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PubMedDate not supplied

Civil rights in a changing health care system.

Title VI of the 1964 Civil Rights Act prohibits discriminatory conduct by recipients of federal financial assistance. The law has been used in the past to challenge discrimination in health care. The evolution of the health care system from fee-for-service to managed care holds much promise for minority persons, who historically have faced serious, extensively documented barriers to health care access. However, managed care providers, like their fee-for-service counterparts, may perpetuate past discriminatory practices in new ways. Understanding new forms of discrimination is important at this stage of the development of managed care, when program design and policy action can most effectively prevent the occurrence of such practices.

Civil Rights↗
PubMedDate not supplied

Allotypes of the a series and their variants in rabbit immunoglobulins.

Six allotypic specificities of the a series are found on rabbit immunoglobulins: a1, a2 and a3 are found both in domestic and wild rabbits Oryctolagus cuniculus; a100, a101 and a102 seem to be present only in wild rabbits. Each of these specificities is a family of variants always present together in a given serum. These variants can be studied through the cross-reactivities detected between the patterns of the a series. The results of studies of cross-reactivities between a1, a3 and the two specificities a100, and a102 and also the cross-reactivity between a2 and a minor variant of the a1 specificity suggested a hypothetical scheme. This hypothesis attempts to take into account the evolution of the specificities of the a series and their variants. This hypothesis also postulates the existence of a set of closely linked genes which control the synthesis of the variants of a given specificity. One could suppose that primordial allelic genes might have appeared from an ancestor gene. By duplication each allele would have led to the appearance of a set of genes coding for a given specificity. These genes might have evolved through mutations and recombinations. In wild rabbits, the observation of an allotype which seems to result from a recombination between the group of genes coding for the a2 variants and the group of genes coding for a3 variants argues in favors of the genetic recombination mechanism.

Animals↗
PubMed1983

Neurologic deficit after carotid endarterectomy: pathogenesis and management.

During a 7-year period, 818 patients underwent carotid endarterectomy (CE) and were evaluated for postoperative neurologic deficits. Three hundred and eighteen had CE performed with a shunt; transient deficits occurred in 2.9% (nine patients) and permanent deficits occurred in 1.6% (five patients). CE was performed without a shunt in 274 patients; transient deficits occurred in 2.9% (eight patients), while permanent deficits occurred in 2.2% (six patients). CE was monitored by surveillance in 226 patients; transient deficits were found in 2.2% (five patients), while permanent deficits occurred in 1.6% (four patients). There was no significant difference in the incidence of postoperative neurologic deficits between the groups (P greater than 0.25). The concept of inadequate collateral cerebral flow during endarterectomy could not, therefore, be indicted as the cause of the postoperative neurologic complications. Technical errors that caused carotid thrombosis or cerebral emboli, and not inadequate collateral cerebral flow, accounted for most of the neurologic deficits after CE. Deficits occurred most frequently in neurologically unstable patients, those who were first seen with stroke in evolution or with postreversible ischemic neurologic deficit and poststroke symptoms. Twenty-two patients awoke from CE with minor transient deficits, and neurologic function rapidly returned. Fifteen patients with profound postoperative deficits had reoperations immediately; intracranial emboli were identified in three patients, while a thrombosed CE site was demonstrated in seven. Three late (greater than 6 hours) postoperative deficits were due to thrombosis of the CE site. Patients with minimal postoperative deficits will improve without intervention, but reoperation is mandatory if a major deficit occurs in the immediate postoperative period. A protocol for the management of the post-CE neurologic deficit is presented.

Adult↗
PubMed1994

Koinophilia.

This paper is concerned with the evolution of the species phenotype (morphology and behaviour) when sexual organisms identify mutant traits by their unusual (or rare) appearance. Mate-seeking individuals are assumed, however, to have no means of distinguishing the occasional beneficial mutation from the others. We show that the resulting preference for mates with predominantly common traits (koinophilia) transforms the prevailing phenotype (as perceived by conspecifics) into an evolutionary stable strategy (ESS), as defined by Maynard-Smith (1974). This has far reaching evolutionary implications, permitting, in particular, the evolution of true "group adaptations". A subsidiary finding shows that koinophilia always has a substantial, immediate, selective advantage over panmixis, rendering koinophilia, itself, an ESS with respect to panmixis. This is particularly pronounced when the mutation rate is high, but beneficial mutations with high fitnesses are rare. The mean fitness of mutations has only a minor effect on the relative advantage of koinophilia.

