A system for quantifying the cooling effectiveness of bicycle helmets.

This article describes the design and development of a system that is capable of quantifying the thermal comfort of bicycle helmets. The motivation for the development of the system stems from the desire both to increase helmet use and to provide the designer with a quantitative method of evaluating the thermal comfort of a helmet. The system consists of a heated mannequin head form, a heated reference sphere, a small wind tunnel, and a data acquisition system.

The effects of social structure, geographical structure, and population size on the evolution of mitochondrial DNA: II. Molecular clocks and the lineage sorting period.

Evolutionary geneticists have increasingly used sequence variation in mitochondrial DNA (mtDNA) as a source of historical information. However, conclusions based on these data remain tentative because a sufficiently clear understanding of the evolutionary dynamics of mtDNA has yet to be developed. In this paper we present the results of computer simulations designed to illustrate the effects of social structure, geographical structure, and population size on the rate of nucleotide substitution and lineage sorting of mtDNA.

Adoption by captive parturient rhesus macaques: biological vs. adopted infants and the cost of being a "twin" and rearing "twins".

Four rhesus macaque (Macaca mulatta) mothers each spontaneously adopted and reared an abandoned, unrelated neonate in addition to their own neonate. Data on relative time spent in maternal contact and who maintained proximity were collected for the biological and adopted "twins" and singleton control infants using focal animal sampling. Infant weight gain and the subsequent conception history for each mother were obtained for the following year.

Four p53 DNA-binding domain peptides bind natural p53-response elements and bend the DNA.

Recent structural studies of the minimal core DNA-binding domain of p53 (p53DBD) complexed to a single consensus pentamer sequence and of the isolated p53 tetramerization domain have provided valuable insights into their functions, but many questions about their interacting roles and synergism remain unanswered. To better understand these relationships, we have examined the binding of the p53DBD to two biologically important full-response elements (the WAF1 and ribosomal gene cluster sites) by using DNA circularization and analytical ultracentrifugation. We show that the p53DBD binds DNA strongly and cooperatively with p53DBD to DNA binding stoichiometries of 4:1.

The local distribution of highly divergent mitochondrial DNA haplotypes in toque macaques Macaca sinica at Polonnaruwa, Sri Lanka.

Surveys of mitochondrial DNA (mtDNA) variation in macaque monkeys have revealed extremely high levels of intraspecific divergence among haplotypes. One consistent pattern that has emerged from these studies is that divergent haplotypes are geographically segregated so that sampling a few matrilines from a given region shows them to be identical, or a closely related subset of haplotypes. Geographically structured mtDNA variation has also been commonly observed in other taxa.

Inhibition of mitochondrial respiration and cyanide-stimulated generation of reactive oxygen species by selected flavonoids.

A continuation of our structure-activity study on flavonoids possessing varied hydroxyl ring configurations was conducted. We tested six additional flavonoids for their ability to inhibit beef heart mitochondrial succinoxidase and NADH-oxidase activities. In every case, the IC50 observed for the NADH-oxidase enzyme system was lower than for succinoxidase activity, demonstrating a primary site of inhibition in the complex I (NADH-coenzyme Q reductase) portion of the respiratory chain.

An insect model for assessing mercury toxicity: effect of mercury on antioxidant enzyme activities of the housefly (Musca domestica) and the cabbage looper moth (Trichoplusia ni).

The effect of mercury as Hg2Cl2 and HgCl2 on the antioxidant enzyme levels and its toxicity was investigated in an insect model comprised of adult females of the common housefly, Musca domestica, and fourth-instar larvae of the cabbage looper moth, Trichoplusia ni. HgCl2 was found to be more toxic than Hg2Cl2 to both M. domestica and T.

Studies of DNA bending and flexibility using gel electrophoresis.

