Showing papers by "University of Iowa published in 1990"

Topics in metric fixed point theory

Abstract: Introduction 1. Preliminaries 2. Banach's contraction principle 3. Nonexpansive mappings: introduction 4. The basic fixed point theorems for nonexpansive mappings 5. Scaling the convexity of the unit ball 6. The modulus of convexity and normal structure 7. Normal structure and smoothness 8. Conditions involving compactness 9. Sequential approximation techniques 10. Weak sequential approximations 11. Properties of fixed point sets and minimal sets 12. Special properties of Hilbert space 13. Applications to accretivity 14. Nonstandard methods 15. Set-valued mappings 16. Uniformly Lipschitzian mappings 17. Rotative mappings 18. The theorems of Brouwer and Schauder 19. Lipschitzian mappings 20. Minimal displacement 21. The retraction problem References.

Vasorelaxant properties of the endothelium-derived relaxing factor more closely resemble S-nitrosocysteine than nitric oxide

Abstract: Studies of cultured bovine aortic endothelial cells using quantitative chemiluminescence techniques have shown that the amount of nitric oxide released under basal conditions, or in response to either bradykinin or the calcium ionophore A23187 is insufficient to account for the vasorelaxant activities of the endothelium-derived relaxing factor (EDRF) derived from the same source. This observation contradicts previous suggestions that nitric oxide and EDRF are the same compound, but may be explained if EDRF is a compound that contains nitric oxide within its structure but is a much more potent vasodilator than nitric oxide. Such a molecule could be one of several nitrosothiols which may yield nitric oxide after a one-electron reduction. The present experiments were carried out to test the possibility that the biological activities of the endothelium-derived relaxing factor might more closely resemble those of one of these compounds, S-nitrosocysteine, than nitric oxide. Nitric oxide release from cultured bovine aortic endothelial cells was detected by chemiluminescence and bioassay experiments compared the vasodilator potencies of nitric oxide, S-nitrosocysteine, and EDRF. The results suggest that EDRF is much more likely to be a nitrosylated compound such as a nitrosothiol than authentic nitric oxide.

Deficiency of a glycoprotein component of the dystrophin complex in dystrophic muscle.

Abstract: Dystrophin, the protein encoded by the Duchenne muscular dystrophy (DMD) gene, exists in a large oligomeric complex. We show here that four glycoproteins are integral components of the dystrophin complex and that the concentration of one of these is greatly reduced in DMD patients. Thus, the absence of dystrophin may lead to the loss of a dystrophin-associated glycoprotein, and the reduction in this glycoprotein may be one of the first stages of the molecular pathogenesis of muscular dystrophy.

Identification and characterization of genes for a second anthranilate synthase in Pseudomonas aeruginosa: interchangeability of the two anthranilate synthases and evolutionary implications

Abstract: Two anthranilate synthase gene pairs have been identified in Pseudomonas aeruginosa. They were cloned, sequenced, inactivated in vitro by insertion of an antibiotic resistance gene, and returned to P. aeruginosa, replacing the wild-type gene. One anthranilate synthase enzyme participates in tryptophan synthesis; its genes are designated trpE and trpG. The other anthranilate synthase enzyme, encoded by phnA and phnB, participates in the synthesis of pyocyanin, the characteristic phenazine pigment of the organism. trpE and trpG are independently transcribed; homologous genes have been cloned from Pseudomonas putida. The phenazine pathway genes phnA and phnB are cotranscribed. The cloned phnA phnB gene pair complements trpE and trpE(G) mutants of Escherichia coli. Homologous genes were not found in P. putida PPG1, a non-phenazine producer. Surprisingly, PhnA and PhnB are more closely related to E. coli TrpE and TrpG than to Pseudomonas TrpE and TrpG, whereas Pseudomonas TrpE and TrpG are more closely related to E. coli PabB and PabA than to E. coli TrpE and TrpG. We replaced the wild-type trpE on the P. aeruginosa chromosome with a mutant form having a considerable portion of its coding sequence deleted and replaced by a tetracycline resistance gene cassette. This resulted in tryptophan auxotrophy; however, spontaneous tryptophan-independent revertants appeared at a frequency of 10(-5) to 10(6). The anthranilate synthase of these revertants is not feedback inhibited by tryptophan, suggesting that it arises from PhnAB. phnA mutants retain a low level of pyocyanin production. Introduction of an inactivated trpE gene into a phnA mutant abolished residual pyocyanin production, suggesting that the trpE trpG gene products are capable of providing some anthranilate for pyocyanin synthesis.

