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Biomedical subjects

J Greenberg

Publications and source records attributed to J Greenberg.

At least 19 recordsLinked to original sources
PubMed2001

Canopy level fluxes of 2-methyl-3-buten-2-ol, acetone, and methanol by a portable relaxed eddy accumulation system.

Canopy level flux measurements of 2-methyl-3-buten-2-ol (MBO), acetone, and methanol were made over a subalpine forest in the Rocky Mountains in Colorado in the summer of 1999. The measurements were carried out using a portable relaxed eddy accumulation system that collected samples on adsorbent cartridges. Midday fluxes of acetone were highest at approximately 2.5 mg of C m-2 h-1. Methanol and MBO fluxes were approximately 1.0 mg of C m-2 h-1 each. These fluxes occurred with average daytime high temperatures of only 18 degrees C. Diurnal fluxes of MBO were strongly correlated with light and temperature. Acetone and methanol did not have simple diurnal patterns. These results indicate that oxygenated volatile organic compounds may make a significant contribution to the flux of reactive carbon to the atmosphere in western U.S. pine forests.

Acetone↗
PubMed2001

Being accepted for who we are: evidence that social validation of the intrinsic self reduces general defensiveness.

Three studies examined the possibility that being liked intrinsically by others--for who one is--reduces self-esteem defense, whereas being liked for what one has achieved does not. All 3 studies contrasted the effects on self-esteem defense of liking based on intrinsic or achievement-related aspects of self. Study 1 showed that thoughts of being liked intrinsically reduced defensive bias toward downward social comparison. Study 2 demonstrated that being liked for intrinsic aspects of self reduced participants' tendency to defensively distance themselves from a negatively portrayed other. Study 3 revealed that being liked for intrinsic aspects of self encouraged a preference for upward over downward counterfactuals for a negative event. In all 3 studies, similar reductions in defensiveness were not found when liking was based on achievements. Discussion focuses on implications for understanding the functional value of different bases of self-worth.

Achievement↗
PubMed2000

Genetic heterogeneity of Usher syndrome: analysis of 151 families with Usher type I.

Usher syndrome type I is an autosomal recessive disorder marked by hearing loss, vestibular areflexia, and retinitis pigmentosa. Six Usher I genetic subtypes at loci USH1A-USH1F have been reported. The MYO7A gene is responsible for USH1B, the most common subtype. In our analysis, 151 families with Usher I were screened by linkage and mutation analysis. MYO7A mutations were identified in 64 families with Usher I. Of the remaining 87 families, who were negative for MYO7A mutations, 54 were informative for linkage analysis and were screened with the remaining USH1 loci markers. Results of linkage and heterogeneity analyses showed no evidence of Usher types Ia or Ie. However, one maximum LOD score was observed lying within the USH1D region. Two lesser peak LOD scores were observed outside and between the putative regions for USH1D and USH1F, on chromosome 10. A HOMOG chi(2)((1)) plot shows evidence of heterogeneity across the USH1D, USH1F, and intervening regions. These results provide conclusive evidence that the second-most-common subtype of Usher I is due to genes on chromosome 10, and they confirm the existence of one Usher I gene in the previously defined USH1D region, as well as providing evidence for a second, and possibly a third, gene in the 10p/q region.

Abnormalities, Multiple↗
PubMed2000

Genomic structure and identification of novel mutations in usherin, the gene responsible for Usher syndrome type IIa.

Usher syndrome type IIa (USHIIa) is an autosomal recessive disorder characterized by moderate to severe sensorineural hearing loss and progressive retinitis pigmentosa. This disorder maps to human chromosome 1q41. Recently, mutations in USHIIa patients were identified in a novel gene isolated from this chromosomal region. The USH2A gene encodes a protein with a predicted molecular weight of 171.5 kD and possesses laminin epidermal growth factor as well as fibronectin type III domains. These domains are observed in other protein components of the basal lamina and extracellular matrixes; they may also be observed in cell-adhesion molecules. The intron/exon organization of the gene whose protein we name "Usherin" was determined by direct sequencing of PCR products and cloned genomic DNA with cDNA-specific primers. The gene is encoded by 21 exons and spans a minimum of 105 kb. A mutation search of 57 independent USHIIa probands was performed with a combination of direct sequencing and heteroduplex analysis of PCR-amplified exons. Fifteen new mutations were found. Of 114 independent USH2A alleles, 58 harbored probable pathologic mutations. Ten cases of USHIIa were true homozygotes and 10 were compound heterozygotes; 18 heterozygotes with only one identifiable mutation were observed. Sixty-five percent (38/58) of cases had at least one mutation, and 51% (58/114) of the total number of possible mutations were identified. The allele 2299delG (previously reported as 2314delG) was the most frequent mutant allele observed (16%; 31/192). Three new missense mutations (C319Y, N346H, and C419F) were discovered; all were restricted to the previously unreported laminin domain VI region of Usherin. The possible significance of this domain, known to be necessary for laminin network assembly, is discussed in the context of domain VI mutations from other proteins.

Amino Acid Sequence↗
PubMed2000

Running from the shadow: psychological distancing from others to deny characteristics people fear in themselves.

