The [18F]fluorodeoxyglucose method for the measurement of local cerebral glucose utilization in man

A method has been developed to measure local glucose consumption in the various structures of the brain in man with three-dimensional resolution. [18F]-2-deoxy-2-fluoro-D-glucose is used as a tracer for the exchange of glucose between plasma and brain and its phosphorylation by hexokinase in the tissue. A mathematical model and derived operational equation are used which enable local cerebral glucose consumption to be calculated in terms of the following measurable variables. An intravenous bolus of [18F]-2-deoxy-2-fluoro-D-glucose is given and the arterial specific activity monitored for a predetermined period of from 30 to 120 minutes. Starting at 30 minutes, the activity in a series of sections through the brain is determined with three-dimensional resolution by an emission tomographic scanner. The method was used to measure local cerebral glucose consumption in two normal volunteers. The values in gray matter structures range from 5.79 mg/100 g per minute in the cerebellar cortex to 10.27 in the visual cortex, whereas, in white matter structures, the values range from 3.64 mg/100 g per minute in the corpus callosum to 4.22 in the occipital lobe. Average values for gray matter, white matter, and whole brain metabolic rates, calculated as a weighted average based on the approximate volume of each structure, are 8.05, 3.80, and 5.90 mg/100 g per minute, respectively. The value of 5.9 mg/100 g per minute compares favorably with values previously reported.

Volatile organic compounds in breath as markers of lung cancer: a cross-sectional study

BACKGROUND

Many volatile organic compounds (VOCs), principally alkanes and benzene derivatives, have been identified in breath from patients with lung cancer. We investigated whether a combination of VOCs could identify such patients.

METHODS

We collected breath samples from 108 patients with an abnormal chest radiograph who were scheduled for bronchoscopy. The samples were collected with a portable apparatus, then assayed by gas chromatography and mass spectroscopy. The alveolar gradient of each breath VOC, the difference between the amount in breath and in air, was calculated. Forward stepwise discriminant analysis was used to identify VOCs that discriminated between patients with and without lung cancer.

FINDINGS

Lung cancer was confirmed histologically in 60 patients. A combination of 22 breath VOCs, predominantly alkanes, alkane derivatives, and benzene derivatives, discriminated between patients with and without lung cancer, regardless of stage (all p<0.0003). For stage 1 lung cancer, the 22 VOCs had 100% sensitivity and 81.3% specificity. Cross-validation of the combination correctly predicted the diagnosis in 71.7% patients with lung cancer and 66.7% of those without lung cancer.

INTERPRETATION

In patients with an abnormal chest radiograph, a combination of 22 VOCs in breath samples distinguished between patients with and without lung cancer. Prospective studies are needed to confirm the usefulness of breath VOCs for detecting lung cancer in the general population.

A dual-process model of defense against conscious and unconscious death-related thoughts: an extension of terror management theory

Distinct defensive processes are activated by conscious and nonconscious but accessible thoughts of death. Proximal defenses, which entail suppressing death-related thoughts or pushing the problem of death into the distant future by denying one's vulnerability, are rational, threat-focused, and activated when thoughts of death are in current focal attention. Distal terror management defenses, which entail maintaining self-esteem and faith in one's cultural worldview, function to control the potential for anxiety that results from knowing that death is inevitable. These defenses are experiential, are not related to the problem of death in any semantic or logical way, and are increasingly activated as the accessibility of death-related thoughts increases, up to the point at which such thoughts enter consciousness and proximal threat-focused defenses are initiated. Experimental evidence for this analysis is presented.

Evidence for terror management theory: I. The effects of mortality salience on reactions to those who violate or uphold cultural values

On the basis of terror management theory, it was hypothesized that when mortality is made salient, Ss would respond especially positively toward those who uphold cultural values and especially negatively toward those who violate cultural values. In Experiment 1, judges recommended especially harsh bonds for a prostitute when mortality was made salient. Experiment 2 replicated this finding with student Ss and demonstrated that it occurs only among Ss with relatively negative attitudes toward prostitution. Experiment 3 demonstrated that mortality salience also leads to larger reward recommendations for a hero who upheld cultural values. Experiments 4 and 5 showed that the mortality salience effect does not result from heightened self-awareness or physiological arousal. Experiment 6 replicated the punishment effect with a different mortality salience manipulation. Implications for the role of fear of death in social behavior are discussed.

