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PubMed1992

A microtitre plate ELISA to measure thrombin-antithrombin complex using pan-specific antibodies.

A sandwich enzyme-linked immunosorbent assay (ELISA) has been developed to measure plasma levels of thrombin-antithrombin complex (TAT). The assay is performed in a microtitre plate using polyclonal antibodies specific for antigenic determinants on prothrombin and antithrombin. Antibody to prothrombin was immobilized on a solid phase, using a titre predetermined to optimize capture of TAT. The performance of the microtitre plate ELISA for TAT has been extensively investigated and compared with the performance characteristics of a tube-based ELISA for TAT which is available commercially (Enzygnost-TAT, from Behringwerke, Marburg, Germany). Studies with plasma containing various levels of prothrombin showed that the zymogen competed with TAT for capture antibody in both assays. Variations in prothrombin levels between plasma samples present a potential source of artifact, but one which does not critically affect the performance of either assay in detecting large elevations in TAT. A high correlation (r = 0.88) was established between the results of plasma samples assayed by both assays, whether citrate or EDTA anticoagulant was used to prepare plasma. High correlations (r > 0.90) were also established for each assay between the results of plasma prepared with EDTA as compared to citrate anticoagulant. Both assays were able to discriminate completely between a group of 16 normal controls and a group of 31 patients with disseminated intravascular coagulation (DIC).

Antibody Specificity↗
PubMed2005

A novel homologue of Human herpesvirus 6 in chimpanzees.

Among the Betaherpesvirinae, human cytomegalovirus is the only virus to possess simian homologues. Indeed, intriguingly, no close simian homologue of the roseoloviruses Human herpesvirus 6 (HHV-6) and Human herpesvirus 7 (HHV-7), the other two human members of the Betaherpesvirinae, has been identified to date. Here, the first simian homologue of HHV-6 is described, which was identified in common chimpanzees and designated PanHV6. By using a degenerate consensus PCR method, three different gene fragments were amplified, corresponding to the DNA polymerase (U38), beta-chemokine receptor (U12) and viral transactivator (U42) genes, with 94-96 % (nucleotide) and 95-97 % (amino acid) sequence identity to the corresponding genes of HHV-6B. Analysis of 77 predominantly wild-caught chimpanzees identified a unique PanHV6 strain in 21 animals, with no viral sequence variation between the different chimpanzee subspecies that were found to be infected. Characterization of this virus represents a great potential to gain a better understanding of the diseases associated with HHV-6.

Animals↗
PubMed2025

A paradoxical population structure of var DBLα types in Africa.

The var multigene family encodes Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1), central to host-parasite interactions. Genome structure studies have identified three major groups of var genes by specific upstream sequences (upsA, B, or C). Var with these ups groups have different chromosomal locations, transcriptional directions, and associations with disease severity. Here we explore temporal and spatial diversity of a region of var genes encoding the DBLα domain of PfEMP1 in Africa. By applying a novel ups classification algorithm (cUps) to publicly-available DBLα sequence datasets, we categorised DBLα according to association with the three ups groups, thereby avoiding the need to sequence complete genes. Data from deep sequencing of DBLα types in a local population in northern Ghana surveyed seven times from 2012 to 2017 found variants with rare-to-moderate-to-extreme frequencies, and the common variants were temporally stable in this local endemic area. Furthermore, we observed that every isolate repertoire, whether mono- or multiclonal, comprised DBLα types occurring with these frequency ranges implying a common genome structure. When comparing African countries of Ghana, Gabon, Malawi, and Uganda, we report that some DBLα types were consistently found at high frequencies in multiple African countries while others were common only at the country level. The implication of these local and pan-Africa population patterns is discussed in terms of advantage to the parasite with regards to within-host adaptation and resilience to malaria control.

Plasmodium falciparum↗
PubMed1994

Exploration of antigenic variation in gp120 from clades A through F of human immunodeficiency virus type 1 by using monoclonal antibodies.

