| 1. |
- Smith, S M, et al.
(författare)
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Role of neutrophils in hemorrhagic shock-induced gastric mucosal injury in the rat
- 1987
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Ingår i: Gastroenterology. - 0016-5085 .- 1528-0012. ; 93:3, s. 466-471
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Tidskriftsartikel (refereegranskat)abstract
- Gastric mucosal clearance of 51Cr-labeled red blood cells (51Cr-RBC) was measured in rats during a 30-min control period, a 30-min ischemic period (hemorrhage to 27 mmHg arterial pressure), and a 60-min reperfusion period (reinfusion of shed blood). In untreated (control) rats, a dramatic rise in the leakage of 51Cr-labeled red blood cells into the gastric lumen was observed during the reperfusion period. Treatment with neutrophil antiserum attenuated 51Cr-labeled red blood cell flux into the gastric lumen. Using the radioactive microsphere technique, neutrophil-depleted animals were shown to have higher blood flows in the ischemic period than the untreated rats. Bleeding of untreated rats to a mean arterial pressure of 40 mmHg resulted in blood flows that were not different from those in antiserum-treated rats bled to 27 mmHg and leakage of 51Cr-labeled red blood cells similar to that measured in antiserum-treated rats. The results of this study indicate that neutrophils play an important role in hemorrhagic shock-induced gastric bleeding.
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| 2. |
- Thomas, C M, et al.
(författare)
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Regulation of replication and maintenance functions of broad host-range plasmid RK2.
- 1985
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Ingår i: Basic life sciences. - 0090-5542. ; 30
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Tidskriftsartikel (refereegranskat)abstract
- Replication of broad host-range plasmid RK2 depends on a cisacting vegatative replication origin oriVRK2 and the polypeptide product(s) of the trans-acting gene trfA as well as on host-specified products. The trfA gene is the second cistron in a polycistronic unit whose first cistron may be kilD, one of 4 known RK2-specified kil loci (kilA, B, C, and D) which are inhibitory for bacterial host or plasmid vector in the absence of kor functions which suppress in trans the effect of their respective kil genes. Transcription of the operon containing trfA is negatively regulated by the products of both the trfB locus (alias korD and korA) and korB. The loci, trfB and korB, are expressed from a single transcriptional unit which we propose to be negatively autoregulated by the products of both loci, although an additional, weaker and unregulated transcript may also express korB. While deletions in the oriVRK2 region have indicated the presence of copy number control elements adjacent to and possibly overlapping with the minimal oriVRK2 segment, the overriding control of copy number seems to reside in the trfB and korB loci which in conjunction appear to reduce expression of the trfA gene to levels limiting for replication. Coregulation of trfA with kil genes may indicate that kil genes play a role in plasmid maintenance other than replication.
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| 3. |
- Landin-Olsson, M, et al.
(författare)
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Epidemiological and genetic aspects on islet autoimmunity in childhood insulin-dependent diabetes.
- 1988
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Ingår i: Genetic susceptibility to environmental factors : a challenge for public intervention : [First International Ernhold Lundström Symposium, Malmö, Sweden, May 14-16, 1987] - [First International Ernhold Lundström Symposium, Malmö, Sweden, May 14-16, 1987]. - 9122012621 ; , s. 87-93
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Bokkapitel (refereegranskat)
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| 4. |
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| 5. |
- Maguire Jr., Gerald Q., et al.
(författare)
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Process migration Effects on scientific computation
- 1987
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report describes the notion of process migration. and points out certain vulnerabilities to architectural assumptions.Computationally intensive processes, typified by scientific computations, are among the best candidates for migration. In architecturally heterogeneous systems, these processes face particular problems due to their dependence on architectural features such as "machine precision". We point out some of these problems. and suggest some solutions.
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| 6. |
- Paul, Jan, et al.
(författare)
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The vibrational bands of carbon monoxide bound to hemes or metal surfaces
- 1985
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Ingår i: Biochimica et Biophysica Acta - Protein Structure and Molecular Enzymology. - : Elsevier BV. - 0167-4838 .- 1879-2588. ; 832:3, s. 257-264
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Tidskriftsartikel (refereegranskat)abstract
- Infrared spectra of imidazole carbonyl complexes of 2,4-substituted hemes are presented. An increased CO stretch frequency is accompanied by a lowered FeC vibrational energy. Hartree-Fock-Slater electron structure calculations discern π and σ contributions to the observed shifts of vibrational energies. We conclude that an enhanced electron availability manifests itself as (i) a lowered ferric/ferrous reduction potential, (ii) increased filling of the 2π orbital of liganded CO which in turn reduces νCO and increases νFec, and (iii) increased basicity of the liganded CO. Analogies between CO liganded to heme and CO adsorbed onto metal surfaces are discussed.
