Biomedical subjects
Publications and source records attributed to D L Long.
4,4'-Bipyridine N,N'-dioxide (L) acts as a hydrogen-bond acceptor in the compounds ([M(NO3)2(H2O)4].L2) (M = Co, Ni) to form doubly-interpenetrated framework materials with sixfold topological connectivity.
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The authors investigated good and poor comprehenders' maintenance of global coherence during reading. Participants read stories in which a character's action was consistent or inconsistent with a description of the character presented earlier in the story. In Experiment 1, the description and action were adjacent in the text (local coherence) or were separated by intervening text (global coherence). Both groups of comprehenders read inconsistent actions more slowly than consistent actions in the local coherence condition, but only good comprehenders showed the reading time difference in the global coherence condition. In Experiment 2, the authors disconfirmed the hypothesis that poor comprehenders fail to maintain global coherence because they fail to activate prior text information. Thus, the results present a paradoxical picture in which poor readers activate relevant knowledge during reading but fail to integrate it into their developing representation.
Previous research has identified two processes that play an important role in anaphor resolution. An activation process increases the accessibility of an anaphor's referent; a suppression process diminishes the accessibility of its nonreferents. In this study, we examined how these processes operate when reference to two story characters shifts rapidly, as it does in story dialogue. Dialogue raises interesting questions about how the antecedent of an anaphor becomes the most activated entity in the reader's discourse model. Do readers suppress an anaphor's nonreferent even though that same entity is likely to be the referent of a subsequent anaphor? Are activation and suppression processes triggered by the anaphor itself or by cues that signal a change of speaker? We found that an anaphor's antecedent is activated differently in dialogue than it is elsewhere in a narrative. Our results suggest that readers use knowledge about the structure of dialogue to anticipate the referent of an upcoming anaphor.
Tumor necrosis factor-alpha (TNF) is initially expressed as a 26-kDa membrane-bound precusor protein (pro-TNF) that is shed proteolytically from the cell surface, releasing soluble 17-kDa TNF. We have identified human ADAM 10 (HuAD10) from THP-1 membrane extracts as a metalloprotease that specifically clips a peptide substrate spanning the authentic cleavage site between Ala76 and Val77 in pro-TNF. To confirm that HuAD10 has TNF processing activity, we cloned, expressed, and purified an active, truncated form of HuAD10. Characterization of recombinant HuAD10 (rHuAD10) suggests that this enzyme has many of the properties (i.e. substrate specificity, metalloprotease activity, cellular location) expected for a physiologically relevant TNF-processing enzyme.
Neural networks can be used as a tool in the explanation of neuropsychological data. Using the Hebbian Learning Rule and other such principles as competition and modifiable interlevel feedback, researchers have successfully modeled a widely used neuropsychological test, the Wisconsin Card Sorting Test. One of these models is reviewed here and extended to a qualitative analysis of how verbal fluency might be modeled, which demonstrates the importance of accounting for the attentional components of both tests. Difficulties remain in programming sequential cognitive processes within a parallel distributed processing (PDP) framework and integrating exceedingly complex neuropsychological tests such as Proverbs. PDP neural network methodology offers neuropsychologists co-validation procedures within narrowly defined areas of reliability and validity.
Recent evidence suggests that cytokines, in addition to regulating hematopoiesis and immune functions, may be important paracrine regulators of bone turnover. Interleukin-1 (IL-1) and IL-6 are cytokines that are produced by and affect both hematopoietic and nonhematopoietic cell types. IL-1 stimulates bone resorption and inhibits osteoblast proliferation and collagen production. Previous reports that IL-6 was secreted in murine osteoblast and bone organ cultures in response to IL-1 and PTH suggested that IL-6 has paracrine effects on bone resorption or formation. To determine whether IL-6 has a paracrine function in human bone, IL-6 expression in cells isolated from normal human bone was investigated. IL-6 mRNA levels in untreated cultures were low and variable, and IL-6 secretion was undetectable. PTH had no effect on IL-6 mRNA levels or IL-6 secretion. IL-1 beta increased IL-6 mRNA levels, maximally 40-fold at 12 h. IL-1 beta increased IL-6 secretion to 0.13 nM, more than 80-fold that of untreated controls at 12 h. IL-1 beta also increased IL-1 beta mRNA levels, maximally 9-fold at 12 h, but did not increase cellular levels or secretion of IL-1 beta protein. Recombinant human IL-6 at 0.5-5 nM stimulated resorption in neonatal mouse calvarial organ cultures but had no effect on human bone-derived cell DNA synthesis or type I procollagen mRNA levels. The results suggest that IL-6 production by human osteoblasts may function to enhance osteolytic activity of IL-1 but does not affect proliferative and matrix biosynthetic aspects of bone formation that were tested. Because osteoblasts and bone marrow cells are in close proximity, IL-6 produced by osteoblasts may also function to amplify IL-1 stimulation of immune responses and hematopoiesis in bone marrow.