The reactivities of a panel of 14 monoclonal antibodies (MAbs) with monomeric gp120 derived from 67 isolates of human immunodeficiency virus type 1 of clades A through F were assessed by using an antigen-capture enzyme-linked immunosorbent assay. The MAbs used were all raised against gp120 or gp120 peptides from clade B viruses and were directed at a range of epitopes relevant to human immunodeficiency virus type 1 neutralization: the V2 and V3 loops, discontinuous epitopes overlapping the CD4-binding site, and two other discontinuous epitopes. Four of the five V3 MAbs showed modest cross-reactivity within clade B but very limited reactivity with gp120s from other clades. These reactivity patterns are consistent with the known primary sequence requirements for the binding of these MAbs. One V3 human MAb (19b), however, was much more broadly reactive than the others, binding to 19 of 29 clade B and 10 of 12 clade E gp120s. The 19b epitope is confined to the flanks of the V3 loop, and these sequences are relatively conserved in clade B and E viruses. In contrast to the limited reactivity of V3 MAbs, CD4-binding site MAbs were much more broadly reactive across clades, two of these MAbs (205-46-9 and 21h) being virtually pan-reactive across clades A through F. Another human MAb (A-32) to a discontinuous epitope was also pan-reactive. The CD4-binding site is strongly conserved between clades; but when considering the epitopes near the CD4-binding site, clade D gp120 appears to be the most closely related to clade B and clade E appears to be the least related. A tentative rank order for these epitopes is B/D-A/C-E/F. V2 MAbs reacted sporadically within and between clades, and no clear pattern was observable. While results from binding assays do not predict neutralization serotypes, they suggest that there may be antigenic subtypes related, but not identical, to the genetic subtypes.

Amino Acid Sequence↗
PubMed2005

Conformity to cultural norms of tool use in chimpanzees.

Rich circumstantial evidence suggests that the extensive behavioural diversity recorded in wild great apes reflects a complexity of cultural variation unmatched by species other than our own. However, the capacity for cultural transmission assumed by this interpretation has remained difficult to test rigorously in the field, where the scope for controlled experimentation is limited. Here we show that experimentally introduced technologies will spread within different ape communities. Unobserved by group mates, we first trained a high-ranking female from each of two groups of captive chimpanzees to adopt one of two different tool-use techniques for obtaining food from the same 'Pan-pipe' apparatus, then re-introduced each female to her respective group. All but two of 32 chimpanzees mastered the new technique under the influence of their local expert, whereas none did so in a third population lacking an expert. Most chimpanzees adopted the method seeded in their group, and these traditions continued to diverge over time. A subset of chimpanzees that discovered the alternative method nevertheless went on to match the predominant approach of their companions, showing a conformity bias that is regarded as a hallmark of human culture.

Aging↗
PubMed1996

Construction and screening of M13 phage libraries displaying long random peptides.

We have constructed two phage display libraries expressing N-terminal pIII fusions in M13 composed of 37 and 43 random amino acid domains, respectively. The D38 library expresses 37 random amino acids with a central alanine residue, and the DC43 library contains 43 random amino acids with a central cysteine flanked by two glycine residues, giving the displayed peptide the potential to form disulfide loops of various sizes. We demonstrate that the majority of random sequences in both libraries are compatible in pentavalent display with phage viability. The M13 phage display vector itself has been engineered to contain a factor Xa protease cleavage site to provide an alternative to acid elution during affinity selection. An in-frame amber mutation has been inserted between the pIII cloning sites to allow for efficient selection against nonrecombinant phage in the library. These libraries have been panned against mAb 7E11-C5, which recognizes the prostate-specific membrane antigen (PSM). Isolated phage display a consensus sequence that is homologous to a region in the PSM molecule.

Amino Acid Sequence↗
PubMed2002

Expression of extracellular matrix components in a highly infiltrative in vivo glioma model.