Gel electrophoretic methods have become established as primary tools in the study and elucidation of sequence-directed curvature both in free DNA and in the operator DNA of several site-specific nucleoprotein complexes. Results using them have been generally consistent with physical methods sensitive to DNA structure and conformation in those instances where direct comparisons can be made, and in a number of cases, gel methods have provided unique information not presently available from other techniques. Two basic strategies have been used: one based upon anomalous gel mobility effects; and a second based upon cyclization properties of curved DNA.

CA runs increase DNA flexibility in the complex of lambda Cro protein with the OR3 site.

The alternating pyrimidine-purine elements CA, CAC, and CACA are anisotropically flexible, as deduced from gel circularization assays on point mutations and single-base mismatches in the OR3 site of lambda phage alone and in the specific complex with the Cro protein. These sequences evidently promote DNA bending in the specific binding region of the complex and may also facilitate overwinding in the central nonbinding region. Effects for CACA are exceptionally large and suggest that an alternative DNA structure may occur in this element.

Coping and job performance.

An organizational field study comprising 42 subjects examined the relationship between growth-oriented coping and subsequent job performance. Growth orientation was measured using the 7-item growth scale obtained from the Lazarus Ways of Coping Checklist. The hypothesized relationship between growth orientation and job performance was confirmed.

Influence of branched-chain fatty acid supplementation on voluntary intake, site and extent of digestion, ruminal fermentation, digesta kinetics and microbial protein synthesis in beef heifers consuming grass hay.

Four heifers (British x British; average BW 372 kg) cannulated at the rumen and duodenum and consuming a grass hay (fescue-orchardgrass) diet were used in a 4 x 4 Latin square and supplemented with four levels (0, 20, 40, and 60 g.head-1.d-1) of supplemental four- and five-carbon VFA (BCFA).

Estimating diet digestibility: a comparison of 11 techniques across six different diets fed to rams.

Six digestion trials were conducted using eight Suffolk rams (four/trial; two trials run concurrently) to determine the ability of 11 techniques to estimate in vivo apparent DM digestibility (DMD). Diets (trials) were as follows: 1) ad libitum access to chopped fescue hay, 2) ad libitum access to alfalfa hay, 3) limit-fed fescue hay, 4) limit-fed alfalfa hay, 5) 25% soybean meal and 75% fescue hay and 6) 40% rolled corn and 60% alfalfa hay. Total feces were collected for 7 d following a 21-d adaptation to each diet.

Captan binding to avian myeloblastosis virus reverse transcriptase and its effect on RNase H activity.

The inhibitor captan (N-trichloromethylthio-4-cyclohexen-1,2-dicarboximide) was used to explore the ribonuclease H (RNase H) active site of avian myeloblastosis virus (AMV) reverse transcriptase. Gel permeation chromatography of purified enzyme showed that [14C]captan bound to the alpha subunit in a ratio of 10:1 and to a 32,000 d polypeptide in a ratio of 4:1. Neither the alpha beta nor the beta subunit bound [14C]captan.

Readability, interest, and coverage of ten introductory textbooks on mental retardation.

Ten introductory textbooks on mental retardation were analyzed with the Flesch formula for reading ease and interest. Reading level of all texts was in the "difficult, college level" category. Seven books were classified as "dull", 3 as "mildly interesting.

Factor analysis of the substance abuse attitude survey with college undergraduates.

Few standardized instruments measure attitudes and beliefs towards substance abuse. The Substance Abuse Attitude Survey, developed for measuring drug attitudes in medical education, was administered to 598 college undergraduates, and a factor analysis was performed. Three coherent and stable factors were identified, e.

Mechanisms for regulating oxygen toxicity in phytophagous insects.

The antioxidant enzymatic defense of insects for the regulation of oxygen toxicity was investigated. Insect species examined were lepidopterous larvae of the cabbage looper (Trichoplusia ni), southern armyworm (Spodoptera eridania), and black swallowtail (Papilio polyxenes). These phytophagous species are subject to both endogenous and exogenous sources of oxidative stress from toxic oxygen radicals, hydrogen peroxide (H2O2) and lipid peroxides (LOOH).

