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At least 1,603 records · Page 89Linked to original sources
PubMed2003

Beyond the male condom: the evolution of gender-specific HIV interventions for women.

As the number of HIV infections in women has increased, there has been a concomitant recognition that prevention efforts to reduce sexual transmission must address the gendered context in which risk behavior occurs. This paper provides a longitudinal perspective on the emergence of the HIV epidemic in U.S. women and the parallel development of interventions to reduce risk. In the first portion of this paper, we briefly discuss the growth of the epidemic among women and how public health responses reflected the early discourse about infected women. We also address methods of protection available to women, and the emerging recognition of the importance of gender relations. In the second half of this paper, we show how gender-specificity in prevention efforts has evolved, using a framework developed by Geeta Gupta (2001) and relying on published reviews of the intervention literature in the past 10 years. Finally, we discuss in detail several recent examples. We conclude with a discussion of future directions.

Condoms↗
PubMed2005

[Asthma epidemiology].

Asthma is excessively common among the individuals (up to 10% in adults and 35% in children). Asthma is differently distributed in the world. Asthma incidence is 1%/y in average. Children are at greater risk of asthma than adults, which could be due to a cohort effect. Severe asthma is reported by 1-3% of the general population (children and adults respectively). Recent population-based data show that the asthma prevalence increase observed worldwide in the past 30 years has now stopped in industrialised countries. Such phenomenon has been paralleled by an increase in the use of asthma medications. The development and phenotypic expression of asthma depends on a complex interaction between genetic and environmental factors. Gene-environment interactions already in early life should be explored to understand asthma epidemiological evolution.

Adult↗
PubMed2006

Repeated morphological evolution through cis-regulatory changes in a pleiotropic gene.

The independent evolution of morphological similarities is widespread. For simple traits, such as overall body colour, repeated transitions by means of mutations in the same gene may be common. However, for more complex traits, the possible genetic paths may be more numerous; the molecular mechanisms underlying their independent origins and the extent to which they are constrained to follow certain genetic paths are largely unknown. Here we show that a male wing pigmentation pattern involved in courtship display has been gained and lost multiple times in a Drosophila clade. Each of the cases we have analysed (two gains and two losses) involved regulatory changes at the pleiotropic pigmentation gene yellow. Losses involved the parallel inactivation of the same cis-regulatory element (CRE), with changes at a few nucleotides sufficient to account for the functional divergence of one element between two sibling species. Surprisingly, two independent gains of wing spots resulted from the co-option of distinct ancestral CREs. These results demonstrate how the functional diversification of the modular CREs of pleiotropic genes contributes to evolutionary novelty and the independent evolution of morphological similarities.

Animals↗
PubMed1999

Neuromolecular computing: a new approach to human brain evolution.

Evolutionary approaches in human cognitive neurobiology traditionally emphasize macroscopic structures. It may soon be possible to supplement these studies with models of human information-processing of the molecular level. Thin-film, simulation, fluorescence microscopy, and high-resolution X-ray crystallographic studies provide evidence for transiently organized neural membrane molecular systems with possible computational properties. This review article examines evidence for hydrophobic-mismatch molecular interactions within phospholipid microdomains of a neural membrane bilayer. It is proposed that these interactions are a massively parallel algorithm which can rapidly compute near-optimal solutions to complex cognitive and physiological problems. Coupling of microdomain activity to permenant ion movements at ligand-gated and voltage-gated channels permits the conversion of molecular computations into neuron frequency codes. Evidence for microdomain transport of proteins to specific locations within the bilayer suggests that neuromolecular computation may be under some genetic control and thus modifiable by natural selection. A possible experimental approach for examining evolutionary changes in neuromolecular computation is briefly discussed.

Brain Chemistry↗
PubMed2002

Unusually expanded SSU ribosomal DNA of primary osmotrophic euglenids: molecular evolution and phylogenetic inference.