The Effects of an Irrelevant Directional CUE on Human Information Processing

Abstract: Publisher Summary This chapter discusses the effects of an irrelevant directional cue on human information processing. A fundamental concern in cognitive psychology and in human factors engineering is to understand the factors that affect the speed of translating information from a display into an appropriate control action. A series of related experiments demonstrate that the location of a stimulus provides an irrelevant directional cue that affects the time required to process the meaning of the stimulus. The reaction time data have revealed that the effect was not because of any simple isomorphic association between ear stimulated and ipsilateral hand. The same command ear stimulated interaction has also occurred for movement time. It is found that movements to the right are faster when the right command is heard in the right ear than when it is heard in the left ear, and, similarly, movements to the left are faster when the left command is heard in the left ear than when it is heard in the right ear. The Simon effect with visual displays is also elaborated in the chapter.

Visceral pain: a review of experimental studies.

Abstract: This paper reviews clinical and basic science research reports and is directed toward an understanding of visceral pain, with emphasis on studies related to spinal processing. Four main types of visceral stimuli have been employed in experimental studies of visceral nociception: (1) electrical, (2) mechanical, (3) ischemic, and (4) chemical. Studies of visceral pain are discussed in relation to the use and 'adequacy' of these stimuli and the responses produced (e.g., behavioral, pseudoaffective, neuronal, etc.). We propose a definition of an adequate noxious visceral stimulus and speculate on spinal mechanisms of visceral pain.

Transfer vectors and microorganisms containing human cytomegalovirus immediate-early promoter-regulatory DNA sequence

Abstract: The cloning of a eucaryotic promoter-regulatory region that functions preferentially in human cells is disclosed. The invention is exemplified by the cloning of a section of the human cytomegalovirus genome comprising a DNA sequence with regulatory and promoter signals and an initiation site for RNA synthesis. The fragment, termed the human cytomegalovirus (HCMV) promoter-regulatory sequence, was obtained from purified HCMV DNA.

Regulation of large cerebral arteries and cerebral microvascular pressure.

Abstract: Resistance of large arteries appears to be greater in the cerebral circulation than in other vascular beds. Large arteries contribute importantly to total cerebral vascular resistance and are major determinants of local microvascular pressure. Recent studies have shown that resistance of large arteries and cerebral microvascular pressure are affected by several physiological stimuli, including changes in systemic blood pressure, increases in cerebral metabolism, activity of sympathetic nerves, and humoral stimuli such as circulating vasopressin and angiotensin. Stimuli such as sympathetic stimulation and vasopressin produce selective responses of large arteries and, thereby, regulate microvascular pressure without a significant change in cerebral blood flow. These findings lead to the new hypothesis that the brain may be sensitive to changes in cerebral microvascular pressure, resulting in activation of compensatory neurohumoral mechanisms. Important changes occur in large cerebral arteries under pathophysiological conditions. Chronic hypertension increases resistance of large cerebral arteries, which protects the microcirculation against hypertension. Atherosclerosis potentiates constrictor responses of large cerebral arteries to serotonin and thromboxane, which may contribute to vasospasm and transient ischemic attacks.

Measuring Brand Value with Scanner Data

Abstract: Using actual consumer choice data from a single-source scanner panel, we construct two measures of brand value which capture different aspects of brand equity. Brand Value measures perceived quality, the value assigned by consumers to the brand, after discounting for current price and recent advertising exposures. Brand Intangible Value isolates the component of brand value which cannot be directly attributed to the physical product, thus measuring the value created by such factors as brand name associations and perceptual distortions. We illustrate these measures in a study of the powder laundry detergent category and briefly relate the results to strategic variables (order of entry and cumulative advertising expenditures).

Controlled prospective study of postpartum mood disorders: comparison of childbearing and nonchildbearing women.

Abstract: A controlled prospective study was undertaken to determine the extent to which pregnancy and the puerperium are associated with increased risk for minor and major depression, depressive symptom-atology, and poor social adjustment. A large sample of childbearing (CB) women were recruited during the second trimester of pregnancy along with an equal sized, matched sample of nonchild-bearing (NCB) women. Ss were assessed multiple times during pregnancy and after delivery by questionnaire and through personal interview on measures of depression and other mood states and marital and social adjustment. There were no differences between CB and NCB Ss with respect to rates of minor and major depression during pregnancy or after delivery. However, CB women experienced significantly higher levels of depressive symptomatology and poor social adjustment than NCB women during late pregnancy and the early puerperium.