Variation in volatile organic compounds in the breath of normal humans

We studied the variation in volatile organic compounds (VOCs) in the breath of 50 normal humans, using gas chromatography and mass spectroscopy. An average breath sample contained 204.2 VOCs (SD=19.8, range 157-241). The alveolar gradient of each VOC (abundance in breath minus abundance in air) varied with rate of synthesis minus rate of clearance. A total of 3481 different VOCs were observed: 1753 with positive alveolar gradients, 1728 with negative alveolar gradients. Twenty-seven VOCs were observed in all fifty subjects. This study confirmed previous reports of wide inter-individual variations. Two new findings were the comparatively small variation in total number of breath VOCs, and the presence of a 'common core' of breath VOCs in all subjects.

Role of consciousness and accessibility of death-related thoughts in mortality salience effects

On the basis of terror management theory, research has shown that subtle mortality salience inductions engender increased prejudice, nationalism, and intergroup bias. Study 1 replicated this effect (increased preference for a pro-U.S. author over an anti-U.S. author) and found weaker effects when Ss are led to think more deeply about mortality or about the death of a loved one. Study 2 showed that this effect is not produced by thoughts of non-death-related aversive events. Studies 2 and 3 demonstrated that this effect occurs only if Ss are distracted from mortality salience before assessment of its effects. Study 4 revealed that although the accessibility of death-related thoughts does not increase immediately after mortality salience, it does increase after Ss are distracted from mortality salience. These findings suggest that mortality salience effects are unique to thoughts of death and occur primarily when such thoughts are highly accessible but outside of consciousness.

Why do people need self-esteem? Converging evidence that self-esteem serves an anxiety-buffering function

Three studies were conducted to assess the proposition that self-esteem serves an anxiety-buffering function. In Study 1, it was hypothesized that raising self-esteem would reduce anxiety in response to vivid images of death. In support of this hypothesis, Ss who received positive personality feedback reported less anxiety in response to a video about death than did neutral feedback Ss. In Studies 2 and 3, it was hypothesized that increasing self-esteem would reduce anxiety among individuals anticipating painful shock. Consistent with this hypothesis, both success and positive personality feedback reduced Ss' physiological arousal in response to subsequent threat of shock. Thus, converging evidence of an anxiety-buffering function of self-esteem was obtained.

Terror management and aggression: evidence that mortality salience motivates aggression against worldview-threatening others

The hypothesis that mortality salience (MS) motivates aggression against worldview-threatening others was tested in 4 studies. In Study 1, the experimenters induced participants to write about either their own death or a control topic, presented them with a target who either disparaged their political views or did not, and gave them the opportunity to choose the amount of hot sauce the target would have to consume. As predicted, MS participants allocated a particularly large amount of hot sauce to the worldview-threatening target. In Studies 2 and 3, the authors found that following MS induction, the opportunity to express a negative attitude toward the critical target eliminated aggression and the opportunity to aggress against the target eliminated derogation. This suggests that derogation and aggression are two alternative modes of responding to MS that serve the same psychological function. Finally, Study 4 showed that MS did not encourage aggression against a person who allocated unpleasant juice to the participant, supporting the specificity of MS-induced aggression to worldview-threatening others.

Terror management theory and self-esteem: evidence that increased self-esteem reduces mortality salience effects

On the basis of the terror management theory proposition that self-esteem provides protection against concerns about mortality, it was hypothesized that self-esteem would reduce the worldview defense produced by mortality salience (MS). The results of Experiments 1 and 2 confirmed this hypothesis by showing that individuals with high self-esteem (manipulated in Experiment 1; dispositional in Experiment 2) did not respond to MS with increased worldview defense, whereas individuals with moderate self-esteem did. The results of Experiment 3 suggested that the effects of the first 2 experiments may have occurred because high self-esteem facilitates the suppression of death constructs following MS.