Intracellular transport of rat serum albumin is altered by a genetically engineered deletion of the propeptide.

Many secreted proteins are synthesized with aminoterminal propeptides which are removed prior to secretion. There is increasing interest in the physiological roles of these propeptides, especially as mediators of intracellular protein trafficking. To investigate whether or not the propeptide of serum albumin offers an advantage in albumin secretion, we used oligonucleotide-directed mutagenesis to delete the 18 base pairs which encode the propeptide from a cDNA gene for rat serum albumin (RSA), inserted the deleted gene into COS cells, and studied the secretion of the gene product (RSA delta pro).

Beta globin gene transcripts originating in the promoter region during early hexamethylene bisacetamide and dimethylsulfoxide induction of Friend erythroleukemia cells.

The beta-globin transcripts which are induced by dimethylsulfoxide (DMSO) and hexamethylene bisacetamide (HMBA) have been characterized in order to assess potential differences in their mechanisms of induction. Transcripts which initiate in the 5' flanking promoter region are likely indicators of promoter accessibility and were therefore characterized during the time course of induction with each inducer in Friend Erythroleukemia cells. S1 analysis with probes labeled at - 12 or +82 relative to the (+1) cap site showed no major differences between 5' ends of the upstream initiated transcripts in cells induced by DMSO or HMBA.

Activation and binding of opsonic fragments of C3 on encapsulated Cryptococcus neoformans by using an alternative complement pathway reconstituted from six isolated proteins.

Encapsulated Cryptococcus neoformans yeast cells are potent activators of the complement system. We examined the interaction of the yeast cells with an alternative complement pathway reconstituted from isolated factor D, factor B, factor H, factor I, C3, and properdin. Incubation of encapsulated cryptococci with the reconstituted pathway led to activation and binding of C3 fragments to the yeast cells that was quantitatively and qualitatively identical to that observed with normal human serum.

Phosphorylation of arabinosyl guanine by a mitochondrial enzyme of bovine liver.

Extracts of mitochondria isolated from bovine liver were shown to phosphorylate araG, forming araGMP as the sole product. When other nucleosides were used as competitors with araG as the substrate for phosphorylation, deoxycytidine, deoxythymidine and guanosine were not significantly inhibitory. However, the phosphorylation of araG was blocked by deoxyguanosine, deoxyadenosine and deoxyinosine.

A method of stereoptically simulating manifolds of three-dimensional objects using only a single display pattern: a shape-depth-texture invariance.

A means of conceptualizing and generating visual displays that are "self-stereoptic manifolds" is described. First, single patterns that can replace pairs of stereograms to produce illusions of depth are defined and an example is shown. Patterns such as these produce illusory three-dimensional objects hanging in space before or behind the display surface.

Molecular basis for defective secretion of the Z variant of human alpha-1-proteinase inhibitor: secretion of variants having altered potential for salt bridge formation between amino acids 290 and 342.

Human alpha-1-proteinase inhibitor (A1PI) deficiency, associated with the Z-variant A1PI (A1PI/Z) gene, results from defective secretion of the inhibitor from the liver. The A1PI/Z gene exhibits two point mutations which specify amino acid substitutions, Val-213 to Ala and Glu-342 to Lys. The functional importance of these substitutions in A1PI deficiency was investigated by studying the secretion of A1PI synthesized in COS cells transfected with A1PI genes altered by site-directed mutagenesis.

Antigen-specific proliferative responses to vesicular stomatitis virus following immunization of cattle with inactive virus.

Peripheral blood mononuclear cells (PBM) from four normal cows with no known exposure to vesicular stomatitis virus (VSV) were cultured with a New Jersey (NJ) serotype (Ogden) VSV that had been UV-irradiated and inactivated. PBM from these animals produced no detectable proliferative response when incubated with varying concentrations of VSV-NJ (Ogden) ranging from 10 ng to 10 micrograms protein/ml. Two of these cows were immunized with an experimental VSV-NJ vaccine and their PBM were tested at various intervals after immunization.