Alcohol-induced neuronal loss in developing rats: increased brain damage with binge exposure.

Abstract: A rat model of third trimester fetal alcohol exposure was used to determine whether a smaller daily dose of alcohol can induce more severe microencephaly and neuronal loss than a larger dose, if the small dose is consumed in such a way that it produces higher blood alcohol concentrations (BACs). The possibility of regional differences within the developing brain to alcohol-induced neuronal loss was also investigated. Sprague-Dawley rat pups were reared artificially over postnatal Days 4-10 (a period of rapid brain growth similar to that of the human third trimester). Two groups received a daily alcohol dose of 4.5 g/kg, administered either as a 5.1% solution in four of the 12 daily feedings or as a 10.2% solution in two of the 12 feedings. A third group received a higher daily dose (6.6 g/kg) administered as a 2.5% solution in every feeding. Gastrostomy and suckle controls were also reared. On postnatal Day 10, the animals were perfused, and brain weights were obtained. In the hippocampal formation, cell counts were made of the pyramidal cells of fields CA1 and CA2/3, the multiple cell types of CA4 and the granule cells of the dentate gyrus. In the cerebellum, Purkinje cells and granule cells were counted in each of the ten lobules of the vermis. The lower daily dose (4.5 g/kg) condensed into two or four feedings produced high maximum BACs (means of 361.6 and 190.7 mg/dl, respectively) and significant microencephaly and cell loss, relative to controls. The higher daily dose (6.6 g/kg), administered continuously, resulted in low BACs (mean of 39.2 mg/dl) and induced no microencephaly or cell loss. Regional differences in neuronal vulnerability to alcohol were evident. In the hippocampus, CA1 neuronal number was significantly reduced only by the most condensed alcohol treatment, while CA3, CA4, and the dentate gyrus populations were not reduced with any alcohol treatment. In the cerebellum, some lobules suffered significantly greater Purkinje cell loss and granule cell loss than did others. The regions in which Purkinje cells were most mature at the time of the alcohol exposure were the most vulnerable to Purkinje cell loss.

Diet-induced atherosclerosis increases the release of nitrogen oxides from rabbit aorta.

Abstract: We examined the hypothesis that impaired endothelium-dependent vasodilation in atherosclerosis is associated with decreased synthesis of nitrogen oxides by the vascular endothelium. The descending thoracic aortae of rabbits fed either normal diet, a high cholesterol diet for 2-5 wk (hypercholesterolemic, HC), or a high cholesterol diet for 6 mo (atherosclerotic, AS) were perfused in a bioassay organ chamber with physiologic buffer containing indomethacin. Despite a dramatic impairment in the vasodilator activity of endothelium-dependent relaxing factor (EDRF) released from both HC and AS aortae (assessed by bioassay), the release of nitrogen oxides (measured by chemiluminescence) from these vessels was not reduced, but markedly increased compared to NL. Thus, impaired endothelium-dependent relaxation in atherosclerosis is neither due to decreased activity of the enzyme responsible for the production of nitrogen oxides from arginine nor to arginine deficiency. Because the production of nitrogen oxides increased in response to acetylcholine in both hypercholesterolemic and atherosclerotic vessels, impairments in signal transduction are not responsible for abnormal endothelium-dependent relaxations. Impaired vasodilator activity of EDRF by cholesterol feeding may result from loss of incorporation of nitric oxide into a more potent parent compound, or accelerated degradation of EDRF.

Comparisons of Multivariate CUSUM Charts

Abstract: We consider several distinct approaches for controlling the mean of a multivariate normal process including two new and distinct multivariate CUSUM charts, several multiple univariate CUSUM charts, and a Shewhart x2 control chart. The performances of th..

Text, context, and the fragmentation of contemporary culture

Abstract: (1990). Text, context, and the fragmentation of contemporary culture. Western Journal of Speech Communication: Vol. 54, Rhetorical Criticism, pp. 274-289.