The type I macrophage scavenger receptor binds to gram-positive bacteria and recognizes lipoteichoic acid

Macrophage scavenger receptors exhibit unusually broad binding specificity for polyanionic ligands and have been implicated in atherosclerosis and various host defense functions. Using a radiolabeled, secreted form of the type I bovine macrophage scavenger receptor in an in vitro binding assay, we have found that this receptor binds to intact Gram-positive bacteria, including Streptococcus pyogenes, Streptococcus agalactiae, Staphylococcus aureus, Enterococcus hirae, and Listeria monocytogenes. Competition binding studies using purified lipoteichoic acid, an anionic polymer expressed on the surface of most Gram-positive bacteria, show that lipoteichoic acids are scavenger receptor ligands and probably mediate binding of the receptor to Gram-positive bacteria. Lipoteichoic acids, for which no host cell receptors have previously been identified, are implicated in the pathogenesis of septic shock due to Gram-positive bacteria. Scavenger receptors may participate in host defense by clearing lipoteichoic acid and/or intact bacteria from tissues and the circulation during Gram-positive sepsis. Since scavenger receptors have been previously shown to bind to and facilitate bloodstream clearance of Gram-negative bacterial endotoxin (lipopolysaccharide), these receptors may provide a general mechanism for macrophage recognition and internalization of pathogens and their cell surface components.

Suppression, accessibility of death-related thoughts, and cultural worldview defense: exploring the psychodynamics of terror management

Previous research has shown that after a mortality-salience (MS) treatment, death thought accessibility and worldview defense are initially low and then increase after a delay, suggesting that a person's initial response to conscious thoughts of mortality is to actively suppress death thoughts. If so, then high cognitive load, by disrupting suppression efforts, should lead to immediate increases in death thought accessibility and cultural worldview defense. Studies 1 and 2 supported this reasoning. Specifically, Study 1 replicated the delayed increase in death accessibility after MS among low cognitive load participants but showed a reversed pattern among participants under high cognitive load. Study 2 showed that, unlike low cognitive load participants, high cognitive load participants exhibited immediate increase in pro-American bias after MS. Study 3 demonstrated that worldview defense in response to MS reduces the delayed increase in death accessibility. Implications of these findings for understanding both terror management processes and psychological defense in general are discussed.

Terror management and tolerance: Does mortality salience always intensify negative reactions to others who threaten one's worldview?

Terror management research has shown that reminding Ss of their mortality leads to intolerance. The present research assessed whether mortality salience would lead to increased intolerance when the value of tolerance is highly accessible. In Study 1, given that liberals value tolerance more than conservatives, it was hypothesized that with mortality salience, dislike of dissimilar others would increase among conservatives but decrease among liberals. Liberal and conservative Ss were induced to think about their own mortality or a neutral topic and then were asked to evaluate 2 target persons, 1 liberal, the other conservative. Ss' evaluations of the targets supported these hypotheses. In Study 2, the value of tolerance was primed for half the Ss and, under mortality-salient or control conditions, Ss evaluated a target person who criticized the United States. Mortality salience did not lead to negative reactions to the critic when the value of tolerance was highly accessible.

Using socially fair treatment to promote acceptance of a work site smoking ban

Announcements of a work site smoking ban were made to 732 clerical workers. The presentations differed in the amount of information given about the need for the ban and the degree of interpersonal sensitivity shown over the personal impact of the ban. Immediately after the announcement, questionnaires were completed to assess participants' acceptance of the ban. High amounts of information thoroughness and of social sensitivity, given separately, enhanced acceptance of the ban, but their combined effects were even greater. Although heavy smokers were least accepting of the ban, they showed the greatest incremental gain in acceptance after exposure to thorough information presented in a highly sensitive manner. By contrast, nonsmokers' acceptance of the ban was uniformly unaffected by the way it was presented to them. Regardless of how much they smoked, all participants recognized the procedural fairness associated with giving thorough information in a socially sensitive manner.