This work demonstrates the expression of extracellular matrix (ECM) components in a highly infiltrative brain tumor model developed by simple inoculation of spheroids from five human glioma biopsy tissues directly into the brains of immunodeficient rats. Non-invasive tumors derived from one glioblastoma biopsy specimen and two glioma cell lines (D-54MG and U-251MG) were also included in this study. The extent of tumor cell infiltration was studied using a pan-human monoclonal anti-vimentin antibody. The cellular origin for several of these ECM components was identified using human-specific monoclonal antibodies and polyclonal antibodies detecting epitopes from both species. Immunostaining revealed a diffuse parenchymal staining of glioma-produced tenascin, whereas vitronectin was produced mainly by the invading glioma cells. ECM components such as laminin, fibronectin and collagen type IV were most probably produced by the host and were mainly associated with the blood vessels in the tumors. However, some parenchymal staining with regional variations was observed. The expression pattern of these components was different in cell lines tumors as compared to the biopsy specimen tumors. The alpha3 and beta1 integrin subunits were mainly observed in areas of tumor cell invasion in the invasive tumors. In conclusion, the observed staining patterns clarify the cellular origin and indicate the possible biological function of tenascin, vitronectin, laminin, fibronectin and collagen type IV in these highly invasive malignant tumors of glial origin.

Animals↗
PubMed2006

Demographic history and genetic differentiation in apes.

Comparisons of genetic variation between humans and great apes are hampered by the fact that we still know little about the demographics and evolutionary history of the latter species. In addition, characterizing ape genetic variation is important because they are threatened with extinction, and knowledge about genetic differentiation among groups may guide conservation efforts. We sequenced multiple intergenic autosomal regions totaling 22,400 base pairs (bp) in ten individuals each from western, central, and eastern chimpanzee groups and in nine bonobos, and 16,000 bp in ten Bornean and six Sumatran orangutans. These regions are analyzed together with homologous information from three human populations and gorillas. We find that whereas orangutans have the highest diversity, western chimpanzees have the lowest, and that the demographic histories of most groups differ drastically. Special attention should therefore be paid to sampling strategies and the statistics chosen when comparing levels of variation within and among groups. Finally, we find that the extent of genetic differentiation among "subspecies" of chimpanzees and orangutans is comparable to that seen among human populations, calling the validity of the "subspecies" concept in apes into question.

Animals↗
PubMedDate not supplied

Maternal correlates of growth in toddler vocabulary production in low-income families.

This study investigated predictors of growth in toddlers' vocabulary production between the ages of 1 and 3 years by analyzing mother-child communication in 108 low-income families. Individual growth modeling was used to describe patterns of growth in children's observed vocabulary production and predictors of initial status and between-person change. Results indicate large variation in growth across children. Observed variation was positively related to diversity of maternal lexical input and maternal language and literacy skills, and negatively related to maternal depression. Maternal talkativeness was not related to growth in children's vocabulary production in this sample. Implications of the examination of longitudinal data from this relatively large sample of low-income families are discussed.

Child, Preschool↗
PubMed2002

Craniodental variation among Macaques (Macaca), nonhuman primates.

BACKGROUND: In terms of structure and function, the skull is one of the most complicated organs in the body. It is also one of the most important parts in terms of developmental and evolutionary origins. This complexity makes it difficult to obtain evolutionary assessments if, as is usually the case with fossils, only part of the skull is available. For this reason this study involves a set of comparisons whereby the smallest functional units are studied first, and these built up, through a triple-nested hierarchical design, into more complex anatomical regions and eventually into the skull-as-a-whole. This design has been applied to macaques (Macaca) in order to reveal patterns of variation at the different levels. The profiles of such variation have been obtained both within and between species. This has lead to a search for the skull parts that have undergone similar selection pressures during evolution and comparable development patterns in both ontogeny and phylogeny. RESULTS: Morphometric analysis (Principal Components) was used to obtain these profiles of species and sex separations based on 77 cranial variables from 11 species of macaques. The results showed that 7 functional units could be aggregated into three functionally reasonable anatomical regions on the basis of similarities in profiles. These were: the masticatory apparatus containing mandible, lower teeth and upper teeth, the face as a whole combining maxilla (actually lower face) and upper face, and the cranium as a whole involving cranium and calvaria. Twenty-six variables were finally selected for analyzing the morphology of the whole skull. This last showed an overall profile similar to that revealed in the masticatory apparatus but also contained additional information pertaining to individual species and species-groups separations. CONCLUSIONS: The study provides a model for carrying out analysis of species separations and sex variation simultaneously. Through this design it seems possible to see cranio-dental elements that may result from similar developmental processes, have similar functional adaptations, and show an appropriately integrated structure morphologically. This study also implies that the biological information drawn from part of skull alone, e.g. as in studies of incomplete fossils may provide misleading information.