Adaptation, Physiological↗
PubMed2002

Molecular evolution of alleles of the glycophorin A gene.

Highly-homologous Glycophorin A (GPA), B and E genes are triplicate genes, and involve many subtypes and minor antigens constructing the Miltenberger subsystem. These genes and most of the variants are hypothesized to arise by recombination, because hot spots are located in the gene sequences. By sequencing exons 1-7 and introns 1-3 of standard alleles of GPA gene, M and N alleles were classified into six variations: provisionally called MN*M101, M102, M201, M202, N101 and N102 in our previous study. Here we further investigated the sequences of introns 4-6 using GPA gene-specific primers and by DNA sequencing, and found eight, five and nine new nucleotide substitutions or deletions in introns 4, 5 and 6, respectively. Using the computer program PHYLIP 3.5, the phylogenetic trees were reconstructed. Phylogenetic analysis of the allele sequences revealed that M200s alleles arose from M101 after the separation of M101 and N101 and branched to M201 and M202 via the accumulation of point mutations. M102 and N102 alleles were estimated to generate via recombination between M101 and N101 occurred around the hot spot. The findings also suggested the existence of other GPA variants with normal antigenicity, and are quite useful in the forensic and anthropological fields.

Journal Article↗
PubMed1990

Evolution of natural populations in the Drosophila melanogaster sigma virus system I. Languedoc (southern France).

In natural populations of Drosophila melanogaster, sigma virus is usually present in a minority of individuals. The virus is transmitted transovarially but is not contagious from fly to fly. Two viral Types (I and II) are found in populations. One of them (Type II) is better adapted to an allele for resistance to the virus, present as a polymorphism in fly populations. Previous observations have led to the hypothesis that a viral Type II originating in central France might be invading populations. The study of Languedoc populations was undertaken to examine this hypothesis. Two striking phenomena were observed. The strong increase in Type II clones frequency (from 0.53 to 0.91) confirmed that there was invasion in this region. The frequency of infected flies also increased dramatically, at levels never observed elsewhere yet, which indicates that Languedoc should present some unusual characteristics. The epidemiological consequences of such a burst, in the case of a pathogenic virus would have to be taken into consideration. Significant changes in other viral characteristics, from 1983 to 1987, in Languedoc populations have also been documented.

Adaptation, Physiological↗
PubMed1976

Enzyme recruitment in evolution of new function.

Ancient cells must have possessed small gene content. Primitive enzymes may have possessed broad specificity and undeveloped regulation mechanisms. The considerable substrate ambiguity of these enzymes resulted in the formation of minor amounts of erroneous products. Fortuitous formation of metabolites offered ancient cells maximum biochemical flexibility with minimal gene content. Gene duplication provided the opportunity for increased gene content and increased specialization of the diverging enzymes, the substrate specialization being further reinforced by the development of regualtory mechanisms. Recuritment of enzymes for new pathways did not necessarily require the sequential and backwardly evolving progression of evolutionary steps required by the hypothesis of retrograde evolution of biochemical pathways. Substrate ambiguity remains a conspicuous feature of many contemporary proteins, and evolutionary exploitation of substrate ambiguity in a variety of organisms is still apparent.

Amino Acids↗
PubMed1999

Evolution of the proportions of two sigma viral types in experimental populations of Drosophila melanogaster in the absence of the allele that is restrictive of viral multiplication.

A minority of flies in natural populations of Drosophila melanogaster are endemically infected by a rhabdovirus, sigma. The virus is vertically transmitted through male and female gametes. Two alleles of a fly locus, the ref(2)P locus, are present as a polymorphism in all populations: O permissive, and P restrictive for viral multiplication and transmission. Two viral types are known, Type I, which is very sensitive to the P allele, and Type II, which is more resistant. Previous observations have shown that, in presence of the P allele, viral Type II is selected for, in both natural and experimental populations. The aim of the present study was to determine whether, in the absence of P, Type I is selected for, or whether the two types are equivalent. For this purpose, experimental populations deprived of the P allele and differing in the initial proportions of the two viral types were established. After several generations, and despite a possible bias toward Type I, the frequencies of Type I and Type II clones differed in the various populations, depending on their initial values. These findings do not rule out selective advantage of viral Type I in the absence of P, but suggest that, if any, this advantage is in no way comparable to that displayed by viral Type II in the presence of P.