Stereotypes and terror management: evidence that mortality salience enhances stereotypic thinking and preferences

If stereotypes function to protect people against death-related concerns, then mortality salience should increase stereotypic thinking and preferences for stereotype-confirming individuals. Study 1 demonstrated that mortality salience increased stereotyping of Germans. In Study 2, it increased participants' tendency to generate more explanations for stereotype-inconsistent than stereotype-consistent gender role behavior. In Study 3, mortality salience increased participants' liking for a stereotype-consistent African American and decreased their liking for a stereotype-inconsistent African American; control participants exhibited the opposite preference. Study 4 replicated this pattern with evaluations of stereotype-confirming or stereotype-disconfirming men and women. Study 5 showed that, among participants high in need for closure, mortality salience led to decreased liking for a stereotype-inconsistent gay man.

Mutations in the pre-mRNA splicing factor gene PRPC8 in autosomal dominant retinitis pigmentosa (RP13)

Retinitis pigmentosa (RP) is a genetically heterogeneous disorder characterized by progressive degeneration of the peripheral retina leading to night blindness and loss of visual fields. With an incidence of approximately 1 in 4000, RP can be inherited in X-linked, autosomal dominant or autosomal recessive modes. The RP13 locus for autosomal dominant RP (adRP) was placed on chromosome 17p13.3 by linkage mapping in a large South African adRP family. Using a positional cloning and candidate gene strategy, we have identified seven different missense mutations in the splicing factor gene PRPC8 in adRP families. Three of the mutations cosegregate within three RP13 linked families including the original large South African pedigree, and four additional mutations have been identified in other unrelated adRP families. The seven mutations are clustered within a 14 codon stretch within the last exon of this large 7 kb transcript. The altered amino acid residues at the C-terminus exhibit a high degree of conservation across species as diverse as humans, Arabidopsis and trypanosome, suggesting that some functional significance is associated with this part of the protein. These mutations in this ubiquitous and highly conserved splicing factor offer compelling evidence for a novel pathway to retinal degeneration.

Acute and long-term effects on limb function of combined modality limb sparing therapy for extremity soft tissue sarcoma

A retrospective review is presented on 145 patients who underwent limb-sparing surgery and radiation therapy (with or without adjuvant chemotherapy) for their primary soft tissue sarcomas of the extremities on protocol between 1975 and 1986. The focus on our analysis was the acute and long term toxicity of treatment on limb function. The most common acute complication was skin reaction, occurring in 52 patients (36%). Long term (occurring after more than 1 year following all treatment) treatment complications in the extremity were as follows: bone fracture = 6%; contracture = 20%; pain requiring narcotics = 7%; edema greater than 2+ = 19%; moderate to severe decrease in range of motion = 32%; moderate to severe decrease in manual muscle strength = 20%; orthotic device required = 9%; cane or crutch required = 7%; chronic infection = 9%; and tissue induration = 57%. Three amputations for treatment complications were required. Inclusion of more than 50% of the joint in the radiation portal was associated with a higher frequency of contracture. High nominal standard dose (greater than 1760 rets, greater than 63 Gy at 1.8 Gy per fraction) resulted in more painful limbs as well as limbs with increased edema, decreased manual muscle strength, decreased range of motion, and skin telangiectasias. Edema was more often noted in patients with a longer radiation portal (greater than 35 cm), as was tissue induration. Chronic ulcer or infection was more frequently seen in patients with lower extremity tumors and when more than 75% of the extremity diameter was irradiated. Although chemotherapy given concurrent with radiation therapy was associated with a higher number of acute skin reactions, this did not appear to translate into increased long term morbidity. The percentage of patients ambulating without assistive devices and with mild or no pain was 84%. Careful attention to the techniques of radiation therapy may have a significant impact on minimizing acute and long term complications of limb sparing treatment for extremity soft tissue sarcoma.