Expansion segments within eukaryotic nuclear SSU ribosomal RNA have been characterized in many diverse organisms. So far, only a few studies have examined the evolutionary history of SSU rDNA variable regions for monophyletic groups. A euglenozoan SSU rDNA data set was analyzed combining phylogenetic inference and examination of expansion segment evolution. Although SSU rDNA length expansion could be ascribed to all Euglenozoa, most unusual length variation occurs within primary osmotrophic euglenids, particularly within the genus Distigma. The longest SSU rRNA gene reported to date can be found in D. sennii, comprising more than 4500 bases. RT-PCR analyses revealed that the complete gene is transcribed into RNA without posttranscriptional modifications. Further investigations uncovered that most of the length extension is due to elongated variable regions V2 and V4, but virtually all variable regions except for V3 are extended within primary osmotrophic euglenids. Analyses of secondary structure revealed several insertion points within variable regions, some of which are of phylogenetic importance. Varying GC content has been detected among species and between expansion segments and core regions. Nevertheless, individual expansion segments of one species as well as variable sequence positions within core regions tend to evolve in parallel concerning nucleotide frequencies. The presence of a large internal repeat within V2 of Distigma sennii hints at a possible mechanism for large-scale sequence length expansion.

Animals↗
PubMed1989

[Evolution of the functional axes of the middle ear in mammals].

In 44 mammalian species, the auditory ossicles have been studied in situ in the tympanic cavity and in vestibular orientation. After the lateral semicircular canal's direction and dimensions have been put in common, measurements have been undertaken leading to a comparison of 4 phylogenic stages. Thus we have observed a rotation of the stapes, of the incus and of the malleus head, a receding of the manubrium of the malleus ending in an inversion of the bone's concavity, an extension of the supposed unfolded chain, a parallelization of the malleolus handle and of the lower incudal apophysis, a slope of the functional axes towards the back, a diminution of the distance between the two lever arms due to a receding of the anterior arm and a diminution of the ratio between these lever arms. These varied changes are linked to the occipital rotation and to the receding of the jaws following humanization.

Anatomy, Comparative↗
PubMed2002

Experimental life-history evolution: selection on the allocation to sexual reproduction and its plasticity in a clonal plant.

Allocation to sexual reproduction is an important life-history trait in clonal plants. Different selection pressures between competitive and competition-free environments are likely to result in the evolution of specialized genotypes and to maintain genetic variation in reproductive allocation. Moreover, selection may also result in the evolution of plastic allocation strategies. The necessary prerequisite for evolution, heritable genetic variation, can best be studied with selection experiments. Starting from a base population of 102 replicated genotypes of the clonal herb Ranunculus reptans, we imposed selection on the proportion of flowering rosettes in the absence of competition (base population: mean = 0.391, broad-sense heritability = 0.307). We also selected on the plasticity in this trait in response to competition with a naturally coexisting grass in a parallel experiment (base population: 14% lower mean in the presence of competition, broad-sense heritability = 0.072). After two generations of bidirectional selection, the proportion of flowering rosettes was 26% higher in the high line than in the low line (realized heritability +/- SE = 0.205 +/- 0.017). Moreover, genotypes of the high line had 11% fewer carpels per flower, a 22% lower proportion of rooted rosettes, and a 39% smaller average distance between rosettes within a clone. In the second experiment, we found no significant responses to selection for high and low plasticity in the proportion of flowering rosettes (realized heritability +/- SE = -0.002 +/- 0.013). Our study indicates a high heritability and potential for further evolution of the proportion of flowering rosettes in R. reptans, but not for its plasticity, which may have been fixed by past evolution at its current level. Moreover, our results demonstrate strong genetic correlations between allocation to sexual reproduction and other clonal life-history characteristics.

Biological Evolution↗
PubMed1997

Silica-induced apoptosis in alveolar and granulomatous cells in vivo.

Silica is a toxicant that can stimulate cells to produce various cellular products such as free radicals, cytokines, and growth factors. Silica and its induced substances may induce apoptosis to regulate the evolution of silica-induced inflammation and fibrosis. To examine this hypothesis, groups of Wistar male rats were intratracheally instilled with different doses of Min-U-Sil 5 silica (Silica, Berkeley Springs, WV). Ten days after the instillation, we obtained cells by bronchoalveolar lavage and placed them on slides by cytospin preparation. The slides were stained with Diff-Quik (Lab Aids, Sydney, NSW, Australia) and examined under oil immersion. A substantial number of cells with apoptotic features were identified in all silica-instilled rats and the apoptosis was confirmed by agarose gel electrophoresis. The number of apoptotic cells was clearly related to silica dosage. Engulfment of apoptotic cells by macrophages was also noted. Neutrophil influx in silica-instilled rats could be saturated with the increase of silica dosage and the number of macrophages in different dose groups changed in parallel with the proportion of apoptotic cells. Fifty-six days after instillation, morphologically apoptotic cells could be identified in granulomatous cells of lung tissue from silica-instilled rats. We conclude that intratracheal instillation of silica could induce apoptosis in both alveolar and granulomatous cells, and the apoptotic change and subsequent engulfment by macrophages might play a role in the evolution of silica-induced effects.

