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101.
George M. White 《Cell biochemistry and biophysics》1987,11(1):25-33
Computers, the human mind, and social systems have common problems of inadequate memory and insufficient data manipulation
speed. In each of these domains, information compression techniques have evolved to reduce storage and processing needs. Among
the techniques for information compression, coding of information in procedures stands out as exceptionally powerful. Procedural
information coding also gives rise to behavior that may be defined as intelligent. It is found in the human mind, in machines
and in social systems. Its use in human thought is aided by language development which promotes regular review of abstract
procedures. A practical consequence of better understanding of procedural information coding is the possibility of training
people to exhibit greater mental capacity, a controversial possibility. This paper explores the impact of data processing
resource limitations, data compression and procedural thinking in men and machines. 相似文献
102.
103.
Every week, for 20 weeks, the growth of naturally occurring grain storage fungi on wheat infested with the three commonest British grain storage mites,Acarus siro, Glycyphagus destructor andTyrophagus longior, was compared with that on uninfested wheat.The number of colonies of theAspergillus glaucus group per gram were always less on grain infested with mites than on uninfested grain.Penicillium spp. were also less numerous on grain which was infested withA. siro but did not appear to be affected by the other mites. In contrast, two fungi which are pathogenic to mites,Aspergillus restrictus andWallemia sebi, were more abundant in the presence of certain mites. The former was associated withG. destructor, the latter withG. destructor andA. siro.The three species of mites either feed on theA. glaucus group andPenicillium spp., or inhibit them by an unknown secretion. Pathogenic fungi are probably avoided. Mites are therefore an important variable in studies on fungal growth during grain drying and storage. 相似文献
104.
Thirty-nine isolates of Cryptococcus neoformans, nineteen serotype AD and twenty serotype BC, were assayed for susceptibility to eight antifungal agents using an in vitro agar dilution assay. Media employed were Kimmig agar and yeast nitrogen base supplemented with 10% glucose. The antifungal agents used were ketoconazole, amphotericin B, 5-fluorocytosine, nystatin, miconazole, BAY N 7133, ICI 153,066, and itraconazole. No clinically significant differences in in vitro minimum inhibitory concentrations were detected between serotypes AD and BC against any of the compounds tested. An adverse medium effect was observed in two of the assays, but the outcome of the AD/BC comparison was not affected. This is the first report in which the in vitro antifungal susceptibilities of Cryptococcus neoformans serotypes are analyzed. 相似文献
105.
George P. Barnes Richard G. Tollefsbol Warren A. Parker John F. Nelson 《Gerodontology》1986,5(2):129-134
Increased longevity and recently intensified emphasis on gerodontology mandate that dental students'exposure to clinical care of the elderly be enhanced. The extent to which individual students can be exposed to geriatric dental care depends on the availability of elderly patients to dental school clinics and the treatment needs of these patients. The purposes of this study were (1) to determine the dental treatment needs of geriatric patients who seek care at a dental school, and (2) to ascertain if differences exist between the needs of older versus relatively young geriatric patients. Data collected on 128 elderly patients during a three month period indicate that 57% of the aged were either edentulous at examination or treatment planned to become edentulous and receive two full dentures. The remaining 43% were treatment planned to remain dentulous and receive therapies other than full upper and lower dentures. More older geriatric patients required full dentures than their younger cohorts. More young elderly required prophylaxes, scalings, root planing therapy, dental restorations, and partial dentures. Additional to their denture requirements, aged patients appear to have sufficient non-prosthetic needs to allow for meaningful gerodontic experience by students. 相似文献
106.
Specific binding sites for vasoactive intestinal polypeptide on nonadherent peripheral blood lymphocytes 总被引:4,自引:0,他引:4
A Danek M S O'Dorisio T M O'Dorisio J M George 《Journal of immunology (Baltimore, Md. : 1950)》1983,131(3):1173-1177
Vasoactive intestinal polypeptide (VIP), an octacosapeptide isolated from porcine duodenum and thought to have neuromodulator function in several functional systems (gastrointestinal tract, brain, lung, genital tract, heart), was recently detected in human neutrophils by radioimmunoassay. Subsequent studies demonstrated a VIP-mediated increase in lymphocyte adenylate cyclase. In this paper, VIP binding studies are presented using viable nonadherent human lymphocytes. Binding of 125I-VIP to nylon wool column-purified lymphocytes is specific, time dependent, rapid, and reversible. Bound radioactivity varies linearly with the number of cells used and is displaceable by non-iodinated VIP in a dose-dependent manner with complete displacement between 1 pM and 50 nM. Scatchard analysis of competition experiments demonstrates one class of specific binding sites with a KD of 0.47 +/- 0.23 nM and a Bmax of 24.9 +/- 7.0 pM. This Bmax represents 1700 binding sites/cell. secretin, gastric inhibitory polypeptide, and glucagon did not effectively compete with 125I-VIP for binding sites. This is the first demonstration of VIP receptors in a purified population of human lymphocytes; the data suggest that VIP may modulate lymphocyte function. 相似文献
107.