Parallel Distributed Processing (PDP), a computational methodology with origins in Associationism, is used to provide empirical information regarding neurobiological systems. Recently, supercomputers have enabled neuroscientists to model brain behavior-relationships. An overview of supercomputer architecture demonstrates the advantages of parallel over serial processing. Histological data provide physical evidence of the parallel distributed nature of certain aspects of the human brain, as do corresponding computer simulations. Whereas sensory networks follow more sequential neural network pathways, in vivo brain imaging studies of attention and rudimentary language tasks appear to involve multiple cortical and subcortical areas. Controversy remains as to whether associative models or Artificial Intelligence symbolic models better reflect neural networks of cognitive functions; however, considerable interest has shifted towards associative models.
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A controlled trial was carried out in 209 primary cadaveric renal transplants to compare the effects of cyclosporine and steroids (double therapy) with those of cyclosporine in lower initial dose, azathioprine, and steroids (triple therapy). Patients have been followed 1-36 months since transplantation. Actuarial two-year graft survival (double 74%, triple 76%) and two-year patient survival (double 90%, triple 93%) were similar for both groups. Further analysis of particular risk factors including age, diabetes, HLA matching, acute renal failure, and use of sequential Minnesota antilymphocyte globulin in patients with delayed graft function also showed similar outcomes with both immunosuppressive regimens. Initial hospitalization time, rate of rejection, incidence of serious infection, and rate of rehospitalization were not different. Mean CsA doses and mean trough whole-blood levels were higher in double-therapy patients at hospital discharge but not by three months posttransplant. There were no differences between the two groups in iothalamate clearance at any time. Hypertension was more frequent six months posttransplant in the triple-therapy group (p less than 0.05). Thus, similar results were obtained with both regimens, and except for hypertension no regimen appeared to have increased side effects up to three years posttransplant.
It has been shown that bone cells produce and secrete several growth factors (GFs) which are also found in the bone matrix. To investigate the role of these growth factors in bone cell metabolism, we compared the effects of different factors separately and in combination with respect to osteoblastic cell proliferation and differentiation. While basic fibroblast GF (FGF), transforming GF beta-1 (TGF beta), and platelet-derived GF (PDGF) enhance DNA synthesis, they had the opposite effect on alkaline phosphatase (ALP) activity in cell extracts: FGF, TGF beta, and PDGF inhibited cell ALP but strongly stimulated DNA synthesis. The IGFs had little effect on cell ALP but increased the release of ALP into the conditioned medium. In mitogenic tests of combinations of GFs, most had at least additive effects at low concentrations, and FGF, TGF beta, and IGF2 produced synergistic effects. Evidence is presented for (1) the modulation of the effects of one GF by the action of other GF, (2) synergistic interactions between FGF, TGF beta, and IGF2, and (3) a possible role for the observed interactions among GF for the mitogenic effect of human bone extract.
The radiation levels were measured in 109 working sites in 12 counties or municipalities of our district where X-ray was used for medical diagnosis. At the same time the effectiveness of some radioprotective facilities was assessed. The results showed that in the working sites with the ordinary protection, the average exposure rate of the surface of the worker's chest was 3.43 x 10(-8) mC/kg.s; in the sites with poor protection the average rate of exposure was the highest (about 273 x 10(-8) mC/kg.s); in the sites with other types of protection the rate was less than 10.80 x 10(-8) mC/kg.s; the exposure rate using lead chairs and aprons was 18.6 times and 5.8 times respectively lower than those without.