Alleles↗
PubMed2005

Paternal genetic effects on offspring fitness are context dependent within the extrapair mating system of a socially monogamous passerine.

Avian extrapair mating systems provide an interesting model to assess the role of genetic benefits in the evolution of female multiple mating behavior, as potentially confounding nongenetic benefits of extrapair mate choice are seen to be of minor importance. Genetic benefit models of extrapair mating behavior predict that females engage in extrapair copulations with males of higher genetic quality compared to their social mates, thereby improving offspring reproductive value. The most straightforward test of such good genes models of extrapair mating implies pairwise comparisons of maternal half-siblings raised in the same environment, which permits direct assessment of paternal genetic effects on offspring traits. But genetic benefits of mate choice may be difficult to detect. Furthermore, the extent of genetic benefits (in terms of increased offspring viability or fecundity) may depend on the environmental context such that the proposed differences between extrapair offspring (EPO) and within-pair offspring (WPO) only appear under comparatively poor environmental conditions. We tested the hypothesis that genetic benefits of female extrapair mate choice are context dependent by analyzing offspring fitness-related traits in the coal tit (Parus ater) in relation to seasonal variation in environmental conditions. Paternal genetic effects on offspring fitness were context dependent, as shown by a significant interaction effect of differential paternal genetic contribution and offspring hatching date. EPO showed a higher local recruitment probability than their maternal half-siblings if born comparatively late in the season (i.e., when overall performance had significantly declined), while WPO performed better early in the season. The same general pattern of context dependence was evident when using the number of grandchildren born to a cuckolding female via her female WPO or EPO progeny as the respective fitness measure. However, we were unable to demonstrate that cuckolding females obtained a general genetic fitness benefit from extrapair fertilizations in terms of offspring viability or fecundity. Thus, another type of benefit could be responsible for maintaining female extrapair mating preferences in the study population. Our results suggest that more than a single selective pressure may have shaped the evolution of female extrapair mating behavior in socially monogamous passerines.

Animals↗
PubMed1996

The relationships between chronic gastritis and gastric acid secretion.

Helicobacter pylori is the main cause of chronic gastritis in humans. Autoimmune mechanisms and Helicobacter heilmannii infection are other causes, both of which are of minor significance in a worldwide perspective. Atrophic gastritis is a quite common late consequence of H. pylori gastritis and will develop on a multifactorial basis, but not in all infected persons. The evolution of atrophic gastritis is a slow and gradually worsening process leading to subtypes, in which the antrum and corpus are affected to dissimilar extent and degree. The distal part of the stomach is the site where the atrophic sequelae (atrophic gastritis and intestinal metaplasia) of H. pylori infection occur most often. A minority of cases develop corpus-limited, or corpus-predominant atrophic gastritis. Along with the worsening of atrophic gastritis, inflammation and density of colonization of the mucosa by H. pylori tend to decrease in grade. In general, the degree of gastric mucosal inflammation, acute and chronic, is positively related to the degree of colonization of the mucosa by H. pylori. Acid secretion and local acidity are factors which modulate the ecology and density of colonization of H. pylori in the stomach, and may thus also modulate the evolution of chronic gastritis into topographically dissimilar subtypes. Acid secretion varies among individuals, this variation being perhaps caused by hereditary differences in parietal cell mass, or by differences in the sensitivity of parietal cells to hormonal or neural stimuli. It is hypothesized that in genuine hypersecretors, H. pylori colonization and subsequent gastritis with atrophic and metaplastic sequelae may be limited to the antrum, while in hyposecretors gastritis predominates in the corpus. In the latter, atrophic gastritis in the corpus then leads to further impairment of acid output. In these cases, H. pylori infection and gastritis may, finally, heal in the antrum, resulting in hypochlorhydria and atrophic gastritis that is limited to, or predominant in the corpus.