Animals↗
PubMed1992

Conservation of the HLA-DQB2 locus in nonhuman primates.

The evolutionary history of MHC class II genes is characterized by several examples of gene duplication, leading both to the creation of distinct subregions such as DR, DQ, and DP, as well as to duplicated loci within each of these subregions. In the human MHC, a prominent example of this diversification occurs within the HLA-DQ subregion, where the nonpolymorphic and transcriptionally "silent" DQB2 locus is highly homologous to the polymorphic expressed DQB1 locus. In order to gain some insight into the mechanisms constraining polymorphism at the DQB2 locus, the second exons of five nonhuman primate DQB2 alleles were sequenced. Six nonhuman primate DQB2 analogous sequences were obtained, two each from chimpanzee and owl monkey cell lines, and one each from gorilla and gibbon cell lines. Notably, the DQB2 sequences from the gibbon, gorilla, and one of the two chimpanzee sequences, although containing some silent nucleotide changes, encode a predicted DQB2 protein with 100% homology to the human DQB2 sequence. The owl monkey DQB2 allelic sequences and the other chimpanzee DQB2 sequence contain additional polymorphisms, but maintain approximately 95% nucleotide sequence identity with human and the other primate sequences. Identification of the owl monkey DQB2 locus indicates that the ancestral DQ gene duplication event occurred at least 40 million years ago, rather than 10 million years, as previously thought. Remarkably, nucleotide sequences from amplified cDNA indicate that the DQB2 gene, and not the DQB1 gene, may be transcribed in the owl monkey line. Substitutions occur at sites comparable to codons of well-recognized allelic variation in the functional DQB1 genes, implying that variation within the DQB2 locus operates under similar selection constraints to the DQB1 locus, with an extremely high degree of conservation through primate evolution.

Animals↗
PubMed1995

Aggravation of laser-treated diabetic cystoid macular edema after prolonged flight: a case report.

A 62-year-old diabetic woman with pan-retinal laser treatment for non-proliferative, bilateral diabetic retinopathy and cystoid macular edema (CME) demonstrated an acute exacerbation of CME after 42 h of prolonged flight in commercial pressurized aircraft. When travelling by air, vital sensory functions of the human body are affected by a variety of disturbing factors. The most important of these--altitude-related oxygen deficiency--is compensated for by homeostatic mechanisms in healthy subjects. However, even with normal oxygen tension, the diabetic retina is hypoxic because the vascular response to oxygen variation is altered. Increased tissue demand for oxygen, owing to decreased ability of the circulating blood to release oxygen, cannot be met. In our patient, the aggravated CME appeared to result from hemodynamic changes induced by flight. In particular, the prolonged environmental oxygen deficiency may have exacerbated the retinal hypoxia leading to acute, vascular decompensation and dramatic plasma leakage with visual loss.

Aerospace Medicine↗
PubMed1993

Role of the mandibular first molar in the development of the supraorbital region in apes and humans.

Our previous studies in apes and humans have demonstrated that the development of the supraorbital ridge is a direct consequence of masticatory forces. The smaller the power arm/load arm ratio of the mandible, the greater the force exerted by the temporalis muscle and the larger the supraorbital ridge. The purpose of the present study is to further elucidate the role of the masticatory apparatus, in particular the role of the first mandibular molar. Measurements of the size of the supraorbital ridges in ape skulls and in human skulls from Tuscany, Italy and St. Lawrence Island, Alaska, were determined using parasagittal CAT scans as in our previous studies. For the purpose of this study, the mesio-distal and buccolingual dimensions of the first molar were measured from the actual tooth in all cases. Statistical analysis shows a positive correlation between the mesio-distal dimension of the mandibular first molar and the size of the ridge in humans (r = 0.61, p < 0.005) and in apes (r = 0.79, p < 0.01), which explains much of the variation in the size of the supraorbital ridge, 37% (0.61(2)) in humans and 62% (0.79(2)) in apes. The role of the mandibular first molar differs in humans versus apes because of differences in masticatory mechanics.