Employer supported child care, work/ family conflict, and absenteeism: a field study

Abstract: This study examined the relations among employer supported child care, work/family conflict and absenteeism. No support was found for the hypothesis that use of a child care center at work would reduce the amount of work/family conflict and absenteeism of employed parents. Consistent with our hypotheses, the results indicated that supportive supervision and satisfaction with child care arrangements (regardless of location) were related to less work/family conflict. Further, it was found that less work/family conflict was related to lower levels of absenteeism. The results have implications for the role of employers in addressing child care concerns of employees.

p185neu Expression in Human Lung Adenocarcinomas Predicts Shortened Survival

Abstract: p185neu is the protein product of the HER2/neu protooncogene. This protein has characteristics of a tyrosine kinase growth factor receptor and is postulated to be important in human carcinogenesis. To define the significance of the expression of this protein in human non-small cell lung cancer, 55 tumors from patients with squamous cell carcinoma (16), adenocarcinoma (29), or large cell carcinoma (10) of the lung were examined for p185neu using immunohistological methods. Five of 16 squamous cell carcinomas and 10 of 29 adenocarcinomas were found to overexpress p185neu relative to levels of expression seen in uninvolved bronchiolar epithelium. For the adenocarcinomas, p185neu expression was associated with older age (66.6 +/- 10.1 versus 57.5 +/- 10.8 years) (P = 0.04) and shortened survival (83.7 +/- 94.1 versus 188.5 +/- 120 weeks) (P = 0.01). In this group, using Cox's multivariate survival analysis, p185neu expression was found to be a significant determinant of survival (P = 0.04) even after accounting for the effect of tumor stage. For the squamous cell carcinomas, p185neu expression was not correlated with any of our clinicopathological parameters. Our findings indicate that non-small cell lung cancers which express p185neu do so at levels higher than that found in normal bronchiolar epithelium, and expression in adenocarcinomas of the lung is independently associated with diminished survival intervals.

Nurses' job satisfaction: a proposed measure.

Abstract: Thirty-three items originally developed to measure three dimensions of nurses' job satisfaction were subjected to a series of checks designed to determine the number of dimensions being measured and the reliability and validity of the measures of these dimensions. Although the hypothesis of only three dimensions was not supported, the eight interpretable factors that did emerge could meaningfully be placed within these three dimensions. The eight factors were satisfaction with extrinsic rewards, scheduling, family/work balance, co-workers, interaction, professional opportunities, praise/recognition, and control/responsibility. Internal consistency and test-retest reliabilities are reported, as well as checks for criterion-related and construct validity.

Face Agnosia and the Neural Substrates of Memory

Abstract: Focal damage to selective regions of the human association cortices can impair the ability to recognize the identity of previously familiar faces, even when visual perception and intellect remain unaltered. In general, the impairment is accompanied by an inability to learn the identity of new faces. The phenomenon has been noted since the turn of the century (Wilbrand 1892), and is known as prosopagnosia, or face agnosia. Its bizarre and unseeming nature lent itself to doubts that it could be caused by specific neural dysfunction, and psychodynamic interpretations were even offered. Recently, however, face agnosia has become the focus of serious study (e.g. Lhermitte et al 1972, Meadows 1974, Newcombe 1979, Benton 1980, Damasio et al 1982). Face agnosia, along with the varied neuropsychological disturbances that may accompany it, can now be analyzed with experimental paradigms and correlated with neuroanatomical loci of damage identified by neuroimaging methods. This affords a rare opportunity to elucidate cognitive and neural mechanisms of perception, learning, and memory in humans.

Political Parties and Confidence in Government: A Comparison of Norway, Sweden and the United States

Abstract: Comparable survey data from Norway, Sweden and the United States are used to examine trends in political trust for the period 1964–86. During the early part of that period trust declined in all three countries; later it recovered for Norway but continued to plummet in Sweden and the United States. Three major features of the party system are hypothesized to explain the difference in these trends for the three countries. These features are: the structural aspects of the party system; the public's cognitive judgements of the parties as representatives of the policy interests; and the possibility that a negative rejection of political parties as undesirable institutions may spill over to citizen evaluations of government more generally.

Magnetic resonance imaging of the brain in schizophrenia. The pathophysiologic significance of structural abnormalities.

Abstract: In a second large series of schizophrenic patients studied with magnetic resonance imaging at the University of Iowa, Iowa City, earlier findings of decreased frontal, cerebral, and cranial size were not replicated. In this second series, control subjects were selected to be educationally equivalent to the schizophrenic patients, a modification in design that may partially account for the failure to replicate. By means of coronal images, ventricular volume was compared in patients and controls and found to differ to a highly significant degree, with the frontal horns being possibly slightly more enlarged than the rest of the ventricular system. A prominent sex effect was also observed, with most of the increased ventricular size occurring in the male patients. Within the male patients, the thalamus was also observed to be significantly smaller, a finding that could be consistent with periventricular injury. Patients with prominent negative symptoms had significantly larger ventricular size than did those with the mixed or positive subtypes. Because of its superior resolution, magnetic resonance imaging appears to offer a more sensitive index of ventricular enlargement than that provided by computed tomography.