Adolescent↗
PubMed1996

Evolution of soluble carbohydrates during the development of pea, faba bean and lupin seeds.

Seeds of pea (Pisum sativum L. cv. Ergo), faba bean (Vicia faba ssp. minor Harz., cv. Tibo) and yellow pea lupin (Lupinus luteus L. cv. Juno) were sampled at different days after flowering (DAF) and their content of soluble carbohydrates was determined. Analysis of samples showed that myo-inositol, fructose, glucose, galactose and sucrose were found in high abundance early in development and their content decreased gradually during maturation. alpha-Galactosides, which includes the content of raffinose, stachyose and verbascose, started to appear later in seed development, at 37 DAF in peas, 40 DAF in faba beans and 45 DAF in lupins. Their accumulation increased considerably during seed growth, and the maximum content was obtained in mature seeds; 3.8% in peas, 4.5% in faba beans and 10.4% in lupins. Results obtained for these sugars during seed development were fitted to modelling curves in order to predict sugar content at different development stages.

Carbohydrates↗
PubMedDate not supplied

[Prevalence of malnutrition in minors under 5 years of age in Tabasco].

OBJECTIVE: To evaluate malnutrition prevalence in children under five years-old in Tabasco, Mexico, during 1996, and their evolution in 1991-1996. MATERIAL AND METHODS: A cross-sectional study, including 1,256 children under five years-old in 593 communities (31 urban and 562 rural) from 17 sanitary districts. RESULTS: The weight/age indicator for malnutrition in children under five years old showed 59% of children had normal nutrition and 41% with malnutrition, distributed as follows: 26.12% slight, 12.62% moderate and 2.39% severe. In children between 1-5 years old, malnutrition prevalence was 45%. CONCLUSIONS: The number of children with malnutrition in Tabasco during the study period (1991-1996) has decreased in proportion to the increase of those with normal nutrition. Based on the health system activities, the number of health districts with critical malnutrition indicators decreased from 6 to 4.

Child, Preschool↗
PubMed2025

Deep Sequencing Reveals Dual Evolution of SARS-CoV-2: Insights Into Defective Genomes From Wuhan-Hu-1 Variants to Omicron Subvariants.

SARS-CoV-2 has evolved from early variants dominating the first (B.1.5, B.1.1) and second (B.1.177) pandemic waves, which exhibited a higher frequency of minority mutants with deletions leading to Defective Viral Genomes (DVGs) in the spike region near the S1/S2 cleavage site than the Alpha, Beta, and Delta variants. The emergence of Omicron has significantly altered the dominant variant profile, with Omicron subvariants now representing 100% of circulating viruses. To monitor the evolution and adaptation of Omicron in the human population, a deep-sequencing study was performed in RNA samples of BA.1, BA.1.1, BA.2, BA.5, BQ.1.1, XBB.1.5 and BA.2.86 Omicron subvariants. The findings reveal two occurrences of similar evolutionary patterns within SARS-CoV-2 characterized by a shift from a significant to a very low production of DVGs. This event suggests that DVGs might play a role in the virus's spread and adaptation for persistence in infected humans.

SARS-CoV-2↗
PubMed2003

Photosystem II: evolutionary perspectives.

Based on the current model of its structure and function, photosystem II (PSII) seems to have evolved from an ancestor that was homodimeric in terms of its protein core and contained a special pair of chlorophylls as the photo-oxidizable cofactor. It is proposed that the key event in the evolution of PSII was a mutation that resulted in the separation of the two pigments that made up the special chlorophyll pair, making them into two chlorophylls that were neither special nor paired. These ordinary chlorophylls, along with the two adjacent monomeric chlorophylls, were very oxidizing: a property proposed to be intrinsic to monomeric chlorophylls in the environment provided by reaction centre (RC) proteins. It seems likely that other (mainly electrostatic) changes in the environments of the pigments probably tuned their redox potentials further but these changes would have been minor compared with the redox jump imposed by splitting of the special pair. This sudden increase in redox potential allowed the development of oxygen evolution. The highly oxidizing homodimeric RC would probably have been not only inefficient in terms of photochemistry and charge storage but also wasteful in terms of protein or pigments undergoing damage due to the oxidative chemistry. These problems would have constituted selective pressures in favour of the lop-sided, heterodimeric system that exists as PSII today, in which the highly oxidized species are limited to only one side of the heterodimer: the sacrificial, rapidly turned-over D1 protein. It is also suggested that one reason for maintaining an oxidizable tyrosine, TyrD, on the D2 side of the RC, is that the proton associated with its tyrosyl radical, has an electrostatic role in confining P(+) to the expendable D1 side.