Administration, Inhalation↗
PubMed1997

Serum leptin concentrations in patients with anorexia nervosa, bulimia nervosa and non-specific eating disorders correlate with the body mass index but are independent of the respective disease.

OBJECTIVE: Leptin, the product of the ob gene, is a recently discovered hormone secreted by adipocytes. Serum leptin concentrations increase in correlation with the percentage of body fat, but little else is known about the physiological actions of leptin in humans. The aim of this study was to determine the role of leptin in severe eating disorders, and whether its levels are correlated with the specific disease or exclusively with body weight. TESTS: Serum concentrations of human leptin were analysed by specific radioimmunoassay and compared with the individual body mass indexes (BMI). The correlations between serum leptin concentrations and BMI, age and height were analysed. PATIENTS: A total of 65 women were studied: 25 patients with anorexia nervosa, 20 women with bulimia nervosa, 6 women with a diagnosis of nonspecific eating disorder, and 14 normal-weight women who acted as controls. At the time of the study, the patients were non-cured, under treatment, and at different stages of therapeutic evolution. MEASUREMENTS: Plasma leptin levels were measured by specific radioimmunoassay. RESULTS: The mean serum leptin in the normal-weight women was 10.5 +/- 1.1 micrograms/l, compared with 7.6 +/- 1.1 micrograms/l in the anorexia nervosa patients (P < 0.05). This reduction in leptin levels was paralleled by the differences in BMI (21.4 +/- 0.4 vs 18.8 +/- 0.2) P < 0.05. These differences between the controls and anorexia nervosa patients were not observed in patients with bulimia nervosa who had a mean serum leptin level of 9.9 +/- 1.4 micrograms/l and BMI of 21.3 +/- 0.6, neither significantly different from controls. On the contrary, patients with non-specific eating disorders showed a large reduction in BMI (17.9 +/- 1.2, P < 0.05 vs control), and a parallel reduction in serum leptin levels, 4.5 +/- 1.0 (P < 0.05 vs controls). When individual values of leptin were plotted against BMI a wide range was observed in all groups; in the control subjects from 5.6 to 17.7 micrograms/l, in anorexia nervosa patients from 2.1 to 28.1 micrograms/l, in patients with bulimia nervosa between 2.6 and 25.9 micrograms/l, and in women with non-specific eating disorder from 2.0 to 8.9. No correlation was observed with the specific disease but in each group a significant correlation was observed only with BMI. CONCLUSIONS: Serum leptin levels in three groups of patients affected by severe eating disorders are not related to the specific pathology but are correlated with the individual BMI. The analysis of leptin values may be a useful index of assessing the adipose tissue stores in the clinical setting, but will be of no help for diagnosis nor prognosis of severe eating disorders.

Adult↗
PubMed2000

The genetics of ivermectin resistance in Caenorhabditis elegans.

The ability of organisms to evolve resistance threatens the effectiveness of every antibiotic drug. We show that in the nematode Caenorhabditis elegans, simultaneous mutation of three genes, avr-14, avr-15, and glc-1, encoding glutamate-gated chloride channel (GluCl) alpha-type subunits confers high-level resistance to the antiparasitic drug ivermectin. In contrast, mutating any two channel genes confers modest or no resistance. We propose a model in which ivermectin sensitivity in C. elegans is mediated by genes affecting parallel genetic pathways defined by the family of GluCl genes. The sensitivity of these pathways is further modulated by unc-7, unc-9, and the Dyf (dye filling defective) genes, which alter the structure of the nervous system. Our results suggest that the evolution of drug resistance can be slowed by targeting antibiotic drugs to several members of a multigene family.

Animals↗
PubMed2001

[Neoral (Cyclosporin microemulsion preconcentrate): pharmacokinetics, pharmacodynamics and its improved clinical outcome].