Adult↗
PubMed1999

Immediate and follow-up findings after stent treatment for severe coarctation of aorta.

Experimental studies have shown that stents implanted at the aorta become incorporated within the aortic wall and can be further expanded in growing animals. Few clinical studies have shown that the stent repair of severe coarctation of aorta provides excellent initial results, and little is known on the follow-up of these patients. We assessed the immediate and follow-up results obtained in a series of 48 patients (mean age 14+/-12 years) with severe coarctation of the aorta who were treated by Palmaz stent implantation; 30 of them (63%) underwent angiographic follow-up studies at a mean of 25+/-11 months after treatment. Quantitative serial analysis of the aortogram (baseline, after treatment, and at follow-up) was performed. Significant relief (mean residual gradient 3+/-4 mm Hg) was always obtained after stent implantation. The isthmus, when hypoplastic (60%), was always expanded with the stent. One associated aneurysm became occluded after the implant. Complications included aortic disruption, stent migration, and decreased or absent femoral pulses. At angiographic follow-up, the stent remained always in place, without recoil. In 22 patients (73%), there were no detectable neointimal proliferation at late angiogram; however, 8 patients (27%) had some degree of intimal thickening (1 to 5 mm), causing mild restenosis in 3 patients treated at early age, and nonsignificant lumen reduction in 5. The serial aortogram analysis revealed a minor but significant increase in nonstented aortic diameters that seemed related to the normal growth of children. No need for stent reexpansion was observed at 2-year follow-up (mean). Two patients (7%) developed late small aneurysm formation at the stented wall; both were occluded by the insertion of coils through the stent orifices. We conclude that stent treatment for severe coarctation of aorta provides excellent immediate and long-term results in young adults and children. However, at early age, restenosis by intimal growth may develop.

Adolescent↗
PubMed1999

Air-pollutant dispersal patterns and vegetation damage in the vicinity of three aluminium smelters in Norway.

Dispersal patterns for fluoride and damage to vegetation was studied near three aluminium smelters in Norway. Leaf samples from three broad-leaved species (Betula pubescens Ehrh., Salix caprea L. and Sorbus aucuparia L.) were collected and leaf injury and the plants overall vitality were evaluated systematically in areas with different distance and direction from the emission sources. Both dispersal patterns and the distribution of damages were mainly determined by the predominant wind direction in the growing season and partly by topography. Damage was restricted to the areas closest to the smelters, within 2 km from the emission sources. Even with the average F- emission as low as 7.1 kg h-1, serious damage to vegetation was observed in built-up areas within 1 km south of the smelter in Mosjøen. Regression analysis showed a correlation between leaf injury and fluoride content in leaves within a locality, but great variation between localities. Leaf injury appeared at concentrations as low as 30 mg kg-1 in some species. An average leaf injury of 1 (scale 0-9) appeared at approximately 100 mg kg-1 in the vicinity of the northernmost smelter, Mosjøen, compared to approximately 150 and 300 mg kg-1 at Husnes and Ovre Ardal, respectively. Fluoride uptake and leaf injury differed among species. Approximately 100 species, mostly woody plants were evaluated for leaf injury and overall vitality. Conifers such as Pinus sylvestris L. and Picea omorika (Pan_) Purk. were sensitive. Except for Populus tremula L., most broad-leaved indigenous species were less sensitive. Species composition in natural areas as well as vegetation use in gardens were affected by pollution. In old gardens at the polluted site Ovre Ardal both the number of plant species and the area used for edible plants was lower compared to old gardens in an unpolluted nearby community. In newer gardens the use of both ornamentals and edible plants was more similar.

Air Pollutants↗
PubMedDate not supplied

The molecular clock runs more slowly in man than in apes and monkeys.