George H. Jones 《Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression》1983,741(3):333-340
Transfer RNAs have been prepared from control and regenerating rat skeletal muscle. The yield of tRNA is highest during the early stages of the regeneration process (5 and 8 days following the induction of regeneration) and decreases to near control values thereafter. The amino acid acceptor activity (extent of aminoacylation) of tRNA from regenerating muscle was also found to be higher for some amino acids than the activity of control tRNA, and the maximum increase in activity was observed between 5 and 8 days following the initiation of regeneration with a decrease to control levels through 15 and 30 days. The isoacceptor pattern, determined by RPC-5 chromatography, for methionyl-tRNAs from control muscle and 5-day regenerating muscle were essentially indistinguishable, while a minor peak of prolyl-tRNA was observed in the population from 5-, 8- and 15-day regenerates which was apparently absent from the control tRNA. Lysyl-tRNAs from control muscle contain two major isoacceptors while a third isoacceptor is observed in the tRNA preparations from 5-, 8- and 15-day regenerating muscle. The relative amount of this third isoacceptor is highest in the 8-day population and decreases in amount in tRNAs from 15- and 30-day regenerates. Control muscle also contains two major glutamyl-tRNA species while a third isoacceptor can be detected in regenerates. The relative amount of this species increases during the early course of the regeneration process but is present at near control levels by 30 days following Marcaine injection. Cell-free protein synthesis using muscle polyribosomes showed that tRNAs from regenerating muscle were more effective in stimulating [35S]methionine incorporation than tRNAs from control muscle. 相似文献
108.
Nedialka G. Markova George G. Markov 《Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression》1983,741(1):7-14
Isopicnic centrifugation in Cs2SO4-Ag+ gradients at pH 7.0 reveals that the genome of the marine snail Rapana thomasiana Grosse (Gastropoda) contains an AT-rich satellite fraction comprising 5% of the DNA. Restriction enzyme analysis shows that the satellite DNA is composed of a number of related subsets arranged in tandem arrays. They have evolved from the segmental amplification of an 1460 bp long monomer unit with a complex inner organization. Most probably, the present basic repeat originates from an ancestral 400–500 bp long sequence in which some insertions and/or deletions have occurred. 相似文献
109.
The genome organization of the marine snail Rapana thomasiana Grosse (Gastropoda), genome size 2.7 pg, was studied by reassociation kinetics, S1-nuclease assay, and restriction enzyme analysis. The slow-reassociating (single-copy) fraction represented only 21% of the genome. The average length of 80% of the single-copy sequences was less than 700 bp and the remaining 20% no longer than 1,400 bp. Longer stretches of unique DNA were not observed. The genome contained an unusually high percent-age of inverted repeats: at standard fragment length the zero-time binding fraction amounted to 25% of the genome. Foldback structures ranging from 200 bp to more than 10 kb were observed after S1-nuclease treatment. They were randomly distributed throughout at least 85% of the genome, and the spacings between them were estimated to be about 1,600 bp on the average. The middle-repetitive DNA (45% of the genome) contained two kinetic components, repeated 430 and 65,000 times per genome, respectively. It was found that the majority of the repetitive sequences are about 300 bp long. Longer repeats (about 2,000 bp) were also observed, comprising a small portion of the genome. The inverted repeats, the middle-repetitive, and the singly-copy sequences were fully interspersed in the genome, thus indicating that R. thomasiana DNA is not organized in either the Xenopus or the Drosophila pattern type. — R. thomasiana is the only mollusc so far in which a satellite DNA has been found. It is organized in tandem repeats of 1,460 bp with a very complex organization but a low degree of divergence. 相似文献
110.
Proliferation of cells undergoing chondrogenesis in vitro 总被引:3,自引:0,他引:3
Mindy George Kenneth P. Chepenik Martin H. Schneiderman 《Differentiation; research in biological diversity》1983,24(1-3):245-249
Abstract. Continuous exposure of chicken embryo limb bud mesenchyme cells undergoing chondrogenesis in vitro to [3 H] thymidine ([3 H]TdR) revealed that more than 90% of the cells synthesized DNA at least once during 120 h of culture. When cells were exposed to [3 H]TdR for 24 h beginning at various times throughout the culture period, the percentage of cells which incorporated [3 H]TdR during each period was approximately 92%. However, when the period for incorporation of radioisotope was limited to two hours, the number of cells which incorporated [3 H]TdR was found to decline during chondrogenesis in vitro. This decline was coincident with the appearance of extracellular matrix material and occurred in those cells which had, and had not, expressed the cartilage phenotype.
We conclude from these studies that (1) practically all of the cells continue to proliferate while chondrogenesis is occurring in vitro, (2) there is an increase in the length of the cell cycle during chondrogenesis in vitro, and (3) withdrawal from the cell cycle is not required for differentiation of mesenchyme into cartilage. 相似文献
We conclude from these studies that (1) practically all of the cells continue to proliferate while chondrogenesis is occurring in vitro, (2) there is an increase in the length of the cell cycle during chondrogenesis in vitro, and (3) withdrawal from the cell cycle is not required for differentiation of mesenchyme into cartilage. 相似文献