Sandimmun displays considerable inter- and intra-patient variability because its absorption is bile-dependent and affected by concomitant intake of food. Neoral is a microemulsion preconcentrate; a microemulsion is a mixture of the lipophilic active substance with accurately balanced amounts of lipophilic solvent, hydrophilic solvent and surfactant. As the result of advanced microemulsion technique, Neoral has more consistent and improved absorption characteristics. Cyclosporin (cyclosporin A) has been used as an immunosuppressive agent. The major pharmacodynamic action of cyclosporin within T cells is calcineurin inhibition. The complex cyclophilin-cyclosporin competitively binds to the Ca(2+)- and calmodulin-dependent phosphatase calcineurin which then inhibits downstream dephosphorylation and activation of NFAT(transcription factor). The greatest calcineurin inhibition is seen 1-2 h after administration of Neoral in parallel to the highest blood concentration. Variability in cyclosporin exposure was also identified as a risk factor for acute rejection in organ transplant recipients. "Absorption profiling" provides a more accurate prediction of drug exposure and leads to less acute rejection and toxicity. The evolution of Neoral monitoring strategies from trough level to absorption profile will raise the standard of performance of Neoral, resulting in clinical benefits for transplant patients.

Animals↗
PubMedDate not supplied

Evidence for nickel in the soluble hydrogenase from the unicellular green alga Scenedesmus obliquus.

Cultures of the green alga Scenedesmus obliquus were grown in the presence of either the chelating reagent EDTA or NiCl2 in various concentrations and assayed for hydrogenase catalyzed photohydrogen evolution after an anaerobic dark adaptation period. Cultivation of algae in the presence of 100 microM EDTA inhibited the formation of hydrogenase activity by 37%. After a cultivation of the cells in the presence of 5-20 microM NiCl2 photohydrogen evolution was increased by 20-40%. Addition of EDTA up to a final concentration of 1.5 mM had no effect on the activity of hydrogenase in cell-free hydrogenase preparations. Cultures grown in the presence of radioactive 63NiCl2 incorporated 63Ni in a parallel fashion to the cell growth. In radioactive labeled hydrogenase preparations a co-elution of radioactivity and hydrogenase activity could be observed using gel filtration chromatography.

Anaerobiosis↗
PubMed2004

Intestinal absorption and biomagnification of organic contaminants in fish, wildlife, and humans.

Methods for the regulatory assessment of the bioaccumulation potential of organic chemicals are founded on empirical measurements and mechanistic models of dietary absorption and biomagnification. This study includes a review of the current state of knowledge regarding mechanisms and models of intestinal absorption and biomagnification of organic chemicals in organisms of aquatic and terrestrial food chains and also includes a discussion of the implications of these models for assessing the bioaccumulation potential of organic chemicals. Four mechanistic models, including biomass conversion, digestion or gastrointestinal magnification, micelle-mediated diffusion, and fat-flush diffusion, are evaluated. The models contain many similarities and represent an evolution in understanding of chemical bioaccumulation processes. An important difference between the biomagnification models is whether intestinal absorption of an ingested contaminant occurs solely via passive molecular diffusion through serial resistances or via facilitated diffusion that incorporates an additional advective transport mechanism in parallel (i.e., molecular ferrying within gastrointestinal micelles). This difference has an effect on the selection of physicochemical properties that best anticipate the bioaccumulative potential of commercial chemicals in aquatic and terrestrial food chains. Current regulatory initiatives utilizing Kow threshold criteria to assess chemical bioaccumulation potential are shown to be unable to identify certain bioaccumulative substances in air-breathing animals. We urge further research on dietary absorption and biomagnification of organic chemicals to develop better models for assessing the bioaccumulative nature of organic chemicals.

Absorption↗
PubMed2003

Changes in tumor vascularization after irradiation, anthracyclin, or antiangiogenic treatment in nitrosomethyl ureas-induced rat mammary tumors.

PURPOSE: Changes in tumor vascularization may be involved in tumor regression after anticancer treatments. We therefore studied the relationship between tumor vascularization and tumor response according to treatment by irradiation (RT), epirubicin (EPI), or antiangiogenic agent TNP-470 in a nitrosomethyl-ureas-induced rat mammary tumor model by measuring the changes in tumor blood flow using high-frequency Power-Doppler sonography. EXPERIMENTAL DESIGN: Mammary tumors were induced in female Sprague-Dawley rats by a single s.c. injection of nitrosomethyl-ureas. After tumor areas reached 2 cm(2), the animals received four weekly injections of epirubicin (EPI group), or a single fraction of 18 Gy (RT group), or six injections of TNP-470 within 12 days (TNP group), or both (RT combined with TNP-470, RT+TNP group). Power-Doppler sonography quantification of tumor vascularization (PDI) was performed before and 12 days after initiation of treatment. Tumor shrinkage was later evaluated and compared with the early changes in PDI values. RESULTS: Compared with the control group, EPI induced an arrest in tumor growth. A similar effect was obtained with TNP-470. There was a decrease in tumor area after RT, but administration of TNP-470 combined with RT did not further enhance this effect. Changes in tumor area paralleled changes in PDI in the EPI group. Furthermore, changes in PDI 7 days after RT were associated with further tumor change in the RT groups, whereas they were independent of the antitumor effect of TNP-470. CONCLUSIONS: Changes in functional tumor vascularization evolution appeared to be closely associated with tumor regression after anticancer treatment.