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| 7. |
- Rundquist, I, et al.
(författare)
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Sciatic nerve blood flow measured by laser Doppler flowmetry and [14C]iodoantipyrine.
- 1985
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Ingår i: American Journal of Physiology. - 0002-9513 .- 2163-5773. ; 248:3 Pt 2, s. H311-317
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Tidskriftsartikel (refereegranskat)abstract
- Blood flow was examined in sciatic nerves of pentobarbital-anesthetized rats by means of laser Doppler flowmetry (LDF) and intravenous [14C]iodoantipyrine infusion. Continuous LDF signals demonstrated slow oscillations and acute, pressure-related changes in flow. The steady-state LDF signal was related linearly to nerve blood flow, as measured with [14C]iodoantipyrine, in intact nerves and nerves stripped of the epineurium. In 14 intact nerves, nerve blood flow averaged 0.27 +/- 0.03 (SE) ml X min-1 X g-1, whereas it averaged 0.13 +/- 0.01 in 5 stripped nerves. Autoradiographs of [3H]-nicotine-infused nerves and intra-arterial injection of 57Co-labeled microspheres demonstrated that flow was not uniform throughout the nerve cross section. The results indicate that LDF can be used to examine nerve blood flow in vivo, demonstrate a linear relation between the LDF signal and flow, and establish absolute values for blood flow in intact and stripped nerves of the anesthetized rat.
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| 8. |
- Smith, Henrik G., et al.
(författare)
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Feeding freqency and parental division of Labour in the double-brooded great tit Parus major
- 1988
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Ingår i: Behavioral Ecology and Sociobiology. - 1432-0762. ; 22, s. 447-453
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Tidskriftsartikel (refereegranskat)abstract
- We studied the relative contribution of each sex and total effort expended in feeding nestlings in the great tit Parus major in relation to artificially altered brood size. A recent model suggests that feeding frequency should reflect the optimal trade-off between parental and fledgling survival, the former being negatively, the latter positively, influenced by high feeding frequencies. In both sexes weight loss was linearly related to feeding frequency. Since fledgling survival increases with nestling weight, the conditions of this model are fulfilled. However, in contrast to the predictions of the model, the total feeding frequency for both sexes combined did not differ between control and enlarged broods, but was lower for reduced ones. This outcome was not the result of a physiologically related inability of the parents to increase their delivery rate. Instead, we suggest that parents with enlarged broods could not find sufficient amounts of prey large enough to be economically worth transporting to the nest. Differences in brood-provisioning rates between the sexes may arise because costs and benefits of feeding nestlings may differ. Females lost more weight than males during the nesting period, but maintained a relatively higher weight during the incubation period. The relationship between weight loss and feeding frequency was similar for both sexes. Male and female brood-feeding frequency was related to brood size in a similar way. This is discussed in light of the great tit's mating system and the fact that the great tit is facultatively double-brooded.
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| 9. |
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| 10. |
- Smith, Jonathan M., et al.
(författare)
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Effects of Copy-on-Write Memory Management on the Response Time of UNIX Fork Operations
- 1988
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Ingår i: Computing Systems. - : Usenix. - 0895-6340. ; 1:3, s. 255-278
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Tidskriftsartikel (refereegranskat)abstract
- We present techniques for analyzing the effect of ‘‘copy-on-write’ ’ page management strategies on the performance of UNIX (TM) fork() operations. The analysis techniques are applied on two workstations, the AT&T 3B2/310 TM and the Hewlett-Packard HP9000/350 TM in order to determine the relationships between the amount of memory in the parent’s data segment, the fraction of this memory which is written by the child, and the improvement in execution time due to ‘‘copy-on-write’’. Since the implementation of ‘‘copy-on-write’ ’ is straightforward with modern MMUs, our results for these workstations are readily generalized to other workstations. The results show that the size of the parent’s allocated memory has little direct effect on performance, due to the fact that only page table entries are copied during the fork() operations. The execution time is most influenced by the amount of memory that must be copied, which can be determined from the product of memory allocated and the fraction of memory written. Thus, the worst case occurs when large address space programs update much of their memory. In order to observe what occurs in practice, we measured two programs that have what are currently considered large address spaces. These programs, which we believe to be representative of the sorts of programs.
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