Stress and Social Support—in Search of Optimal Matching

Abstract: Theoretical and practical advantages are discussed of a model that specifies the type of social support that is most beneficial (i.e., most effective in preventing deleterious physical or mental health consequences) following different kinds of stressful life events. Prior attempts to specify such optimal combinations of stress and social support are reviewed, and a new optimal matching model is proposed. Issues that must be addressed in the validation of optimal stress-support models are discussed, and methodological suggestions for future research endeavors in this area are offered.

Cyanogenesis in Plants

Abstract: Several thousand plant species, including many economically important food plants, synthesize cyanogenic glycosides and cyanolipids. Upon tissue disruption, these natural products are hydrolyzed liberating the respiratory poison hydrogen cyanide. This phenomenon of cyanogenesis accounts for numerous cases of acute and chronic cyanide poisoning of animals including man. This article reviews information gathered during the past decade about the enzymology and molecular biology of cyanogenesis in higher plants. How compartmentation normally prevents the large-scale, suicidal release of HCN within the intact plant is discussed. A renewed interest in the physiology of these cyanogenic compounds has revealed that, in addition to providing protection for some species against herbivory, they may also serve as storage forms for reduced nitrogen.

Two cytosolic components of the human neutrophil respiratory burst oxidase translocate to the plasma membrane during cell activation.

Abstract: The superoxide-forming respiratory burst oxidase of human neutrophils is composed of membrane-associated catalytic components and cytosolic constituents required for oxidase activation. This study concerns the hypothesis that cytosolic oxidase components translocate to a membrane fraction when neutrophils are stimulated and the oxidase is activated. A polyclonal antiserum that recognizes two discrete cytosolic oxidase components of 47 and 67 kD was used to probe transfer blots of electrophoresed membrane and cytosol fractions of resting and stimulated neutrophils. In contrast to their strictly cytosolic localization in unstimulated cells, both proteins were detected in membrane fractions of neutrophils activated by phorbol esters and other stimuli. This translocation event was a function of stimulus concentration as well as time and temperature of exposure to the stimulus. It was inhibited by concentrations of N-ethylmaleimide that blocked superoxide formation but was unaffected by 2-deoxyglucose. There was a correlation between translocation of the cytosolic proteins and activation of the oxidase as determined by superoxide formation. Quantitative analyses suggested that approximately 10% of total cellular p47 and p67 became membrane-associated during phorbol ester activation of the oxidase. Analysis of Percoll density gradient fractions indicated that the target membrane for translocation of both proteins was the plasma membrane rather than membranes of either specific or azurophilic granules. In the cell-free oxidase system arachidonate-dependent but membrane-independent precipitation of the cytosolic oxidase proteins was demonstrated. The data show that activation of the respiratory burst oxidase in stimulated human neutrophils is closely associated with translocation of the 47- and 67-kD cytosolic oxidase components to the plasma membrane. We suggest that this translocation event is important in oxidase activation.

Cloning of a 67-kD neutrophil oxidase factor with similarity to a noncatalytic region of p60c-src.

Abstract: Chronic granulomatous diseases (CGDs) are characterized by recurrent infections resulting from impaired superoxide production by a phagocytic cell, nicotinamide adenine dinucleotide phosphate (reduced) (NADPH) oxidase Complementary DNAs were cloned that encode the 67-kilodalton (kD) cytosolic oxidase factor (p67), which is deficient in 5% of CGD patients Recombinant p67 (r-p67) partially restored NADPH oxidase activity to p67-deficient neutrophil cytosol from these patients The p67 cDNA encodes a 526-amino acid protein with acidic middle and carboxyl-terminal domains that are similar to a sequence motif found in the noncatalytic domain of src-related tyrosine kinases This motif was recently noted in phospholipase C-gamma, nonerythroid alpha-spectrin (fodrin), p21ras-guanosine triphophatase-activating protein (GAP), myosin-1 isoforms, yeast proteins cdc-25 and fus-1, and the 47-kD phagocyte oxidase factor (p47), which suggests the possibility of common regulatory features