index were sufficient to discriminate between individuals possessing the B antigen (B and AB) and those not possessing the B antigen (A and O) in the White subsample. However, height in itself can account for the detected difference, B individuals being taller than non-B individuals by a mean value of 2.4 cm. A concordant, but not significant effect was found in the Black subsample. Further tests support the conclusion that the strongest association is between ABO blood type and height.  相似文献   
22.
Culture conditions are described for the production of extracellular β-d-xylosidase (xylobiase, exo-1,4-β-d-xylosidase, 1,4-β-d-xylan xylohydrolase, EC 3.2.1.37) in shake flasks by Sclerotium rolfsii. At the 1% cellulose level, a maximum activity of 0.82 U ml?1is obtained in media containing either 1% corn steep liquor or 1% defatted coconut cake. The β-d-xylosidase has a molecular weight of 170 000 and catalyses the hydrolysis of 4-nitrophenyl-β-d-xylopyranoside optimally at pH 4.5 and 50°C. The energy of activation is 44 kJ mol?1and the pI and Kmare 6.8 and 0.038 mm, respectively.  相似文献   
23.
Summary Extracellular recordings have been made from ganglion cells of the lemon shark retina: ON, OFF and ON-OFF units were recorded. Spectral sensitivity measurements under darkadapted conditions reveal a max of 519–522 nm. This may be due to two photoreceptor systems. A second class of ganglion cells was characterized as receiving input from a single 544 nm visual pigment system.  相似文献   
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Mixtures of (14)C-labelled glucose plus pyruvate were incubated either with rat diaphragm or slices of rat liver. Incorporation of glucose carbon into glycogen was compared with its incorporation into glucose 6-phosphate relative to the incorporation of pyruvate carbon into these metabolic products. There was no preferential incorporation of glucose carbon relative to pyruvate carbon into glycogen compared with glucose 6-phosphate in the liver slices, but there was in diaphragm. On the assumption that glucose 6-phosphate is a necessary intermediate in the conversion of pyruvate carbon into glycogen, this is evidence for the existence in muscle, but not in liver, of more than one pool of glucose 6-phosphate or of a pathway from glucose to glycogen without glucose 6-phosphate as an intermediate. Galactose carbon, relative to pyruvate carbon, was preferentially incorporated into liver glycogen, so that a substrate converted in liver into glycogen without glucose 6-phosphate as an intermediate could be detected by this approach.  相似文献   
25.
A cellobiose-utilizing bacterium isolated from sugar cane bagasse and identified as a strain of Alcaligenes faecalis (ATCC 21400) produced an inducible beta-glucoside-splitting enzyme. The enzyme was purified by a series of streptomycin and ammonium sulfate fractionations and by Sephadex and diethylaminoethyl column chromatography. The final preparation was purified 130-fold, with a recovery of about 10% of the initial enzyme activity. The enzyme had a wide pH range, with optimal activity at pH 6.0 to 7.0. The enzyme was stable in solution at pH 6.5 to 7.8 when kept at 30 C for 2 hr, but it was destroyed by temperatures above 55 C. At 58 and 60 C, the time required to inactivate 90% of the initial activity was 16 and 6.5 min, respectively. An activation energy of 9,500 cal/mole and a K(m) of 1.25 x 10(-4)m were obtained by using p-nitrophenyl beta-glucoside as a substrate. The K(i) value and hydrolysis of cellobiose by the enzyme indicated a high affinity of the enzyme for the cellobiose. The enzyme had its specificity on beta-glucosidic linkage and the rate of hydrolisis of glucosides depended upon the nature of the aglycon moiety. The inactivation studies showed the presence of sulfhydryl groups in the enzyme. The activity of the enzyme was easily destroyed by the Cu(++) and Hg(++) ions. The Michaelis-Menton relationship and the rate of heat inactivation indicated the presence of one type of noninteracting active site in the bacterial beta-glucosidase. Molecular weight of the enzyme was estimated by gel filtration (Sephadex G-200) and sucrose density gradient, and a value of 120,000 to 160,000 was obtained.  相似文献   
26.
In investigating the response of systems to random input events, dead times in registering these events are met with, as in the case of neuronal behaviour. These situations are studied in terms of product densities making use of the renewal nature of the problem. Different types of cumulative responses of systems are investigated. Some interesting features of a system, which breaks down at a critical value of the cumulative response are analysed.  相似文献   
27.
Isolation and Characterization of a Cellulose-utilizing Bacterium   总被引:12,自引:5,他引:7       下载免费PDF全文
A cellulose-decomposing aerobic and mesophilic bacterium has been isolated from soils of sugar cane fields. The terminal dilution method was adapted to isolate a single clone of cellulolytic organism from closely related contaminants. The cultural and physiological characteristics of the isolate were studied, and the organism was identified as a member of the genus Cellulomonas. The isolate excreted cellulase into the menstruum, and it hydrolyzed various cellulosic materials producing cellobiose as the final breakdown product in the menstruum. When sugar cane bagasse was properly treated with alkali and heat, the organism could decompose up to 90% of the initial substrate within 5 days. Amino acid analysis of the cell crop revealed a high content of lysine, and the essential amino acid pattern compared favorably with that of Food and Agricultural Organization reference protein.  相似文献   
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