Chlorophyll↗
PubMed1997

Interspecies exchange of a Hoxd enhancer in vivo induces premature transcription and anterior shift of the sacrum.

The precise activation, in space and time, of vertebrate Hox genes is an essential requirement for normal morphogenesis. In order to assess for the functional potential of evolutionary conserved Hox regulatory sequences, a phylogenetically conserved bipartite regulatory element necessary for proper spatial and temporal activation of the Hoxd-11 gene was replaced by its fish counterpart in the HoxD complex of mice, using an ES cell-based targeted exchange. Fetuses carrying this replacement activated Hoxd-11 transcription prematurely, which led to a rostral shift of its expression boundary and a consequent anterior transposition of the sacrum. These results demonstrate the high phylogenetic conservation of regulatory mechanisms acting over vertebrate Hox complexes and suggest that minor time difference (heterochronies) in Hox gene activation may have contributed to important morphological variations in the course of evolution.

Animals↗
PubMed2004

Anterior spinal cord infarction owing to possible fibrocartilaginous embolism.

Anterior spinal artery syndrome is characterised by acute flaccid quadriparesis or paraparesis, disturbance of pain and temperature sensation, and loss of sphincter control. Fibrocartilaginous embolism is a rarely recognised, but important cause of spinal cord infarction. Fibrocartilaginous embolisation usually occurs after minor trauma without major bony lesions, typically with an intervening symptom-free interval and progressive 'stroke-in-evolution' course. There is evidence that the embolus originates from the intervertebral disc, but the mechanism whereby disc fragments enter the spinal vessels is not well understood. We describe the evolution of MRI findings in a case of anterior spinal artery territory infarction thought to be secondary to fibrocartilaginous embolism.

Acute Disease↗
PubMed2001

Epidural hematoma from a cranial eosinophilic granuloma.

The formation of an epidural hematoma from an eosinophilic granuloma of the skull is an exceptional occurrence. A 9-year-old boy presented with severe headache, somnolence and vomiting following a minor head injury. Cranial computerized tomography scan showed a seemingly depressed skull fracture together with an epidural hematoma in evolution. A neoplasm and an epidural hematoma were removed at operation. Histopathological study of the excised mass confirmed the diagnosis of eosinophilic granuloma.

Bone Diseases↗
PubMed1993

Complementation of Escherichia coli unc mutant strains by chloroplast and cyanobacterial F1-ATPase subunits.

The genes encoding the five subunits of the F1 portion of the ATPases from both spinach chloroplasts and the cyanobacterium Synechocystis sp. PCC 6803 were cloned into expression vectors and expressed in Escherichia coli. The recombinant subunits formed inclusion bodies within the cells. Each particular subunit was expressed in the respective unc mutant, each unable to grow on non-fermentable carbon sources. The following subunits restored growth under conditions of oxidative phosphorylation: alpha (both sources, cyanobacterial subunit more than spinach subunit), beta (cyanobacterial subunit only), delta (both spinach and Synechocystis), and epsilon (both sources), whereas no growth was achieved with the gamma subunits from both sources. Despite a high degree of sequence homology the large subunits alpha and beta of spinach and cyanobacterial F1 were not as effective in the substitution of their E. coli counterparts. On the other hand, the two smallest subunits of the E. coli ATPase could be more effectively replaced by their cyanobacterial or chloroplast counterparts, although the sequence identity or even similarity is very low. We attribute these findings to the different roles of these subunits in F1: The large alpha and beta subunits contribute to the catalytic centers of the enzyme, a function rendering them very sensitive to even minor changes. For the smaller delta and epsilon subunits it was sufficient to maintain a certain tertiary structure during evolution, with little emphasis on the conservation of particular amino acids.

Amino Acid Sequence↗