The molecular clock hypothesis postulates that the rate of molecular evolution is approximately constant over time. Although this hypothesis has been highly controversial in the past, it is now widely accepted. The assumption of rate constancy has often been taken as a basis for reconstructing the phylogenetic relationships among organisms or genes and for dating evolutionary events. Further, it has been taken as strong support for the neutral mutation hypothesis, which postulates that the majority of molecular changes in evolution are due to neutral or nearly neutral mutations. For these reasons, the validity of the rate constancy assumption is a vital issue in molecular evolution. Recent studies using DNA sequence data have raised serious doubts about the hypothesis. These studies provided support for the suggestion made from immunological distance and protein sequence data that a rate slowdown has occurred in hominoid evolution, and showed, in agreement with DNA hybridization studies, that rates of nucleotide substitution are significantly higher in rodents than in man. Here, rates of nucleotide substitution in rodents are estimated to be 4-10 times higher than those in higher primates and 2-4 times higher than those in artiodactyls. Further, this study provides strong evidence for the hominoid slowdown hypothesis and suggests a further rate-slowdown in hominoid evolution. Our results suggest that the variation in rate among mammals is primarily due to differences in generation time rather than changes in DNA repair mechanisms. We also propose a method for estimating the divergence times between species when the rate constancy assumption is violated.

Animals↗
PubMed2005

Functionally relevant protein motions: extracting basin-specific collective coordinates from molecular dynamics trajectories.

Functionally relevant motion of proteins has been associated with a number of atoms moving in a concerted fashion along so-called "collective coordinates." We present an approach to extract collective coordinates from conformations obtained from molecular dynamics simulations. The power of this technique for differentiating local structural fluctuations between classes of conformers obtained by clustering is illustrated by analyzing nanosecond-long trajectories for the response regulator protein Spo0F of Bacillus subtilis, generated both in vacuo and using an implicit-solvent representation. Conformational clustering is performed using automated histogram filtering of the inter-C(alpha) distances. Orthogonal (varimax) rotation of the vectors obtained by principal component analysis of these interresidue distances for the members of individual clusters is key to the interpretation of collective coordinates dominating each conformational class. The rotated loadings plots isolate significant variation in interresidue distances, and these are associated with entire mobile secondary structure elements. From this we infer concerted motions of these structural elements. For the Spo0F simulations employing an implicit-solvent representation, collective coordinates obtained in this fashion are consistent with the location of the protein's known active sites and experimentally determined mobile regions.

Amino Acid Sequence↗
PubMed1992

Cost-benefit analysis of a regional system for vaccination against pneumonia, meningitis type B, and typhoid fever.

In early 1989 PAHO began examining a proposal for a regional program that would develop and disseminate vaccines of particular interest to its Member Countries. As part of that examination, a cost-benefit analysis was performed. That general analysis, presented here, sought to point up key factors that would strongly influence whether or not the program's benefits outweighed its costs. The program's two fundamental components, vaccine development and vaccine administration, were evaluated separately. Using a discount rate (r) of 10%, 10-year vaccine development costs were estimated at US$80.3 million in constant dollars. It was felt that enough people (at least 19.5 million a year) would be vaccinated so that the program would benefit from economics of scale. The total discounted number of vaccinations administered over a 20-year period was expected to be in the range of 400 to 506 million. Using these figures, estimates were made of the maximum that could be spent on vaccine administration without exceeding anticipated benefits. Considering only treatment costs saved through vaccination, assuming all sick people were treated, the ceiling cost for vaccinating one person against one target disease would be in the range of US$0.52-0.58. Even if not all the sick were treated, however, the Regional Vaccine System (SIREVA) would still appear justified if the benefits per disease case prevented were found to average between US$1,000 and US$2,000. Even so, it should be noted that these estimates are subject to a good deal of additional variation because of uncertainties regarding the worth of many elements evaluated--including the costs of lost work time, disability, and mortality--and because some of the elements involved--such as pain, suffering, and death--fall outside the purely economic realm.

Cost Savings↗