Four experiments tested the hypothesis that people distance themselves from others who display characteristics they fear in themselves. In Study 1, participants were given false feedback that they were high or low in repressed anger and were given information about a person who became angry and responded in a violent or nonviolent manner. High anger feedback participants distanced themselves only from the violent person. In Study 2, high anger feedback led to distancing from a violent other but not a dishonest other, whereas dishonesty feedback led to distancing from a dishonest other but not a violent other. The results of Studies 3 and 4 replicated and extended the distancing effect with an anger induction: Participants who were insulted distanced themselves from an angry/violent person, and verbalizing their emotions about being insulted eliminated this effect. Implications for understanding defenses against undesirable self-attributions are discussed.

Analysis of Variance↗
PubMed2000

The body as a source of self-esteem: the effect of mortality salience on identification with one's body, interest in sex, and appearance monitoring.

The present research investigated the role of the physical body as a source of self-esteem and tested the hypothesis derived from terror management theory that reminding people of their mortality increases self-esteem striving in the form of identification with one's body, interest in sex, and appearance monitoring. The results revealed that individuals high in body esteem responded to mortality salience manipulations with increased identification with their physical bodies in Study 1 and with increased interest in sex in Study 2. Study 3 showed that reminders of death led to decreased appearance monitoring among appearance-oriented participants who were low in body esteem. These findings provide insight into why people often go to extreme lengths to meet cultural standards for the body and its appearance.

Adolescent↗
PubMed2000

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.

Adolescent↗
PubMed2000

Effect of age on the profile of alkanes in normal human breath.

Ethane and pentane in breath are markers of oxidative stress, produced by ROS-mediated lipid peroxidation of n-3 and n-6 polyunsaturated fatty acids (PUFAs), but little is known about other n-alkanes in normal human breath. We investigated the spectrum of alkanes in normal human alveolar breath, and their variation with age. Fifty normal humans were studied (age range 23-75, median 35). Volatile organic compounds (VOCs) in alveolar breath were captured on sorbent traps and assayed by gas chromatography and mass spectroscopy. Alveolar gradients (concentration in breath minus concentration in ambient room air) of alkanes were determined. C4-C20 alkanes were observed in breath and room air. Their mean alveolar gradients were negative from C4 to C12 and positive from C13 to C20. The mean alveolar gradients of four alkanes (C5-C8) were significantly less negative in the older subjects (p < 0.05). There were no significant differences between males and females. Normal human breath contained a spectrum of alkanes which may include new markers of oxidative stress. The mean rate of clearance (via cytochrome p450) exceeded the mean rate of synthesis (by ROS-mediated oxidative stress) for C4-C12 alkanes, while synthesis was greater than clearance for C13-C20 alkanes. The elevated alkane profile in older subjects was consistent with an age-related increase in oxidative stress, though an age-related decline in alkane clearance rate may have contributed.

Adult↗
PubMed2000

Modeling intervention efficacy for high-risk women. The WINGS Project.

This study evaluates the effectiveness of two strategies--communication and condom skills training--for increasing condom-protected sex in a sample of 510 high-risk women ages 17 to 61. Baseline and 3- and 6-month postintervention interview data were gathered in three cities participating in a randomized trial of a six-session, group skill-building intervention. This analysis was conducted for the entire sample and for six subgroups categorized by age, single or multiple partners, and history of childhood sexual abuse. The dependent variable was the odds ratio of protected sex acts at each follow-up. Structural equation modeling was used to estimate effects for two intervention pathways. The pathway through condom skills increased the odds of protected sex for the intervention group (chi 2 difference = 35, df = 2, p < .05) as well as for all subgroups. The pathways through communication were significant for the intervention group (chi 2 difference = 23, df = 3, p < .05) but fully effective only for participants under 30 and participants who reported childhood sexual abuse. The effectiveness of both pathways diminished at 6 months. WINGS demonstrates that condom skills training can increase protected sex for a heterogeneous group of women. Further research needs to examine how such skill training translates into use of condoms by male partners. To increase the duration of intervention effects, booster sessions may need to be incorporated.

Adolescent↗
PubMed1999

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.

Breath Tests↗
PubMed1999

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.

Aged↗
PubMed1999

Alström syndrome: further evidence for linkage to human chromosome 2p13.

Alström syndrome is a rare autosomal recessive disorder characterized by retinal degeneration, sensorineural hearing loss, early-onset obesity, and non-insulin-dependent diabetes mellitus. The gene for Alström syndrome (ALMS1) has been previously localized to human chromosome 2p13 by homozygosity mapping in two distinct isolated populations - French Acadian and North African. Pair-wise analyses resulted in maximum lod (logarithm of the odds ratio) scores of 3.84 and 2.9, respectively. To confirm these findings, a large linkage study was performed in twelve additional families segregating for Alström syndrome. A maximum two-point lod score of 7.13 (theta = 0.00) for marker D2S2110 and a maximum cumulative multipoint lod score of 9.16 for marker D2S2110 were observed, further supporting linkage to chromosome 2p13. No evidence of genetic heterogeneity was observed in these families. Meiotic recombination events have localized the critical region containing ALMS1 to a 6.1-cM interval flanked by markers D2S327 and D2S286. A fine resolution radiation hybrid map of 31 genes and markers has been constructed.

Base Sequence↗
PubMed1999

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.

Adult↗
PubMed1999

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.

Adult↗