Molecular analysis of juvenile Huntington disease: the major influence on (CAG)n repeat length is the sex of the affected parent

Juvenile Huntington disease (HD), characterised by onset of symptoms before the age of 20 with rigidity and intellectual decline, is associated with a predominance of affected fathers. In order to investigate the molecular basis for the observed parental effect, we have analysed the CAG trinucleotide repeat within the HD gene in 42 juvenile onset cases from 34 families. A highly significant correlation was found between the repeat length and age of onset (r = -0.86, p < 10(-7) and it was determined that the sex of transmitting parent was the major influence on CAG expansion leading to earlier onset. Neither the size of the parental upper allele, the age of parent at conception of juvenile onset child, nor the grandparental sex conferred a significant effect upon expansion. Affected sib pair analysis of CAG repeat length, however, revealed a high correlation (r = 0.91, p < 10(-7). Furthermore, analysis of nuclear and extended families showed a familial predisposition to juvenile onset disease. This study demonstrates that the sex of transmitting parent is the major influence on trinucleotide expansion and clinical features in juvenile Huntington disease.

Linkage of Usher syndrome type I gene (USH1B) to the long arm of chromosome 11

Usher syndrome is the most commonly recognized cause of combined visual and hearing loss in technologically developed countries. There are several different types and all are inherited in an autosomal recessive manner. There may be as many as five different genes responsible for at least two closely related phenotypes. The nature of the gene defects is unknown, and positional cloning strategies are being employed to identify the genes. This is a report of the localization of one gene for Usher syndrome type I to chromosome 11q, probably distal to marker D11S527. Another USH1 gene had been previously localized to chromosome 14q, and this second localization establishes the existence of a new and independent locus for Usher syndrome.

Death, sex, love, and neuroticism: why is sex such a problem?

Terror management theory posits that sex is a ubiquitous human problem because the creaturely aspects of sex make apparent our animal nature, which reminds us of our vulnerability and mortality. People minimize this threat by investing in the symbolic meaning offered by the cultural worldview. Because people high in neuroticism have difficulty finding or sustaining meaning, sex is a particular problem for them. In Study 1, mortality salience caused high-neuroticism participants to find the physical aspects of sex less appealing. Study 2 revealed that for such individuals thoughts of physical sex increase the accessibility of death-related thoughts. This finding was replicated in Study 3, which also showed that providing meaning by associating sex with love reduces the accessibility of death-related thoughts in response to thoughts of physical sex. These findings provide insight into why people high in neuroticism have conflicting thoughts about sexuality and why sexuality is so often regulated and romanticized.

I am not an animal: mortality salience, disgust, and the denial of human creatureliness

The present research investigated the need to distinguish humans from animals and tested the hypothesis derived from terror management theory that this need stems in part from existential mortality concerns. Specifically, the authors suggest that being an animal is threatening because it reminds people of their vulnerability to death; therefore, reminding people of their mortality was hypothesized to increase the need to distance from animals. In support, Study 1 revealed that reminders of death led to an increased emotional reaction of disgust to body products and animals. Study 2 showed that compared to a control condition, mortality salience led to greater preference for an essay describing people as distinct from animals; and within the mortality salient condition but not the control condition, the essay emphasizing differences from other animals was preferred to the essay emphasizing similarities. The implications of these results for understanding why humans are so invested in beautifying their bodies and denying creaturely aspects of themselves are discussed.

Depression, self-focused attention, and expectancies for positive and negative future life events for self and others

In two studies, we examined depressed and nondepressed persons' judgments of the probability of future positive and negative life events occurring to themselves and to others. Study 1 demonstrated that depressed subjects were generally less optimistic than their nondepressed counterparts: Although nondepressed subjects rated positive events as more likely to happen to themselves than negative events, depressed subjects did not. In addition, relative to nondepressed subjects, depressed subjects rated positive events as less likely to occur to themselves and more likely to occur to others and negative events as more likely to occur to both self and others. Study 2 investigated the role that differential levels of self-focused attention might play in mediating these differences. On the basis of prior findings that depressed persons generally engage in higher levels of self-focus than nondepressed persons do and the notion that self-focus activates one's self-schema, we hypothesized that inducing depressed subjects to focus externally would attenuate their pessimistic tendencies. Data from Study 2 supported the hypothesis that high levels of self-focus partially mediate depressive pessimism: Whereas self-focused depressed subjects were more pessimistic than nondepressed subjects, externally focused depressed subjects were not. The role of attentional focus in maintaining these and other depressive pessimistic tendencies was discussed.