Animals↗
PubMed2006

[The best of interventional cardiology in 2005].

During 2005, the evolution of interventional cardiology has largely been dominated by the trial of active endoprostheses, whose advantage has been consistently shown by various studies, mete-analyses and surveys. Extending their use to new indications and evaluating new drugs have also been studied. In parallel, clinical trials have been performed in the promising field of percutaneous treatment of valvular heart disease, particularly mitral insufficiency and calcified aortic stenosis in the adult.

Blood Vessel Prosthesis↗
PubMed1994

[A longitudinal analysis of dysfunctional pathology of the TMJ: an assessment of a sample of patients not undergoing therapy].

Concerning the different interpretation on the pathological and clinical evolution of the TMJ dysfunctions, the most common of these pathology is the condyle-disk incoordination. This study analyzed the evolution of TMJ dysfunctions examined at the maxillo-facial department of the University of Rome "La Sapienza". The non therapeutic approach does not consider an addition al control-sample of the non treated being itself a control-sample of a parallel work whose aim was to analyze patients who had undergone a complete therapeutic cycle.

Adolescent↗
PubMed2004

The Fusarium oxysporum f. sp. ciceris/Cicer arietinum pathosystem: a case study of the evolution of plant-pathogenic fungi into races and pathotypes.

The use of resistant cultivars is one of the most practical and cost-efficient strategies for managing plant diseases. However, the efficiency of resistant cultivars in disease management is limited by pathogenic variability in pathogen populations. Knowledge of the evolutionary history and potential of the pathogen population may help to optimize the management of disease-resistance genes, irrespective of the breeding strategy used for their development. In this review, we examine the diversity in virulence phenotypes of Fusarium oxysporum f. sp. ciceris, the causal agent of Fusarium wilt of chickpeas, analyze the genetic variability existing within and among those phenotypes, and infer a phylogenetic relationship among the eight known pathogenic races of this fungus. The inferred intraspecific phylogeny shows that each of those races forms a monophyletic lineage. Moreover, virulence of races to resistant chickpea cultivars has been acquired in a simple stepwise pattern, with few parallel gains or losses. Although chickpea cultivars resistant to Fusarium wilt are available, they have not yet been extensively deployed, so that the stepwise acquisition of virulence is still clearly evident.

Biological Evolution↗
PubMed1979

Polygamy and the evolution of human longevity.

An alternative to previous explanations of the rapid increase in man's longevity and intelligence during the several million years of his recent evolution from pre-hominid, clearly shorter-lived and less intelligent, primate ancestors is presented. The general thesis is that a very greatly accelerated rate of incorporation of favorable genes or gene combinations can be achieved in surprisingly few generations among social animals provided that dominant males become the patriarchs of many descendents by virtue of their partial or complete monopoly on available females. The conclusion is that man probably differs from his ancesters of 0.5 to 5 million years ago by many thousands of genes (both structural and regulatory) rather than the dozens or few hundreds that have been postulated on the basis of more classical treatments of selection pressures, gene frequency changes and mutation rates. The concepts developed here formally apply only to two alternative alleles, rather than to groups of genes which segregate independently, or to characters determined by multiple alleles. The appropriate mathematical treatment of the latter real situation is not readily visualized; nor is account taken of the likelihood that different tribes of pre-humans developed different specializations via the above mechanisms which were then (later) combined into an emerging human stock through matings between members of different tribes. The very great variability both in longevity and in intelligence between different races of animals such as dogs, which have been the objects of deliberate genetic selection by humans for particular heritable traits, may parallel our own recent history, even though the selection mechanism (deliberate human selection vs. polygamous dominance) is quite different in the two cases. The onset of civilizations consisting of amalgums between smaller, previously competing tribes, together with the humanitarian responsibilities to each other we share as a species, ironically has probably arrested further evolution of human longevity (and perhaps of intelligence) in the modern world. Possibly even retrogressive changes are occurring, except in those rare sub-populations in which special social and cultural practices tend to favor selective perpetuation of characteristics which are usually viewed as beneficial.

Alleles↗