A randomized, double-blind study was conducted to determine the possible effects of aspartame on the plasma amino acid profiles of 23 diabetic patients with renal failure who were undergoing maintenance hemodialysis. Subjects were given a single dose of 10 mg aspartame/kg (approximately equivalent to 25 packets of Equal [NutraSweet Consumer Products, Inc, Chicago, IL] or the amount of phenylalanine in a 300-mL glass of milk) or a placebo in a crossover study design. Three postdialysis blood samples were drawn just before and 1 and 2 h after aspartame or placebo consumption. After aspartame consumption statistically significant increases in only two amino acids, phenylalanine and tyrosine, were noted at 1 and 2 h when compared with placebo values. The increases in phenylalanine were within the normal postprandial range for healthy subjects; no other increases in essential or nonessential amino acids, except for tyrosine, were detected. This study supports the view that aspartame is safe for diabetic subjects with chronic renal failure.
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Groups of Caesarean-derived, colostrum-deprived lambs were inoculated by the intratracheal route with Pasteurella haemolytica 4 to 6 days after the inoculation of parainfluenza virus type 3 (PI3). Some were killed immediately (0 h) and others 24 h later. Control groups were inoculated with PI3 alone, P. haemolytica alone or media alone. Pulmonary phagocytic cells, P. haemolytica and PI3 were recovered by pulmonary lavage. The phagocytes were separated into alveolar macrophage (AM) and neutrophil fractions by density gradient centrifugation and examined biochemically and microbiologically. Twenty-four hours after the inoculation of P. haemolytica bacterial proliferation to greater than 0 h levels had occurred in four of six animals inoculated with P. haemolytica alone, two of eight inoculated with P. haemolytica 4 days after PI3 and all of eight inoculated with P. haemolytica 6 days after PI3. Mean bacterial numbers in animals inoculated with P. haemolytica 6 days after PI3 and killed at 24 h (10(9.1 +/- 1.9)) were significantly higher than they were in the other two groups killed at this time (PI3 4 days, P. haemolytica 24 h, mean = 10(5.3 +/- 1.7); P. haemolytica alone 24 h, mean = 10(4.5 +/- 2.9)). Pneumonic lesions were also more severe in the first group. This defect in pulmonary clearance and increase in the severity of pneumonia in animals inoculated with P. haemolytica 6 days after PI3 coincided with a 1000-fold decrease in virus titres in the lung between Day 6 and Day 7 after virus inoculation and the first detectable evidence of the host's immune response. The virus infection resulted in a significant increase in the number of AM that could be recovered from the lung and an increase in the number of AM with cytoplasmic vacuolation. However, there was no difference in the total number of AM or the number of vacuolated AM between animals that controlled the P. haemolytica infection and those in which proliferation of P. haemolytica occurred. The inoculation of P. haemolytica resulted in a 100-fold increase in the number of neutrophils in the lavage fluid, but there were no differences between virus-infected and uninfected animals, nor was there a difference between animals that controlled the P. haemolytica infection and those that did not.(ABSTRACT TRUNCATED AT 400 WORDS)
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The confluent sinus pressure was measured in eight mongrel dogs in the head-up position to compare the effectiveness of positive end-expiratory pressure (PEEP) and jugular venous compression in increasing cerebral venous pressure. When the head was elevated 30 cm above the heart, confluent sinus pressure decreased from 9.6 +/- 1.8 (mean +/- SEM) to -5.3 +/- 0.5 mmHg. At constant arterial carbon dioxide tension (PaCO2 = 28 +/- 2 mmHg), PEEP (20 cmH2O) did not increase cerebral venous pressure. However, when the jugular veins were compressed with a neck tourniquet with pressures of 20-140 mmHg, cerebral venous pressure increased rapidly. When neck tourniquet pressure was maintained at 40 mmHg, confluent sinus pressure in all dogs was increased and sustained at 2.4 +/- 0.8 mmHg. Carotid artery pressure measured distal to the tourniquet was not altered. The efficacy of extrathoracic venous pressure elevation (neck tourniquet) is greater than intrathoracic (PEEP), and this may relate to the Starling resistor effects of neck veins and the presence of jugular venous valves. We conclude that prophylactic use of PEEP in the prevention of air embolism during the sitting position may not be as effective as jugular venous compression.
The drainage and instillation of poorly absorbable corticosteroids has recently been suggested as an laternative to the present modes of therapy for uremic pericarditis. One patient who underwent such a therapeutic approach subsequently had a left internal mammary artery to right internal mammary vein arteriovenous fistula develop. To our knowledge, this is the first report of the development of arteriovenous fistula after either pericardiocentesis or intrapericardial instillation of steroids.