DNA haplotype analysis of Huntington disease reveals clues to the origins and mechanisms of CAG expansion and reasons for geographic variations of prevalence

This study of allelic association using three intra- and two extragenic markers within 150 kb of the Huntington disease (HD) mutation has provided evidence for linkage disequilibrium for four of five markers. Haplotype analysis of 67 HD families using markers in strong linkage disequilibrium with HD identified two haplotypes underlying 77.6% of HD chromosomes. Normal chromosomes with these two haplotypes had a mean number of CAG repeats significantly larger than and an altered distribution of CAG repeats compared with other normal chromosomes. Furthermore, haplotype analysis of five new mutation families reveals that HD has arisen on these same two chromosomal haplotypes. These findings suggest that HD arises more frequently on chromosomes with specific DNA haplotypes and higher CAG repeat lengths. We then studied CAG and CCG repeat lengths in the HD gene on 896 control chromosomes from different ancestries to determine whether the markedly reduced frequency of HD in Finland, Japan, China and African Blacks is associated with an altered frequency of DNA haplotypes and subsequently lower CAG lengths on control chromosomes compared to populations of Western European descent. The results show a highly significant inverse relationship between CAG and CCG repeat lengths. In populations with lowered prevalence rates of HD, CAG repeat lengths are smaller and the distribution of CCG alleles is markedly different from Western European populations. These findings suggest that, in addition to European emigration, new mutations make a contribution to geographical variation of prevalence rates and is consistent with a multistep model of HD developing from normal chromosomes with higher CAG repeat lengths.

Effect of age on the breath methylated alkane contour, a display of apparent new markers of oxidative stress

Reactive oxygen species (ROS) are toxic byproducts of mitochondrial energy production that inflict oxidative stress, a constant barrage of damage to DNA, proteins, lipids, and other biologically important molecules. Oxidative stress has been implicated as a pathologic mechanism in aging and in several diseases. We developed a display of apparent new markers of oxidative stress in human beings, the breath methylated alkane contour (BMAC). The BMAC is a three-dimensional display of C4 to C20 alkanes and monomethylated alkanes in breath, with x-axis = carbon chain length, z-axis = methylation site, and y-axis = alveolar gradient (relative abundance in breath minus relative abundance in room air). In 102 normal human subjects of 9 to 89 years of age, alveolar gradients of components of the BMAC increased significantly with age. The mean alveolar gradient of all components of the BMAC varied from negative in the youngest quartile (ages 9 to 31 years) to positive in the oldest quartile (ages 74 to 89 years)(P < 2.10(-9)). These findings were consistent with an increase in oxidative stress with advancing age, although an age-related decline in clearance by cytochrome p450 may have contributed. The BMAC provides a display of apparent new markers of oxidative stress with potential applications in aging research, clinical diagnosis, pharmacology, and toxicology.

Increased pentane and carbon disulfide in the breath of patients with schizophrenia

AIMS

To determine the concentrations of pentane (a marker of lipid peroxidation) and other volatile organic compounds in the breath of patients with schizophrenia.

METHODS

Volatile organic compounds were assayed by gas chromatography/mass spectroscopy (GC/MS) in 88 subjects--25 with acute schizophrenic psychosis, 26 with psychiatric disorders other than schizophrenia, and 37 normal volunteers.

RESULTS

The mean alveolar gradients of pentane and carbon disulfide (CS2) were significantly higher in the patients with schizophrenia than in the control groups.

CONCLUSIONS

Schizophrenia may be accompanied by accelerated lipid peroxidation in cell membranes, as well as increased manufacture of CS2, a known neurotoxin.